Listing of Recent AOML Publications

**In Press**

Enfield, D.B. Evolution and historical perspective of the 1997-1998 El Niño-Southern Oscillation event. Bulletin of Marine Science (in press).

The ocean thermal history of the 1997-98 El Niño episode is described in detail, with emphasis on developments along the equator and eastern Pacific coastlines. The temporal evolution of the warming and its causes are traced from the western Pacific, past the Galapagos Islands, and on to the subpolar gyres off North and South America. Along the equator, the event was characterized by a subsurface warm anomaly that slowly made its way from west to east across the Pacific from mid-1996 until early 1997, whence it triggered the onset of surface anomalies at the eastern terminus of the equatorial waveguide. The thermocline depression off Ecuador intensified from mid-1997 through the end of the year, culminating in a mature phase with maximum sea surface temperature anomalies (SSTA) around November-December 1997. The event gradually abated thereafter until the beginning of the subsequent cool phase (La Niña) was detected in July 1998. Following their arrivals at the eastern boundary, equatorial Kelvin waves proceeded poleward into both hemispheres as coastal trapped waves, carrying the thermocline depression signal with them along with associated nutrient deficiencies and ecosystem impacts. The poleward propagation of SSTA was more uniform and faster south of the equator, reaching south-central Chile with amplitudes of 2°C or greater. North of the equator the propagation was discontinuous, with decreased anomalies south of 20°N and a revival of SSTA in excess of 2°C, north of there, but with considerably larger time lags than observed off Chile. The possible reasons for these interhemispheric differences are discussed.

Wang, C. On the ENSO mechanisms. Advances in Atmospheric Science (in press).

The El Niño-Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific Ocean-atmosphere interactions. The oscillatory nature of ENSO requires both positive and negative ocean-atmosphere feedbacks. The positive feedback is dated back to Bjerknes' hypothesis in the 1960s, and different negative feedbacks have been proposed since the 1980s associated with the delayed oscillator, the western Pacific oscillator, the recharge-discharge oscillator, and the advective-reflective oscillator. The delayed oscillator assumes that wave reflection at the western boundary provides a negative feedback for the coupled system to oscillate. The western Pacific oscillator emphasizes equatorial wind in the western Pacific that provides a negative feedback for the coupled system. The recharge-discharge oscillator argues that discharge and recharge of equatorial heat content causes the coupled system to oscillate. The advective-reflective oscillator emphasizes the importance of zonal advection associated with wave reflection at both the western and eastern boundaries. All of these physics are summarized in a unified ENSO oscillator. The delayed oscillator, the western Pacific oscillator, the recharge-discharge oscillator, and the advective-reflective oscillator can be extracted as special cases of the unified oscillator. As suggested by this unified oscillator, all of the previous ENSO oscillator mechanisms may be operating in nature.

Wang, C., and R.H. Weisberg. Ocean circulation influences on SST in the equatorial cental Pacific. Journal of Geophysical Research (in press).

Velocity data from an array of acoustic Doppler current profilers moored about 0, 140°W from May 1990 through June 1991 during the Tropical Instability Wave Experiment are used in conjunction with Tropical Atmosphere Ocean array data and a blended sea surface temperature (SST) product to study the processes that control SST variations. The horizontal velocity data allow us to calculate the vertical velocity component by vertically integrating the continuity equation. Given the three-dimensional temperature flux divergence, we examine the role of the ocean circulation on SST. Upwelling and downwelling are found to be associated with cooling and warming, respectively, suggesting that a vertical velocity component of either sign affects SST. Both the temperature flux divergence and advective formulations for the ocean circulations influence in the temperature budget show times when the ocean circulation appears to provide the primary control on SST and times when this is not the case, with the flux divergence formulation performing better than the advective formulation. Statistically, within a bandwidth encompassing the tropical instability waves and the intraseasonal variations, roughly half of the SST variation is accounted for by the ocean circulation. These results are encouraging, given that data sets with different spatial and temporal scales have been used. They suggest that future field experimentation which utilizes a flux divergence array with velocity and temperature data sampled at the same spatial and temporal scales will yield quantitatively improved results. The analyses also show that the ocean circulation on average provides a cooling effect requiring the net surface heat flux to be positive on average to maintain the mean background state. The cooling effect is mainly controlled by mean ocean circulation and temperature fields. **2001**

Daly, K.L., W.O. Smith, G.C. Johnson, G.R. DiTullio, D.R. Jones, C.W. Mordy, R.A. Feely, D.A. Hansell, and J.-Z. Zhang. Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean: Implications for carbon flux. Journal of Geophysical Research, 106(C4):7107-7124 (2001).

We investigated the hydrography, nutrients, and dissolved and particulate carbon pools in the western Pacific sector of the Antarctic Circumpolar Current (ACC) during austral summer 1996 to assess the region's role in the carbon cycle. Low fCO₂ values along two transects indicated that much of the study area was a sink for atmospheric CO₂. The fCO₂ values were lowest near the Polar Front (PF) and the Subtropical Front (STF), concomitant with maxima of chlorophyll a and particulate and dissolved organic carbon. The largest biomass accumulations did not occur at fronts, which had high surface geostrophic velocities (20-51 cm s^-1), but in relatively low velocity regions near fronts or in an eddy. Thus, vertical motion and horizontal advection associated with fronts may have replenished nutrients in surface waters but also dispersed phytoplankton. Although surface waters north of the PF have been characterized as a "high nutrient-low chlorophyll" region, low silicic acid (Si) concentrations (2-4 µM) may limit production of large diatoms and therefore the potential carbon flux. Low concentrations (4-10 µM Si) at depths of winter mixing constrain the level of Si replenishment to surface waters. It has been suggested that an increase in aeolian iron north of the PF may increase primary productivity and carbon export. Our results, however, indicate that while diatom growth and carbon export may be enhanced, the extent ultimately would be limited by the vertical supply of Si. South of the PF, the primary mechanism by which carbon is exported to deep water appears to be through diatom flux. We suggest that north of the PF, particulate and dissolved carbon may be exported primarily to intermediate depths through subduction and diapycnal mixing associated with Subantarctic Mode Water and Antarctic Intermediate Water formation. These physical-biological interactions and Si dynamics should be included in future biogeochemical models to provide a more accurate prediction of carbon flux.

Enfield, D.B., and A.M. Mestas-Nunez. Interannual to multidecadal climate variability and its relationship to global sea surface temperatures. In: Interhemispheric Climate Linkages, V. Markgraf (ed.). Academic Press, 17-29 (ISBN 0124726704) (2001).

As a benchmark to help profile paleoclimates across the Americas we develop an overview of what is known of modern climate variability on a planetary scale, with emphasis on climate manifestations in the Western Hemisphere. From instrumental observations taken as early as the mid-19th century, we look at both atmospheric and oceanic variables and consider their relationships on timescales ranging from interannual to multidecadal. We focus on three of the most important climate modes: the interannual El Niño-Southern Oscillation (ENSO), the interdecadal Pacific Decadal Oscillation (PDO), and the multidecadal North Atlantic Oscillation (NAO). The variable of greatest interest is sea surface temperature (SST) because it is arguably the least understood of the atmospheric boundary conditions for prehistoric climates and yet one of the most critical for effecting atmospheric model simulations of those climates. The analysis begins by computing a global distribution of the trend in SST, which turns out to be highly non-uniform, with characteristics that may reflect low-frequency changes in shallow water mass formation. We then compute a global, canonical mode for ENSO that preserves the amplitude and phase structures of interannual ENSO variability worldwide. The ranking of the modal amplitudes of ENSO events differs from the absolute amplitudes obtained by indexing SST data directly. This reflects the importance of the (non-ENSO) decadal-multidecadal climate modes in modifying the intensity of ENSO-related ocean warmings. Comparing the global mode between the ends of the 19th and 20th centuries, we see essentially no difference in amplitudes and frequency of ENSO on the global warming timescale, although such changes have occurred on shorter, multidecadal timescales. Upon removal of the global ENSO mode from the data, the residual variability is subjected to two different analyses that extract very similar spatio-temporal patterns of SST for the PDO- and NAO-like climate modes. The climate variations with longer timescales (PDO, NAO) together account for about the same amount of variance as ENSO, globally, and in some regions, e.g., the northeastern North Pacific, may rival ENSO in their climate and marine impacts. The NAO, in particular, involves an Atlantic-Pacific connection that may arise through fluctuations in the polar vortex, an aspect which may also characterize previous climates. In our discussion, we speculate on what might be learned from the instrumental record regarding possible characteristics of ancient climates, especially regarding the possibility that ENSO may have been considerably different or even absent in the mid-Holocene.

Enfield, D.B., A.M. Mestas-Nunez, and P.J. Trimble. The Atlantic multidecadal oscillation and its relation to rainfall and river flows in the continental U.S. Geophysical Research Letters, 28(10):2077-2080 (2001).

North Atlantic sea surface temperatures for 1856-1999 contain a 65-80 year cycle with a 0.4°C range, referred to as the Atlantic Multidecadal Oscillation (AMO) by Kerr (2000). AMO warm phases occurred during 1860-1880 and 1940-1960, and cool phases during 1905-1925 and 1970-1990. The signal is global in scope, with a positively correlated co-oscillation in parts of the North Pacific, but it is most intense in the North Atlantic and covers the entire basin there. During AMO warmings most of the United States sees less than normal rainfall, including Midwest droughts in the 1930s and 1950s. Between AMO warm and cool phases, Mississippi River outflow varies by 10% while the inflow to Lake Okeechobee, Florida varies by 40%. The geographical pattern of variability is influenced mainly by changes in summer rainfall. The winter patterns of interannual rainfall variability associated with El Niño-Southern Oscillation are also significantly changed between AMO phases.

Goldenberg, S.B., C.W. Landsea, A.M. Mestas-Nunez, and W.M. Gray. The recent increase in Atlantic hurricane activity. Causes and implications. Science, 293:474-479 (2001).

The years 1995 to 2000 experienced the highest level of North Atlantic hurricane activity in the reliable record. Compared with the generally low activity of the previous 24 years (1971 to 1994), the last six years have seen a doubling of overall activity for the whole basin, a 2.5-fold increase in major hurricanes (>50 m/s), and a fivefold increase in hurricanes affecting the Caribbean. The greater activity is caused by simultaneous increases in North Atlantic sea-surface temperatures and decreases in vertical wind shear, both of which are known to favor hurricane formation. Because these changes exhibit a multidecadal time scale, the present high level of hurricane activity is likely to persist for an additional 10 to 40 years. The shift in climate calls for a reevaluation of preparedness and mitigation strategies.

Goni, G.J., and W.E. Johns. A census of North Brazil Current rings observed from TOPEX/POSEIDON altimetry: 1992-1998. Geophysical Research Letters, 28(1):1-4 (2001).

Six years of TOPEX/POSEIDON altimeter data are used to investigate the formation of rings and eddies shed by the North Brazil Current. Upper layer thickness maps were used to identify 34 of these features formed in the North Brazil Current retroflection region, an average of more than five rings and eddies per year. The ensemble of ring trajectories closely parallels the 500 m isobath, and one out of six rings penetrate into the Caribbean Sea through the southern Lesser Antilles. The rest of the rings and eddies follow a northern trajectory past Barbados once they reach 58°W. Their estimated mean translation speed is 14 km/day and their mean length scale is approximately 100 km. Our results suggest that the formation rate of NBC rings and eddies is nearly twice that previously thought, and that they may account for more than one-third of the interhemispheric transport within the Atlantic meridional overturning cell.

Hood, E.M., R.H. Wanninkhof, and L. Merlivat. Short time scale variations of fCO₂ in a North Atlantic warm-core eddy: Results from the GASEX-98 carbon interface ocean atmosphere (CARIOCA) buoy data. Journal of Geophysical Research, 106(C2):2561-2572 (2001).

During a Lagrangian deliberate tracer study in the North Atlantic, the 1998 Gas Exchange Experiment, hourly measurements of wind speed, sea surface temperature, fCO₂, and fluorescence were made from two carbon interface ocean atmosphere (CARIOCA) drifting buoys in a warm-core eddy near 46°N and 21.5°W over a period of approximately 20 days. Shipboard measurements of fCO₂ near the buoys were used to verify the buoy operation, calibrate the buoy measurements, and assess the performance of the fCO₂ sensor. The strong air-sea fCO₂ gradient in the eddy and intense atmospheric forcing during the experiment provided ideal conditions for demonstrating the potential of autonomous drift buoy measurements for studies of surface ocean biogeochemistry, where changes of fCO₂ were rapid and large. During the experiment, a storm occurred with wind speeds reaching as high as 16-17 m s^-1, leading to a sharp decrease in sea surface temperature and an increase in fCO₂ of ~30 µatm. The magnitude of this sudden change in fCO₂ is equal to approximately half of the annual range of fCO₂ in this area. The air-sea flux estimate for the ~20 day experiment using the Wanninkhof (1992) gas transfer velocity formulation was -0.012 mol m^-2 d^-1 and using the Liss and Merlivat (1986) formulation was -0.007 mol m^-2 d^-1. The storm event, lasting three to four days, accounted for ~38% of the flux over this period. Approximately 16 hours after the onset of the storm, there was an increase in surface fluorescence coincident with the initial increase in fCO₂. Nitrate measurements made from the ship in the eddy show a sharp peak in surface concentrations ~24 hours after the increase in winds and ~6-8 hours after the increase in surface fluorescence. After the upwelling of the NO₃ the fluorescence increases more sharply while the fCO₂ decreases, consistent with biological productivity. The surface fluorescence measurements remain higher than prestorm conditions for ~5 days after the NO₃ has disappeared.

Kaplan, J., and M. DeMaria. On the decay of tropical winds after landfall in the New England area. Journal of Applied Meteorology, 40(2):280-286 (2001).

A version of the Kaplan and DeMaria empirical model for predicting the decay of tropical cyclone 1-min maximum sustained surface winds after landfall is developed for the New England region. The original model was developed from the National Hurricane Center (NHC) best-track wind estimates for storms that made landfall in the United States south of 37°N from 1967 to 1993. In this note, a similar model is developed for U.S. storms north of 37°N, which primarily made landfall in New York or Rhode Island and then moved across New England. Because of the less frequent occurrence of New England tropical cyclones, it was necessary to include cases back to 1938 to obtain a reasonable sample size. In addition, because of the faster translational speed and the fairly rapid extratropical transition of the higher-latitude cases, it was necessary to estimate the wind speeds at 2-h intervals after landfall, rather than every 6 h, as in the NHC best track. For the model development, the estimates of the maximum sustained surface winds of nine landfalling storms (seven hurricanes and two tropical storms) at 2-h intervals were determined by an analysis of all available surface data. The wind observations were adjusted to account for variations in anemometer heights, averaging times, and exposures. Results show that the winds in the northern model decayed more (less) rapidly than those of the southern model, when the winds just after landfall are greater (less) than 33 knots. It is hypothesized that this faster rate of decay is due to the higher terrain near the coast for the northern sample and to the more hostile environmental conditions (e.g., higher vertical wind shear). The slower decay rate when the winds fall below 33 knots in the northern model might be due to the availability of a baroclinic energy source as the storms undergo extratropical transition.

Katsaros, K.B., E.B. Forde, P. Chang, W.T. Liu. QuikSCAT facilitates early identification of tropical depressions in 1999 hurricane season. Geophysical Research Letters, 28(6):1043-1046 (2001).

Far from land and surface ship observations, most tropical depressions are identified by examining images from geostationary satellites for the presence of rotation of the convective cloud masses. During the 1999 hurricane season, surface wind maps obtained by the SeaWinds scatterometer for the tropical Atlantic and Caribbean Sea were examined to test the hypotheses that tropical depressions (TDs) could be observed with this satellite sensor, before identification by the traditional means. SeaWinds was able to detect the presence of tropical depressions by early observations of a closed circulation in the surface winds. The satellite's unprecedented large swath width of 1800 km allows twice a day observation of most of the tropical oceans.

Katzberg, S.J., R.A. Walker, J.H. Roles, T. Lynch, and P.G. Black. First GPS signals reflected from the interior of a tropical storm: Preliminary reults from Hurricane Michael. Geophysical Research Letters, 28(10):1981-1984 (2001).

Using GPS signals reflected from the ocean surface is developing into a simple technique for measuring sea-state and inferring surface wind speeds. Theoretical models have been developed which are considered valid to approximately 24 meters per second. The GPS reflection technique has an obvious extension to extremely high sea states, cyclones, and extra-tropical storms. In October 2000, a GPS system mounted in a NOAA Hurricane Hunter research aircraft was flown into Hurricane Michael off the South Carolina coast. The first acquisition of GPS signals reflected from the sea surface inside tropical cyclones was accomplished. This paper presents some examples of the data sets, as well as early wind speed retrieval results using direct extensions of current models. Data from the GPS wind speed retrievals, as well as from direct aircraft measurements, are compared and discussed.

Liu, W.T., and K.B. Katsaros. Air-sea fluxes from satellite data. In Ocean Circulation and Climate: Observing and Modeling the Global Ocean, G. Siedler, J. Church, and J. Gould (eds.). Academic Press, 173-180 (2001).

No abstract.

Mestas-Nunez, A.M., and D.B. Enfield. Eastern equatorial Pacific SST variability: ENSO and non-ENSO components and their climatic associations. Journal of Climate, 14(3):391-402 (2001).

Using an updated Kaplan et al. global SST anomaly (SSTA) dataset (1870-1999), we construct a canonical representation of El Niño-Southern Oscillation (ENSO). When this canonical ENSO is subtracted from the data, we are left with a residual (non-ENSO) dataset for SSTA that includes inter-seasonal to multi-decadal variability. Over the eastern equatorial Pacific (NINO3) the canonical ENSO accounts for about 79% of the total SSTA variability, while the residual, dominated by decadal time scales, accounts for the rest. In particular, about 40-50% of the amplitudes of the strong 1982-83 and 1997-98 El Niño events were accounted for by the residual variability. The non-ENSO variability is characterized by the known shift from cold to warm eastern tropical Pacific in the mid-late 1970s as well as by a non-stationary interannual variance increase during the 1980s and 1990s. Composite maps of surface (SST, sea level pressure and winds) and tropospheric (divergent winds, velocity potential, and vertical velocity) variables are used to compare the spatial patterns characterizing the canonical ENSO and the residual components of the NINO3 variability. We find that the residual composites only share large amplitude fluctuations of SST anomalies in the equatorial Pacific east of the dateline. When these composites are separated into decadal and interannual components, the decadal part resembles closely the structure of the Pacific Decadal Oscillation (PDO). The major patterns of tropospheric variability associated with the ENSO and decadal non-ENSO components are quite different. At low latitudes, they imply nearly opposite impacts on far-field regional climates, based on their respective warming (or cooling) phases within the NINO3 region. This unexpected result for low latitude climate associations runs contrary to the naive expectation (recently shown to be true for North America) that a decadally warm tropical east Pacific will reinforce the climate effects associated with ENSO alone. This indicates that in the tropics climate outlooks may be more accurate if based on separately analyzed relationships between these SSTA components and their associated climate fluctuations.

Mestas-Nunez, A.M., D.B. Chelton, and D.B. Enfield. North Pacific circulation variability from TOPEX/POSEIDON sea level observations. Proceedings, 5th Pacific Ocean Remote Sensing Conference (PORSEC), Goa, India, December 5-8, 2000. National Institute of Oceanography, 1:263-267 (2001).

We analyze seven years (October 1992-October 1999) of sea level observations from the TOPEX/POSEIDON (T/P) satellite altimeter data to investigate the large-scale ocean circulation variability of the North Pacific from seasonal to interannual time scales. We focus in the mid-latitude western regions and use the T/P observations to estimate the barotropic volume transport variability of the Kuroshio, Oyashio, and Kuroshio Extension currents. We base our transport variability estimates on altimetric sea level differences, and our results agree well with simple wind-driven Sverdrup theory and with a global numerical ocean model simulation.

Millero, F.J., W.T. Hiscock, F. Huang, M. Roche, and J.-Z. Zhang. Seasonal variation of the carbonate system in Florida Bay. Bulletin of Marine Science, 68(1):101-123 (2001).

The carbonate system has been studied in the Florida Bay from 1997 to 2000. Measurements of pH, total alkalinity (TA), and total inorganic carbon dioxide (TCO₂) were made from 20 stations in the Bay and used to calculate the partial pressure of carbon dioxide (pCO₂) and the saturation states of aragonite (OMEGA_Arg) and calcite (OMEGA_Cal). The results were found to correlate with the salinity. The pH was low and the pCO₂ was high for the freshwater input from the mangrove fringe due to the photochemical and biological oxidation of organic material. The TA and TCO₂ for the freshwater input are higher than seawater due to the low values of pH and OMEGA. The pH was high and the pCO₂ was low in November in regions where the chlorophyll is high due to biological production. During the summer when the salinity is the highest, the normalized values of TA and TCO₂ were lower than average seawater, due to the inorganic precipitation of CaCO₃ caused by the resuspension of sediments or the biological loss by macroalgae. A transect across the mangrove fringe near the outflow of Taylor Slough shows that PO₄ and TA increases as the freshwater enters the Bay. This is thought to be due to the dissolution of CaCO₃ in the low pH waters from the bacterial and photo oxidation of plant material.

Millero, F.J., F. Huang, X. Zhu, X. Liu, and J.-Z. Zhang. Adsorption and desorption of phosphate on the calcite and aragonite in seawater. Aquatic Geochemistry, 7(1):33-56 (2001).

The adsorption and desorption of phosphate on calcite and aragonite were investigated as a function of temperature (5-45°C) and salinity (0-40) in seawater pre-equilibrated with CaCO₃. An increase in temperature increased the equilibrium adsorption; whereas an increase in salinity decreased the adsorption. Adsorption measurements made in NaCl were lower than the results in seawater. The higher values in seawater were due to the presence of Mg²⁺ and Ca²⁺ ions. The increase was five times greater for Ca²⁺ than Mg²⁺. The effects of Ca²⁺ and Mg²⁺ are diminished with the addition of SO₄^2-, apparently due to the formation of MgSO₄ and CaSO₄ complexes in solution and/or SO₄^2- adsorption on the surface of CaCO₃. The adsorbed Ca²⁺ and Mg²⁺ on CaCO₃ (at carbonate sites) may act as bridges to PO₄^3- ions. The bridging effect of Ca²⁺ is greater than Mg²⁺, apparently due to the stronger interactions of Ca²⁺ with PO₄^3-. The apparent effect of salinity on the adsorption of PO₄ was largely due to changes in the concentration of HCO₃^- in the solutions. An increase in the concentration of HCO₃^- caused the adsorption of phosphate to decrease, especially at low salinities. The adsorption at the same level of HCO₃^- (2 mM) was nearly independent of salinity. All of the adsorption measurements were modeled empirically using a Langmuir-type adsorption isotherm [[PO₄]_ad = K_m C_m [PO₄]_T /(1 + K_m [PO₄]_T)], where [PO₄]_ad and [PO₄]_T are the adsorbed and total dissolved phosphate concentrations, respectively. The values of C_m (the maximum monolayer adsorption capacity, mol/g) and K_m (the adsorption equilibrium constant, g/(mol)) over the entire temperature (t, °C) and salinity (S) range were fitted to [C_m = 17.067 + 0.1707t - 0.4693S + 0.0082S² (sigma = 0.7)] [ln K_m = -2.412 + 0.0165t - 0.0004St - 0.0008S² (sigma = 0.1)]. These empirical equations reproduce all of our measurements of [PO₄]_ad up to 14 µmol/g and within ±0.7 µmol/g. The kinetic data showed that the phosphate uptake on carbonate minerals appears to be a multi-step process. Both the adsorption and desorption were quite fast in the first stage (less than 30 min) followed by a much slower process (lasting more than one week). Our results indicate that within 24 hours aragonite has a higher sorption capacity than calcite. The differences between calcite and aragonite become smaller with time. Consequently, the mineral composition of the sediments may affect the short-term phosphate adsorption and desorption on calcium carbonate. Up to 80% of the adsorbed phosphate is released from calcium carbonate over one day. The amount of PO₄ left on the CaCO₃ is close to the equilibrium adsorption. The release of PO₄ from calcite is faster than from aragonite. Measurements with Florida Bay sediments produced results between those for calcite and aragonite. Our results indicate that the calcium carbonate can be both a sink and source of phosphate in natural waters.

Morisseau-Leroy, N., M.K. Solomon, and G.P. Momplaisir. Oracle 9i SQLI Programming. Osborne McGraw-Hill, 608 pp. (ISBN 0072190930) (2001).

No abstract.

Rogers, R.F., and J.M. Fritsch. Surface cyclogenesis from convectively-driven amplification of mid-level mesoscale convective vortices. Monthly Weather Review, 129(4):605-637 (2001).

Mesoscale convective vortices (MCVs) are mid-tropospheric warm-core cyclonic circulations that often develop in the stratiform region of mesoscale convective systems. Typically, divergent, anticyclonically-circulating, mesoscale cold anomalies appear both above and below the MCV. The upper level cold anomaly is usually found near the tropopause while the low-level anomaly is surface-based and exhibits locally higher pressure. One aspect of MCVs that has received much attention recently is the role that they may play in tropical cyclogenesis. Of special interest is how an MCV amplifies when deep convection redevelops within the borders of its mid-level cyclonic circulation and how the amplified MCV transforms the divergent surface-based cold pool with anomalously high surface pressure into a convergent cyclonic circulation with anomalously low pressure. The Pennsylvania State University/National Center for Atmospheric Research mesoscale model MM5 is used to simulate an MCV that was instrumental in initiating, within the borders of the mid-level vortex's circulation, several successive cycles of convective development and decay over a two-day period. After each cycle of convection, both the horizontal size of the cyclonic circulation and the magnitude of the potential vorticity associated with the vortex were observed to increase. The simulation reproduces the development and evolution of the MCV and associated convective cycles. Mesoscale features responsible for the initiation of convection within the circulation of the vortex and the impact of this convection on the structure and evolution of the vortex are investigated. A conceptual model is presented to explain how convective redevelopment within the MCV causes low-level heights to fall and cyclonic vorticity to grow downward to the surface. Applying this conceptual model to a tropical marine environment is also considered.

Sainz-Trapaga, S.M., G.J. Goni, and T. Sugimoto. Identification of the Kuroshio Extension, its bifurcation and northern branch from altimetry and hydrographic data during October 1992-August 1999: Spatial and temporal variability. Geophysical Research Letters, 28(9):1759-1762 (2001).

A methodology is proposed using altimeter-derived upper layer thickness and baroclinic transport to identify the Kuroshio Extension, the Bifurcation Point, and the Northern Branch, by combining TOPEX/POSEIDON altimeter and climatological data within a two-layer reduced gravity model. Results obtained from the Japanese coast to 175°W show that the location of the Bifurcation Point presents interannual variability that is related with upstream conditions. The longitude of the Bifurcation Point ranged from 147 to 160°E. Estimates of baroclinic transport at the Kuroshio Extension and its Northern Branch decrease steadily to the east trough, the region of study from 35 to 11 and from 10 to 3 Sv, respectively.

Schmid, C., R.L. Molinari, and S.L. Garzoli. New observations of the intermediate depth circulation in the tropical Atlantic. Journal of Marine Research, 59(2):281-312 (2001).

The intermediate depth (around 1000 m) circulation in the interior tropical Atlantic has been described as several narrow flow bands. Due to a lack of data, these currents have previously only been poorly resolved in space and time. Recent observations, obtained during the mid-1997 Seward Johnson cruise and from PALACE floats which cover the period summer 1997 to spring 2000, allow a more detailed description of the intermediate depth circulation in the tropical Atlantic. The PALACE trajectories display several well defined currents between the equator and 4°N at 800 to 1100 m. Two regimes separated by the eastern edge of the Mid-Atlantic Ridge seem to exist at these latitudes. Velocities in the eastern regime are lower than in the western regime and, at some latitudes, the zonal flow in the two regimes is going in opposite directions. Farther south, between 4°S and 2°S, westward velocities of the central South Equatorial Current dominate the circulation. The flow north of 4°N and south of 4°S is governed by up to several month-long periods of eastward or westward flow, with only weak preferences for either direction. The southern region is characterized by the (meandering) transition between the central South Equatorial Current and the South Equatorial Countercurrent. It has been proposed earlier that these two currents do not extend eastward beyond about 10°W, and that the intermediate water follows a cyclonic path east of 10°W between about 5°S and 25°S. This could be interpreted as an intermediate expression of the Angola Gyre. Such a circulation is not found in the present data set. It is also noted that no significant cross-equatorial flow is found in the PALACE data.

Wang, C. A unified oscillator model for the El Niño-Southern Oscillation. Journal of Climate, 14(1):98-115 (2001).

The delayed oscillator, the western Pacific oscillator, the recharge-discharge oscillator, and the advective-reflective oscillator have been proposed to interpret the oscillatory nature of the El Niño-Southern Oscillation (ENSO). All of these oscillator models assume a positive ocean-atmosphere feedback in the equatorial eastern and central Pacific. The delayed oscillator assumes that the western Pacific is an inactive region and wave reflection at the western boundary provides a negative feedback for the coupled system to oscillate. The western Pacific oscillator emphasizes an active role of the western Pacific in ENSO. The recharge-discharge oscillator argues that discharge and recharge of equatorial heat content cause the coupled system to oscillate. The advective-reflective oscillator emphasizes the importance of zonal advection associated with wave reflection at both the western and eastern boundaries. Motivated by the existence of these different oscillator models, a unified oscillator model is formulated and derived from the dynamics and thermodynamics of the coupled ocean-atmosphere system. Consistent with ENSO anomaly patterns observed in the tropical Pacific, this oscillator model considers sea surface temperature anomalies in the equatorial eastern Pacific, zonal wind stress anomalies in both the equatorial central Pacific and the equatorial western Pacific, and thermocline depth anomalies in the off-equatorial western Pacific. If the western Pacific wind-forced response is neglected, thermocline and zonal wind stress anomalies in the western Pacific are decoupled from the coupled system, and the unified oscillator reduces to the delayed oscillator. If wave reflection at the western boundary is neglected, the unified oscillator reduces to the western Pacific oscillator. The mathematical form of the recharge-discharge oscillator can also be derived from this unified oscillator. Most of the physics of the advective-reflective oscillator are implicitly included in the unified oscillator, and the negative feedback of wave reflection at the eastern boundary is added to the unified oscillator. With appropriate model parameters chosen to be consistent with those of previous oscillator models, the unified oscillator model oscillates on interannual time scales.

Wang, C., and D.B. Enfield. The tropical Western Hemisphere warm pool. Geophysical Research Letters, 28(8):1635-1638 (2001).

The Western Hemisphere warm pool (WHWP) of water warmer than 28.5°C extends from the eastern North Pacific to the Gulf of Mexico and the Caribbean, and at its peak, overlaps with the tropical North Atlantic. It has a large seasonal cycle and its interannual fluctuations of area and intensity are significant. Surface heat fluxes warm the WHWP through the boreal spring to an annual maximum of SST and areal extent in the later summer/early fall, associated with eastern North Pacific and Atlantic hurricane activities and rainfall from northern South America to the southern tier of the United States. SST and area anomalies occur at high temperatures where small changes can have a large impact on tropical convection. Observations suggest that a positive ocean-atmosphere feedback operating through longwave radiation and associated cloudiness is responsible for the WHWP SST anomalies. Associated with an increase in SST anomalies is a decrease in atmospheric sea level pressure anomalies and an anomalous increase in atmospheric convection and cloudiness. The increase in convective activity and cloudiness results in less longwave radiation loss from the surface, which then reinforces SST anomalies.

Zhang, J.-Z. Oxidation of hydrogen sulfide by various oxidants in natural waters. Trends in Geochemistry, 1(2000):53-68 (2001).

This article reviews the literature on the oxidation of H₂S by various oxidants, including oxygen, hydrogen peroxide, iodate, chromate, ferrate, Fe(III) hydroxides, and Mn(IV) oxides, in natural waters. The rates of H₂S oxidation increased with oxidants in a order of chromate, oxygen, hydrogen peroxide, iodate, Fe(III) hydroxides, Mn(IV) oxides, and ferrate. Effect of pH on the rates of oxidation by various oxidants indicated that HS^- is a reactive species while H₂S is less reactive or, in some cases, non-reactive. The oxidation by oxygen has been a subject of extensive studies and its rates have been measured over a wide range of environmental conditions such as pH, temperature, and salinity. Dissolved and particulate metals have a significant effect on the rates of oxidation and the product formation. The reaction conditions and resulting product formation (S, S_n^2-, SO₃^2-, S₂O₃^2- and SO₄^2-) were examined to unravel the reaction pathway.

Zhang, J.-Z., R.H. Wanninkhof, and K. Lee. Enhanced new production observed from the diurnal cycle of nitrate in an oligotrophic anticyclonic eddy. Geophysical Research Letters, 28(8):1579-1582 (2001).

A diurnal study in an anticyclonic eddy provides the first evidence of nutrient dynamics consistent with the observed trends in solar radiation, oxygen concentration changes, and estimates of the eddy diffusive flux of nitrate from nitracline. A new production rate of 24 mmol C m^-2 d^-1 was determined from nitrate inventory changes at nM levels in the mixed layer using a liquid waveguide technique combined with eddy diffusion estimates across the base of the mixed layer from temporal changes in the vertical penetration of SF₆. The new production supported by nitrate from deepening of the mixed layer after storm events is two times larger than that from the daily diffusive flux. Our results demonstrate that new production in the oligotrophic ocean can be enhanced by a supply of nitrate through the eddy turbulence-induced diffusive flux and entrainment during storms. **2000**

Aberson, S.D. A tropical cyclone ensemble forecasting system for the North Atlantic Basin. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F585, NG12A-05 (2000).

A real-time, 41-member VICBAR orthonormalized bred-mode ensemble forecasting system has been run once per day during the 1998 and 1999 hurricane seasons, and twice per day during the 2000 hurricane season, in the North Atlantic basin. VICBAR is a movable, nested-mesh shallow-water model using the National Centers for Environmental Prediction Aviation and Medium-Range Forecast Models as both initial and time-dependent boundary conditions. The numerics are based on cubic b-splines so as to eliminate discontinuities on the mesh boundaries. The deterministic run has provided skillful forecasts competitive with other track forecast models since 1989. The 850-200 hPa mass-weighted flow is combined with a vortex representative of the tropical cyclone including an asymmetry for the initial motion. Within 1500 km of the storm center, the forecast is wholly barotropic; more than 2500 km away from the storm center, the forecast is entirely that of the global model, with a transition region between the two circles. Forecasts extend to 120 h. This is the first ensemble forecasting system available for tropical cyclone track prediction in the Atlantic. Global models are either unable to skillfully forecast tracks, or, in some ensemble forecasting systems, the tropical regions are not perturbed. The three-year sample will be evaluated to show the value of the ensemble forecasting system, whether the ensemble spans the reality of the track, whether the ensemble mean provides an improved forecast over individual ensemble members and the control forecast, and whether the system can provide probabilistic forecasts of events such as landfall. Further uses of the ensemble, such as providing information for operational hurricane targeting missions with the National Oceanic and Atmospheric Administration's Gulfstream-IV jet aircraft, and for ensemble-based data assimilation schemes, add to the potential value of the ensemble.

Aberson, S.D. Improvements to the ensemble of tropical cyclone track forecasting models in the North Atlantic basin. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A140-A146 (2000).

No abstract.

Aberson, S.D. The first three years of operational targeting with the NOAA Gulfstream-IV. Preprints, 4th Symposium on Integrated Observing Systems, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, 198-199 (2000).

No abstract.

Aberson, S.D. Three years of tropical cyclone synoptic surveillance in the Atlantic basin. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 108-109 (2000).

Since 1997, NOAA has performed more than 50 synoptic surveillance missions in the core and environments of tropical cyclones threatening the United States mainland, Puerto Rico, and the Virgin Islands with their G-IV and P3 aircraft. GPS dropwindsonde observations are taken approximately every 250 km along the flight tracks and sent to the National Centers for Environmental Prediction and the National Hurricane Center for incorporation in numerical guidance and for subjective evaluation. The impact of these data on both track and intensity forecasts will be presented. Since small differences in initial conditions are known to grow in the numerical models at different rates, targeting the fastest growing modes has been studied. Results of such targeting, including methods to find target locations and sampling strategies, will be presented.

Aberson, S.D. Woman and minorities in meteorology since 1950. Program of the 80th Annual Meeting and Exhibition, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, 70-71 (2000).

No abstract.

Aberson, S.D. Women's trends: The changing status of women in the profession/society. Preprints, 9th Symposium on Education, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, 70-71 (2000).

No abstract.

Aberson, S.D., and K. Bedka. The operational ensemble of tropical cyclone track guidance at the National Hurricane Center (1976-1998). Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 177-178 (2000).

A suite of operational track forecast models has been run at NHC in support of NHC s task to provide tropical cyclone track forecasts. Official NHC forecasts have improved at a rate faster than 1% during the 1990s, suggesting substantial improvements to the numerical guidance. This operational ensemble since 1976 has been analyzed as a set to mark the improvements of the guidance with time. The improvements in the ability of the guidance to span the actual track of tropical cyclones, the performance of the ensemble mean with time, and changes in individual model performance are to be presented.

Atlas, D., C.W. Ulbrich, F.D. Marks, R.A. Black, E. Amitai, P.T. Willis, and C.E. Samsury. Partitioning tropical oceanic convective and stratiform rains by draft strength. Journal of Geophysical Research, 105(D2):2259-2267 (2000).

The discrimination of convective from stratiform tropical oceanic rains by conventional radar-based textural methods is problematic because of the small size and modest horizontal reflectivity gradients of the oceanic convective cells. In this work, the vertical air motion measured by an aircraft gust probe is used as a discriminator which is independent of the textural methods. A threshold draft magnitude approximately equal to 1 m s^-1 separates the two rain types. Simultaneous airborne in-situ observations of drop size distributions (DSD) made during the Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) were used to compute Z, R, and other integral parameters. The data were quality controlled to minimize misclassifications. The convective and stratiform rains, observed just below the melting level but adjusted to surface air density, are characterized by power law Z-R relations (Z = 129R^1.38 [convective]) and 224R^1.28 [stratiform]). However, at R < 10 mm h^-1, the convective population is essentially coincident with the small-drop size, small-Z portion of the stratiform population. Tokay and Short (1996) found a similar result when their algorithm did not separate the rain types unambiguously at R < 10 mm h^-1. The physical reasons for the wide variability of the drop size spectra and Z-R points in stratiform rain and their overlap with that of convective rain are proposed. The subtle distinctions in the microphysical properties and the Z-R relations by rain type could not be found by Yuter and Houze using the same airborne DSD data set as that in this work and a radar-based textural classification algorithm.

Beal, L.M., R.L. Molinari, T.K. Chereskin, and P.E. Robbins. Reversing bottom circulation in the Somali Basin. Geophysical Research Letters, 27(16):2565-2568 (2000).

Two sets of direct velocity measurements were taken, concurrent with hydrographic data, in the bottom waters of the northern Somali Basin in June and September 1995. The velocities indicate a temporal flow reversal in the bottom circulation, which is consistent with the changing density structure between the sections. In June, there is evidence of a southward Deep Western Boundary Current with a transport of 5 Sv. By September, flow close to the boundary is northward, with a transport of 2.6 Sv. Furthermore, the deep density gradient across the interior of the Somali Basin also changes between occupations, implying a cyclonic circulation in June and anticyclonic flow in September. Rossby wave activity is high in this region during the southwest monsoon, yet there is also evidence of a strong barotropic component to the Great Whirl in September, which may cause the reversal in the abyssal circulation.

Bentamy, A., P. Flament, Y. Quilfen, K.B. Katsaros, and H. Roquet. Analysis of ocean surface winds derived from ERS-1, ERS-2, and NSCAT measurements. CERSAT News, Issue No. 11, 2 pp. (2000).

No abstract.

Black, M.L., and J.L. Franklin. GPS dropsonde observations of the wind structure in convective and non-convective regions of the hurricane eyewall. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 448-449 (2000).

GPS dropsonde observations in the inner core regions of tropical cyclones have shown remarkable vertical variation in the wind structure. Vertical profiles from sondes released in the convective portions of the hurricane eyewall frequently exhibit multiple low to mid-level wind maxima. These maxima may contain peak winds significantly higher than those measured at typical reconnaissance altitudes (3 km). Convective mixing is thought to be a mechanism that may bring this high momentum air to altitudes at or near the sea-surface. In non-convective regions, both outside and within the eyewall, however, the wind profiles typically do not have the large low-level wind maxima and the wind speed frequently decreases rapidly toward the surface in the boundary layer. Preliminary analyses of dropsonde wind profiles have suggested systematic differences in the shape of these soundings. An important result from these analyses is that the surface wind speed is a substantially higher fraction of the wind at altitude in convective regions than in non-convective or stratiform regions. We plan on classifying several hundred dropsonde observations according to the convective environment they fall through. The classifications will be based upon simultaneous radar observations from NOAA P-3 research flights into tropical cyclones in various stages of development. Individual profiles from convective and non-convective regions of the storms will be presented to highlight some of the observed differences in wind structure. A brief statistical analyses is planned to describe the variance in the mean structure derived from these classifications. A discussion of some of the possible physical mechanisms for the difference in the observed wind profiles will be discussed.

Black, M.L., A.B. Damiano, and S.R. White. Meteorological aspects of the first eye penetration by the NOAA G-IV aircraft. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A97 (2000).

No abstract.

Black, M.L., A.B. Damiano, and S.R. White. The first eyewall penetration by the NOAA G-IV aircraft. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 175-176 (2000).

On August 9, 1999, NOAA's Aircraft Operations Center (AOC) was tasked by the Tropical Prediction Center/National Hurricane Center and the Central Pacific Hurricane Center (CPHC) to deploy the NOAA Gulfstream G-IV jet aircraft and crew to Honolulu, Hawaii for synoptic surveillance missions around Hurricanes Eugene and Dora. Both of these storms had tracked westward across the eastern Pacific basin into the area of responsibility of CPHC (west of 140°W) and posed potential threats to Hawaii. After a successful G-IV mission around Hurricane Eugene on 12 August, a similar flight-track was designed to collect synoptic data from GPS dropsondes around Hurricane Dora on 14 August. At the time, Dora was steadily weakening from a peak intensity of 120 kts on 13 August with maximum sustained surface winds forecast to be 70 kts during the mission. Dora was a compact hurricane with a circular, well-defined eye and had only a couple of weak rainbands outside of the central dense overcast. A deviation from the proposed flight track was planned to fly the G-IV on a heading towards the eye during the closest approach to Hurricane Dora. The maneuver's purpose was to observe the structure of a hurricane at altitudes >40,000 feet with the aircraft's nose radar system. During the flight, the G-IV crew observed that Hurricane Dora was closer to the flight track than was forecast, so that when the aircraft turned toward the south side of the storm, the eyewall was approximately 80 nmi away. After a brief discussion of the structure of Dora and safety considerations, the flight director and aircraft commander decided to fly into the eye before heading back to the original track. This represented the first time that the G-IV would penetrate the eyewall of a hurricane, and would do so at an altitude of 45,000 feet (~145 mb). The aircraft flew through a thick cirrus cloud cover in the eyewall and that thinned while in the eye. Two GPS dropsondes were released while in (above) the eye of Hurricane Dora, and a third sonde was dropped just outside of the southwest eyewall while the G-IV was exiting the storm. Both of the eye drops drifted near or into the eyewall as they descended and one of them showed winds in excess of 80 kts at altitudes below 3000 ft. During the penetration, wind speeds at a flight level of 45,000 feet were approximately 5 kts and the wind direction showed anticyclonic flow.

Black, P.G., E.W. Uhlhorn, M.D. Powell, and J. Carswell. A new era in hurricane reconnaissance: Real-time measurement of surface wind structure and intensity via microwave remote sensing. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A122-A126 (2000).

No abstract.

Black, P.G., E.W. Uhlhorn, M.D. Powell, and J. Carswell. A new era in hurricane reconnaissance: Real-time measurement of surface wind structure and intensity via microwave remote sensing. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 199-200 (2000).

No abstract.

Black, P.G., E.W. Uhlhorn, J.J. Cione, G.J. Goni, L.K. Shay, S.D. Jacob, E.J. Walsh, and E.A. D'Asaro. Hurricane intensity change modulated by air-sea interaction effects based on unique airborne measurements during the 1998-1999 hurricane seasons. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J7-J8 (2000).

No abstract.

Boebel, O., S. Anderson-Fontana, C. Schmid, I. Ansorge, P. Lazarevich, J.R.E. Lutjeharms, M. Prater, T. Rossby, and W. Zenk. KAPEX RAFOS float data report, 1997-1999. Part A: The Agulhas and South Atlantic Current components. GSO Technical Report 2000-2/UCT Oceanography Report 2000-1, 194 pp. (2000).

No abstract.

Bosart, L.F., W.E. Bracken, J. Molinari, C.S. Velden, and P.G. Black. Environmental influences on the rapid intensification of Hurricane Opal (1995) over the Gulf of Mexico. Monthly Weather Review, 128(2):322-352 (2000).

Hurricane Opal intensified rapidly and unexpectedly over the Gulf of Mexico between 1800 UTC 3 October 1995 and 1000 UTC 4 October 1995. During this period, the storm central pressure decreased from 963 to 916 hPa and sustained winds reached 68 m s-1. Analyses that include high-resolution GOES-8 water vapor winds and European Centre for Medium-Range Weather Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP) gridded datasets are employed to examine the rapid intensification phase of Opal. Opal first reached tropical storm strength on 29V30 September 1995 as it interacted with a trough while situated over the Yucatan Peninsula. Opal deepened moderately (20 hPa) in the 24 h ending 1200 UTC 2 October as it achieved minimal hurricane strength and as it turned northeastward. The deepening occurred in conjunction with an environmental flow interaction as determined by an Eliassen balanced vortex outflow calculation. As Opal accelerated toward the Gulf coast by 1200 UTC 3 October, it approached the equatorward jet-entrance region of a progressive synoptic-scale trough. The trough tail extended southwestward toward the lower Texas coast. As the poleward portion of the trough moved eastward, the equatorward end of the trough lagged behind, stretched meridionally, and partially fractured as it encountered a deformation region over the northwest Gulf. Enhanced outflow and increased divergence in the upper troposphere poleward of Opal was associated with the deformation zone and the partially fractured trough tail. An analysis of the 300-200-hPa layer-averaged divergence and 6-h divergence change based on an analysis of the water vapor winds shows a significant increase in the magnitude and equatorward extension of the divergence core toward Opal that begins at 1200 UTC 3 October and is most apparent by 1800 UTC 3 October and 0000 UTC 4 October. This divergence increase is shown to precede convective growth in the eyewall and the onset of rapid intensification and is attributed to a jet-trough-hurricane interaction in a low-shear environment. Calculations of balanced vortex outflow based on the ECMWF and NCEP gridded datasets confirms this interpretation. A crucial finding of this work is that the jet-trough-hurricane interaction and explosive intensification of Opal begins near 0000 UTC 4 October when the storm is far from its maximum potential intensity (MPI), and the 850-200-hPa shear within 500 km of the center is weak (2-3 m s^-1). In this first stage of rapid intensification, the winds increase by almost 15 m s^-1 to 52 m s^-1 prior to the storm reaching an oceanic warm-core eddy. The second stage of rapid intensification occurs between 0600 and 1000 UTC 4 October when Opal is over the warm-core eddy and sustained winds increase to 68 m s^-1. During this second stage, conditions are still favorable for a jet-trough-hurricane interaction as demonstrated by the balanced vortex outflow calculation. Opal weakens rapidly after 1200 UTC 4 October when the storm is near its MPI, the shear is increasing, and the eye is leaving the warm-core eddy. This weakening occurs as Opal moves closer to the trough. It is suggested that an important factor in determining whether a storm-trough interaction is favorable or unfavorable for intensification is how far a storm is from its MPI. The results suggest that a favorable storm-trough interaction ("good trough") can occur when a storm is far from its MPI. It is suggested that although the ECMWF (and to lesser extent NCEP) analyses reveal the trough-jet-hurricane interaction through the balanced vortex outflow calculation, that the failure of the same models to predict the rapid intensification of Opal can be attributed to the inability of the model to resolve the eye and internal storm structure and the associated influence of the trough-jet-hurricane interaction on the diabatically driven storm secondary circulation. The analyses also indicate that the high spatial and temporal resolution of the GOES-8 water vapor winds reveal important mesoscale details of the trough-jet-hurricane interaction that would otherwise be hidden.

Campos, E., A. Busalacchi, S.L. Garzoli, J. Lutjeharms, R. Matano, P. Nobre, D.B. Olson, A. Piola, C. Tanajura, and I. Wainer. The South Atlantic and the climate. OCEANOBS99: International Conference on the Ocean Observing System for Climate, Saint Raphael, France, October 18-22, 1999. Centre National d'Etudes Spatiales, 16 pp. (2000).

As a contribution to the OCEANOBS99 objectives, we give a brief description of the present knowledge of the South Atlantic and identify some key processes and areas which need to be monitored in order to understand the role of that part of the ocean in the global climate. Included are suggestions of strategies for a first approximation towards an ocean climate monitoring system in the South Atlantic.

Chai, F., R. Dugdale, R.T. Baraber, M. Jiang, and T.-H. Peng. Ecosystem modeling in the equatorial Pacific upwelling region. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS29, OS11P-06 (2000).

The equatorial Pacific Ocean is the dominant oceanic source of carbon dioxide to the atmosphere, an annual net flux of 1.0 Pg carbon. This net sea-to-air flux of carbon is the result of a complex interplay between physical and biological processes in the region. A physical-biogeochemical model has been developed and used to investigate physical variations, ecosystem responses, and biogeochemical consequences. The ecosystem model, embedded into a three-dimensional circulation model, is capable of reproducing the low silicate, high nitrate, low chlorophyll (LSHNLC) conditions in the equatorial Pacific upwelling region. Linkage of the ecosystem components to the carbon system provides a model estimated sea-to-air flux of carbon which is comparable with the observations. The ecosystem responses to the tropical instability waves have been documented to exam the transition from a "balanced" to "bloom" state of phytoplankton production. The physical-biogeochemical model results show a consistent decrease of the sea-to-air CO₂ flux during El Niño events.

Cione, J.J., P.G. Black, and S.H. Houston. Surface observations in the hurricane environment. Monthly Weather Review, 128(5):1550-1561 (2000).

Composite analyses of marine surface observations from 37 hurricanes between 1975 and 1998 show that the difference between the sea surface temperature and the surface air temperature significantly increases just outside the hurricane inner core. This increase in the sea-air contrast is primarily due to a reduction in surface air temperature and is more likely to occur when sea temperatures are at least 27°C. Results show that 90% of the observed cooling occurs 3.25°-1.25° latitude from the hurricane center, well outside the region of strongest surface winds. Since surface pressure only decreases 3 mb over this interval, the 2°C drop in air temperature is not a result of adiabatic expansion. For the subset of observations that contained moisture measurements, surface specific humidity decreased 1.2 g kg^-1 4.5°-1.75° latitude from the storm center. This finding suggests that the observed reduction in surface air temperature is not simply a result of near-surface evaporation from sea spray or precipitation. An alternate explanation may be that outside the hurricane inner core, unsaturated convective downdrafts act to dry and evaporatively cool the near-surface environment. Between 3.25° and 1.25° radius, composite analyses show that low-level inflow is not isothermal, surface moisture is not constant, and the near-surface environment is not in thermodynamic equilibrium with the sea. Calculations based on these observations show that theta_e decreases between 4.0° and 1.25° radius and then quickly rises near the inner core as surface pressures fall and specific humidity increases. Surface fluxes of heat and moisture are also observed to significantly increase near the inner core. The largest increase in surface sensible heat flux occurs radially inward of 1.5°, where surface winds are strong and sea-air temperature contrasts are greatest. As a result, the average Bowen ratio is 0.20°-0.5° radius from the composite storm center. This increase in sensible heat flux (in conjunction with near-saturated conditions at low to midlevels) may help explain why average surface air temperatures inside 1.25° radius remain relatively constant, despite the potential for additional cooling from evaporation and adiabatic expansion within the high wind inner core.

Cione, J.J., E.W. Uhlhorn, and P.G. Black. Atmospheric boundary layer and upper ocean structure observed in Hurricane Erika (1997). Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J70-J71 (2000).

No abstract.

Cione, J.J., P. Molina, J. Kaplan, and P.G. Black. SST time series directly under tropical cyclones: Observations and implications. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 1-2 (2000).

No abstract.

Cook, T.M., L.K. Shay, P.G. Black, G.J. Goni, M.M. Huber, S.D. Jacob, and J.J. Cione. Coupled air-sea interactions during Hurricane Bonnie. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J68-J69 (2000).

No abstract.

Cosca, C.E., R.A. Feely, R.H. Wanninkhof, J. Boutin, J. Etcheto, and M.J. McPhaden. Seasonal and interannual variations of the fCO₂-SST relationships in the equatorial Pacific. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS28, OS11O-11 (2000).

In order to utilize satellite temperature data for determining high-resolution variations of CO₂ distributions in the equatorial Pacific, we have developed seasonal and interannual fCO₂-SST relationships from shipboard data. The data were gathered onboard the NOAA ships Baldridge, Discoverer, and Ka'imimoana from 1992 through 1998 as a companion project to the biannual deployment of the TAO moorings. The cruises during the 6-year period included 55 10°S to 10°N crossings of the equatorial Pacific between 95°W and 165°E, and spanned two major ENSO events (1992-1994 and 1997-1998). Data were collected during the warm boreal spring season (February through June) and during the cooler boreal fall season (July through December) of each year, making it possible to examine the interannual and seasonal variability of the fCO₂-SST relationship. A linear fit through all 55 data sets yields an inverse correlation between SST and fCO₂, with an R² of 0.583 and an RMS of 28.4 µatm. When separated, there is a significant difference between the regression lines for El Niño versus non-El Niño data sets. During non-El Niño periods, we observed seasonal differences in the fCO₂-SST relationship. The regression lines through the spring and fall data sets have higher R² and lower RMS values than the composite non-El Niño regression line, and the slopes are significantly different at the 95% confidence level. The slope for the fall season is less negative than during spring, suggesting higher biological productivity occurred during the fall non-El Niño seasons. The regression line for the composite El Niño data, which shows no significant seasonal variability, has a slope very similar to the non-El Niño spring slope, indicating less influence by biological processes. These relationships have been combined with satellite-based temperature data to provide a composite time-space map of DELTA-fCO₂ in the equatorial Pacific.

Cushman-Roisin, B., O.E. Esenkov, and B.J. Mathias. A particle-in-cell-method for the solution of two-layer shallow-water equations. International Journal of Numerical Methods in Fluids, 32:515-543 (2000).

A particle-in-cell (PIC) numerical method developed for the study of shallow-water dynamics, when the moving fluid layer is laterally confined by the intersection of its top and bottom surfaces, is described. The effect of ambient rotation is included for application to geophysical fluids, particularly open-ocean buoyant vortices in which the underlying density interface outcrops to the surface around the rim of the vortex. Extensions to include the dynamical effect of a second moving layer (baroclinicity) and the presence of a lateral rigid boundary (sidewall) are also described. Although the method was developed for oceanographic investigations, applications to other fluid mechanics problems would be straightforward.

D'Asaro, E.A., and P.G. Black. Turbulence in the ocean boundary layer below Hurricane Dennis. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J62-J63 (2000).

No abstract.

Dodge, P.P., S.M. Spratt, F.D. Marks, D.W. Sharp, and J.F. Gamache. Dual-Doppler analyses of mesovortices in a hurricane rainband. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 302-303 (2000).

The U.S. Weather Research Program identified landfalling tropical cyclones as a major focus for research in the coming years. In 1998, the Hurricane Research Division (HRD) of NOAA's Atlantic Oceanographic and Meteorological Laboratory coordinated experiments with other agencies and university groups in Hurricanes Bonnie, Earl, and Georges. On these flights, airborne Doppler radar data were collected to combine with WSR-88D radar data in three-dimensional analyses to document evolution of tropical cyclones as they make landfall, and to provide data for testing WSR-88D tropical cyclone algorithms. Hurricane Bonnie made landfall in near Wilmington, North Carolina as a Category 2 hurricane on 26 August. There were two HRD missions near the time of landfall. The first flight concentrated on examining the structure of the spiral rainbands and the second flight surveyed the hurricane as it interacted with the coast. During the flights, there was a vigourous rainband ~180 km northeast of the center with several mesocyclones (as identified on the Morehead City WSR-88D) that later produced confirmed tornadoes on land. Both NOAA aircraft had to deviate around strong cells in this band, between 1540 and 1830 UTC, and those deviations resulted in small Doppler analysis boxes enclosing some of the mesocyclones. A companion paper (Spratt et al.) uses dropsondes and adjacent radiosondes to describe the local environment in which the Bonnie mesocylones were embedded, and in this paper we will present windfield analyses, from combining WSR-88D and airborne Doppler radar data, that provide the three dimensional structure of the mesocyclones. The Doppler data are too coarse to resolve actual tornadoes, but the parent mesoscale circulations are clearly resolved.

Dunion, J.P., S.H. Houston, M.D. Powell, C.S. Velden, and P.G. Black. Using surface adjusted GOES low-level cloud-drift winds to improve the estimation of tropical cyclone outer wind radii. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 488-489 (2000).

No abstract.

Dye, J.E., E. Defer, A. Grainger, M. Poellot, H. Christian, M. Bateman, D. Mach, M. Stewart, P.T. Willis, and F. Merceret. Electric field and associated microphysical measurements in the anvil of a decaying Florida thunderstorm. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F91, A62D-09 (2000).

The ABFM 2000 (Airborne Field Mill Mission 2000) was conducted during June 2000 to investigate the decay time and spatial distribution of electric fields and microphysical and radar structure in anvils of dissipating storms near Kennedy Space Center (KSC). The University of North Dakota Citation jet aircraft was flown with six electric field meters to determine the 3-D electric field, an array of particle probes to characterize particle concentrations, sizes and types, and standard instruments for measuring state parameters. Ground-based instruments included the KSC Lightning Ranging and Detection System (LDAR), KSC field mill network, KSC cloud-to-ground lightning network, radar, and rawinsondes. In this paper we present measurements from the June 13 case in which the Citation investigated the temporal and spatial distribution of electric fields and microphysics of the anvil from before last lightning to 2 hours after the last flash. Numerous penetrations were made across the anvil early in the flight and later along the anvil axis. Although electric fields were in excess of 50 kV/m near the core, the fields decreased with distance from the core and became less than a few kV/m at distances of about 50-60 km from the storm core even while lightning was occurring. The stronger fields tended to be associated with reflectivities greater than 20 dBz and concentrations of particles larger than 1 mm size.

Enfield, D.B., and A.M. Mestas-Nunez. Global modes of ENSO and non-ENSO SST variability and their associations with climate. In: El Niño and the Southern Oscillation: Multiscale Variability and its Impacts on Natural Ecosystems and Society, H.F. Diaz and V. Markgraf (eds.). Cambridge University Press, 89-112 (ISBN 0521621380) (2000).

In this chapter we review much of the recent work by others regarding the nature of the global modes of sea surface temperature (SST) variability and the SST involvement in interannual to multidecadal climate variability. We also perform our own analysis of global SST so as to describe and separate the SST variability associated with El Niño-Southern Oscillation (ENSO) from the low-frequency modes not associated with ENSO (non-ENSO). ENSO is a global phenomenon with significant phase propagation between basins, which we preserve and describe using complex EOF (CEOF) analysis, and subsequently remove from the global SST data. A second CEOF analysis of the residuals reveals three non-ENSO modes of low-frequency variability that are identified with and related to signals described in the reviewed literature: (1) a secular trend representing the global warming signal with associated superimposed decadal variability; (2) an interdecadal mode with maximal realization in the extratropical North Pacific; and (3) a multidecadal mode with maximal realization in the extratropical North Atlantic. Regression- and SVD-based analyses of the relationships between the SST data and a high-quality precipitation data set demonstrate for the interannual-to-decadal time scales of the western hemisphere tropics that (a) tropical Atlantic SSTA is comparable to the Pacific ENSO in its relevance to regional rainfall and is not redundant with respect to ENSO; and (b) non-ENSO variability explains a significant fraction of the total covariance between the two variables. We are led to conclude that present operational climate predictions can be significantly improved by extending numerical SST predictions from the Pacific to the world ocean and by enabling these models to emulate the observed non-ENSO modes of global variability.

Enfield, D.B., and A.M. Mestas-Nunez. Tropospheric direct circulations associated with the climatic components of SST variability in the equatorial Pacific. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J49-J50 (2000).

No abstract.

Esenkov, O.E. A numerical study of the dynamics of the Somali Current system. Ph.D. Thesis, University of Miami/Rosenstiel School of Marine and Atmospheric Science, 140 pp. (2000).

The evolution of surface circulation, salinity budget, and processes at intermediate depth in the northwestern Indian Ocean were studied with the open boundary version of the Miami Isopycnic Coordinate Ocean Model (MICOM). Under climatological wind and thermodynamic forcing, the model develops solutions that are in good agreement with global MICOM results and with observations. When the observed winds (Legler et al., 1989) force the model, interannual variability of the surface fields increases significantly. However, coalescence of the two large eddies in the end of the summer monsoon, which was observed in some years, does not occur in the model. To identify what processes facilitate the merger, a series of experiments was performed with modified model parameters and forcing fields. The eddies coalesced when half-slip, rather than no-slip, boundary conditions were used. In this case, less positive vorticity was produced at the coast, resulting in reduced blocking effect on the propagation of the southern eddy. The Socotra Island, which is submerged in the standard model, hinders movement of the northern anticyclone, leading to stronger interaction between the eddies and their subsequent merging. A more realistic coalescence occurs in an experiment where winds are held constant after reaching the peak summer value. Freshwater fluxes from the east and south were previously considered important for the salinity budget in the Arabian Sea, where evaporation exceeds precipitation; however, the model demonstrated that only cross-equatorial transport of low-salinity water in the upper 400 m is essential. About 86% of this water is advected below the surface layer at the western boundary. The strongest interaction between the mixed layer and the oceanic interior occurs during the summer in the coastal upwelling regions off Somalia. Forty-three percent of all upwelled water comes from depths between 100 m and 200 m, thus signifying the importance of mid-depth circulation and water mass distribution for the surface processes. Both observations and model solutions demonstrate strong annual cycle and alongshore variability of coastal subsurface circulation. A cross-equatorial northward flow below the surface, which exists throughout the year, is disconnected from currents farther north. A southward undercurrent north of 5°N is present during the winter monsoon. Water for the current is supplied by flows from the north and northeast. The former originates in the Persian Gulf and carries higher-salinity water, while the latter contribution is mainly from the Gulf of Aden. Separation of the southward undercurrent near 4°N is not caused by its interaction with a topographical ridge, as was previously suggested. Agreement with the observations north of 5°N improves when the Socotra Island is present in the model.

Feely, R.A., C.E. Cosca, R.H. Wanninkhof, M.J. McPhaden, C.S. Meinen, J. Boutin, and J. Etcheto. The role of ENSO on the phasing of the CO₂ signal in the equatorial Pacific. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS279, OS42J-02 (2000).

Recent modeling studies, based upon inversions of atmospheric CO₂, delta¹³C, and O₂/N₂ records from Cape Grim, Tasmania by Rayner et al. (1999), have suggested a decrease in the equatorial Pacific Ocean source of CO₂ to the atmosphere which precedes the SOI by about seven to ten months. In order to test this model result, we have utilized satellite temperature data to obtain high-resolution variations of fCO₂ distributions in the eastern equatorial Pacific based on shipboard fCO₂-SST relationships. The data were gathered onboard the NOAA ships Baldridge, Discoverer, and Ka'imimoana from 1992 through 1998 as a companion project to the biannual deployment of the TAO moorings. The results indicate rapid drops in surface water fCO₂ at 110°W, 125°W and 140°W several months ahead of the peak SST anomalies associated with the 1986-1887, 1991-1992, and 1997-1998 warm ENSO events. These rapid changes in fCO₂ are inversely correlated with the integrated volume of the warm water above the 20°C isotherm in the eastern equatorial Pacific. During the onset phase of warm ENSO events, the propagation of Kelvin waves from west to east along the equatorial waveguide results in a deepening of the thermocline and a rapid decrease in surface water fCO₂. The phasing of the beginning of the decrease in fCO₂ is approximately six to eight months ahead of the minimum in the SOI index. During strong El Niño events, such as the 1997-2998 ENSO event, seawater fCO₂ values decrease by as much as 125 µatm over the course of a few weeks, indicating a rapid decrease in the outgassing of CO₂ near the equator. These results help to explain the dramatic decrease in the growth rate of CO₂ in the atmosphere that occurs at the beginning of each ENSO event.

Feely, R.A., C.L. Sabine, R.H. Wanninkhof, R.M. Key, G.C. Johnson, F.J. Millero, K. Lee, T.-H. Peng, J.L. Bullister, A. Kozyr, and M.F. Lamb. Synthesis of global ocean CO₂ survey data. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F691, OS72E-01 (2000).

The synthesis of the global ocean CO₂ survey data is proceeding by ocean basin. Between 1991 and 1998, investigators analyzed dissolved inorganic carbon (DIC) and one or more other carbon system parameters (TAlk, pCO₂, or pH) on WOCE/JGOFS/OACES cruises in the Indian, Pacific, and Atlantic Oceans. The analysis of the Indian Ocean data is published in Sabine et al., GBC, 13, 179-198, 1999) and can be obtained at: http://cdiac.esd.ornl.gov/oceans/glodap/index.html. DIC and TAlk were measured on all cruises, with an estimated overall accuracy of 2-4 µmol kg^-1, respectively. For the Pacific Ocean, investigators from 15 different laboratories and four countries analyzed at least two of the four measurable ocean carbon parameters. Several different lines of evidence were used to examine the consistency among data sets and recommend adjustments. The analysis included comparison of calibration techniques, results from certified reference material analyses, precision of at-sea replicate analyses, agreement between shipboard analyses and replicate shore-based analyses, comparison of deep water values at locations where two or more cruises overlapped or crossed, consistency with other hydrographic parameters, and internal consistency with multiple carbon parameter measurements. With the adjustments recommended here, the data can be combined to generate a Pacific Ocean data set with over 36,000 unique sample locations. The best data coverage was for DIC, which has an estimated overall accuracy of ~3 µmol kg^-1 after the recommended adjustments. TAlk, the second most common carbon parameter, has an estimated overall accuracy of ~5 µmol kg^-1. The data have been integrated into a unified, internally-consistent data set and the physical and chemical controls of the basinwide distributions of DIC and TAlk will be discussed. The synthesis of the Atlantic data is just getting underway and will be conducted in association with the European Carbon Dioxide in the North Atlantic Ocean (CARINA) Project, with a projected completion date of mid-2002.

Feuer, S.E., M.L. Black, and J.L. Franklin. The asymmetric wind structure of tropical cyclones in various shear environments. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 450-451 (2000).

The Hurricane Research Division (HRD) of NOAA's Atlantic Oceanographic and Meteorological Laboratory conducts an annual field program involving research flights into tropical cyclones with NOAA WP-3D aircraft. As part of this program, dropwindsondes are launched from the aircraft during a variety of airborne experiments. Since 1996, dropsondes based on satellite navigation from built-in Global Positioning System (GPS) modules have been deployed in and around the tropical cyclones. These GPS sondes demonstrate a remarkable ability to accurately measure kinematic and thermodynamic quantities, including winds to an accuracy of 0.5-2.0 m s^-1 at approximately 5 m resolution, as they descend from flight level to the surface. This study focuses on documenting the vortex-scale wind structure in the middle and lower troposphere of three hurricanes: Bonnie (1998), Guillermo (1997), and Bret (1999), which had experienced high, moderate, and low 200-850 mb environmental shear, respectively. These hurricanes are all well sampled by GPS sondes released within 300 km of the center during HRD's Vortex Motion and Evolution (VME) and modified Air-Sea Interaction experiments. Objective analyses of the dropsonde data are performed to resolve significant wind features approximately 50-300 km from the center and filter out smaller scales. Using the analyzed field, the distribution of kinematic asymmetries is contrasted among the storms and is related to the shear and reflectivity fields simultaneously collected from airborne radar systems. Variations in the height of analyzed wind features are also described.

Ffield, A., K. Vranes, A.L. Gordon, R.D. Susanto, and S.L. Garzoli. Temperature variability within Makassar Strait. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS17, OS11I-05 (2000).

The Indonesian throughflow impacts the global climate system by carrying warm Pacific water from about 5°N, through the Indonesian Seas, into the Indian Ocean at 12°S. As part of the U.S./Indonesian Arlindo program, recent mooring observations of ocean temperature provide the first high-resolution, long-term record of temperature variability in the Makassar Strait of the Indonesian Seas. The mooring observations span the entire cycle of the strong 1997/1998 El Niño, and they reveal the complexity of the Makassar Strait thermocline with significant short and long period temperature variations as a function of both depth and time. A high correspondence (r = 0.67) is found between variability in the average thermocline temperature, to variability in the southward Makassar volume transport: during high (low) volume transport, the average temperature of the thermocline is also high (low). In addition, during the measurement period, the Makassar thermocline temperature corresponds strongly (r = -0.87) to NINO3. This implies that the Makassar temperature field, when coupled with the throughflow, transmitted the equatorial Pacific El Niño and La Niña temperature fluctuations into the Indian Ocean with potential consequences to the climate system. The Makassar mooring temperature observations are related to 15 years of regional XBT data to better estimate the semi-annual, annual (monsoonal), and interannual (ENSO) characteristics of the mooring temperature observations, and of the Makassar Strait thermocline in general. The potential of Makassar XBT measurements to efficiently monitor the Makassar throughflow as part of the developing global monitoring system is assessed.

Ffield, A., K. Vranes, A.L. Gordon, R.D. Susanto, and S.L. Garzoli. Temperature variability within the Makassar Strait. Geophysical Research Letters, 27(2):237-240 (2000).

Recent mooring observations of ocean temperature provide the first high-resolution, long-term record of temperature variability in the Makassar Strait of the Indonesian Seas. The mooring observation span the entire cycle of the strong 1997/1998 El Niño. A high correlation (r = 0.67) is found between variability in the average thermocline temperature, to variability in the southward Makassar volume transport: during high (low) volume transport, the average temperature of the thermocline is also high (low). In addition, from nearly 15 years of XBT data, the Makassar thermocline temperature is shown to be highly correlated (r = 0.77) to SOI. This reveals that the Makassar temperature field, when coupled with the throughflow, transmits the equatorial Pacific El Niño and La Niña temperature fluctuations into the Indian Ocean. The ENSO variability in the internal energy transport is calculated: 0.63 PW during the La Niña months of December 1996 through February 1997, and 0.39 PW during the El Niño months of December 1997 through February 1998.

Fine, R.A., L. Merlivat, W. Roether, W.M. Smethie, and R.H. Wanninkhof. Observing tracers and the carbon cycle. OCEANOBS99: International Conference on the Ocean Observing System for Climate, Saint Raphael, France, October 18-22, 1999. Centre National d'Etudes Spatiales, 14 pp. (2000).

A program for repeated sampling of tracers and variables essential for quantitative understanding of the carbon cycle is recommended within CLIVAR/GOOS. The program is critical to our monitoring and understanding of climate change, both natural and anthropogenic. The objectives are: quantification of changes in the rates and spatial patterns of oceanic carbon uptake, fluxes, and storage of anthropogenic CO₂; detection and possible quantification of changes in water mass renewal and mixing rates; and provision of a stringent test of the time integration of models' natural and anthropogenic climate variability. The strategy is to put in place a global observing network for tracers and CO₂ to document the continuing large-scale evolution of these fields. Hydrographic lines are advocated, although it is realized that there has to be a limit on these observations due to logistical and resource constraints. Thus, there is the need to supplement these observations with time series and autonomous measurements to provide detail in the temporal evolution of the fields.

Fleurant, C.I., W.D. Wilson, W. Johns, S.L. Garzoli, R.H. Smith, D. Fratantoni, P. Richardson, and G.J. Goni. CTD/O₂, LADCP, and XBT measurements collected aboard the R/V Seward Johnson, February-March 1999: North Brazil Current Rings Experiment, cruise 2 (NBC-2). NOAA Data Report, OAR-AOML-37, 291 pp. (2000).

Summaries of conductivity-temperature-depth (CTD/O₂), lowered acoustic Doppler current profiler (LADCP), and expendable bathythermograph (XBT) measurements and hydrographic data acquired on an oceanographic research cruise during the winter of 1999 aboard the Harbor Branch Oceanographic Institution ship R/V Seward Johnson are presented. Data acquisition and processing systems are described, and calibration procedures are documented. Station location, CTD/O₂, LADCP, XBT summary data listings, and profiles are included for each station.

Fleurant, C.I., W.D. Wilson, W. Johns, S.L. Garzoli, R.H. Smith, D. Fratantoni, P. Richardson, and G.J. Goni. CTD/O₂, LADCP, and XBT measurements collected aboard the R/V Seward Johnson, February-March 2000: North Brazil Current Rings Experiment, cruise 3 (NBC-3). NOAA Data Report, OAR-AOML-38, 251 pp. (2000).

Summaries of conductivity-temperature-depth (CTD)/O₂, lowered acoustic Doppler current profiler (LADCP) measurements, and hydrographic data acquired on an oceanographic research cruise during the winter of 2000 aboard the Harbor Branch Oceanographic Institution ship R/V Seward Johnson are presented. Data acquisition and processing systems are described, and calibration procedures are documented. Station location, CTD/O₂, LADCP summary data listings, and profiles are included for each station.

Fleurant, C.I., W.D. Wilson, W. Johns, S.L. Garzoli, R.H. Smith, D. Fratantoni, P. Richardson, and G.J. Goni. CTD/O₂, LADCP, and XBT measurements collected aboard the R/V Seward Johnson, November-December 1998: North Brazil Current Rings Experiment, cruise 1 (NBC-1). NOAA Data Report, OAR-AOML 39, 274 pp. (2000).

Summaries of conductivity-temperature-depth (CTD/O₂), lowered acoustic Doppler current profiler (LADCP), expendable bathythermograph (XBT) measurements, and hydrographic data acquired on an oceanographic research cruise during the fall of 1998 aboard the Harbor Branch Oceanographic Institution ship R/V Seaward Johnson are presented. Data acquisition and processing systems are described, and calibration procedures are documented. Station location, CTD/O₂, LADCP, XBT summary data listings, and profiles are included for each station.

Franklin, J.L., M.L. Black, and K. Valde. Eyewall wind profiles in hurricanes determined by GPS dropwindsondes. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 446-447 (2000).

No abstract.

Friedman, H.A., F. Horsfall, and E. Van Coverden. Pipeline: What does the future hold for the society and the profession as we access those in the educational pipeline. Preprints, 9th Symposium on Education, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, 75 (2000).

The composition of students in the educational pipeline is examined with respect to the number of women and minorities enrolled in colleges and universities that offer degree programs in atmospheric, oceanographic, and hydrologic sciences. Data from recent AMS surveys of its members and from information supplied by colleges and universities are examined to ascertain if some change has taken place, especially with respect to women and minorities in science fields. Barriers to a more diverse composition in the profession are discussed.

Gamache, J.F., M.L. Black, and H.E. Willoughby. Radial variation of azimuthally averaged flow across the hurricane core as observed with airborne Doppler radar. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 416-417 (2000).

Examination of the variation of azimuthally averaged zonal and meridional winds in the cores of Hurricanes Olivia and Jimena indicate that the vertical shear increased with increasing radius. Divergent wind fields computed for the hurricane core have azimuthally averaged flow that tends to oppose the overall wind shear, which is in agreement with one of the model results shown by Jones. Additionally, in the core, winds at smaller radii imply a more vertically aligned storm center than do winds at larger radii. These results will be documented in several hurricanes, including Olivia and Jimena.

Garraffo, Z.D., W.E. Johns, E.P. Chassignet, and G.J. Goni. Impact of North Brazil Current rings on the eastern Caribbean. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS69, OS12P-04 (2000).

The influence of North Brazil Current (NBC) rings on the eastern Caribbean is investigated using new results from a high-resolution North Atlantic model simulation, ship surveys, drifters, and Topex/Poseidon (T/P) altimetry. North Brazil Current rings are large (~400-km diameter) anticyclonic eddies that periodically pinch off from the North Brazil Current Retroflection and propagate northwestward toward the Lesser Antilles, carrying with them water masses and biogenic materials from the equator and Amazon regions. Results from the high-resolution MICOM North Atlantic model and from five years of T/P altimetry now suggest that approximately five NBC rings are formed each year, nearly twice what had been previously documented. New shipboard surveys obtained as part of an intensive 1998-2000 in-situ study of NBC rings have shown that these rings can have highly varying vertical structures, ranging from shallow (<200 m) to deep (>1000 m) features, and even subsurface intensified rings with maximum swirl velocities in the thermocline. A similar range of features is produced in the MICOM-simulated rings. The model results and altimetry suggest that the strongest and deepest reaching NBC rings are the ones most likely to travel well northward along the Lesser Antilles arc before breaking up and dispersing their waters. The passage of the rings along the island arc and their interaction with the island topography strongly influences flow and transport variations through the Lesser Antilles passages.

Garzoli, S.L., and G.J. Goni. Combining altimeter observations and oceanographic data for ocean circulation and climate studies. In Satellites, Oceanography, and Society, D. Halpern (ed.). Elsevier Oceanographic Series, 63:79-95 (2000).

Calibrating Topography Experiment (TOPEX)/Poseidon (T/P) altimeter data to inverted echo sounder measurements is one of the methodologies developed to advance the study of the South Atlantic Ocean. The mass transport of the main boundary currents can be monitored using dynamic height time series obtained from altimeter-derived sea surface height anomalies. A two-layer model yields upper-layer thickness and surface dynamic height of the ocean in areas of strong vertical stratification to identify and track anticyclonic rings, such as those shed from the Agulhas retroflection, which play an important role in the interocean exchange of heat and mass. Interannual variability of boundary currents, derived from analysis of the first five years of T/P data, is discussed. A combination of T/P data and in-situ observations provides significant contributions to the study of ocean dynamics for climate applications.

Garzoli, S.L., D.B. Enfield, G. Reverdin, G. Mitchum, R.H. Weisberg, P. Chang, and J. Carton. COSTA: A Climate Observing System for the Tropical Atlantic. OCEANOBS99: International Conference on the Ocean Observing System for Climate, Saint Raphael, France, October 18-22, 1999. Centre National d'Etudes Spatiales, 19 pp. (2000).

This paper summarizes the discussions that took place during the COSTA (Climate Observing System for the Tropical Atlantic) workshop held in Miami, Florida during May 1999. The main objective of the workshop was to coordinate the present efforts in the region and to set the scientific basis for an extended and more permanent observing system. The intent of the COSTA workshop, based in the CLIVAR (global) and ACVE (basin) experience, was to formulate the basis for an extended and more permanent (regional) tropical Atlantic observing system, building on the present existing monitoring programs and process studies, and the current scientific underlayment. The first part of this paper establishes the importance and the role of the tropical Atlantic in climate fluctuations and their impact in society. This is followed by a description of the climate variability in the Atlantic sector, its relationship to tropical Atlantic variability, especially sea surface temperature (SST), and to the North Atlantic Oscillation and meridional overturning circulation. The possible mechanisms behind tropical Atlantic SST fluctuations and their relation to climate is also discussed, highlighting, in particular, the role of surface fluxes in the off-equatorial regions, the equatorial ocean-atmosphere interactions, and their relationships to movements of the Inter-Tropical Convergence Zone. The second part of this paper summarizes the scientific discussions and recommendations from the working groups who centered their discussions in the following themes: (1) SST and surface fluxes; (2) sea level and subsurface structure; (3) circulation; and (4) modeling and data assimilation. Finally, the present status of the observing system and a summary of recommendations is presented.

Goldenberg, S.B. Intraseasonal predictability of Atlantic basin hurricane activity. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 59-60 (2000).

The Atlantic basin hurricane season officially lasts from 1 June through 30 November. The vast majority of the activity (>95% of the major hurricane activity) occurs during the peak months August, September, and October. Previous analyses have demonstrated that early season (June-July) overall tropical cyclone activity has no relationship to the activity during the remainder of the season. Results will be presented that demonstrate that if the June-July activity is stratified properly, it can yield a strong predictive signal for the activity during the rest of the season. The occurrence of a certain type of activity in June or July is, in fact, a sufficient (but not necessary) condition for a year with above-average activity. Results will also be discussed showing how just as the June-July activity contains a signal to help predict the activity for the coming months, June-September (or simply August-September) activity can give a clear indication of what is to come during the final peak month of October.

Goldenberg, S.B., C.W. Landsea, and G.D. Bell. Summary of the 1999 Atlantic hurricane season: A climatic perspective. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A251-A256 (2000).

The tropical cyclone activity from the 1999 Atlantic hurricane season will be related to observed fluctuations in various climatic factors such as ENSO, Atlantic SSTs, and vertical shear. The character of the season's activity will also be discussed with respect to different time scales: multi-decadal, interannual, and intraseasonal. Implications for Atlantic activity in the coming season (2000) and decade will also be addressed. For the last two seasons, NOAA has issued forecasts of the Atlantic basin hurricane activity as a collaboration between scientists at NOAA's Climate Prediction Center, Hurricane Research Division, and National Hurricane Center. Verifications of the forecasts for the 1998 and 1999 seasons will be discussed.

Goldenberg, S.B., C.W. Landsea, and G.D. Bell. Summary of the 1999 Atlantic hurricane season: A climatic perspective. Proceedings, 24th Annual Climate Diagnostics and Prediction Workshop, Tucson, AZ, November 1-5, 1999. National Weather Service, 1-4 (2000).

No abstract.

Goni, G.J., S.M. Sainz-Trapaga, and T. Sugimoto. Transport estimates and variability of the Kuroshio Extension Current from satellite altimetry data. AGU 2000 Western Pacific Geophysics Meeting, Tokyo, Japan, June 27-30, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(22):WP77-WP78, OS32B-06 (2000).

Satellite altimetry observations of sea level in combination with historical vertical profiles of ocean density and dynamical modeling provide an excellent tool to understand the global meso- and large-scale ocean circulation. A two-layer dynamical model is used in conjunction with six years of TOPEX/POSEIDON (T/P) altimeter-derived sea height anomaly to monitor the upper ocean transport in a region east of Japan from 1993 to 1998. The key objective of this work is to estimate the upper layer thickness and investigate the baroclinic transport variability along a selected T/P groundtrack, in which a two-year time series of the 14°C isotherm derived from inverted echo sounders is available. The upper layer thickness field is used to monitor the Kuroshio Extension front, which is found to fluctuate between 33.7°N and 36.5°N. The across-track upper layer velocity and baroclinic transports are used to monitor the Kuroshio Extension axis. Estimates in this work reveal that the axis fluctuates between 32.1°N and 35.9°N. Two events are identified, one in 1996 and another in 1997, with unusual southern paths of the Kuroshio Extension axis, and related to large variations in baroclinic transport values. It is speculated that these extreme southern excursions of the axis may be compensating for large changes in relative vorticity and upper layer thickness.

Goni, G.J., L.K. Shay, P.G. Black, S.D. Jacob, T.M. Cook, J.J. Cione, and E.W. Uhlhorn. Role of the upper ocean structure on the intensification of Hurricane Bret from satellite altimetry. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J5-J6 (2000).

No abstract.

Hendee, J.C. A data-driven soft real-time expert system for producing coral bleaching alerts. Ph.D. Thesis, Nova Southeastern University, 131 pp. (2000).

In the Florida Keys there are many physical, chemical, and biological events of interest and concern to personnel of the Florida Keys National Marine Sanctuary, marine biologists, oceanographers, fishermen, and divers. Large volumes of continuously-generated meteorological and oceanographic data from instruments in the SEAKEYS (Sustained Ecological Research Related to Management of the Florida Keys Seascape) network help to understand these events. However, since no one has the time to look at every printout of data from every station, every day, seven days a week, it is highly desirable to have an automated system that can monitor parameters of interest and produce specialized alerts of specific events, as indicated by prescribed or abnormal ranges, or combinations of parameters. A soft real-time expert system was developed to produce such alerts based on data input from the SEAKEYS network. The prototype system collected data from the Sombrero Reef station in the network and produced automated e-mail and World-Wide Web alerts when conditions were thought to be conducive to, or predictive of, coral bleaching, which occurs under environmental conditions stressful to corals. Configuration of the system included a point system for three coral bleaching models (high sea temperature only, high sea temperature plus low winds, high sea temperature plus low winds plus low tide). The approach is an important development in the use of knowledge-based systems to solve environmental problems, as it provides for knowledge synthesis (in the form of data summaries) from any environmental ASCII data stream or table, be it real-time or not.

Hendee, J.C. An environmental information synthesizer for expert systems: A framework for use in near real-time detection of harmful algal blooms. Proceedings, 17th International Conference of The Coastal Society: Coasts at the Millennium, Portland, OR, July 9-12, 2000. The Coastal Society, 233-241 (2000).

As an enhancement to the SEAKEYS environmental monitoring network in the Florida Keys National Marine Sanctuary, software called the Environmental Information Synthesizer for Expert Systems (EISES) has been utilized together with a specially developed expert system to model and report the near real-time sensing of environmental conditions conducive to the onset of a harmful algal bloom (HAB, e.g., "red tide"). Actual near real-time in-situ fluorometry data was matched with wind speeds and photosynthetically active radiation at the Long Key SEAKEYS station in Florida Bay to simulate the onset of an HAB. These incidences were e-mailed to the knowledge engineer as they occurred, and could in the future be e-mailed to regulatory agencies, or posted to a Web site, as is done with a similarly developed expert system for coral bleaching. This approach shows promise with the future remote detection of HAB pigment data via in-situ or satellite sensors.

Houston, S.H., P.P. Dodge, M.D. Powell, M.L. Black, G.M. Barnes, and P.S. Chu. Surface winds in hurricanes from GPS-sondes: Comparisons with observations. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 339 (2000).

The Hurricane Research Division (HRD) of NOAA began dropping NCAR Global Positioning System (GPS) sondes in the vicinity of tropical cyclones (TC) on an experimental basis in 1996. High-resolution vertical profiles of wind speed and direction, temperature, dew point, and pressure were collected from flight-level to the surface. The boundary layer and near surface winds measured by sondes are considered particularly important, since few surface wind instruments operate in sustained wind speeds greater than 50 m/s. There have been some uncertainties about whether the profiles of boundary layer (especially near the surface) winds and thermodynamic measurements made by sondes in TC convective eyewalls were representative of conditions observed at the surface. In addition, the averaging times of sonde winds relative to fixed earth measurements from standard anemometers have been uncertain. Based on the preliminary results from data in relatively high winds from three hurricanes in 1998, the sondes appeared to be recording very accurate and representative wind speeds when compared to in-situ measurements from marine platforms. There appeared to be a slight negative bias in the sondes' reported surface wind speeds, while there was hardly any bias in the wind speeds adjusted to 10 m using the mean boundary layer winds averaged over the lowest 500 m layer. The pressure and temperature observations also showed good agreement between the sondes and surface platforms. Although these results are very preliminary, it appeared that the sondes provided accurate measurements in the boundary layer and near surface observations which are extremely beneficial for operational and research purposes. The sample size has been increased during the 1999 hurricane season. Therefore, more definitive statistics for sondes and surface platform comparisons that were available during the 1996-1999 hurricane seasons will be presented at the conference.

Jacob, S.D., L.K. Shay, P.G. Black, and S.H. Houston. Upper ocean response to hurricane wind asymmetries. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J66-J67 (2000).

No abstract.

Jacobs, S.D., L.K. Shay, A.J. Mariano, and P.G. Black. The 3D oceanic mixed layer response to Hurricane Gilbert. Journal of Physical Oceanography, 30(6):1407-1429 (2000).

Upper-ocean heat and mass budgets are examined from three snapshots of data acquired during and after the passage of Hurricane Gilbert in the western Gulf of Mexico. Measurements prior to storm passage indicated a warm core eddy in the region with velocities of O(1) m s^-1. Based upon conservation of heat and mass, the three-dimensional mixed layer processes are quantified from the data. During and subsequent to hurricane passage, horizontal advection due to geostrophic velocities is significant in the eddy regime, suggesting that prestorm oceanic variability is important when background flows have the same magnitude as the mixed layer current response. Storm-induced near-inertial currents lead to large vertical advection magnitudes as they diverge from and converge toward the storm track. Surface fluxes, estimated by reducing flight-level winds to 10 m, indicate a maximum wind stress of 4.2 N m^-2 and a heat flux of 1200 W m^-2 in the directly forced region. The upward heat flux after the passage of the storm has a maximum of 200 W m^-2 corresponding to a less than 7 m s^-1 wind speed. Entrainment mixing across the mixed layer base is estimated using three bulk entrainment closure schemes that differ in their physical basis of parameterization. Entrainment remains the dominant mechanism in controlling the heat and mass budgets irrespective of the scheme. Depending on the magnitudes of friction velocity, surface fluxes and/or shear across the mixed layer base, the pattern and location of maximum entrainment rates differ in the directly forced region. While the general area of maximum entrainment is in the right-rear quadrant of the storm, the shear-induced entrainment scheme predicts a narrow region of cooling compared to the stress-induced mixing scheme and observed SST decreases. After storm passage, the maximum contribution to the mixed layer dynamics is associated with shear-induced entrainment mixing forced by near-inertial motions up to the third day as indicated by bulk Richardson numbers that remained below criticality. Thus, entrainment based on a combination of surface fluxes, friction velocity, and shear across the entrainment zone may be more relevant for three-dimensional ocean response studies.

Jiang, M., F. Chai, R.C. Dugdale, R.T. Barber, T.-H. Peng, Y. Chao, and F.P. Wilkerson. Physical-biogeochemical modeling: Modulation of decadal variability on ENSO events in the equatorial Pacific. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F702, OS11B-18 (2000).

Although decadal scale physical changes have been observed at several locations in the Pacific Ocean, how these subtle but pervasive variations have altered ecosystem processes and biogeochemical fluxes remains largely unclear. To improve our understanding of physical variability and the ecosystem response in the Pacific Ocean, a coupled physical-biogeochemical model has been developed. A 10-component biogeochemical model has been embedded in a Modular Ocean Model (MOM) with modifications and configurations for the Pacific Ocean by Chao et al. at the JPL. The model is used to simulate both physical and biogeochemical conditions between 1955-1993. Based on this long-term model simulation, we present the results focused on the role of decadal variations on the ENSO events occurring before/after the climatic regime shift in 1976/1977. It is generally agreed that the signals of Pacific Decadal Oscillation (PDO) primarily originate from the northwest Pacific and affect the equatorial Pacific through intergyre exchanges or atmospheric teleconnections. The detailed nature of ENSO events may be modulated by these persistent processes. As a consequence, the ecosystem behaviors in the equatorial Pacific should be affected by the modulated ENSO, primarily through the depth of nutricline and upwelling variability. With preliminary modeled results, we examine the possible decadal trends of macro-nutrients (nitrate and silicate), which are regulating the primary production, and the evolution of nutrient concentrations during ENSO before and after climatic shifts. The phytoplankton responses to different levels of available macro-nutrients are studied as well.

Jones, R.W., and H.E. Willoughby. Linear motion of a two-layer baroclinic hurricane in shear. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 83-84 (2000).

No abstract.

Kang, W.-J., J.H. Trefy, T.A. Nelsen, H.R. Wanless. Direct atmospheric inputs versus runoff fluxes of mercury to the lower Everglades and Florida Bay. Environmental Science and Technology, 34(19):4058-4063 (2000).

Age-dated sediments from the lower Everglades and Florida Bay provide a record of inputs of excess Hg from direct atmospheric input versus runoff. Direct atmospheric fluxes of excess Hg to sediments in the lower Everglades and Florida Bay, calculated using a mass balance model for excess ²¹⁰Pb, currently average 24 ± 9 µg m^-2 yr^-1 and are comparable with recent results from bulk atmospheric deposition. In contrast, present-day runoff fluxes of excess Hg to area sediments are variable, ranging from about 4-160 µg m^-2 yr^-1. The runoff flux now carries 60-80% of the total flux of excess Hg to the sediments in areas near river sloughs but less than 20% of the total flux of excess Hg in more remote areas of Florida Bay. These results show the greater importance of runoff relative to direct atmospheric deposition for Hg inputs to many areas of the lower Everglades and immediately adjacent Florida Bay. Thus, the choice of future water management strategies can play an important role in controlling Hg inputs to the lower Everglades and portions of Florida Bay.

Kaplan, J., and M. DeMaria. Large-scale characteristics of rapidly intensifying tropical cyclones in the North Atlantic basin. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 232-233 (2000).

An analysis of recent operational Atlantic basin tropical cyclone forecasts issued by the National Hurricane Center indicates that tropical cyclone intensity forecasting has proven to be less skillful than has tropical cyclone track prediction. Moreover, the forecasting of rapid intensity change has proven to be especially difficult, as was underscored by the failure of operational models to adequately predict the rapid intensification of Hurricanes Opal (1995) and Bret (1999). In this study, data obtained from the SHIPS database for the period from 1989-1999 will be utilized to identify the large-scale conditions that appear to be conducive to rapid intensification. This will be accomplished by evaluating the magnitude of various synoptic variables (e.g., vertical shear, relative-eddy angular momentum fluxes) that were present at the start of each period of rapid intensification to determine if these conditions were significantly different from those associated with storms whose rates of intensification were much less rapid. In addition, data collected by the Hurricane Research Division during the 1999 hurricane season may also be employed to determine if the statistical results obtained by analyzing the SHIPS database can be confirmed by more detailed case studies.

Katsaros, K.B. Millennium perspectives. Bulletin of the American Meteorological Society, 81(4):837-838 (2000).

No abstract.

Katsaros, K.B., and R.T. Pinker. Algorithm improvement for novel applications in earth science research. Proceedings, First Meteosat Second Generation Research Announcement of Opportunity Workshop, Bologna, Italy, May 17-19, 2000. European Space Agency, ESA SP-452, 103-106 (2000).

No abstract.

Katsaros, K.B., P. Vachon, P.G. Black, P.P. Dodge, and E.W. Uhlhorn. Wind fields from SAR: Could they improve our understanding of storm dynamics? John Hopkins APL Technical Digest, 21(1):86-93 (2000).

Four hurricane images obtained by RADARSAT are examined for what they reveal about the storms. Features seen include strong variations in backscatter from the surface in and around convective cells associated with rain cells and rainbands, coupled with increased backscatter in regions of high wind outflow. Long linear features of scale 3-6 km are observed in three of the four hurricanes, probably from secondary circulations in the atmospheric boundary layer (roll vortices). They occur between convective rainbands, where the descending motion could produce a well-defined boundary layer. Although the origins of and the mechanisms producing the features are still not clear, the high resolution, wide-swath coverage modes of synthetic aperture radar provide new observations and present important questions for further research.

Kelly, P.S., K.M.M. Lwiza, R.K. Cowen, and G.J. Goni. Low-salinity pools at Barbados, West Indies: Their origin, frequency, and variability. Journal of Geophysical Research, 105(C8):19,699-19,708 (2000).

A vertical array of conductivity-temperature sensors moored off the west coast of Barbados, West Indies, from May 1996 to November 1997 revealed a heterogeneous and variable salinity pattern punctuated by six intrusions of low-salinity water (<34.5 psu) into the region. A typical intrusion extended to 30 m depth and lasted ~25 days, although one intrusion extended to 47 m and lasted 94 days. Water samples taken during an intrusion in May 1997 have Radium 228/226 activity ratios of approximately 1, consistent with previous measurements in Barbados of water that originated in the Amazon River mixing zone. The Amazon water likely was translated to Barbados in rings spawned from the North Brazil Current. Analysis of sea height anomaly derived from the TOPEX/Poseidon satellite supports this conclusion and reveals that, contrary to previous studies, rings are shed throughout the year, mostly during spring. The intrusions of low-salinity water and their associated velocities dramatically changed the already variable flow in our study area. We believe the complex salinity and flow we observed represented the disorganized remnants of rings that were at or near the ends of their lives. The changes we observed in the velocity and water structure are interesting in their own right as evidence of the Barbados region as a mixing zone and for their influence on recruitment of larval fishes to the reef along the island's west coast.

Kiesling, T.L., J. Fell, and P.B. Ortner. Rapid molecular identification of copepods froma plankton tow. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS234, OS41F-04 (2000).

Florida Bay is a 1000 square mile subtropical lagoon located between the Florida Keys and the Florida mainland. Like other estuarine systems, Florida Bay serves as a nursery ground for commercially and recreationally important species of fish. Despite the fact that the primary source of food for many first-feeding larval fish is copepod nauplii, the trophodynamic role of the zooplankton community in Florida Bay has historically been ignored. There is currently a multi-agency effort underway to describe the Florida Bay zooplankton community. Along with traditional sorting methods, molecular methods are being designed to identify and quantify juvenile stages of copepods so that their trophodynamic role can be more accurately defined. We have developed a microtiter plate based hybridization assay to identify copepod species in a mixed sample. With this method, species-specific probes based on DNA sequence are used to identify the copepod species. This method is superior to other PCR-based identification procedures, which require several PCR reactions using several species-specific primers to determine the identity of the DNA. Our technique requires one PCR reaction, which creates an amplicon using universal primers that target a region containing the probe sequences. This amplicon can be tested with a macroarray of several different probes on a single plate. This is especially important when dealing with the limited amounts of DNA that are extracted from these small metazoans. We isolated eight of the most common species of copepods found in Florida Bay, extracted their DNA and sequenced the large subunit of ribosomal DNA for each species. The rDNA sequences were compared and species-specific probes were designed based on base pair differences. Each probe was immobilized to the wells of a microtiter plate. The plates were hybridized with amplified and labeled target DNA from a mixed sample of copepods. If the DNA from the species in question was present in the DNA mix, it would bind to the species-specific probe. The labeled target DNA, once bound to the probe, can be detected via a colorimetric assay. With this method, We were able to identify each of six species of copepods from mixed samples. Testing is now proceeding with the juvenile forms of the copepods. Efforts are also underway to make the method quantitative.

King, D.B., J.H. Butler, S.A. Montzka, S.A. Yvon-Lewis, and J.W. Elkins. Implications of methyl bromide supersaturations in the temperate North Atlantic Ocean. Journal of Geophysical Research, 105(D15):19,763-19,769 (2000).

Methyl bromide saturation anomalies measured in the springtime North Atlantic and summertime North Pacific Oceans during 1998 revealed persistent supersaturations in the temperate waters of the northeastern Atlantic but undersaturtions in tropical waters of both oceans. A comparison of data from this study with those from a previous cruise to the northeastern Atlantic suggests that methyl bromide is cycled seasonally in these waters and perhaps in all temperate open-ocean waters. This means that the calculated net flux of methyl bromide into the oceans is slightly less negative than previously reported. With these new insights we estimate that the global air-sea flux of methyl bromide ranges from -11 to -20 Gg yr^-1. Data combined from this and three previous cruises support a flux dependence upon sea surface temperature, as reported recently by Groszko and Moore (1998). Whereas sea surface temperature can account for 40-70% of the observed variability in methyl bromide globally, it is able to reproduce only a small fraction of the observed seasonal cycle in the temperate northeastern Atlantic. The development of reliable predictions of air-sea fluxes of methyl bromide will require information on additional variables as well.

King, D.B., J.H. Butler, S.A. Montzka, S.A. Yvon-Lewis, and J.W. Elkins. Correction to "Implications of methyl bromide supersaturations in the temperate North Atlantic Ocean." Journal of Geophysical Research, 105(D20):24,713-24,714 (2000).

No abstract.

King, D.B., J.H. Butler, S.A. Yvon-Lewis, S.A. Montzka, and J.W. Elkins. Measurements of climatically important halocarbons in the North Pacific Ocean. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F277, B22A-01 (2000).

Atmospheric halocarbons are significant contributors to stratospheric ozone depletion and radiative heating of the atmosphere. Although we have a reasonable understanding of the budgets of those species that are solely anthropogenic, the calculated budgets of many naturally produced halocarbons are not in balance. The oceanic contribution to these budgets can be complex, is often large, and currently is not that well understood. Future changes in global climate likely will alter the concentrations of natural halocarbons in the air and seawater, and, consequently, their air-sea fluxes. Field measurements identify gross sensitivities that models can then use to assess the potential effects of such changes in global climate. NOAA/CMDL has measured the saturations of about 20 halocarbons during five separate research cruises, dating back to 1994. These field missions have encompassed a number of oceanic regions over different seasons. The results provide clues as to the overall behavior of these gases in the surface ocean and lower atmosphere. Here we present data from our most recent field project to the North Pacific Ocean (10°N-58°N) during September and October of 1999. CH₃Br was generally undersaturated, with supersaturations observed in some coastal waters. CH₃Cl was supersaturated south of 48°N, yet undersaturated in the Gulf of Alaska. CH₃I was supersaturated everywhere. Other brominated compounds, such as CH₂Br₂ and CHBr₃, were generally supersaturated with higher values occurring in the subtropics. A correlation between CH₂Br₂ and CHBr₃ seawater partial pressures suggests that these compounds have similar oceanic sources and/or sinks. Nucleophilic substitution can account for only some of the production of these compounds, implying that production from unidentified processes, such as photolysis or biology, is important. Relationships between the methyl halides and sea surface temperature can be useful in developing predictive models of organic halide concentrations and fluxes to the atmosphere. Correlations with other physical properties, such as chlorophyll, wind speed, and solar irradiance, are also investigated.

Lamb, M.F., C.L. Sabine, R.M. Key, J.L. Bullister, F.J. Millero, R.H. Wanninkhof, T.-H. Peng, A. Kozyr, and R.A. Feely. Dissolved inorganic carbon crossover points in the Pacific Ocean. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS122, OS22F-03 (2000).

Between 1991 and 1996, carbon measurements were made on 25 U.S. WOCE, U.S. JGOFS, and NOAA OACES cruises in the Pacific Ocean. These cruises were co-sponsored by the National Science Foundation, the U.S. Department of Energy, and NOAA's Climate and Global Change Program. Although at least two carbon parameters were measured on all of the cruises, dissolved inorganic carbon (DIC) was the only parameter common to all of the cruises. The measurements were collected over six years by ten different laboratories. Together, these data comprise the most comprehensive high-precision survey of carbon distributions in the Pacific Ocean with a greater than ten-fold increase in the number of samples analyzed than for the GEOSECS expedition of the early 1970s. As a part of the JGOFS Synthesis and Modeling Project, we have been working to combine these data into an internally consistent, unified data set. Additional DIC data collected by international investigators have also been included, where possible, to fill in holes in the U.S. survey program. In an effort to ensure the accuracy and internal consistency of these data, we have compared the deep water (>2000 m) DIC values measured on different cruises in areas where two or more cruises overlapped or crossed (within ~100 km). Data from each of the comparison stations were plotted against the density anomaly referenced to 3000 dbar (sigma 3). Polynomial fits of the data from each cruise were evaluated at evenly-spaced intervals over the density range common to both sets of stations. These results, together with information on the calibration procedures, analyses of Certified Reference Materials (CRMs), the quality of duplicate analyses, internal consistency with other carbon parameters, and with large-scale correlations with hydrographic parameters, were used to suggest minor adjustments to some of the cruises to optimize the internal consistency of the data. Our results show that a unified Pacific data set of over 30,000 samples can be achieved with an estimated precision and accuracy of ±2 µmol/kg.

Lamb, M.F., C.L. Sabine, R.A. Feely, F.J. Millero, R.H. Wanninkhof, R.M. Key, G.C. Johnson, K. Lee, T.-H. Peng, A. Kozyr, J.L. Bullister, and D. Greeley. Consistency and proposed adjustments of Pacific Ocean CO₂ survey data. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F700, OS11B-10 (2000).

Between 1991 and 1996, carbon measurements were made on 24 WOCE/JGOFS/OACES survey cruises in the Pacific Ocean. This combined database will be used to determine the distribution and inventory of carbon parameters in the Pacific Ocean, and will enhance our understanding of the ocean carbon cycle, including estimates of the anthropogenic CO₂ uptake by the oceans. Of the four measurable carbon parameters, (dissolved inorganic carbon (DIC), total alkalinity (TAlk), fugacity of CO₂ (fCO₂), and pH), DIC was measured on all the cruises, and TAlk was the second most measured. We examined the data where cruises overlapped using several independent techniques, and have proposed adjustments that will result in a consistent, unified data set. Based on our results, we recommend DIC adjustments for P16N, P17N, and P2, and TAlk adjustments for P8S, P17C, P17N, P2 and P31. Details of our proposed adjustments are posted at http://cdiac.esd.ornl.gov/oceans/glodap/index.html. This CO₂ data set represents the most comprehensive high-precision survey of carbon distributions in the Pacific Ocean since the GEOSECS expedition, and provides an order of magnitude improvement in the quality and quantity of Pacific DIC and Talk data. With the proposed adjustments, DIC and TAlk have an estimated overall accuracy of ~3 and 5 µmol kg^-1 respectively.

Landsea, C.W. Climate variability of tropical cyclones: Past, present, and future. In Storms (Volume 1), R.A. Peilke, Sr. and R.A. Peikle, Jr. (eds.). Routledge, New York (ISBN 041517239X), 220-241 (2000).

No abstract.

Landsea, C.W., and J.A. Knaff. Application of the El Niño-Southern Oscillation CLImatology and PERsistence (CLIPER) forecasting scheme. Experimental Long-Lead Forecast Bulletin, 9(1):32-34 (2000).

No abstract.

Landsea, C.W., and J.A. Knaff. Application of the El Niño-Southern Oscillation CLImatology and PERsistence (CLIPER) forecasting scheme. Experimental Long-Lead Forecast Bulletin, 9(2):31-33 (2000).

No abstract.

Landsea, C.W., and J.A. Knaff. How much "skill" is there in forecasting El Ni Niño? Weatherzine, 23:2-4 (2000).

No abstract.

Landsea C.W., and J.A. Knaff. How much skill was there in forecasting the very strong 1997-1998 El Niño? Bulletin of the American Meteorological Society, 81(9):2107-2120 (2000).

The very strong 1997-1998 El Niño was the first major event in which numerous forecasting groups participated in its real-time prediction. A previously developed simple statistical tool, the El Niño-Southern Oscillation Climatology and Persistence (ENSO-CLIPER) model, is utilized as a baseline for determination of skill in forecasting this event. Twelve statistical and dynamical models were available in real time for evaluation. Some of the models were able to outperform ENSO-CLIPER in predicting either the onset or the decay of the 1997-1998 El Niño, but none were successful at both for a medium-range two season (6-8 months) lead time. There were no models, including ENSO-CLIPER, able to anticipate even one-half of the actual amplitude of the El Niño's peak at medium-range (6-11 months) lead. In addition, none of the models showed skill (i.e., lower root-mean-square error than ENSO-CLIPER) at the zero season (0-2 months) through the two season (6-8 months) lead times. No dynamical model and only two of the statistical models (the canonical correlation analysis [CCA] and the constructed analog [ANALOG]) outperformed ENSO-CLIPER by more than 5% of the root-mean-square error at the three season (9-11 months) and four season (12-14 months) lead time. El Niño impacts were correctly anticipated by national meteorological centers one-half year in advance, because of the tendency for El Niño events to persist into and peak during the boreal winter. Despite this, the zero to two season (0-8 month) forecasts of the El Niño event itself were no better than ENSO-CLIPER and were in that sense, not skillful, a conclusion that remains unclear to the general meteorological and oceanographic communities.

Landsea, C.W., and J.A. Knaff. How much skill was there in forecasting the very strong 1997-1998 El Niño? Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J46 (2000).

No abstract.

Landsea, C.W., C.A. Anderson, G. Clark, P. Hungerford, C. Neumann, M. Zimmer, and J. Fernandez-Partagas. The Atlantic hurricane database re-analysis project: Results for 1851-1885. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A230-A231 (2000).

No abstract.

Landsea, C.W., C. Anderson, N. Charles, G. Clark, J. Fernandez-Partagas, P. Hungerford, C. Neumann, and M. Zimmer. The Atlantic hurricane database re-analysis project: Results for 1851-1885. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 542-543 (2000).

No abstract.

Lawrence, J.R., S.D. Gedzelman, and J.F. Gamache. Tropical cyclogenesis and stable isotope ratios of water. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 260-261 (2000).

No abstract.

Leaman, K.D., W.D. Wilson, and Z.D. Garraffo. Physical variability of surface currents in the the Panama-Colombia Gyre: Nature, causes, and comparisons with a high-resolution numerical model. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS33, OS11R-09 (2000).

As part of the National Oceanographic Partnership Program Year of the Ocean (YOTO) contribution, a total of 32 WOCE surface drifters have to date been launched in the southwestern Caribbean Sea using vessels of the Colombian Navy. These deployments consist of groups of eight surface drifters launched nominally every three to four months on a line between Cartagena and San Andres Island. All drifters have been drogued at a depth of 15 m and are designed to report surface positions and temperatures. This launch program is planned to continue through at least the next year with launches of six floats roughly every three months. These drifter tracks can be found at Web pages for the NOPP drifters (www.drifters.doe.gov), the IAS oceanography page (IASlinks.org), or the Intra-Americas Sea Initiative page (www.rsmas.miami.edu/groups/IASI/IASIhome.htm). The purpose of these deployments is to explore the structure and variability of a prominent circulation feature in the southwestern Caribbean known as the Panama-Colombia Gyre (PCG). This cyclonic gyre has been revealed by the drifter tracks obtained so far to be a permanent feature of the circulation but one that shows considerable seasonal and shorter-term variability as well. Retention times for drifters launched in the PCG are order several months. Very few drifters from the open Caribbean find their way into the PCG; however, a large number of PCG drifters exit the PCG at various locations and times, and a significant number of these become trapped in shelf waters south of Cuba. This latter fact has implications for biological problems of larval transport and interconnectivity of coastal habitats. Observed drifter tracks are compared to numerical surface drifters "deployed" in a high-resolution isopycnic-coordinate numerical model. Similar seasonal variability is observed in both real and numerical drifter trajectories; in particular, a deformation of the flow field in late summer has been observed in the model, as well as in two sequential years of drifter observations. Over longer periods, numerical drifter concentrations in the PCG decrease until a balance is achieved between northward Ekman advection and diffusion of drifters from the interior.

Lee, K., J.-Z. Zhang, and R. Wanninkhof. Carbon export in nitrate-depleted tropical and subtropical oceans: Implication of nitrogen fixation. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F693, OS72E-12 (2000).

The export of carbon from surface waters to the interior of the ocean is a central mechanism controlling the net uptake of carbon dioxide from the atmosphere. Existing estimates of the vertical carbon export vary greatly in regional and global comparisons. We estimate the biologically-mediated vertical carbon export, referred to as "new production," from the mean annual cycle of total inorganic carbon concentration normalized to salinity (NDIC = DIC × 35/S) in the mixed layer. It is assumed that the decrease in NCT from early spring to fall is solely caused by biological uptake and subsequent transport out of the upper oceans. Seasonal drawdown of NDIC in the mixed layer is quantified from regional algorithms relating NDIC to sea surface temperature (SST) and nitrate (NO₃^-) combined with seasonal changes in climatological SST and NO₃^- fields, and separately from the surface partial pressure of CO₂ and alkalinity fields using thermodynamic models. The two independent methods show similar regional trends and yield global new production values of 7.5 GtC/yr and 8.6 GtC/yr, respectively. A significant fraction of the global total, 0.8-1.1 GtC/yr, is exported in the absence of measurable nitrate levels in the oligotrophic tropical and subtropical oceans. This estimate is a direct indication of carbon export supported by nitrogen fixation. The value constitutes a significant fraction (30-50%) of the total new production in the oligotrophic oceans.

Lee, K., F.J. Millero, R.H. Byrne, R.A. Feely, and R. Wanninkhof. The recommended dissociation constants for carbonic acid seawater. Geophysical Research Letters, 27(2):229-232 (2000).

A coherent representation of carbonate dissociation constants and measured inorganic carbon species is essential for a wide range of environmentally important issues such as oceanic uptake of anthropogenic CO₂ and carbon cycle depictions in ocean circulation models. Previous studies have shown varying degrees of discordance between calculated and measured CO₂-system parameters. It is unclear if this is due to errors in thermodynamic models or in measurements. In this work, we address this issue using a large field data set (15,300 water samples) covering all ocean basins. Our field data, obtained using laboratory-calibrated measurement protocols, are most consistent with calculated parameters using the dissociation constants of Mehrbach et al. (1973) as refit by Dickson and Millero (1987). Thus, these constants are recommended for use in the synthesis of the inorganic carbon data collected during the global CO₂ survey during the 1990s and for characterization of the carbonate system in seawater.

Lee, K., R.H. Wanninkhof, R.A. Feely, F.J. Millero, and T.-H. Peng. Global relationships of total inorganic carbon with temperature and nitrate in surface seawater. Global Biogeochemical Cycles, 14(3):979-994 (2000).

High quality total inorganic carbon (C_T) measurements made in the major ocean basins as part of the Joint Global Ocean Flux Study (JGOFS), the National Oceanic and Atmospheric Administration/Ocean Atmosphere Carbon Exchange Study (NOAA/OACES), and the Department of Energy/World Ocean Circulation Experiment (DOE/WOCE) programs are related to sea surface temperature (SST) and nitrate (NO₃^-). A simple two-parameter function with SST and NO₃^- of the form NC_T = a + b SST + c SST² + d NO₃^- fits salinity (S)-normalized surface C_T (NC_T = C_T × 35/S) data for different parts of the oceans within an area-weighted error of ±7 µmol kg^-1 (1 sigma). Estimated values of NC_T using the derived algorithms with NO₃^- and SST are compared with values calculated from the surface partial pressure of CO₂ (pCO_2SW) (Takahashi et al., 1997) and total alkalinity (A_T) (Millero et al., 1998) fields using thermodynamic models. Comparisons of the estimated values of NC_T with measurements not used to derive the same algorithms, and comparisons with the values calculated from global A_T and pCO_2SW fields, give a realistic uncertainty of ±15 µmol kg^-1 in estimated C_T. The derived correlations of NC_T with SST and NO₃^- presented here make it possible to estimate surface C_T over the ocean from climatological SST, S, and NO₃^- fields.

Lee, W.-C., and F.D. Marks. An objective method to determine tropical cyclone center near landfall from WSR-88D data: The GBVTD-simplex algorithm. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 310-311 (2000).

No abstract.

Lee, W.-C., and F.D. Marks. Tropical cyclone kinematic structure retrieved from single Doppler radar observations, Part II: The GBVTD-simplex center finding algorithm. Monthly Weather Review, 128(6):1925-1936 (2000).

This paper is the second of a series and focuses on developing an algorithm to objectively identify tropical cyclone (TC) vorticity centers using single-Doppler radar data. The first paper dealt with the formulation of a single-Doppler radar TC wind retrieval technique, the ground-based velocity-track-display (GBVTD), and the results are verified using analytical TCs. It has been acknowledged that the quality of the GBVTD-retrieved TC circulation strongly depends on accurately knowing its center position. However, existing single-Doppler radar center finding algorithms are limited to estimate centers for axisymmetric TCs. The proposed algorithm uses a simplex method to objectively estimate the TC vorticity center by maximizing GBVTD-retrieved mean tangential wind. When tested with a number of axisymmetric and asymmetric analytical TCs, the accuracy of the TC centers estimated by the GBVTD-simplex algorithm is approximately equal to 340 m from the true center. When adding 5 m s^-1 random noise to the Doppler velocities, the accuracy of the TC centers is nearly unchanged at 350 m. When applying the GBVTD-simplex algorithm to Typhoon Alex (1987), the estimated uncertainty varies between 0.1 and 2 km. When the overall velocity gradient is weak, the uncertainties in the retrieved TC centers are usually large. The GBVTD-simplex algorithm sometimes has problems finding a solution when a large sector of Doppler radar data is missing in conjunction with weak velocity gradients. The GBVTD-simplex algorithm significantly reduces the uncertainties in estimating TC center position compared with existing methods and improves the quality of the GBVTD-retrieved TC circulation. The GBVTD-simplex algorithm is computationally efficient and can be easily adapted for real-time applications.

Lee, W.-C., B. J.-D. Jou, P.-L. Chang, and F.D. Marks. Tropical cyclone kinematic structure retrieved from single-Doppler radar observations. Part III: Evolution and structures of Typhoon Alex (1987). Monthly Weather Review, 128(12):3982-4001 (2000).

This paper is the third of a series that focuses on the applications of the ground-based velocity track display (GBVTD) technique and the GBVTD-simplex center finding algorithm developed in the previous two papers to a real tropical cyclone (TC). The evolution and structure of Typhoon Alex (1987), including full tangential winds, mean radial winds, one component of the mean flow, and their derived axisymmetric angular momentum and perturbation pressure fields are reconstructed from 16 volume scans (6.5 h of data with a 2-h gap) from the Civil Aeronautic Administration (CAA) Doppler radar while Typhoon Alex moved across the mountainous area in northern Taiwan. This analysis retrieves a plausible and physically consistent three-dimensional primary circulation of a landfalling TC using a single ground-based Doppler radar. Highly asymmetric wind structures were resolved by the GBVTD technique where the maximum relative tangential wind at z = 2 km evolved from 52 m s^-1 (before landfall), to less than 40 m s^-1 (after landfall), to less than 35 m s^-1 (entering the East China Sea). Alex's eye began to fill with precipitation while its intensity decreased rapidly after landfall, a characteristic of circulations disrupted by terrain. The mean radial wind field revealed a layer of low-level inflow in agreement with past TC observations. The outward slope of the eyewall reflectivity maximum was consistent with the constant angular momentum contours within the eyewall. After Alex entered the East China Sea, its circulation became more axisymmetric. The axisymmetric perturbation pressure field was retrieved using the gradient wind approximation, which, when used in conjunction with one or more surface pressure measurements within the analysis domain, can estimate the central pressure. The retrieved perturbation pressure fields at two time periods were compared with surface pressures reported in northern Taiwan. Considering the assumptions involved and the influence of terrain, good agreement (only 1V2-mb deviation) was found between them. This agreement indicates the relative quality of the GBVTD-retrieved axisymmetric circulation and suggests GBVTD-retrieved quantities can be useful in operational and research applications.

Lonfat, M., F.D. Marks, and S. Chen. A study of the rain distribution in tropical cyclones using TRMM/TMI. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 480-481 (2000).

No abstract.

Lonfat, M., F.D. Marks, and S. Chen. Characterization of the rain distribution in tropical cyclones using TRMM/TMI-PR. AGU 2000 Spring Meeting, Washington, D.C., May 30-June 3, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(19):S237-S238, H42B-16 (2000).

The goals of this study are (1) to improve our understanding of tropical cyclone (TC) precipitation fields by developing a climatology of rainfall distribution and vertical profiles of hydrometeors and heating in TCs around the globe, and (2) to develop methodologies to validate operational and research model forecasts of TC rainfall distribution and structure. Surface rain estimates from the NASA Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Precipitation Radar (PR) were used to study the global TC rainfall distribution. From November 1997 to December 1998, 87 storms were observed, providing approximately 1200 events, ranging from tropical storm intensity to category 4 hurricanes. At the time of the satellite measurement, approximately 70% of the events were tropical storms, 25% were category 1-2 hurricanes, and 5% were category 3 or higher. Although the sample size for major hurricanes is smaller than other categories, we have more than 50 observations, which is an order of magnitude larger than previous studies. TMI was used to develop the climatology, as the instrument swath allows a more extended coverage of the storms than PR. For each event, we derive mean rain rates in 10-km rings around the TC center. Averaging these distributions produces rates up to 5 mm h^-1 close to the center. Rain rates decrease rapidly below 1 mm h^-1 by 200 km radius. We examine the rain rate distribution as a function of the storm intensity and geographical location. Close to the storm center, the mean rates are greater than 15 mm h^-1 for category 3 and higher hurricanes, and about 3 mm h^-1 for tropical storms. Rain distributions show strong asymmetries in the rain patterns between the different basins. PR data were used on several individual 1999 storm cases (Floyd and Bret) and compared to TMI distributions. This comparison pointed out a problem in version 4 of the TMI surface rain algorithm. We are also in the process of comparing our TC rain rate distributions with a high-resolution model simulation. Our study provides a broad description of hurricane precipitation distributions, which is of fundamental use as a climatological basis, notably for simulation purpose, and gives a feedback for TRMM/TMI algorithm improvement as well.

Lonfat, M., F.D. Marks, and S.S. Chen. Comparison of TRMM/TMI-PR and airborne radar rainfall distributions in severe Atlantic hurricanes. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F158, A21G-08 (2000).

The goals of this study are to improve our understanding of tropical cyclone (TC) precipitation fields by constructing rainfall distributions in severe hurricanes, and to validate Tropical Rainfall Measuring Mission (TRMM) results by comparing distributions with aircraft radar observations. Surface rain estimates from the NASA TRMM Microwave Imager (TMI) and Precipitation Radar (PR) are used to determine rainfall distributions for five major 1998-1999 Atlantic hurricanes (category 3 or higher). Only TRMM orbits which fully observe TC cores are considered, in order to improve comparisons with aircraft data. Airborne radar data aboard the NOAA WP-3D aircrafts are examined for individual cases such as Floyd. For each event, we derive mean rain rates in 10 km rings around the TC center. Averaging distributions for TRMM/TMI produces rates up to 8 mm h^-1 close to the center, within about 70 km. Rates are below 1 mm h^-1 by 250 km. Rain rates from TRMM/PR are similar in magnitude close to the center, but decrease more sharply with radial distance than TMI rates. Probability density functions (PDF) are constructed as well. Both TMI and PR PDF resemble normal distributions. The TMI distribution is narrower and shifted to larger rain rates than the PR curve. Peaks are located at about 8 and 5 mm h^-1 respectively. TRMM/PR results seem to match better with airborne radar distributions than TMI does.

Luo, J., P.B. Ortner, D. Forcucci, and S.R. Cummings. Diel vertical migration of zooplankton and mesopelagic fish in the Arabian Sea. Deep-Sea Research, II, 47(7-8):1451-1473 (2000).

Acoustic (153 kHz ADCP and 12 kHz hull-mounted transducers) data and MOCNESS (MOC01 and MOC10) net tow samples collected in the Arabian Sea during the Spring Intermonsoon (April/May) and Southwest Monsoon (August) in 1995 documented substantial diel migrations of fish and zooplankton despite the year-round presence of an oxygen minimum (<0.2 ml l^-1 at 125-150 m). Fish and zooplankton layers were distinguished by comparing 12 kHz sonar and 153 kHz ADCP backscatter data, which indicated that the strongly migrating layers were predominantly composed of fishes. Fish vertical migration speeds were independently estimated from the slopes of the volume scattering layers and from the vertical velocity components of the ADCP, yielding average speeds of 4 and 3 cm s^-1 and maximum speeds of 13 and 10 cm s^-1, respectively. A few migrating zooplankton layers were identified with an average speed of about 2 cm s^-1 and maximum speeds as high as 8 cm s^-1. Migration depths for both zooplankton and fish differed somewhat amongst stations and appeared to be related to local hydrographic conditions (principally the vertical gradients in DO and water temperature). Zooplankton displacement volumes at individual sites suggested that zooplankton biomass during the Southwest Monsoon could be as much as fivefold greater than during the Spring Intermonsoon. This observation was confirmed for the region in general by first deriving a relationship between ADCP backscatter intensity and daytime zooplankton biomass and then comparing the latter between cruises using daytime ADCP data taken along a 1500 km transect that extended from the coast of Somalia to the center of the northern basin.

Marks, F.D., M.L. Black, and H.A. Friedman. 2000 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, FL (published for limited distribution), 97 pp. (2000).

No abstract.

Marks, F.D., L. Selevan, and J.F. Gamache. WSR-88D derived rainfall distributions in Hurricane Danny (1997). Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 298-299 (2000).

A tropical cyclone (TC) poses a significant quantitative precipitation forecast (QPF) problem as evidenced by the recent tragic loss of life and property from rainfall during Hurricanes Mitch (1998) and Floyd (1999). Improved QPF is one of the primary objectives of the U. S. Weather Research Program (USWRP), and a specific goal of the Hurricane at Landfall effort under USWRP. Estimates of rainfall based on radar and other remote sensors offer promising avenues for improvement. The current level of QPF skill for TCs in the United States is to predict the peak storm rainfall amount using the "rule of thumb" first proposed by Kraft in the late 1950s, which states that the maximum storm rainfall amount will be 100 inches divided by the storm forward motion in knots. While this "rule of thumb" provides a reasonable estimate of the peak storm total rain, it provides no information about the distribution of rain in space or time. There is also no adjustment in the rule for storm intensity, topography, or other dynamical or microphysical parameters. A major stumbling block to improving over this simple "rule of thumb" is a lack of a comprehensive climatology of TC precipitation, i.e., a description of the distribution of rain in space and time. This study focuses on the distribution of WSR-88D radar derived rain in space and time during Hurricane Danny from 17-21 September 1997. The WSR 88D radars provides 1-h mean rain estimates (R) over a domain extending to 230 km range from the radar with a 4 × 4 km resolution (Digital Precipitation Array, DPA). Over the four days, Danny, a category 1 hurricane, was visible from four different WSR-88D radars as it tracked slowly east-northeastward along the Gulf coast. The rain estimates from the four radars provide an excellent opportunity to estimate the TC precipitation distribution in space and time as the storm passed along the Louisiana, Mississippi, and Alabama coasts. The radial distribution of the mean R is calculated in 10 km radial bands out to 300 km from the storm center for each hour and for the total four-day period. The probability distribution of R is also computed for each 10 km radial band in 1 dBR (10log_10R) steps from 0.3-300 mm h^-1 (-5 to 25 dBR) for each hour and the total four-day period. These distributions in range and intensity are compared to results from earlier studies done using rain gage estimates.

Mayer, D.A., M.O. Baringer, R.L. Molinari, G.J. Goni. Comparison of hydrographic and altimetric estimates of sea level height variability in the Atlantic Ocean. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F740, OS21D-13 (2000).

Using an ensemble of expendable bathythermograph (XBT) profiles and TOPEX/Poseidon (T/P) altimeter data, we have considered how much can be inferred about the internal field of mass from sea level changes for the period 1993 through 1997. Sea height anomalies (SHA) derived from T/P data are compared to temperature anomalies (TA) and to dynamic height anomalies (DHA) from 10°S to 40°N along two well sampled XBT sections on the western and eastern sides of the Atlantic Ocean. XBT profiles were matched (time/location) to SHA, converted into DHA using TS relationships and then binned monthly into 2° of latitude by 4° of longitude boxes. The vertical mass distribution cannot always be inferred from SHA alone. Specifically, the relationships between SHA and both TA and DHA can be problematic if SHA are small. This occurs in the transition regions between the tropics (where temperature variability is largest in the thermocline due to wind-driven ocean dynamics), and in the subtropics (where variability is largest near the surface due to surface fluxes). Transition regions are characterized by competing influences between surface and thermocline variability that act in opposition; hence, SHA are not particularly well suited in drawing inferences about the temperature of the upper ocean. Generally, the relationships between SHA and DHA for residual signals (obtained by removing the annual cycle) are poor. The exceptions are in two areas of large sea height variability in the western basin where there is significant interannual variability. The first is in the tropics in the vicinity of the tropical gyre trough, and the second is in the Gulf Stream near 70°W, 38°N. An analysis of Panulirus data at (32.2°N, 64.5°W) suggests that in-situ data may be needed down to at least 1000 m where interannual variability accounts for about 40% of the SHA variance.

McAdie, C.J., and P.P. Dodge. Maximum sustained winds in Hurricane Irene as measured by the Miami WSR-88D. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 212-213 (2000).

No abstract.

McArthur, C., R. Ferry, and J.R. Proni. Amenities monitoring for dredged material disposal management. Proceedings, 17th Conference of the Coastal Society: Coasts at the Millennium, Portland OR, July 9-12, 2000. The Coastal Society, 6 pp. (2000).

Valuable amenities are present throughout U.S. coastal waters, from coral reefs, to oyster beds, to coastal fisheries. In essentially every case in which navigation and/or maintenance dredging is contemplated, the issues of potential impact of dredging activities on nearby amenities arise. In order to evaluate that potential impact, long-term monitoring of amenities is required. Key management issues related to amenities include: (1) reduction or elimination of dredging impacts; (2) scheduling ("windows") for dredging and dredged material disposals; (3) monitoring of transport to, and effects upon amenities; and (4) compliance with defined procedures for dredging activities. While the data needed for management decisions may vary from location to location, certain basic measurement needs appear almost universally: (1) characterization and quantification of dredged sediments arriving at amenities sites; (2) determination of "natural" sediment ranges at amenities sites; (3) photosynthetic light reductions; (4) sediment resuspension and transport; and (5) other sources of materials of potential impact to amenities sites. Dredging and disposal must also be considered in the context of temporal "windows." In the Miami Offshore Disposal Site project, data for management of dredging activities is coordinated between the disposal and amenities (coral reef) sites where dumping windows are determined by realtime current meter data, indicating potential transport to the reef site. In the Pacific Northwest, "curtains" of dredge-related sediment may inhibit upstream spawning activities of valued fisheries resources and thus they are subject to similar temporal windows.

Mestas-Nunez, A.M. Orthogonality properties of rotated empirical modes. International Journal of Climatology, 20(12):1509-1516 (2000).

The properties (spatial orthogonality and temporal uncorrelatedness) of orthogonally-rotated empirical modes depend on the normalization of the modes, prior to rotation. It is shown here that these properties also depend on how the empirical modes are formulated. The preferred convention is one that allows us to reconstruct the data from the unrotated or rotated modes. When the empirical modes are normalized so that the spatial eigenvectors are unit length (i.e., EOFs), the rotated modes preserve spatial orthogonality but are no longer temporally uncorrelated. Relaxing the temporal orthogonality in this way does not prejudice conclusions that can be inferred regarding the temporal couplings of the rotated modes.

Mestas-Nunez, A.M., and D.B. Enfield. El Niño-Southern Oscillation: Canonical and non-canonical aspects. Proceedings, 24th Annual Climate Diagnostics and Prediction Workshop, Tucson, AZ, November 1-5, 1999. National Weather Service, 111-114 (2000).

The main goal of this paper is to investigate and compare the atmospheric signatures associated with the canonical ENSO and residual components of the SST anomaly variability in the eastern tropical Pacific. An expanded version of this paper will appear in the Journal of Climate (Mestas-Nuñez and Enfield, 2001).

Molinari, R.L., and J.F. Festa. Effect of subjective choices on the objective analysis of sea surface temperature data in the tropical Atlantic and Pacific Oceans. Oceanologica Acta, 23(1):3-14 (2000).

Many subjective choices are required to perform an objective interpolation (OI) analysis of environmental variables. Herein, we consider the effects on the statistical analysis of sea surface temperature (SST) using (1) a structure function or covariance analysis, (2) different analytical expressions to represent the statistics of the raw data, and (3) different historical SST data sets. The historical data sets are the well-sampled Comprehensive OceanAtmospheric Data Set (COADS) and the poorly sampled historical expendable bathythermograph (XBT) data set. Results from these analyses are used to generate error maps for a poorly-sampled, two month XBT array and a proposed well-sampled profiling float array. For the relatively data-rich COADS analysis, decorrelation scales are the same using either the structure function or covariance analyses. Results differ for the data-poor XBT analysis. Representative decorrelation scales in the Pacific (Atlantic) are about 11-14 (6-10) degrees in the zonal direction and 4-7 (3-6) degrees in the meridional direction. As COADS SST data are less precise than XBT SST data, error and signal variances are greater for the former. The choice of analytical fit to the raw data (needed to generate error maps) has a dramatic effect on the resulting uncertainty fields. Gaussian fits, because of their parabolic shape near the origin, result in smaller errors than exponential fits for the same observing array. Finally, the proposed float array can achieve the accuracies needed to resolve satisfactory upper layer heat content changes over larger areas than the present XBT network.

Morisseau-Leroy, N., M.K. Solomon, and J. Basu. Oracle 8i: Java Component Programming. Osborne McGraw-Hill (ISBN 0072127376), 697 pp. (2000).

No abstract.

Murillo, S.T., W.-C. Lee, and F.D. Marks. Evaluating the GBVTD-tropical center finding simplex algorithm. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 312-313 (2000).

The GBVTD simplex algorithm has been tested using axisymmetric and asymmetric analytic tropical cyclones by Lee et al. (1999). The algorithm objectively identifies the tropical cyclone center by maximizing the GBVTD-derived mean tangential wind field. Lee and Marks (1999) applied the GBVTD simplex algorithm to Typhoon Alex (1987). However, a true center was not available to verify the accuracy of the algorithm. This study applies the GBVTD simplex algorithm to Hurricane Danny (1997). The estimated storm track derived by the algorithm is compared to radar and aircraft storm fixes. The derived track is in good agreement with the true storm track within 2 km. Results will be presented that show how the GBVTD simplex algorithm improves the quality of the GBVTD retrieved wind analysis.

Nelsen, T.A., S.J. Stamates, B.J. Elkind, W.P. Dammann, and J.R. Proni. Field evaluation of the temporal and spatial variations in total suspended matter and current fields at Chesapeake Bay Site 104 and contiguous areas. Final Report, U.S. Army Corps of Engineers, MIPR No. W81W3@00604995, 47 pp. (2000).

No abstract.

Nolan, D.S., M.T. Montgomery, and P.D. Reasor. Studies of the wavenumber one instability in hurricane-like vortices. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 29-30 (2000).

No abstract.

Ooyama, K.V. A dynamic and thermodynamic foundation for modeling the moist atmosphere with classical thermodynamics and parameterized microphysics. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 561-562 (2000).

No abstract.

Otero, S., N. Morisseau-Leroy, N. Carrasco, and M.D. Powell. A distributed real-time hurricane wind analysis system. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 197-198 (2000).

No abstract.

Parrish, J.R., M.L. Black, S.H. Houston, P.P. Dodge, and J.J. Cione. The structure of Hurricane Irene over South Florida. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 456-457 (2000).

On October 15, 1999, Hurricane Irene made landfall on the southwest coast of Florida and tracked to the northeast across the peninsula before emerging into the Atlantic Ocean north of Palm Beach. Irene was a Category 1 hurricane at landfall with maximum sustained surface winds estimated at 65 kts and a central pressure of ~982 mb. A NOAA WP-3D aircraft conducted a landfall research mission during the time Irene was crossing Florida. The aircraft, operated by the Aircraft Operations Center (AOC) and staffed by scientists from HRD, flew at an altitude of 8,000 feet and completed a flight track that provided coverage over the South Florida Peninsula and adjacent coastal waters in the Gulf of Mexico, Florida Bay, and Atlantic Ocean. In addition to the in-situ wind and thermodynamic measurements at flight-level, observations from the airborne Doppler tail radar, lower-fuselage radar, GPS dropsondes, and step-frequency microwave radiometer (SFMR, surface wind speeds) were collected by the AOC and HRD crew. A detailed description of the wind and thermodynamic structure of Irene while over South Florida will be presented. Of particular interest is comparisons of flight-level wind measurements with surface observations from regular observing sites over land and from C-MAN and buoy measurements, and those from the GPS dropwindsondes and the SFMR. Satellite imagery showed that intense, deep convection was occurring over the center of Irene, obscuring the eye and eyewall that was visible on radar displays beneath the high clouds. An unusual aspect of Irene was the extremely dry air that was entraining into the west side of the storm and that may have contributed to some of the observed asymmetries and to the clear-air turbulence encountered by the P-3 aircraft.

Peng, T.-H., and F. Chai. Modeling the carbon cycle in the equatorial Pacific Ocean. Proceedings, Marine Environment: The Past, Present, and Future, Kaohsiung, Taiwan, January 26-28, 1999. Sueichan Press, 240-255 (2000).

An ocean ecosystem model of the equatorial Pacific Ocean has been developed with new and export productivity regulated by Si and Fe to synthesize and analyze data collected during the JGOFS process-study-oriented survey cruises in 1992. The data also include those obtained by NOAA/OACES cruises in concert with the JGOFS EqPac process study. The circulation model is based on the Modular Ocean Model of the NOAA/GFDL ocean general circulation model. The ecosystem model is originally formulated by Chai et al. (1996), and is now expanded to consist of nine components describing two sizes of phytoplankton, two sizes of zooplankton, two detritus pools, and three dissolved nutrients: silicate, nitrate, and ammonium. The carbonate chemistry is parameterized in the model to evaluate the variations of pCO₂ and, hence, the CO₂ flux across the air-sea interface. At this initial stage, a test case by using a 1D model is performed to simulate low-silicate, high-nitrate, and low-chlorophyll conditions in the equatorial Pacific, and to investigate how the carbon system behaves in this ecosystem structure. The model includes the vertical upwelling and diffusion processes. The modeled upwelling rate and vertical diffusivity, from a 3D circulation model, were initially averaged for the region with latitudes 5°S to 5°N, and longitude 180° to 90°W, the "cold tongue" of the equatorial Pacific. Temperature is used to calibrate model upwelling and vertical diffusion rates. Comparison of model results with the observations made during the NOAA/OACES EqPac 1992 expeditions indicates that the vertical profiles of DIC, NO₃, and Si(OH)₄ are consistent with the measurements made in the fall season when the ocean was in a normal non-El Niño condition. A tight fit of profiles between model and observation is not possible because of spatial variations of the observed values. A 3D simulation is required, which is in progress. The 1D model CO₂ evasion rate is estimated to be 2.9 mol/m²/yr, which is consistent with the range of estimates from measurements made during non-El Niño conditions.

Powell, M.D. Performance of the HRD real-time Hurricane Wind Analysis System in 1999. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A232-A237 (2000).

No abstract.

Powell, M.D. Tropical cyclones during and after landfall. In Storms (Volume 1), R. Peilke, Sr. and R. Peikle, Jr. (eds.). Routledge, New York (ISBN 041517239X), 196-219 (2000).

No abstract.

Powell, M.D., and S.D. Aberson. Accuracy of U.S. hurricane landfall forecasts in the Atlantic basin (1976-1998). Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A138-A139 (2000).

No abstract.

Powell, M.D., and S.D. Aberson. Accuracy of U.S. hurricane landfall forecasts in the Atlantic basin (1976-1998). Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 326 (2000).

No abstract.

Powell, M.D., A. Lazar-Viront, and D. Bowman. Documentation of automatic weather station wind exposure in tropical cyclone areas. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A260-A264 (2000).

No abstract.

Powell, M.D., T.A. Reinhold, and R.D. Marshall. Tropical cyclone boundary layer wind variability. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J57 (2000).

No abstract.

Proni, J.R. Using acoustical methods to study and monitor the discharge of sewage and dredged-material in the coastal ocean. Proceedings, Fifth European Conference on Underwater Acoustics (ECUA 2000), Lyon, France, July 10-13, 2000. European Acoustics Association, Volume 1, 755-760 (2000).

Acoustical backscatter has been shown to be very effective in the study and monitoring of sewage efffluent and dredged material released into the coastal waters. Acoustical detection of a detrainment phenomenon in discharge plumes shows the extreme sensitivity of effluent distributions to small water column density changes. Acoustic measurements, as part of an ensemble of sensor systems, reveal turbidity changes occurring at environmentally valuable biological communities such as coral reefs and oyster beds. Examples of acoustic observations are presented.

Quilfen Y., A. Bentamy, P. Delecluse, K.B. Katsaros, and N. Grima. Prediction of sea level anomalies using ocean circulation model forced by scatterometer wind and validation using TOPEX/Poseidon data. IEEE Transactions on Geoscience and Remote Sensing, 38(4):1871-1884 (2000).

Uncertainties in the surface wind field have long been recognized as a major limitation in the interpretation of results obtained by oceanic circulation models. It is especially true in the tropical oceans, where the response to wind forcing is very strong on short time scales. The purpose of this paper is to show that these uncertainties can be greatly reduced by using spaceborne wind sensors that provide accurate measurements on a global basis. Surface winds over the global oceans have been measured by scatterometry since the launch of the European Remote Sensing Satellite (ERS-1) in August 1991 by the European Space Agency, Noordwijk, The Netherlands, and is currently provided by ERS-2, launched in April 1995. The ground-track wind vectors are processed to compute mean weekly surface winds onto a 1° square grid at the Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER), Plouzane, France. These winds are validated by comparison with the buoy array in the tropical Pacific Ocean, showing good agreement. In order to further evaluate this wind field, the three-dimensional ocean model OPA7 developed at Laboratoire d'Océanographie Dynamique et de Climatologie, Paris, France, is forced over the tropical oceans by the ERS-derived wind stress fields and by fields from the atmospheric model "Arpege/Climat." Selected ocean parameters are defined in order to validate the ocean model results with measurements of the tropical ocean and global atmosphere (TOGA) buoys in the Pacific Ocean. The ability of the model to describe the short scale (a few weeks to a few years) oceanic variability is greatly enhanced when the satellite-derived surface forcing is used. In this paper, we present further comparison of the ocean model results with the TOPEX-Poseidon altimeter measurements. Simulated and measured sea level variability are described over the three tropical oceans. The annual and semi-annual signals, as well as the interannual variability, partly linked to the El Niño-Southern Oscillation (ENSO) phenomenon, are well simulated by the OPA7 model when the satellite winds are used. Furthermore, it shows that the objective method, kriging technique, used to interpolate the mean ERS wind fields, dramatically reduces the effects of the satellite bandlike sampling. In the last part of this paper, we focus on the relationship between the wind stress anomalies and the sea level anomalies in the case of the 1997-1998 El Niño event. It clearly shows that sea level anomalies in the eastern and western parts of the Pacific are strongly linked to wind stress anomalies in the central Pacific. The forthcoming scatterometers aboard the METOP and ADEOS satellites will provide a much better coverage. It will enable the wind variability spatial and temporal scales to be resolved better, in order that wind uncertainties no longer blur the interpretation of ocean circulation numerical model results.

Reasor, P.D., and M.T. Montgomery. 3D alignment and co-rotation of weak, TC-like vortices via linear vortex Rossby waves. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 268-269 (2000).

No abstract.

Reasor, P.D., M.T. Montgomery, F.D. Marks, and J.F. Gamache. Low-wavenumber structure and evolution of the hurricane inner core observed by airborne dual-Doppler radar. Monthly Weather Review, 128(6):1653-1680 (2000).

The asymmetric dynamics of the hurricane inner-core region is examined through a novel analysis of high temporal resolution, three-dimensional wind fields derived from airborne dual-Doppler radar. Seven consecutive composites of Hurricane Olivia's (1994) wind field with 30-min time resolution depict a weakening storm undergoing substantial structural changes. The symmetric and asymmetric mechanisms involved in this transformation are considered separately. To zeroth order the weakening of the primary circulation is consistent with the axisymmetric vortex spindown theory of Eliassen and Lystad for a neutrally-stratified atmosphere. Vertical shear, however, increased dramatically during the observation period, leading to a strong projection of the convection onto an azimuthal wavenumber 1 pattern oriented along the maximum vertical shear vector. Recent theoretical ideas elucidating the dynamics of vortices in vertical shear are used to help explain this asymmetry. The role of asymmetric vorticity dynamics in explaining some of the physics of hurricane intensity change motivates a special focus on Olivia's vorticity structure. It is found that an azimuthal wavenumber 2 feature dominates the asymmetry in relative vorticity below 3-km height. The characteristics of this asymmetry deduced from reflectivity and wind composites during a portion of the observation period show some consistency with a wavenumber 2 discrete vortex Rossby edge wave. Barotropic instability is suggested as a source for the wavenumber 2 asymmetry through a series of barotropic numerical simulations. Trailing bands of vorticity with radial wavelengths of 5-10 km are observed in the inner core approximately 20 km from the storm center, and may be symmetrizing vortex Rossby waves. Elevated reflectivity bands with radial scales comparable to those of the vorticity bands, also near 20-25-km radius, may be associated with these vorticity features.

Roemmich, D., O. Boebel, Y. Desaubies, H. Freeland, B. King, P.-Y. Letraon, R.L. Molinari, W.B. Owens, S. Riser, U. Send, K. Takeuchi, and S. Wijffels. Argo: The global array of profiling floats. OCEANOBS99: International Conference on the Ocean Observing System for Climate, Saint Raphael, France, October 18-22, 1999. Centre National d'Etudes Spatiales, 12 pp. (2000).

A broad-scale global array of temperature/salinity (T/S) profiling floats, known as Argo, is planned as a major component of the ocean observing system, with deployment scheduled to begin in 2000. Conceptually, Argo builds on the existing upper-ocean thermal networks, extending their spatial and temporal coverage, depth range and accuracy, and enhancing them through addition of salinity and velocity measurements. The name Argo is chosen to emphasize the strong complementary relationship of the global float array with the Jason altimeter mission. For the first time, the physical state of the upper ocean will be systematically measured and assimilated in near real time. Objectives of Argo fall into several categories. Argo will provide a quantitative description of the evolving state of the upper ocean and the patterns of ocean climate variability, including heat and freshwater storage and transport. The data will enhance the value of the Jason altimeter through measurement of subsurface vertical structure (T(z), S(z)) and reference velocity, with sufficient coverage and resolution for interpretation of altimetric sea surface height variability. Argo data will be used for initialization of ocean and coupled forecast models, data assimilation, and dynamical model testing. A primary focus of Argo is seasonal to decadal climate variability and predictability, but a wide range of applications for high-quality global ocean analyses is anticipated. The initial design of the ARGO network is based on experience from the present observing system, on newly gained knowledge of variability from the TOPEX/Poseidon altimeter, and on estimated requirements for climate and high-resolution ocean models. Argo will provide 100,000 T/S profiles and reference velocity measurements per year from about 3000 floats distributed over the global oceans at 3-degree spacing. Floats will cycle to 2000 m depth every 10 days, with a 4-5 year lifetime for individual instruments. All Argo data will be publicly available in near real-time via the GTS, and in scientifically quality-controlled form with a few months delay. Global coverage should be achieved during the Global Ocean Data Assimilation Experiment, which together with CLIVAR and GCOS/GOOS, provide the major scientific and operational impetus for Argo. The design emphasizes the need to integrate Argo within the overall framework of the global ocean observing system. International planning for Argo, including sampling and technical issues, is coordinated by the Argo Science Team. Nations presently having Argo plans that include float procurement or production include Australia, Canada, France, Germany, Japan, the U.K., and the U.S.A., plus a European Union proposal. Combined deployments from these nations may exceed 700 floats per year as early as 2001. Broad participation in Argo by many nations is anticipated and encouraged either through float procurement, logistical support for float deployment, or through analysis and assimilation of Argo data.

Rogers, R.F. Surface-based modification of convectively-generated mesovortices and its implications for tropical cyclogenesis. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 151-152 (2000).

Numerical simulations have been performed on a long-lived midlevel mesovortex over the continental United States that was instrumental in initiating and organizing multiple cycles of deep convection. These simulations showed how the cycles of convective redevelopment amplify the mid- to upper-level warm core of the vortex, causing the cyclonic vorticity to strengthen in the midlevels and penetrate down into the lower troposphere, briefly reaching the surface. However, low-level cooling caused by convective and mesoscale downdrafts and adiabatic ascent offsets the impact of the mid- to upper-level warming, limiting the extent to which the cyclonic vorticity penetrates to the surface. In this study the impact of weakening the surface-based cold pool on the structure of the simulated mesovortex is investigated. Methods for weakening the cold pool in the simulations include: eliminating the convective (subgrid-scale) and mesoscale (resolvable-scale) downdrafts and replacing the lower land boundary with a water surface of varying temperatures. The resultant structures of the mesovortex for these different conditions are compared to explain how a mesovortex, with cyclonic vorticity initially confined to the midlevels, can grow downward to the surface, marking a key step in the tropical cyclogenesis process.

Rogers, R.F., J.M. Fritsch, and W.C. Lambert. A simple technique for using radar data in the dynamic initialization of a mesoscale model. Monthly Weather Review, 128(7):2560-2574 (2000).

A simple technique for using radar reflectivity to improve model initialization is presented. Unlike previous techniques, the scheme described here does not infer rain rates and heating profiles from assumed relationships between remotely-sensed variables and precipitation rates. Rather, the radar data are only used to tell the model when and where deep moist convection is occurring. This information is then used to activate the model's convective parameterization scheme in the grid elements where convection is observed. This approach has the advantage that the convective precipitation rates and heating profiles generated by the convective parameterization are compatible with the local (grid element) environment. The premise is that if convection is forced to develop when and where it is observed during a data assimilation period, convectively-forced modifications to the environment will be in the correct locations at the model initial forecast time and the resulting forecast will be more accurate. Three experiments illustrating how the technique is applied in the simulation of deep convection in a warm-season environment are presented: a control run in which no radar data are assimilated, and two additional runs where radar data are assimilated for 12 h in one run and 24 h in the other. The results indicate that assimilating radar data can improve a model's description of the mesoscale environment during the pre-forecast time period, thereby resulting in an improved forecast of precipitation and the mesoscale environment.

Rogers, R.F., S.S. Chen, J.E. Tenerelli, and M. Lonfat. A numerical study of the distribution of precipitation in Hurricane Bonnie (1998). Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 408-409 (2000).

As the damage that accompanied the floods from Hurricanes Georges and Mitch of 1998 and Floyd and Irene of 1999 dramatically highlighted, rainfall is one of the most significant impacts that accompanies a landfalling tropical cyclone. However, quantitative precipitation forecasting (QPF) is one of the most difficult problems in tropical cyclone forecasting. Rainfall measured at a particular location during the landfall of a tropical cyclone depends on many factors, such as the location with respect to the storm's track, the intensity and distribution of rainfall around the storm, the translational speed of the storm, and local effects such as topography and orientation of the coast. Understanding how these and other factors influence the precipitation distribution of landfalling hurricanes is an important step in improving hurricane QPFs. In this study, the distribution of precipitation from Hurricane Bonnie (1998) is explored by performing a numerical simulation using the primitive-equation, nonhydrostatic mesoscale model MM5. A six-day simulation is performed, and precipitation fields from the innermost domain (5-km grid length) are compared against observations. The wealth of observational information that accompanied the third phase of the NASA Convection and Moisture Experiment (CAMEX-3) field program, including the NASA TRMM satellite and various airborne observations from the NOAA P-3's and G-IV and the NASA DC-8 and ER-2, are used to validate the simulation. Statistics related to precipitation distribution, such as radial profiles of rainfall, radial-height profiles of hydrometeors, and probability distributions of various rainfall thresholds, are presented for the simulation and the observations from the TRMM satellite. Validation of these parameters will lend confidence in the skill of the model in capturing the precipitation distribution and enable an investigation of the physical processes governing the distribution to be performed in a later study.

Rogers, R.F., S.D. Aberson, J. Kaplan, S.B. Goldenberg, B. Damiano, R. McNamara, and J. Parrish. Pronounced upper-tropospheric temperature anomalies encountered by the Gulfstream-IV in the vicinity of deep convection. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 15-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., 275-279 (2000).

In several instances during the 1999 hurricane season, temperature sensors aboard the NOAA Gulfstream-IV (G-IV) aircraft measured significant temperature increases (some as large as 40°C) while flying between 41,000 and 45,000 feet in the vicinity of deep convection. Similar temperature anomalies have been encountered by commercial aircraft flying at similar altitudes and balloon measurements taken at high temporal frequency in the proximity of deep convection. In this presentation, the observations gathered from the G-IV are summarized and compared to observations taken previously. While it is still not certain whether or not the anomalies measured by the sensors aboard the G-IV last year owed their existence to real meteorological phenomena or to instrument deficiencies, it is important to document this occurrence, since the response of the aircraft's autopilot is to change altitude and airspeed. Suggestions for how to avoid this from happening again are also offered.

Sabine, C.L., R.H. Wanninkhof, R.M. Key, C. Goyet, and F.J. Millero. Seasonal CO₂ fluxes in the tropical and subtropical Indian Ocean. Marine Chemistry, 72(1):33-53 (2000).

Improved estimates of the variability in air-sea CO₂ fluxes on seasonal and interannual time scales are necessary to help constrain the net partitioning of CO₂ between the atmosphere, oceans, and terrestrial biosphere. Few direct measurements of the carbon system have been made in the main Indian Ocean basin. In the mid 1990s, several global carbon measurement programs focused on the Indian Ocean, greatly increasing the existing carbon database for this basin. This study examines the combined surface CO₂ measurements from three major U.S. programs in the Indian Ocean: the global carbon survey cruises, conducted in conjunction with the World Ocean Circulation Experiment (WOCE); the NOAA Ocean-Atmosphere Carbon Exchange Study (OACES) Indian Ocean survey; and the Joint Global Ocean Flux Study (JGOFS) Arabian Sea Process Study. These data are fit with multiparameter linear regressions as a function of commonly-measured hydrographic parameters. These fits are then used with NCEP/NCAR reanalysis and Levitus 94 gridded values to evaluate the seasonal variability of surface seawater CO₂ in the tropical and subtropical Indian Ocean and to estimate the magnitude of the Indian Ocean as a net sink for atmospheric CO₂. The net annual flux for the Indian Ocean (north of 36°S) was -12.4 ± 0.5 × 10¹² mol of carbon (equivalent to -0.15 Pg C) in 1995. The relatively small net flux results from the very different surface water pCO₂ distributions and seasonal variations in the northern and southern Indian Ocean. The equatorial and northern hemisphere regions have values that are generally above atmospheric values. During the southwest monsoon, pCO₂ values in the Arabian Sea coastal upwelling region are among the highest observed in the oceans. The upwelling is seasonal in nature, however, and only affects a relatively small area. The Indian Ocean equatorial region generally has values slightly above atmospheric. Unlike the Pacific and Atlantic Oceans, however, no clear equatorial upwelling signature was observed in 1995. The Southern Hemisphere Indian Ocean, which represents the largest region by area, generally has values below atmospheric. The strongest undersaturations are observed in the austral winter, with summer values reaching near or slightly above atmospheric.

Sabine, C.L., R.A. Feely, R.M. Key, F.J. Millero, R.H. Wanninkhof, T.-H. Peng, A. Kozyr, J.L. Bullister, K. Lee, and M.F. Lamb. Anthropogenic CO₂ distributions in the Pacific. AGU 2000 Fall Meeting, San Francisco, CA, December 15-19, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(48):F692, OS72E-02 (2000).

As a part of the JGOFS synthesis and modeling project, researchers have been working to synthesize the WOCE/JGOFS/NOAA global carbon survey data to better understand carbon cycling in the oceans. Working with international investigators, we have compiled a Pacific Ocean data set with over 36,000 unique sample locations analyzed for at least two carbon parameters. These data are being used to estimate the distribution of anthropogenic CO₂ in the Pacific using the delta-C technique. The physical and geochemical makeup of the Pacific waters, however, poses a particular challenge for the anthropogenic calculations. This measurement-based approach requires a number of assumptions that will be examined with respect to the Pacific. Preliminary estimates of the anthropogenic CO₂ distribution indicate that the largest inventories are in the subtropical South and North Pacific. These distributions will be discussed and compared with three-dimensional global carbon model estimates.

Sabine, C.L., M.F. Lamb, J.L. Bullister, R.A. Feely, G.L. Johnson, R.M. Key, A. Kozyr, K. Lee, F.J. Millero, T.-H. Peng, and R.H. Wanninkhof. U.S. JGOFS team examines Pacific Ocean CO₂ data quality. International WOCE Newsletter, 38:10-14 (2000).

No abstract.

Sainz-Trapaga, S.M., G.J. Goni, and T. Sugimoto. Identification and variability of the Kuroshio Extension and its northern branch from altimeter and hydrographic data during October 1992-August 1999. AGU 2000 Western Pacific Geophysics Meeting, Tokyo, Japan, June 27-30, 2000. Supplement to EOS, Transactions, American Geophysical Union, 81(22):WP80, OS41A-08 (2000).

The Kuroshio Extension to the east of Japan is an eastward-flowing, meandering jet with current velocities at its core over 100 cm s^-1. This jet presents two quasi-stationary meanders with crests at 144°E and 150°E, and becomes wider and weaker to the east. These and other hydrodynamic modifications along its course can be related to the Shatsky Rise and the Emperor Sea Mounts, the main bathymetric features encountered by the Kuroshio Extension while flowing to the east. The Kuroshio Extension usually bifurcates between 150°E and 165°E, where its northern branch deviates northeastward along the Shatsky Rise approaching the subarctic front. Due to the lack of a long-term and continuous monitoring system, several aspects of the variability at the different regions of the Kuroshio Extension remains unclear. In this work, altimeter-derived sea height anomaly data from November 1992 to August 1999 is combined with climatological hydrographic data within a two-layer reduced gravity ocean model to identify the Kuroshio Extension and its northern branch, to estimate their baroclinic transports, and to study their variabilities, from the Japanese coast to 175°W. Results reveal different patterns of variability to the east and west of 155°E. East of 155°E, the Kuroshio Extension and its northern branch show a clear seasonal cycle. The location of the Kuroshio Extension and its northern branch have both maximum standard deviations from the mean between 150°E and 170°E. This area is characterized by the separation of the northern branch from the Kuroshio Extension. Moreover, the northern branch deviates to the northeast while the main path to the southeast, showing here its lower mean axis position. The location of the Bifurcation Point, partly determined by the bottom topography, correlates also with the Kuroshio Extension axis location and its transport.

Sandrik, A., C.W. Landsea, and B. Jarvinen. The North Florida hurricane of 29 September 1896: A historical case of extreme inland high winds. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 547-548 (2000).

No abstract.

Schmid, C., S.L. Garzoli, and R.L. Molinari. The intermediate depth circulation in the tropical Atlantic. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union,80(49):OS44, OS12D-18 (2000).

The intermediate circulation in the interior tropical Atlantic consists, according to the current knowledge, of several narrow zonal currents. Especially south of the equator, many changes of direction have been reported. Due to a lack of data, this flow pattern is only poorly resolved in space and time. Recent observations, both during the mid-1997 Seward Johnson cruise and from PALACE trajectories which extend from mid-1997 to today, allow a more detailed description of the intermediate depth circulation in the tropical Atlantic. The PALACE floats indicate that the intermediate layer flow between the equator and about 4°N consists of two different regimes which are separated by the eastern edge of the Mid-Atlantic Ridge. Velocities in the eastern regime are lower. The zonal flow in the two regimes is going in opposite directions at certain latitudes. We will discuss how the different regimes are related to the water masses and the interbasin exchange. Further south, between 4° and 2°S, westward velocities are clearly dominating the circulation. This latitude range is often occupied by the central South Equatorial Current. The flow between 8° and 4°S is governed by short periods (up to several months) of flow towards the east or west with only weak preferences of either one of the directions. This region is characterized by the (meandering) transition between the central South Equatorial Current and the South Equatorial Countercurrent. It has been proposed earlier that these two currents do not extend beyond about 8°W and that the intermediate water follows a cyclonic path east of 10°W between about 5° and 25°S. This could be seen as an intermediate expression of the Angola Gyre. Such a circulation is not visible in the PALACE trajectories to date.

Schmid, C., G. Siedler, and W. Zenk. Dynamics of intermediate water circulation in the subtropical South Atlantic. Journal of Physical Oceanography, 30(12):3191-3211 (2000).

The circulation of the low-salinity Antarctic Intermediate Water in the South Atlantic and the associated dynamical processes are studied, using recent and historical hydrographic profiles, Lagrangian and Eulerian current measurements as well as wind stress observations. The circulation pattern inferred for the Antarctic Intermediate Water supports the hypothesis of an anticyclonic basin-wide recirculation of the intermediate water in the subtropics. The eastward current of the intermediate anticyclone is fed mainly by water recirculated in the Brazil Current and by the Malvinas Current. An additional source region is the Polar Frontal Zone of the South Atlantic. The transport in the meandering eastward current ranges from 6 Sv to 26 Sv (1 Sv = 10⁶ m³ s^-1). The transport of the comparably uniform westward flow of the gyre varies between 10 Sv and 30 Sv. Both transports vary with longitude. At the western boundary near 28°S, in the Santos Bifurcation, the westward current splits into two branches. About three quarters of the 19 Sv at 40°W go south as an intermediate western boundary current. The remaining quarter flows northward along the western boundary. Simulations with a simple model of the ventilated thermocline reveal that the wind-driven subtropical gyre has a vertical extent of over 1200 m. The transports derived from the simulations suggest that about 90% of the transport in the westward branch of the intermediate gyre and about 50% of the transport in the eastward branch can be attributed to the wind-driven circulation. The structure of the simulated gyre deviates from observations to some extent. The discrepancies between the simulations and the observations are most likely caused by the interoceanic exchange south of Africa, the dynamics of the boundary currents, the nonlinearity, and the seasonal variability of the wind field. A simulation with an inflow/outflow condition for the eastern boundary reduces the transport deviations in the eastward current to about 20%. The results support the hypothesis that the wind field is of major importance for the subtropical circulation of Antarctic Intermediate Water followed by the interoceanic exchange. The simulations suggest that the westward transport in the subtropical gyre undergoes seasonal variations. The transports and the structure of the intermediate subtropical gyre from the Parallel Ocean Climate Model (Semtner/Chervin model) agree better with observations.

Schubert, W.H., S.A. Hausman, M. Garcia, K.V. Ooyama, and H.-C. Kuo. Potential vorticity in a moist atmosphere. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 563-564 (2000).

No abstract.

Shay, L., G.J. Goni, and P.G. Black. Effects of a warm oceanic feature on Hurricane Opal. Monthly Weather Review, 128(5):1366-1383 (2000).

On 4 October 1995, Hurricane Opal deepened from 965 to 916 hPa in the Gulf of Mexico over a 14-h period upon encountering a warm core ring (WCR) in the ocean shed by the Loop Current during an upper-level atmospheric trough interaction. Based on historical hydrographic measurements placed within the context of a two-layer model and surface height anomalies (SHA) from the radar altimeter on the TOPEX mission, upper-layer thickness fields indicated the presence of two warm core rings during September and October 1995. As Hurricane Opal passed directly over one of these WCRs, the 1-min surface winds increased from 35 to more than 60 m s^-1, and the radius of maximum wind decreased from 40 to 25 km. Pre-Opal SHAs in the WCR exceeded 30 cm where the estimated depth of the 20°C isotherm was located between 175 and 200 m. Subsequent to Opal's passage, this depth decreased approximately 50 m, which suggests upwelling underneath the storm track due to Ekman divergence. The maximum heat loss of approximately 24 Kcal cm^-2 relative to depth of the 26°C isotherm was a factor of 6 times the threshold value required to sustain a hurricane. Since most of this loss occurred over a period of 14 h, the heat content loss of 24 Kcal cm^-2 equates to approximately 20 kW m^-2. Previous observational findings suggest that about 10%-15% of upper-ocean cooling is due to surface heat fluxes. Estimated surface heat fluxes based upon heat content changes range from 2000 to 3000 W m^-2 in accord with numerically simulated surface heat fluxes during Opal's encounter with the WCR. Composited AVHRR-derived SSTs indicated a 2°-3°C cooling associated with vertical mixing in the along-track direction of Opal except over the WCR where AVHRR-derived and buoy-derived SSTs decreased only by about 0.5°-1°C. Thus, the WCR's effect was to provide a regime of positive feedback to the hurricane rather than negative feedback induced by cooler waters due to upwelling and vertical mixing as observed over the Bay of Campeche and north of the WCR.

Shay, L.K., G.J. Goni, P.G. Black, S.D. Jacob, J.J. Cione, and E.W. Uhlhorn. Global analogues of deep warm upper ocean layers: Hurricane heat potential estimates. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J3-J4 (2000).

No abstract.

Smith, N.R., D.E. Harrison, R. Bailey, O. Alves, T. Delcroix, K. Hanawa, B. Keeley, G. Meyers, R.L. Molinari, and D. Roemmich. The role of XBT sampling in the ocean thermal network. OCEANOBS99: International Conference on the Ocean Observing System for Climate, Saint Raphael, France, October 18-22, 1999. Centre National d'Etudes Spatiales, 26 pp. (2000).

This paper evaluates the present role of the XBT program and proposes a strategy for the future under the assumption that there are other direct and indirect contributions to sampling the temperature and salinity of the ocean. Since the focus is on XBT sampling, the paper restricts its scope to the upper ocean, mostly above 1000 m. The conclusions of the paper are based on a study and workshop that were convened specifically to look at the design of the ship-of-opportunity network and to look at options for its implementation in the future under the assumption that Argo happens. The paper also addresses issues related to data distribution and management. The primary conclusion is that the network of the future should place greatest emphasis on line sampling, at intermediate to high densities, and assume that a proposed profiling float array, Argo, will largely take over the role formerly occupied by area (broadcast) sampling. It is argued that line sampling exclusively addresses several needs of the ocean observing system that cannot easily be addressed by other forms of sampling. Further, it is argued that such a mode complements other in-situ components such as moorings and floats, as well as remotely-sensed surface topography. A new network is outlined with a strategy for implementation that ensures continuity between existing and planned networks. We conclude the data management system that was established around the SOOP program requires substantial renovation if it is to adequately address the needs of the data gatherers and suppliers, and the data users (modelers, scientists, operational applications).

Spratt, S.M., F.D. Marks, P.P. Dodge, and D.W. Sharp. Examining the pre-landfall environment of mesovortices within a Hurricane Bonnie (1998) outer rainband. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 300-301 (2000).

No abstract.

Tenerelli, J.E., S.S. Chen, M. Lonfat, R. Foster, and R.F. Rogers. Surface winds in Hurricane Floyd: A comparison between numerical simulations, aircraft data, and QuikScat satellite data. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 418-419 (2000).

A principal benefit of numerical simulations of hurricanes is that they provide detailed, high-resolution information on the structure and evolution of the atmosphere that cannot be obtained through current observational techniques. However, simulations can be strongly dependent on the initial and boundary data, as well as on the physical parameterizations in the numerical model, and so it is necessary to compare simulation results with observational data when available. The objectives of this study are to: (1) validate model simulations of Hurricane Floyd with all available observations, including in-situ and remote sensing data sets; and (2) explore the impact of the observations on high-resolution model simulations. One important aspect of the model simulations is the surface wind field. The surface wind has a substantial impact on the fluxes of heat and moisture at the surface, which in turn have a large influence on the storm intensity and structure. Yet, near the surface, the model results are influenced greatly by the parameterization of boundary layer and surface processes. Hurricane Floyd presents an excellent opportunity for model-observation intercomparison of winds near the surface. Several swaths of data from NASA's QuikScat satellite were obtained while Floyd was over water. Additionally, surface winds derived from NOAA/HRD aircraft observations were obtained at several times during the life of the storm. In this study, we conduct a four-day long simulation of Floyd using the PSU/NCAR nonhydrostatic mesoscale model (MM5) with one fixed mesh and two levels of moving nested grid. We compare surface winds derived from QuikScat and aircraft data to the surface winds in our numerical simulation of Floyd. Additionally, we compare vertical profiles of reflectivity and hydrometeors from the simulations with those derived from the TMI and PR instruments on NASA's TRMM satellite. Although the TRMM swaths, the QuikScat swaths, and HRD data are not coincident in time, the MM5 simulations' continuity in time allows a comparison with all observational data sources. The MM5 can be used as a cross-validation platform. This model-observation comparison is the first step towards the goal of assimilating observed surface winds into the MM5.

Uhlhorn, E.W., K.B. Katsaros, and M.D. Powell. Assimilation of scatterometer-derived winds into real-time tropical cyclone surface wind analyses. Preprints, 10th Conference on Satellite Meteorology and Oceanography, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, 214-215 (2000).

No abstract.

Uhlhorn, E.W., P.G. Black, L.K. Shay, J.J. Cione, S.D. Jacob, and G.J. Goni. Warm core ocean features in the central and eastern Gulf of Mexico. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 147-148 (2000).

No abstract.

Wainer, I., P. Gent, and G.J. Goni. Annual cycle of the Brazil-Malvinas confluence region in the National Center for Atmospheric Research climate system model. Journal of Geophysical Research, 105(C11):26,167-26,177 (2000).

The objective of this study is to compare the mean and seasonal variability of the circulation in the southwest Atlantic with observations. The results used in the comparison are from the last 200 years of a 300-year control integration of the Climate System Model (CSM). The area of study includes the confluence region between the subtropical and subpolar waters represented by the Brazil and Malvinas Currents. The seasonal variation of transport and its relationship to changes in the wind stress forcing and in the sea surface temperature are examined and compared to available oceanographic observations. This study shows that a coarse resolution climate model, such as the CSM, can successfully reproduce major characteristics of the Brazil-Malvinas confluence seasonality, although the mesoscale features involving recirculation and meander dynamics are not resolved. The CSM transport values in the region of 38°S are consistent with hydrographically-derived values. The transport of the CSM Brazil Current is higher during austral summer and smaller during austral winter. Conversely, the Malvinas Current transport is weaker during austral summer and stronger during austral winter. This is also consistent with observations. The CSM seasonal cycle in transport associated with both the Brazil and Malvinas Currents and its meridional displacement is closely linked to the seasonal variations in the local wind stress curl. However, the displacement is much smaller in the model than in observations. The CSM results show that the latitudinal displacement of the 24°C and 17°C at the South American coast between austral summer and winter is 20° and 12°, respectively. This is very similar to the displacement seen in observations.

Walsh, E.J., C.W. Wright, D.C. Vandemark, W.B. Krabill, A.W. Garcia, S.H. Houston, M.D. Powell, P.G. Black, and F.D. Marks. Hurricane directional wave spectrum spatial variation in the open ocean and at landfall. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A116-A121 (2000).

The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA/GSFC airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane research aircraft at 1.5 km height. The data were acquired on 24 August 1998 when Hurricane Bonnie was east of the Bahamas and moving slowly to the north. Two days later, the SRA documented the directional wave spectrum spatial variation again as Bonnie made landfall near Wilmington, North Carolina.

Walsh, E.J., C.W. Wright, D.C. Vandemark, W.B. Krabill, A.W. Garcia, S.H. Houston, M.D. Powell, P.G. Black, and F.D. Marks. Hurricane directional wave spectrum spatial variation at landfall. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 327-328 (2000).

No abstract.

Wang, C. A unified theory for the El Niño-Southern Oscillation. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, Florida, May 29-June 2, 2000. American Meteorological Society, Boston, J42-J43 (2000).

No abstract.

Wang, C. On the atmospheric responses to tropical Pacific heating during the mature phase of El Niño. Journal of Atmospheric Sciences, 57(22):3767-3781 (2000).

The atmospheric heating and sea surface temperature (SST) anomalies during the mature phase of El Niño are observed to show both eastern and western Pacific anomaly patterns, with positive anomalies in the equatorial eastern/central Pacific and negative anomalies in the off-equatorial western Pacific. The detailed spatial patterns of the heating anomalies differ from the SST anomalies. The heating anomalies are more equatorially confined than the SST anomalies, and maxima of positive and negative heating anomalies are located farther to the west than the SST anomalies. The Gill/Zebiak atmospheric model assumes that the atmospheric initial heating has the same spatial patterns as the SST anomalies. This assumption results in some unrealistic model simulations for El Niño. When the model heating anomaly forcing is modified to resemble the observed heating anomalies during the mature phase of El Niño, the model simulations have been improved to: (1) successfully simulate equatorial easterly wind anomalies in the western Pacific; (2) correctly simulate the position of maximum westerly wind anomalies; and (3) reduce unrealistic easterly wind anomalies in the off-equatorial eastern Pacific. This paper shows that off-equatorial western Pacific negative atmospheric heating (or cold SST) anomalies are important in producing equatorial easterly wind anomalies in the western Pacific. These off-equatorial cold SST anomalies in the western Pacific also contribute to equatorial westerly wind anomalies observed in the central Pacific during the mature phase of El Niño. Although off-equatorial cold SST anomalies in the western Pacific are smaller than equatorial positive SST anomalies in the eastern Pacific, they are enough to produce atmospheric responses of comparable magnitude to the equatorial eastern Pacific. This is because the atmospheric mean state is convergent in the western Pacific and divergent in the equatorial eastern Pacific. By either removing the atmospheric mean convergence or removing off-equatorial cold SST anomalies in the western Pacific, the atmospheric responses show no equatorial easterly wind anomalies in the western Pacific. In the Gill/Zebiak model, the mean wind divergence field is an important background state, whereas the mean SST is secondary.

Wang, C. The El Niño-Southern Oscillation. Proceedings, International Conference on Climate and Environment Variability and Predictability, Shanghai, China, August 7-11, 2000. International Commission on Dynamic Meteorology/International Association of Meteorology and Atmospheric Sciences, 126 (2000).

No abstract.

Wang, C., and R.H. Weisberg. The 1997-1998 El Niño evolution relative to previous Niño events. Journal of Climate, 13(2):488-501 (2000).

The evolution of the 1997-1998 El Niño is described using NCEP sea surface temperature (SST) and outgoing longwave radiation (OLR) data, NCEP-NCAR reanalysis sea level pressure (SLP) fields, and FSU surface wind data. From November 1996 to January 1997, the eastern Pacific is characterized by equatorial cold SST and high SLP anomalies, while the western Pacific is marked by off-equatorial warm SST anomalies and off-equatorial anomalous cyclones. Corresponding to this distribution are high OLR anomalies in the equatorial central Pacific and low OLR anomalies in the off-equatorial far western Pacific. The off-equatorial anomalous cyclones in the western Pacific are associated with a switch in the equatorial wind anomalies over the western Pacific from easterly to westerly. These equatorial westerly anomalies then appear to initiate early SST warmings around the date line in January/February 1997 and around the far eastern Pacific in March 1997. Subsequently, both the westerly wind and warm SST anomalies, along with the low OLR anomalies, grow and progress eastward. The eastward propagating warm SST anomalies merge with the slower westward spreading warm SST anomalies from the far eastern Pacific to form large-scale warming in the equatorial eastern and central Pacific. The anomaly patterns in the eastern and central Pacific continue to develop, reaching their peak values around December 1997. In the western Pacific, the off-equatorial SST anomalies reverse sign from warm to cold. Correspondingly, the off-equatorial SLP anomalies in the western Pacific also switch sign from low to high. These off-equatorial high SLP anomalies initiate equatorial easterly wind anomalies over the far western Pacific. Like the equatorial westerly wind anomalies that initiate the early warming, the equatorial easterly wind anomalies over the far western Pacific appear to have a cooling effect in the east and, hence, help facilitate the 1997-1998 El Niño decay. The paper also compares the 1997-1998 El Niño with previous warm events, and discusses different ENSO mechanisms relevant to the 1997-1998 El Niño.

Wilkerson, J.C., and J.R. Proni. Monitoring tropical and subtropical rainfall over the ocean using underwater acoustic techniques. Proceedings, Fifth European Conference on Underwater Acoustics (ECUA 2000), Lyon, France, July 10-13, 2000. European Acoustics Association, Volume 1, 741-746 (2000).

Measurements of underwater sound produced by rain were made at three U.S. coastal sites to determine feasibility and limitations of acoustic detection and classification of rainfall over water. In the study, concurrent radar observations were used to identify convective and stratiform regions of the precipitating clouds overhead. Acoustic-derived classifications of rain type, based on information in the 4-30 kHz frequency band, were in general agreement with radar-derived classifications. A correlation of 0.9 was found to exist between sound spectrum levels (in decibels) in the 4-10 kHz frequency band and rain rate, suggesting the use of acoustical methods for rainfall estimation. Testing of the acoustic technique in deep water is currently underway at the U.S. Navy Atlantic Undersea Test and Evaluation Center, Bahamas. Examples of acoustic spectra are presented.

Willoughby, H.E. Costs and benefits of hurricane forecasting. Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 557 (2000).

No abstract.

Willoughby, H.E. The proposed upgrade of NOAA's Gulfstream-IV for tropical cyclone reconnaissance. Minutes, 54th Interdepartmental Hurricane Conference, Houston, TX, February 14-18, 2000. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A239-A241 (2000).

No abstract.

Willoughby, H.E. and R.W. Jones. Are the beta gyres really normal modes? Preprints, 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, 187-188 (2000).

No abstract.

Wilson, W.D., and K.D. Leaman. The NOPP Year of the Ocean drifter program: A new Lagrangian perspective on IAS circulation. AGU 2000 Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000. Supplement to EOS, Transactions, American Geophysical Union, 80(49):OS234, OS41E-24 (2000).

Since March of 1998, 130 "WOCE-type" drifting buoys, drogued at 15 m, have been launched in the Gulf of Mexico and the Caribbean Sea and its approaches, providing in excess of 15,000 "drifter days" of data to date. Buoys were provided by the U.S. National Ocean Partnership Program (NOPP); launch coordination was provided by scientists at NOAA/AOML and UM/RSMAS; and logistical and data processing support was provided by the NOAA/AOML Global Drifter and Data Assembly Centers. Buoys were launched with the cooperation of commercial ships, the Colombian Navy, the U.S. Coast Guard, and research vessels working in the region. Drifter track figures and data have been made available in real time via the World-Wide Web at www.IASlinks.org and www.drifters.doe.gov. Repeated launches were concentrated in three areas: The Panama-Colombia gyre in the southwest Caribbean; the island passages in the eastern Caribbean; and in the North Brazil Current rings, a primary source of mesoscale variability upstream of the Caribbean. This strategy was designed to maintain maximum coverage within the IAS, as well as study propagation of variability through the region, the formation and intensification of the Caribbean Current, and the structure and permanence of the circulation within the Panama-Colombia gyre. Individual drifter tracks are shown which illustrate pathways and time scales of connectivity within the region. There is also sufficient data coverage to estimate fields of mean velocity, velocity variability, and several different indicators of dispersal. Drifter-derived fields are compared to existing estimates of mean velocity (ship drift, climatological, geostrophic, and Ekman estimates) and variability (ship drift, altimetry). Discussion will focus on the usefulness of Lagrangian measurements for larval and other transport studies, and diagnostics of the large-scale IAS circulation field. A companion presentation by Leaman and Wilson will focus on drifters in the Panama-Colombia Gyre and comparison with the high-resolution MICOM model. The merits of a cooperative plan for maintaining long-term drifter coverage of the IAS will be considered.

Wilson, W.D., and K.D. Leaman. Transport pathways through the Caribbean: The tropical origins of the Gulf Stream. Current, 16(1):14-18 (2000).

No abstract.

Wright, C.W., E.J. Walsh, D.C. Vandemark, W.B. Krabill, A.W. Garcia, S.H. Houston, M.D. Powell, P.G. Black, and F.D. Marks. Hurricane directional wave spectrum spatial variation in the open ocean. Proceedings, 10th Conference on Interaction of the Sea and Atmosphere, Ft. Lauderdale, FL, May 29-June 2, 2000. American Meteorological Society, Boston, J1-J2 (2000).

No abstract.

Yvon-Lewis, S.A. Methyl bromide in the atmosphere and ocean. IGACtivities Newsletter, 19:9-12 (2000).

No abstract.

Zhang, J.-Z. Shipboard automated determination of trace concentrations of nitrite and nitrate in oligotrophic water by gas-segmented continuous flow analysis with a liquid waveguide capillary flow cell. Deep-Sea Research, Part I, 47(6):1157-1171 (2000).

Incorporation of a liquid waveguide capillary flow cell to a gas-segmented continuous flow auto-analyzer significantly enhances the sensitivity of automated colorimetric analysis. Nanomolar concentrations of nitrite and nitrate in oligotrophic surface seawater can be accurately determined. The advantages of this technique are low detection limit, high precision, and automation for rapid analysis of a large number of samples. This technique has been successfully used on shipboard measurements of about 1000 seawater samples during a one-month cruise in North Atlantic.

Zhang, J.-Z. The use of pH and buffer intensity to quantify the carbon cycle in the ocean. Marine Chemistry, 70(1-3):121-131 (2000).

The pH of seawater is governed by the content of total carbon dioxide and ionic equilibra between hydrogen ions and various inorganic carbon species in seawater. Buffer intensity is defined as a measure of the ability of seawater to accommodate the addition of acid or base without appreciable pH change. It can be calculated from pH and total carbon dioxide of seawater. pH data in conjunction with buffer intensity can be used to quantify the carbon cycle in the ocean. The total amount of acid that has been released or consumed by any biogeochemical processes can be calculated from the change in pH multiplied by buffer intensity of seawater, dC_H = d(beta-pH). This approach has been used to quantify the remineralization process in the Antarctic Intermediate Water in the South Pacific. Based on the observational data (pH, total carbon dioxide, O₂, and nutrient measurements on P18 cruise), calculated elemental remineralization ratios are 173, 107, and 14.3 for O/P, C/P and N/P, respectively. The dissolution of calcium carbonate accounts for 21.5% of carbon increased from the remineralization in the Antarctic Intermediate Water.

Zhang, J.-Z., and C.R. Kelble. Gas-segmented continuous flow analysis of iron in water with a long liquid waveguide capillary flow cell. Proceedings, 8th International Conference on Flow Analysis, Warsaw, Poland, June 25-29, 2000. International Union of Pure and Applied Chemistry, 107 (2000).

A long liquid waveguide capillary flow cell has been successfully adapted into a gas-segmented continuous flow auto-analyzer for trace analysis of iron. The flow cell was made of a new material, Teflon AF-2400, that has a refractive index (1.29) lower than water (1.33). Total reflection of light can be achieved when the light beams intersect the water/AF-2400 Teflon tubing interfaces at greater than critical angle. Teflon AF-2400 is superior to currently used materials in both refractivity and mechanical stability. This allows the construction of a long liquid waveguide capillary flow cell in helical, rather than linear shape, with compact dimension. Small sample volumes are required since the internal volume of a 2 m-long liquid waveguide capillary flow cell with 550 µm ID is only approximately 0.5 cm³. According to the Lambert-Beer law, the absorbance of a sample in spectrophotometry is proportional to the light path length in the flow cell. Utilization of this long flow cell significantly enhances the sensitivity of automated colorimetric analysis of iron by the ferrozine method. Nanomolar concentrations of iron in natural water can be accurately determined. The advantages of this technique are low detection limit, small sample volume, high precision, and automation for rapid analysis of a large number of samples. This technique has potential application in many spectrophotometric detections to augment the capability of gas-segmented continuous flow analysis and flow injection analysis.

Zhang, J.-Z., C.J. Fischer, and P.B. Ortner. Comparison of open tubular cadmium reactors and packed cadmium columns in automated gas-segmented continuous flow nitrate analysis. International Journal of Environmental Analytical Chemistry, 76(2):99-113 (2000).

Detailed procedures are provided for preparing packed cadmium columns to reduce nitrate to nitrite. Experiments demonstrated the importance of conditioning both open tubular cadmium reactor (OTCR) and packed copper-coated cadmium columns to achieve 100% reduction efficiency. The effects of segmentation bubbles in the OTCR upon reduction efficiency and baseline noise in nitrate analysis are investigated using an auto-analyzer. Metal particles derived from segmentation bubbles in OTCR result in i nterference with continuous flow analyses. Therefore, packed columns are recommended for determination of low level nitrate in natural waters.

Zhang, J.-Z., R.H. Wanninkhof, and K. Lee. New production in oligotrophic waters: Estimation based on diel cycle of nitrate. Proceedings, Joint Global Ocean Flux Study (JGOFS) Open Science Conference, Bergen, Norway, April 13-17, 2000. JGOFS International Project Office, 76-77 (2000).

New production can be estimated from accurate measurements of inventory change in nitrate at nM levels in the photic zone. A strong diel cycle was observed in nitrate concentrations in response to photosynthesis in the eastern North Atlantic during the GASEX-98 cruise. During a diel study, nitrate concentration was 92 nM in the morning and decreased to 12 nM by 6 p.m. It increased after dark, presumably due to the diffusive flux from the nitracline. Oxygen showed a similar diel cycle with a change in concentration of about 2 µM. The vertical eddy diffusivity was derived from temporal changes in concentrations of a deliberate tracer, SF6, below the mixed layer. Together with vertical nitrate distributions, the nitrate flux from nitracline throughout the nighttime can account for a nitrate concentration of 102 nM by morning, which is in good agreement with measured nitrate of 92 nM at 6 a.m. The new production estimated from changes of nitrate inventory in the photic zone during the day was 28 mmole C/m² d. Increases in the mixed layer nitrate were observed during storm events that deepened the mixed layer and brought the nitrate to the surface. The storm-induced nitrate disappeared within two days, indicating a rapid uptake by phytoplankton. The relative importance of sporadic storm events versus daily diffusive flux in supply nitrate to new production can be estimated based on nitrate inventory changes in the photic zone.

Zhang, J.-Z., C.W. Mordy, L.I. Gordon, A. Ross, and H.E. Garcia. Temporal trends in deep ocean Redfield ratios. Science, 289:1839 (2000).

No abstract. **1999**

Aberson, S.D. Ensemble-based products to improve tropical cyclone forecasting. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 843-844 (1999).

No abstract.

Aberson, S.D. Targeting and sampling strategies to improve hurricane forecasts. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 105-107 (1999).

No abstract.

Aberson, S.D., and J.L. Franklin. Impact on hurricane track and intensity forecasts of GPS dropwindsonde observations from the first-season flights of the NOAA Gulfstream-IV jet aircraft. Bulletin of the American Meteorological Society, 80(3):421-428 (1999).

In 1997, the Tropical Prediction Center (TPC) began operational Gulfstream-IV jet aircraft missions to improve the numerical guidance for hurricanes threatening the continental United States, Puerto Rico, and the Virgin Islands. During these missions, the new generation of Global Positioning System dropwindsondes were released from the aircraft at 150-200-km intervals along the flight track in the environment of the tropical cyclone to obtain profiles of wind, temperature, and humidity from flight level to the surface. The observations were ingested into the global model at the National Centers for Environmental Prediction, which subsequently served as initial and boundary conditions to other numerical tropical cyclone models. Because of a lack of tropical cyclone activity in the Atlantic basin, only five such missions were conducted during the inaugural 1997 hurricane season. Due to logistical constraints, sampling in all quadrants of the storm environment was accomplished in only one of the five cases during 1997. Nonetheless, the dropwindsonde observations improved mean track forecasts from the Geophysical Fluid Dynamics Laboratory hurricane model by as much as 32%, and the intensity forecasts by as much as 20% during the hurricane watch period (within 48 h of projected landfall). Forecasts from another dynamical tropical cyclone model (VICBAR) also showed modest improvements with the dropwindsonde observations. These improvements, if confirmed by a larger sample, represent a large step toward the forecast accuracy goals of TPC. The forecast track improvements are as large as those accumulated over the past 20-25 years, and those for forecast intensity provide further evidence that better synoptic-scale data can lead to more skillful dynamical tropical cyclone intensity forecasts.

Albrecht, B., T. Faber, A. Savtchenko, D. Churchill, F.D. Marks, and P.G. Black. Surface-based remote sensing of a landfalling tropical storm. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 489-492 (1999).

No abstract.

Atlas, D., C.W. Ulbrich, F.D. Marks, E. Amitai, and C.R. Williams. Systematic variation of drop size and radar-rainfall relations. Journal of Geophysical Research, 104(D6):6155-6169 (1999).

Time histories of the characteristics of the drop size distribution of surface disdrometer measurements collected at Kapingamarangi Atoll were partitioned for several storms using rain rate, R, reflectivity factor Z, and median diameter of the distribution of water content D₀. This partitioning produced physically based systematic variations of the drop size distribution (DSD) and Z-R relations in accord with the precipitation types viewed simultaneously by a collocated radar wind profiler. These variations encompass the complete range of scatter around the mean Z-R relations previously reported by Tokay and Short (1996) for convective and stratiform rain and demonstrate that the scatter is not random. The systematic time or space variations are also consistent with the structure of mesoscale convective complexes with a sequence of convective, transition, and stratiform rain described by various authors. There is a distinct inverse relation between the coefficient A and the exponent of the Z-R relations which has been obscured in prior work because of the lack of proper discrimination of the rain types. Contrary to previous practice, it is evident that there is also a distinct difference in the DSD and the Z-R relations between the initial convective and the trailing transition zones. The previously reported Z-R relation for convective rain is primarily representative of the transition rain that was included in the convective class. The failure of present algorithms to distinguish between the initial convective and the trailing transition rains causes an erroneous apportionment of the diabatic heating and cooling and defeats the primary intent of discriminating stratiform from convective rains.

Alvarez-Zarikian, C., P.L. Blackwelder, T. Hood, T.A. Nelsen, and C.M. Featherstone. A century of hydrological variability in the lower Everglades National Park as interpreted from stable isotopes on ostracods and foraminifers. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 198 (1999).

Stable isotopic analysis of selected ostracods and foraminifers were carried out from high-resolution sediment cores collected from Oyster and Florida Bays. The core localities provide distinctive environmental conditions in which the effects of freshwater runoff, rainfall, and, consequently, salinity, can be assessed. Oyster Bay lies at the end of the Shark River Slough and is an area that experiences extreme salinity fluctuations due to the interaction between freshwater runoff and marine water input from the Gulf of Mexico due to tidal flow. A second core, collected near Jimmy Key, in the center of Florida Bay, provides a contrasting salinity history in which salinity has remained close to marine during this century. Stable isotope (¹³C, ¹⁸O) trends of ostracods and foraminifers at Oyster Bay and Jimmy Key suggest a general transition to more saline conditions over this time period. Relative abundance of salinity-sensitive species confirmed this observations. Moreover, stable isotopes indicate an increase in salinity variability over time, which is represented in the microfaunal assemblage by survivor-mode dominance by highly-tolerant species, both in foraminifers and ostracods, that occurred during a period of drought or highly evaporative conditions during the mid to late 1980s that also lead to reduced flow from Shark River Slough. Fluctuations on stable isotope values appeared to be more a direct response to regional rainfall than freshwater runoff; however, distinct patterns can be temporally correlated to freshwater management strategies by the South Florida Water Management District.

Alvarez-Zarikian, C., T. Hood, P. Blackwelder, T.A. Nelsen, P. Swart, H. Wanless, J. Trefry, and W.-J. Kang. Paleoecological significance of temporal fluctuations in assemblages and isotopic composition of ostracoda and foraminifera from Florida Bay. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. EOS, Transactions, American Geophysical Union, 80(17):S178, OS31A-17 (1999).

Microfaunal populations and stable isotopic analysis of selected ostracods and benthic foraminifers were examined from high-resolution sediment cores in the lower Everglades/Florida Bay ecosystem. Microfaunal characteristics and population fluctuations can be temporarily related to forces of natural (hurricanes, precipitation) and anthropogenic (historic practices from the South Florida Water Management District [SFWMD]) origin since the turn of the century. Dramatic shifts in community structure are observed in both microfaunal groups and are represented by major swings in species diversity and dominance, and total loss of numerous species. Before the 1960s, significant crashes in the community structure of both groups were temporally correlated with major hurricanes, but fairly rapid recoveries indicate a relatively resilient community. Community changes during the 1970s were most systematic, and temporally correlate with changes in SFWMD policy. In Oyster Bay, the 1970s Monthly Water Allocation Plan corresponds to a boom period for ostracods and benthic foraminfers possibly due to a more efficient water flow and exchange. This is followed by a dramatic crash in both groups corresponding to the start of the SFWMD's Rainfall Plan and the closing of the Buttonwood Canal in the early 1980s, from which neither community has recovered. Sediment cores from Oyster Bay and near Jimmy Key in Florida Bay show a reduction in the number of species and a pronounced dominance of survivor-type species since that time. delta-180 data from ostracods and foraminifers shift to heavier values during this period, indicating drought conditions. Microfaunal and isotopic data from this study complemented with an analysis of historical rainfall, gauged freshwater flow, and limited near-shore salinity data show a significant increase in the magnitude and range of seasonal salinity variability due to fluctuations in regional rainfall and the current water management plan, resulting in significantly drier conditions in the lower portion of Shark River Slough.

Amat, L.R., M.D. Powell, and S.H. Houston. A real-time, Internet-based application for the archival, quality control, and analysis of hurricane surface wind observations. Preprints, 15 International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 573-576 (1999).

No abstract.

Atakturk, S.S., and K.B. Katsaros. Wind stress and surface waves observed on Lake Washington. Journal of Physical Oceanography, 29(4):633-650 (1999).

New results from turbulent flux measurements made over Lake Washington include the following:

(1) The only direct measure of the vertical transport of the horizontal momentum, heat, and matter in the surface boundary layer is the so-called eddy correlation method. However, even if the measurement errors are negligible, the results obtained from point observations may show large scatter due to lack of stationarity and horizontal homogeneity in the turbulent field and to the sampling variability. Scatter may be greatly reduced by spatial averaging. In this study, such an effect is achieved by determining the surface roughness length; hence, the neutral drag coefficient from the measured wave height spectrum, which reflects the atmospheric input integrated over the fetch. Applicability and usefulness of the approach for general field measurements and remote sensing is discussed.

(2) The evolution of the wave field observed on Lake Washington agrees in peak frequency and the slope of the equilibrium range parameter as a function of "wind forcing" with other observations, while the magnitude is significantly smaller (by a factor of 2.1) than the values obtained from larger bodies of water. Based on the results obtained from a wave model, we attribute this observed difference to the narrower width of the water body on Lake Washington. These findings indicate that the state-of-the-art spectral parameterization of surface waves has limitations in describing the observations from a natural but small body of water.

Baringer, M.O., and R.L. Molinari. Atlantic Ocean baroclinic heat flux at 24-26°N. Geophysical Research Letters, 26(3):353-356 (1999).

The spatially varying, interior geostrophic baroclinic heat flux component of the total meridional oceanic heat flux near 24°N in the Atlantic Ocean is examined using four transatlantic hydrographic sections including the October 1957 Discovery II IGY section, the September 1981 Atlantis section, the August 1992 Hesperides section, t he February 1998 Ronald H. Brown section and the 1982 Levitus and the Lozier, Owens, Curry climatologies. The 1992 section is complemented by shorter western boundary sections obtained concurrently during the Trident cruise. We find an average southward baroclinic heat flux of 0.9 0.3 PW with an annual cycle amplitude of 0.3 PW. More than 90% of the annual cycle is captured within 30° of the western boundary.

Baringer, M.O., and J.F. Price. A review of the physical oceanography of the Mediterranean Outflow. Marine Geology, 155(1-2):63-82 (1999).

The physical oceanography of the Mediterranean Sea is reviewed with particular emphasis on the Mediterranean outflow in the Gulf of Cadiz. In this region the dense Mediterranean water forms a high velocity bottom current that interacts strongly with the sea floor. The major energy source for the plume comes from the release of potential energy as the plume descends the continental slope, and the major energy sink is work against bottom stress, which is as large as 4 Pa where the plume begins to descend the continental slope. In this region the current makes a nearly inertial turn that would otherwise appear to be steered by the underlying topography. The Mediterranean plume entrains the overlying North Atlantic Central Water and thereby loses much of its density anomaly. The mixed Mediterranean water becomes neutrally buoyant in the lower portion of the North Atlantic thermocline near Cape St. Vincent. There are then two preferred transport modes having somewhat different temperature and salinity whose distinct characteristics can be found far into the open North Atlantic. The temperature, salinity and volume of the Mediterranean water in the Strait of Gibraltar and in the Gulf of Cadiz appear to be roughly constant since modern measurements have been made. The estimated westward transport of Mediterranean water has gone down considerably as direct measurement techniques have been applied. A recent estimate is that the westward transport of pure Mediterranean water is only about a half a Sv (1 Sv = 10⁶ m³/s); the transport of mixed Mediterranean water in the western Gulf of Cadiz is larger by about a factor of three or four because of the entrainment of North Atlantic water.

Bentamy, A.P., P. Queffeulou, Y. Quilfen, and K.B. Katsaros. Ocean surface wind fields estimated from satellite active and passive microwave instruments. IEEE Transactions on Geoscience and Remote Sensing, 37(5):2469-2486 (1999).

This study examines the consistency of surface wind speeds estimated from the European Remote Sensing Satellite (ERS-1) scatterometer, ERS-1 altimeter, and the special sensor microwave/imager (SSM/I). The goal is to combine these wind estimates to produce surface wind fields. With this in mind, a comparison with buoy wind measurements and comparison among the three sensors is performed. According to the in-situ data, the rms errors of the three wind estimates are all within 2 m/s. The differences between the remotely-sensed and buoy wind speeds are studied according to atmospheric and oceanic variables, and their impact is shown. A large data base is obtained from the comparisons among the three sensor winds. The rms values of the differences between the scatterometer and the altimeter and between the scatterometer and the SSM/I are 1.67 and 1.45 m/s, respectively. There is no global bias between the scatterometer and the SSM/I, but between the scatterometer and the altimeter wind speeds, the bias is about 0.3 m/s. Furthermore, it is shown that the difference between the scatterometer and the altimeter wind estimates is dependent on the significant wave height, while the difference between the scatterometer and the SSM/I winds is dependent on the integrated water vapor content. The comparison enables some corrections to be made for consistency and combining products. The use of combining scatterometer, altimeter, and SSM/I wind estimates is illustrated by two examples.

Berberian, G.A., and A.Y. Cantillo. Oceanographic conditions in the Gulf of Mexico and Straits of Florida: Fall 1976. NOAA Data Report, OAR AOML-36 (PB2000-106209), 64 pp. (1999).

NOAA conducted an investigation in the Gulf of Mexico and the Straits of Florida of oceanographic conditions and nutrients and trace metal levels in seawater during September and October 1976 aboard the NOAA Ship Researcher. This report lists the chemical data obtained from 118 stations. Collection and analyses methodologies, as well as results, are described.

Bishop, C.H., S. Majumdar, I. Szunyogh, Z. Toth, and S.D. Aberson. Using ensembles to simulate the impact of targeted observations. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 117-118 (1999).

No abstract.

Black, M.L. Recent observations of the hurricane eyewall: Unusual and complex structure. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 313-316 (1999).

No abstract.

Black, M.L., and J.L. Franklin. Recent observations of the convective structure associated with low-level wind maxima in the hurricane eyewall. Preprints, 29th International Conference on Radar Meteorology, Montreal, Quebec, Canada, July 12-16, 1999. American Meteorological Society, Boston, 370-373 (1999).

No abstract.

Black, R.A., and J. Hallett. Electrification of the hurricane. Journal of the Atmospheric Sciences, 56(12):2004-2028 (1999).

A survey of reports of electrical activity in hurricanes and typhoons from flight notes and personal experience (18 years, >230 eyewall penetrations for R. A. Black; ~20 years for J. Hallett, plus that of others at the Hurricane Research Division), and perusal of flight notes dating from 1980, show that lightning in and within 100 km or so of the eyewall is usually sparse. However, occasionally, significant electrical activity (>one flash per minute) occurs in or near the eyewall. National Oceanic and Atmospheric Administration WP-3D aircraft penetrations through a number of storms relate the lightning occurrence to strong vertical velocity (>10 m s^-1) and the presence of supercooled liquid cloud droplets extending to temperatures below 20°C. Specific measurements of cloud properties during eyewall penetrations show that the supercooled cloud water content increases with upward velocities > ~5.0 m s^-1, as does the presence of large (>2 mm) supercooled drops. Measurements at temperatures >-13°C show that the transition of supercooled cloud water to ice along an outward radial in all systems is associated with local electric fields (occasionally >20 kV m^-1) and negative charge above positive charge. In systems with stronger vertical velocity there is a larger region of supercooled cloud extending to lower temperatures where charge separation may occur, as judged by the presence of regions containing graupel, small ice, and cloud droplets. The ratio of ice to supercooled water increases radially outward from the eyewall and depends upon altitude (temperature). The spatial distribution of charge is further influenced by the relation of vertical velocity to the radial flow, with the upper charge regions tending to be advected outward. In symmetrical, mature hurricanes, supercooled water usually occurs only in regions at temperatures above about -5°C. The upward transport of supercooled cloud water is limited by a balance between water condensed in the eyewall updraft and its erosion by ice in downdrafts descending in the outward regions of the eyewall. This ice originates from both primary and secondary ice nucleation in the updraft. This is consistent with an exponential increase in ice concentration, as the rate at which the ice particle concentrations increase depends on the production of secondary particles by preexisting graupel, some of which ultimately grow into new graupel, and its outward transport in the anvil flow aloft. Penetrations at temperatures as low as -15°C show the presence of electric fields consistent with specific laboratory-derived criteria for charge separated during ice-graupel collisions, given that a liquid water-dependent sign reversal temperature may occur. Such a reversal may result from either a changing temperature in the vertical, a changing cloud liquid water content in the horizontal, or a combination of the two. Since cloud-to-ground (CG) lightning can be observed with remote detection networks that provide the polarity and frequency of CG lightning, there is potential that hurricane evolution may be detected remotely and that lightning may be usable as an indicator of a change in the storm intensity and/or track.

Blackwelder, P.L., T. Hood, C. Alvarez-Zarikian, P. Swart, C.M. Featherstone, and T.A. Nelsen. Historical salinity effects on microfauna in the lower Everglades and Florida Bay. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 181 (1999).

A multi-faceted approach examines the relationship between microfauna (ostracods and foraminifers) and salinity in Florida Bay and its environs. Several "levels" of microfaunal population variability were examined, which range from overall population characteristics to species- and individual-specific isotopic composition and morphological differences. These levels include documentation of changes in population abundance and diversity over time with variability in salinity and individual species-specific responses, which produce decipherable salinity-related records. Isotopic composition of stained individuals living in the surface sediment in each environment, as well as documentation of salinity related ostracod valve morphological change are studied. Attention is focused on those species capable of withstanding the greatest salinity fluctuations. Core and surface microfaunal populations at Oyster Bay, Jimmy Key, and First National Bank are compared and contrasted. These three sites comprise distinct environmental regimes with well-documented salinity records. Oyster Bay has experienced the greatest salinity variability of the three sites, as well as freshest overall conditions over the last 100 years. The Jimmy Key site, in the center of the Bay, has experienced higher average salinity with less variability over this period. Taphonomic microfaunal studies routinely utilize population characteristics as a tool for paleoenvironmental reconstruction. This study extends population work to include species and individual-specific characteristics, which may record salinity variability. In addition to the field and core collections, we are culturing ostracods to examine isotopic and morphological relationships under controlled conditions. This multi-faceted approach extends our population characterization work to include documentation of physiological response of individuals within the microfaunal populations to documented changes in salinity. This data will extend the use of microfauna as indicators of modern and paleo-salinity change.

Boebel, O., C. Schmid, and W. Zenk. Kinematic elements of Antarctic Intermediate Water in the western South Atlantic. Deep Sea Research, Part II, 46(1-2):355-392 (1999).

The northward flowing Antarctic Intermediate Water (AAIW) is a major contributor to the large-scale meridional circulation of water masses in the Atlantic. Together with bottom and thermocline water, AAIW replaces North Atlantic Deep Water that penetrates into the South Atlantic from the north. On the northbound propagation of AAIW from its formation area in the southwestern region of the Argentine Basin, the AAIW progresses through a complex spreading pattern at the base of the main thermocline. This paper presents trajectories of 75 subsurface floats, seeded at AAIW depth. The floats were acoustically tracked, covering a period from December 1992 to October 1996. Discussions of selected trajectories focus on mesoscale kinematic elements that contribute to the spreading of AAIW. In the equatorial region, intermittent westward and eastward currents were observed, suggesting a seasonal cycle of the AAIW flow direction. At tropical latitudes, just offshore the intermediate western boundary current, the southward advection of an anticyclonic eddy was observed between 5°S and 11°S. Farther offshore, the flow lacks an advective pattern and is governed by eddy diffusion. The westward subtropical gyre return current at about 28°S shows considerable stability with the mean kinetic energy to eddy kinetic energy ratio being around one. Farther south, the eastward deeper South Atlantic Current is dominated by large-scale meanders with particle velocities in excess of 60 cm s^-1. At the Brazil-Falkland Current Confluence Zone, a cyclonic eddy near 40°S, 50°W seems to act as injector of freshly mixed AAIW into the subtropical gyre. In general, much of the mixing of the various blends of AAIW is due to the activity of mesoscale eddies, which frequently reoccupy similar positions.

Boebel O., C. Schmid, G. Podesta, and W. Zenk. Intermediate water in the Brazil-Malvinas Confluence Zone: A Lagrangian view. Journal of Geophysical Research, 104(C9):21,063-21,082 (1999).

The subsurface flow within the subantarctic and subtropical regions around the Brazil-Malvinas Confluence Zone is studied, using daily hydrographic and kinematic data from four subsurface floats and a hydrographic section parallel to the South American shelf. The trajectories are mapped against sea-surface flow patterns as visible in concurrent satellite sea-surface temperature images, with focus on the November 1994 and October/November periods. The unprecedented employment of Lagrangian-S diagrams enables us to trace the advection of patches of fresh Antarctic Intermediate Water (AAIW) from the Confluence Zone into the subtropical region. The fresh AAIW consists of a mixture of subtropical AAIW and Malvinas Current core water. Within the subtropical gyre, these patches are discernible for extended periods and drift over long distances, reaching north to 34.26°S and east to 40.26°W. The cross-frontal migration of quasi-isobaric floats across the Confluence Zone from the subtropical to the subantarctic environment is observed on three occasions. The reverse process, float migration from a subpolar to a subtropical environment was observed once. These events were located near 40.26°S, 50.26°W, the site of a reoccurring cold core feature. Subsurface float and SST data comparison reveals similarities with analogous observations made in the Gulf Stream (Rossby, 1996) where cross-frontal processes were observed close to meander crests. The limited number of floats of this study and the complex structure of the Brazil-Malvinas Confluence Zone, however, restricts the analysis to a description of two events.

Boebel, O., R.E. Davis, M. Ollitrault, R.G. Peterson, P.L. Richardson, C. Schmid, and W. Zenk. Direct observations of the western South Atlantic intermediate depth circulation. Geophysical Research Letters, 26(21):3329-3332 (1999).

The subsurface oceanic circulation is an important part of the Earth climate system. Subsurface currents traditionally are inferred indirectly from distributions of temperature and dissolved substances, occasionally supplemented by current meter measurements. Neutrally-buoyant floats, however, now enable us to obtain for the first time directly measured intermediate depth velocity fields over large areas such as the western South Atlantic. Here, our combined data set provides unprecedented observations and quantification of key flow patterns, such as the Subtropical Gyre return flow (12 Sv; 1 Sverdrup = 10⁶ m³ s^-1), its bifurcation near the Santos Plateau and the resulting continuous narrow and swift northward intermediate western boundary current (4 Sv). This northward flowing water passes through complex equatorial flows and finally enters into the North Atlantic.

Bosart, L.F., W.E. Bracken, J. Molinari, C.S. Velden, and P.G. Black. Environmental influences on the rapid intensification of Hurricane Opal (1995) over the Gulf of Mexico. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 983-984 (1999).

No abstract.

Bourles, B., R.L. Molinari, E. Johns, W.D. Wilson, and K.D. Leaman. Upper layer currents in the western tropical North Atlantic (1989-1991). Journal of Geophysical Research, 104(C1):1361-1376 (1999).

Shipboard Acoustic Doppler Current Profiler (ADCP) measurements and hydrographic observations of temperature, salinity, and dissolved oxygen are used to examine the upper water column flow field in the North Brazil Current (NBC) retroflection region of the western tropical Atlantic Ocean. Observations are presented from six cruises, one conducted in August 1989 and the other five conducted during the Western Tropical Atlantic Experiment (WESTRAX) between January 1990 and September 1991. The upper water column is divided into two layers, an upper thermocline layer located between the surface and the 24.5 sigma theta isopycnal surface, and a lower subthermocline layer located between the 24.5 and 26.75 isopycnals. In the upper layer the NBC retroflects north of the equator to form the eastward flowing North Equatorial Counter Current (NECC). During the six cruises the retroflection appeared complete. However, data coverage did not extend shoreward of the 200 m isobath, so the possibility of a continuous flow over the shelf still remains. There were also indications of several NBC rings which had apparently separated from the NBC retroflection and drifted to the northwest towards the eastern Caribbean Sea. North of the NBC retroflection and the NECC, the North Equatorial Current (NEC) flows west as the southern limb of the subtropical gyre. Part of the NEC is observed to retroflect cyclonically to join the eastward NECC flow. In the lower layer, beneath the NBC, the North Brazil Undercurrent (NBUC) retroflects to feed the eastward North Equatorial Undercurrent (NEUC). To the north, a deeper component of the NEC recurves to also contribute to the NEUC.

Boutin, J., J. Etcheto, Y. Dandonneau, D.C.E. Bakker, R.A. Feely, H.Y. Inoue, M. Ishii, R.D. Ling, P.D. Nightingale, N. Metzl, and R.H. Wanninkhof. Satellite sea surface temperature: A powerful tool for interpreting in-situ pCO₂ measurements in the equatorial Pacific Ocean. Tellus B, 51(2):490-508 (1999).

In order to determine the seasonal and interannual variability of the CO₂ released to the atmosphere from the equatorial Pacific, we have developed pCO₂-temperature relationships based upon shipboard oceanic CO₂ partial pressure measurements, pCO₂, and satellite sea surface temperature, SST, measurements. We interpret the spatial variability in pCO₂ with the help of the SST imagery. In the eastern equatorial Pacific, at 5°S, pCO₂ variations of up to 100 µatm are caused by undulations in the southern boundary of the equatorial upwelled waters. These undulations appear to be periodic with a phase and a wavelength comparable to tropical instability waves, TIW, observed at the northern boundary of the equatorial upwelling. Once the pCO₂ signature of the TIW is removed from the Alize II cruise measurements in January 1991, the equatorial pCO₂ data exhibit a diel cycle of about 10 µatm with maximum values occurring at night. In the western equatorial Pacific, the variability in pCO₂ is primarily governed by the displacement of the boundary between warm pool waters, where air-sea CO₂ fluxes are weak, and equatorial upwelled waters which release high CO₂ fluxes to the atmosphere. We detect this boundary using satellite SST maps. East of the warm pool, DELTA-P is related to SST and SST anomalies. The 1985-1997 CO₂ flux is computed in a 5° wide latitudinal band as a combination of DELTA-P and CO₂ exchange coefficient, K, deduced from satellite wind speed, U. It exhibits up to a factor 2 seasonal variation caused by K-seasonal variation and a large interannual variability, a factor 5 variation between 1987 and 1988. The interannual variability is primarily driven by displacements of the warm pool that makes the surface area of the outgassing region variable. The contribution of DELTA-P to the flux variability is about half of the contribution of K. The mean CO₂ flux computed using either the Liss and Merlivat (1986) or the Wanninkhof (1992) K-U parameterization amounts to 0.11 GtC yr^-1 or to 0.18 GtC yr^-1, respectively. The error in the integrated flux, without taking into account the uncertainly on the K-U parameterization, is less than 31%.

Bove, M.C., J.B. Elsner, C.W. Landsea, X. Niu, and J.J. O'Brien. Effect of El Niño on U.S. landfalling hurricanes, revisited. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 278-281 (1999).

No abstract.

Broecker, W.S., S. Sutherland, and T.-H. Peng. A possible 20th-century slowdown of Southern Ocean deep water formation. Science, 286(5442):1132-1135 (1999).

Chlorofluorocarbon-11 inventories for the deep Southern Ocean appear to confirm physical oceanographic and geochemical studies in the Southern Ocean, which suggests that no more than 5 × 10⁶ cubic meters per second of ventilated deep water is currently being produced. This result conflicts with conclusions based on the distributions of the carbon-14/carbon ratio and a quasi-conservative property, PO₄, in the deep sea, which seem to require an average of about 15 × 10⁶ cubic meters per second of Southern Ocean deep ventilation over about the past 800 years. A major reduction in Southern Ocean deep water production during the 20th century (from high rates during the Little Ice Age) may explain this apparent discordance. If this is true, a seesawing of deep water production between the northern Atlantic and Southern Oceans may lie at the heart of the 1500-year ice-rafting cycle.

Broecker, W.S., E. Clark, D.C. McCorkle, T.-H. Peng, I. Hajdas, and G. Bonani. Evidence for a reduction in the carbonate ion content of the deep sea during the course of the Holocene. Paleoceanography, 14(6):744-752 (1999).

The paleo carbonate ion proxy proposed by Broecker et al. (1999) is applied in a search for trends in the Holocene acidity of waters in the transition zone between North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW). A clear signal emerges that the carbonate ion content of waters in this zone declined during the last 8000 years. In order to determine whether this decline represents a strengthening of the northward penetrating tongue of low CO₃ content AABW or a global reduction of CO₃ ion, measurements were made on a core from the Ontong Java Plateau in the western equatorial Pacific. Evidence for a similar decline in CO₃ ion over the course of the Holocene was obtained, lending support of the latter explanation. Such a drop is consistent with the recent finding by Indermuhle et al. (1999) that the CO₂ content of the atmosphere (as recorded in the Taylor Dome Antarctica ice core) rose by 20 to 25 ppm during the last 8000 years.

Butler, J.H., D.B. King, and S.A. Yvon-Lewis. Computation of the air-sea exchange coefficient from halocarbon disequilibria. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S46, A31C-10 (1999).

Studies conducted by NOAA during the past decade show that it is possible to use measurements of halocarbon saturation anomalies to calculate air-sea gas transfer velocities. These methods provide independent, averaged measures of air-sea transfer in the open ocean and are based upon the exchange of halocarbon across the air-sea interface on a broad scale; the source and sink are both ubiquitous. Computations can be made for conservative halocarbons, such as CFC-11 or CFC-12, for a hydrolyzable halocarbon such as CH₃CCl₃, or even for a chemically and biologically reactive compound such as CH₃Br, if accompanied by measures of production and degradation. During GasEx-98, we acquired data on a number of trace halocarbons from which we can estimate air-sea exchange. The method that appears to be most useful with respect to this data set involves computations from disequilibria of conservative gases (e.g., CFCs) during heating of a water mass. Unfortunately, the waters during much of the cruise were not sufficiently warm for hydrolysis of CH₃CCl₃ to be the dominant loss mechanism. Nevertheless, disequilibrium computations for this gas did require consideration of hydrolysis. We also attempted to obtain air profiles of halocarbons, but most gases were not sufficiently supersaturated for this to be reliable. Exceptions were CH₃I and isoprene (a hydrocarbon), both of which were highly supersaturated and which, under limited sampling conditions, yielded reasonable profiles in the air.

Butler, J.H., D.B. King, S.A. Yvon-Lewis, J.M. Lobert, S.A. Montzka, and J.W. Elkins. Seasonal and temporal variability in the distribution of methyl bromide in the surface ocean. International Union of Geodesy and Geophysics, XXII General Assembly, Birmingham, England, July 18-30, July 1999. IUGG99 Abstracts, A110 (1999).

The ocean is both the largest source and the second largest sink for methyl bromide (CH₃Br) in the atmosphere, yet we still don't fully understand how the ocean regulates the atmospheric burden of this gas, nor can we predict accurately how the oceanic fluxes of methyl bromide will respond to global change. From first-order calculations, it is clear that the steady-state, net flux of this gas from the ocean will act in opposition to changes in the atmospheric burden. However, the distribution of the oceanic sources and sinks of CH₃Br appears to be patchy on both small and large scales. The open oceans are typically undersaturated in CH₃Br, with coastal waters typically supersaturated. Warm waters tend to be undersaturated; cooler waters can be super- or undersaturated. However, there are significant exceptions to any generalities. Although the chemical degradation of dissolved CH₃Br is predominantly a function of sea-surface temperature, production appears to be mainly biological and there is strong evidence for biological degradation as well. Here, we examine the distribution of methyl bromide from recent studies of its saturation in the Pacific, Atlantic, and Southern Oceans to examine spatial and temporal dependencies upon its net flux and, consequently, its production and degradation.

Cantillo, A.Y., L. Pikula, and K. Hale. Preliminary data and document rescue of material relevant to the south Florida ecosystem. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 246 (1999).

There are significant amounts of unpublished documents and data on the marine and estuarine environment of Florida that are so far unavailable to the scientific community, academia, and the general public. These data and documents are important because they represent the Florida coastal ecosystems in times past, and are the basis for comparing past with current conditions. Currently, an innovative prototype data and document rescue effort is underway that combines the expertise of a senior scientist with that of librarians. Its main purpose is to inventory unpublished documents and data, perform a quality-assurance review of the scientific content, convert the material to electronic and printed form, and make it available through printed and online resources. If the data and documents are not rescued, they will be lost as printed material physically deteriorates, personnel retire, and corporate memory disappears. Examples of rescued documents relevant to the south Florida ecosystem are presented and the data and document rescue approach discussed.

Cantillo, A.Y., K. Hale, R. Caballero, E. Collins, and L. Pikula. Environmental history of Biscayne Bay. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 218 (1999).

Biscayne Bay is surrounded on the north by the growing urban areas of Dade County, which includes Miami and Miami Beach, and on the south by the sparsely inhabited Homestead area and the northern Florida Keys. Its environmental history is closely related to the development of the Greater Miami area. Urban development of the northern part of the Bay during the 1920s began the decline that remained largely unchecked until the early 1970s. Recently, environmental degradation of the Bay has reversed. This work describes the major events impacting the Bay's ecosystem and how it has changed over time.

Carsey, T.P. Shipboard measurements of active nitrogen gases during INDOEX. AGU 1999 Fall Meeting, San Francisco, CA, December 13-17, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(46):F162, A22A-01 (1999).

A suite of active nitrogen gases (NO, NO₂, and NO_y) were measured on board the NOAA ship Ronald H. Brown during the INDOEX experiment during February-March 1999. The cruise track included crossing of the Indian Ocean ITCZ, as well as several air mass types in that region including clean marine and heavily anthropogenically influenced air masses. The results will be presented and discussed in the context of related meteorological and chemical data.

Checkley, D.M., P.B. Ortner, F.E. Werner, L.R. Settle, and S.R. Cummings. Spawning habitat of the Atlantic menhaden in Onslow Bay, North Carolina. Fisheries Oceanography, 8:22-36 (1999).

The Continuous, Underway Fish Egg Sampler (CUFES) was used to sample pelagic eggs of the Atlantic menhaden (Brevoortia tyrannus) from a 3-m depth off North Carolina in winter 1993-1994 and 1994-1995. Simultaneous measurements were made of temperature, salinity, and the concentration of chlorophyll a. The maximal concentration of eggs was 346 eggs m^-3. Eggs were highly aggregated in patches which occurred between the Gulf Stream and mid-shelf fronts (17-23°C, 36.0-36.4 ppm). Unexpectedly, eggs were found almost exclusively in water of 20-60 m (mode 20 m) bottom depth. Thus, spawning appears related to bathymetry as well as hydrography. Variograms for egg concentration indicated a mean (± SE) patch scale of 3.6 ± 1.7 km and a high degree of spatial variance explained by CUFES sampling. Lagrangian modeling of particles moving in response to tides, winds, and a prescribed flow from the north indicated that the region of observed, maximal occurrence of eggs is favorable for the retention of eggs and larvae on the shelf adjacent to inlets used to enter nursery areas.

Cione, J.J., P.G. Black, and S.H. Houston. Cooling and drying within the hurricane near-surface environment? Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 1027-1030 (1999).

No abstract.

Cook, S.K. Vertical thermal structure of midshelf waters: Water temperatures and climatological conditions south of New England, 1974-1983. NOAA Technical Report, NMFS-134, 43 pp. (1999).

No abstract.

DeMaria, M., and J. Kaplan. An updated Statistical Hurricane Intensity Prediction Scheme (SHIPS) for the Atlantic and eastern North Pacific basins. Weather and Forecasting, 14(3):326-337 (1999).

Updates to the Statistical Hurricane Intensity Prediction Scheme (SHIPS) for the Atlantic basin are described. SHIPS combines climatological, persistence, and synoptic predictors to forecast intensity changes using a multiple regression technique. The original version of the model was developed for the Atlantic basin and was run in near-real time at the Hurricane Research Division beginning in 1993. In 1996, the model was incorporated into the National Hurricane Center operational forecast cycle, and a version was developed for the eastern North Pacific basin. Analysis of the forecast errors for the period 1993-1996 shows that SHIPS had little skill relative to forecasts based upon climatology and persistence. However, SHIPS had significant skill in both the Atlantic and east Pacific basins during the 1997 hurricane season. The regression coefficients for SHIPS were rederived after each hurricane season since 1993 so that the previous season's forecast cases were included in the sample. Modifications to the model itself were also made after each season. Prior to the 1997 season, the synoptic predictors were determined only from an analysis at the beginning of the forecast period. Thus, SHIPS could be considered a "statistical-synoptic" model. For the 1997 season, methods were developed to remove the tropical cyclone circulation from the global model analyses and to include synoptic predictors from forecast fields, so the current version of SHIPS is a "statistical-dynamical" model. It was only after the modifications for 1997 that the model showed significant intensity forecast skill.

Dickerson, R.R., K.P. Rhoads, T.P. Carsey, S.J. Oltmans, J.P. Burrows, and P.J. Crutzen. Ozone in the remote marine boundary layer: A possible role for halogens. Journal of Geophysical Research, 104(D17):21,385-21,395 (1999).

On the spring 1995 cruise of the National Oceanic and Atmospheric Administration research vessel Malcolm Baldrige, we measured very large diurnal variations in ozone concentrations in the marine boundary layer. Average diurnal variations of about 32% of the mean were observed over the tropical Indian Ocean. We simulated these observations with the Model of Chemistry in Clouds and Aerosols, a photochemical box model with detailed aerosol chemistry. The model was constrained with photolysis rates, humidity, aerosol concentrations, NO, CO, and O₃ specified by shipboard observations and ozonesondes. Conventional homogeneous chemistry, where ozone photolysis to O(¹D) and HO_x chemistry dominate ozone destruction, can account for a diurnal variation of only about 12%. On wet sea-salt aerosols (at humidities above the deliquesence point), absorption of HOBr leads to release of BrCl and Br₂, which photolyze to produce Br atoms that may provide an additional photochemical ozone sink. After eight days of simulation, these Br atoms reach a peak concentration of 1.2 × 10⁷ cm^-3 at noon and destroy ozone through a catalytic cycle involving BrO and HOBr. Reactive Br lost to HBr can be absorbed into the aerosol phase and reactivated. The model predicts a diurnal variation in O₃ of 22% with aerosol-derived Br reaction explaining much, but not all, of the observed photochemical loss. The lifetime of ozone under these conditions is short, about two days. These results indicate that halogens play an important role in oxidation processes and the ozone budget in parts of the remote marine boundary layer.

Digby, S., T. Antczak, R. Leben, G. Born, S. Barth, R. Cheney, D. Foley, G.J. Goni, G. Jacobs, and L. Shay. Altimeter data for operational use in the marine environment. Proceedings, Oceans '99 MTS/IEEE Conference, Seattle, WA, September 13-16, 1999. Marine Technology Society, 605-613 (1999).

TOPEX/Poseidon has been collecting altimeter data continuously since October 1992. Altimeter data have been used to produce maps of sea surface height, geostrophic velocity, significant wave height, and wind speed. This information is of proven use to mariners as well as to the scientific community. Uses of the data include commercial and recreational vessel routing, ocean acoustics, input to geographic information systems developed for the fishing industry, identification of marine mammal habitats, fisheries management, and monitoring ocean debris. As with sea surface temperature data from the Advanced Very High Resolution Radiometer (AVHRR) in the late 1980s and early 1990s, altimeter data from TOPEX/Poseidon and ERS-1 and -2 are in the process of being introduced to the marine world for operational maritime use. It is anticipated that over the next few years companies that specialize in producing custom products for shipping agencies, fisheries, and yacht race competitors will be incorporating altimeter data into their products. The data are also being incorporated into weather and climate forecasts by operational agencies both in the United States and Europe. This paper will discuss these products, their uses, operational demonstrations, and means of accessing the data.

Doddridge, B.G., W.T. Luke, C.A. Piety, R.R. Dickerson, A.M. Thompson, J.C. Witte, J.E. Johnson, T.S. Bates, P.K. Quinn, and T.P. Carsey. Trace gas and aerosols over the Atlantic Ocean during the ACE-Aerorsols cruise. AGU 1999 Fall Meeting, San Francisco, CA, December 13-17, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(46):F163, A22A-09 (1999).

The ACE-Aerosols cruise was conducted on board the NOAA R/V Ronald H. Brown (R-104) on January 14-February 20, 1999. This paper focuses on measurements conducted during a North-South Atlantic Ocean transect from Norfolk, Virginia to Cape Town, South Africa, January 14-February 8, 1999. Hourly-averaged marine boundary layer (MBL) carbon monoxide data ranged from 105 to 200 ppbv and 45 to 75 ppbv in the northern and southern hemisphere (SH), respectively. Aerosol optical depth showed significant variability along the same transect, with elevated values dominated by upper level transport from Africa. Hourly MBL ozone data ranged from 6 to 40 ppbv, showing a diurnal cycle superimposed upon a strong hemispheric gradient, and were strongly influenced by several pollution episodes, corroborated by bulk aerosol chemistry data. Using these tracers, along with computed air parcel trajectories, cruise data indicate substantial influence of Saharan, equatorial, and SH subtropical regions of Africa on the remote Atlantic Ocean MBL.

Dodge, P.P., R.W. Burpee, and F.D. Marks. The kinematic structure of a hurricane with sea-level pressure less than 900 mb. Monthly Weather Review, 127(6):987-1004 (1999).

A National Oceanic and Atmospheric Administration aircraft recorded the first Doppler radar data in a tropical cyclone with a minimum sea level pressure (MSLP) <900 mb during a reconnaissance mission in Hurricane Gilbert on 14 September 1988, when its MSLP was ~895 mb. A previous mission had found an MSLP of 888 mb, making Gilbert the most intense tropical cyclone yet observed in the Atlantic basin. Radar reflectivity identified the hurricane eye, inner and outer eyewalls, a stratiform region between the eyewalls, and an area outside the outer eyewall that contained a few rainbands but that had mostly stratiform rain. Pseudo-dual Doppler analyses depict the three-dimensional kinematic structure of the inner eyewall and a portion of the outer eyewall. The vertical profiles of tangential wind and reflectivity maxima in the inner eyewall are more erect than in weaker storms, and winds >50 m s^-1 extended to 12 km, higher than has been reported in previous hurricanes. The inner eyewall contained weak inflow throughout most of its depth. In contrast, the portion of the outer eyewall described here had shallow inflow and a broad region of outflow. The stratiform region between the two eyewalls had lower reflectivities and was the only region where the vertically incident Doppler radar data seemed to show downward motion below the freezing level. Gilbert's structure is compared with other intense Atlantic and eastern North Pacific hurricanes with MSLP >900 mb. Storms with lower MSLP have higher wind speeds in both inner and outer eyewalls, and wind speeds >50 m s^-1 extend higher in storms with lower MSLP. Hurricanes Gilbert and Gloria (1985), the strongest Atlantic hurricanes yet analyzed by the Hurricane Research Division, had different outer eyewall structures. Gloria's outer eyewall had a deep region of inflow, while Gilbert's inflow layer was shallow. This may explain differences in the subsequent evolution of the two storms.

Dodge, P.P., S.H. Houston, W.-C. Lee, J.F. Gamache, and F.D. Marks. Windfields in Hurricane Danny (1997) at landfall from combined WSR-88D and airborne Doppler radar data. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 61-62 (1999).

No abstract.

Donnelly, W.J., J.R. Carswell, R.E. McIntosh, P.S. Chang, J.C. Wilkerson, F.D. Marks, and P.G. Black. Revised ocean backscatter models at C and Ku-bands under high wind conditions. Journal of Geophysical Research, 104(C5):11,485-11,498 (1999).

A series of airborne scatterometer experiments designed to collect C and Ku-band ocean backscatter data in regions of high ocean surface winds has recently been completed. Over 100 hours of data were collected using the University of Massachusetts C and Ku-band scatterometers, CSCAT and KUSCAT. These instruments measure the full azimuthal normalized radar cross section (NRCS) of a common surface area of the ocean simultaneously at four incidence angles. Our results demonstrate limitations of the current empirical models, CMOD4, SASSII and NSCAT1, that relate ocean backscatter to the near surface wind at high wind speeds. The discussion focuses on winds in excess of 15 m/sec in clear atmospheric conditions. The scatterometer data is collocated with measurements from ocean data buoys and GPS dropsondes, and a Fourier analysis is performed as a function of wind regime. A three-term Fourier series is fit to the backscatter data, and a revised set of coefficients is tabulated. These revised models, CMOD4HW and KUSCAT1, are the basis for a discussion of the NRCS at high wind speeds. Our scatterometer data show a clear over prediction of the derived NRCS response to high winds based on the CMOD4, SASSII and NSCAT1 models. Furthermore, saturation of the NRCS response begins to occur above 15 m/sec. Sensitivity of the upwind and crosswind response is discussed with implications towards high wind speed retrieval. wind speed retrieval.

Ellsberry, R.L., and F.D. Marks. The Hurricane Landfall Workshop summary. Bulletin of the American Meteorological Society, 80(4):683-685 (1999).

No abstract.

Enfield, D.B., and E.J. Alfaro. The dependence of Caribbean rainfall on the interaction of tropical Atlantic and Pacific Oceans. Journal of Climate, 12(7):2093-2103 (1999).

Seasonally-stratified analyses of rainfall anomalies over the Intra-Americas Sea and surrounding land areas and of onset and end dates of the Central American rainy season show that the variability of the tropical Atlantic sea surface temperature anomaly (SSTA) is more strongly associated with rainfall over the Caribbean and Central America than is tropical eastern Pacific SSTA. Seasonal differences include the importance of antisymmetric configurations of tropical Atlantic SSTA in the dry season but not in the rainy season. Both oceans are related to rainfall, but the strength of the rainfall response appears to depend on how SSTA in the tropical Atlantic and eastern Pacific combine. The strongest response occurs when the tropical Atlantic is in the configuration of a meridional dipole (antisymmetric across the ITCZ) and configuration of a meridional dipole (antisymmetric across the ITCZ) and the eastern tropical Pacific is of opposite sign to the tropical North Atlantic. When the tropical North Atlantic and tropical Pacific are of the same sign, the rainfall response is weaker. The rainy season in lower Central America tends to start early and end late in years that begin with warm SSTs in the tropical North Atlantic, and the end dates are also delayed when the eastern equatorial Pacific is cool. This enhancement of date departures for zonally antisymmetric configurations of SSTA between the North Atlantic and Pacific is qualitatively consistent with the results for rainfall anomalies.

Enfield, D.B., and A.M. Mestas-Nunez. Contrary tropospheric direct circulations associated with Pacific decadal variability and canonical ENSO oscillations. AGU 1999 Fall Meeting, San Francisco, CA, December 13-17, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(46):F180, A31D-07 (1999).

Our analysis shows that the intensity of the 1982-1983 and 1997-1998 El Niño events, occurring only 15 years apart, are among the three or four warmest in 130 years of trans-Pacific sampling. However, when the 130 year record of global sea surface temperatures (SST) is subjected to a complex empirical orthogonal function (CEOF) analysis, the leading mode has all the known characteristics (amplitude and phase) of the El Niño-Southern Oscillation (ENSO), yet the associated canonical variation of SST in the equatorial Pacific does not include the spectacular amplitudes of the 1980s and 1990s, seen in the unanalyzed SST data. When the equatorial reconstruction of the global ENSO mode is subtracted from the SST data, the residual equatorial variability (NINO3 region) is seen to have a pronounced decadal variability, with many of the characteristics that others have identified with the Pacific Decadal Oscillation (PDO). As much as 50% of the total amplitudes of the NINO3 SST anomalies in 1982-1983 and 1997-1998 are explained by this residual, which was unusually high after 1978. In this paper, we describe and compare the surface oceanic (SST) and atmospheric (pressure, winds) characteristics associated with these two components of the NINO3 variability (ENSO and residual). We also examine the anomalous direct circulation (Walker and Hadley circulations) of the global troposphere associated with each component. The tropospheric analysis, of greatest interest to this session, yields a startling result: the anomalous direct circulation associated with the canonical ENSO warmings in the NINO3 series is in most ways opposite to that associated with the residual (decadal) warmings. The contrary behavior of the two components extends to convection near the dateline, over the Amazon basin and over the Indian Ocean, while the Hadley circulations in the Pacific and Atlantic sectors are also affected in opposite ways. A unique feature of the decadal component is the occurrence of a stronger winter monsoon over India and northeast Africa, in association with warm background SSTs in the eastern equatorial Pacific.

Enfield, D.B., and A.M. Mestas-Nunez. Multiscale variabilities in global sea surface temperatures and their relationships with tropospheric climate patterns. Journal of Climate, 12(9):2719-2733 (1999).

El Niño-Southern Oscillation (ENSO) is a global phenomenon with significant phase propagation within and between basins. We capture and describe this in the first mode of a complex empirical orthogonal function (CEOF) analysis of sea surface temperature anomaly (SSTA) from the mid-19th century through 1991. We subsequently remove the global ENSO from the SSTA data, plus a linear trend everywhere, in order to consider other global modes of variability uncontaminated by the intra- and inter-basin effects of ENSO. An ordinary EOF analysis of the SSTA residuals reveals three non-ENSO modes of low-frequency variability that are related to slow oceanic and climate signals described in the literature. The first two modes have decadal-to-multidecadal time scales with high loadings in the Pacific. They bear some spatial similarities to the ENSO pattern but are broader, more intense at high latitudes, and differ in the time domain. A CEOF analysis confirms that they are not merely the phase-related components of a single mode and that all three modes are without significant phase propagation. The third mode is a multidecadal signal with maximal realization in the extratropical North Atlantic southeast of Greenland. It is consistent with studies that have documented connections between North Atlantic SSTA and the tropospheric North Atlantic Oscillation (NAO). All three SSTA modes have mid-tropospheric associations related to previously classified Northern Hemisphere teleconnection patterns. The relationships between SSTA modes and tropospheric patterns are consistent with the ocean-atmosphere interactions discussed in previous studies to explain low-frequency climate oscillations in the North Pacific and North Atlantic sectors. The first three leading modes of non-ENSO SSTA are most related, respectively, to the tropospheric patterns of the Pacific North American (PNA), the North Pacific (NP) and the Arctic Oscillations (AO), respectively. The 500 hPa pattern associated with the third SSTA mode also bears similarities to the NAO in its Atlantic sector. This North Atlantic mode has a region of high, positive SSTA loadings in the Gulf of Alaska, which appear to be connected to the North Atlantic SSTA by a tropospheric bridge effect in the AO.

Enfield, D.B., A.M. Mestas-Nunez, D.A. Mayer, and L. Cid-Serrano. How ubiquitous is the dipole relationship in tropical Atlantic sea surface temperatures? Journal of Geophysical Research, 104(C4):7841-7848 (1999).

Several kinds of analysis are applied to the departures of sea surface temperatures from climatology (SSTA, 1856-1991) to determine the degree to which SSTA of opposite sign in the tropical North and South Atlantic occur. Antisymmetric ("dipole") configurations of SSTA on basin scales are not ubiquitous in the tropical Atlantic. Unless the data are stratified by both season and frequency, inherent dipole behavior cannot be demonstrated. Upon removing the global ENSO signal in SSTA (which is symmetric between the North and South Atlantic) from the data, the regions north or south of the intertropical convergence zone have qualitatively different temporal variabilities and are poorly correlated. Dipole configurations do occur infrequently (12-15% of the time), but no more so than expected by chance for stochastically-independent variables. Non-dipole configurations that imply significant meridional SSTA gradients occur much more frequently, nearly half of the time. Cross-spectral analysis of seasonally averaged SSTA indices for the North and South Atlantic show marginally significant coherence with antisymmetric phase in two period bands: 8-12 years for the boreal winter-spring, and 2.3 years for the boreal summer-fall. Antisymmetric coherence is optimal for a small sub-region west of Angola in the South Atlantic, with respect to SSTA of basin scale in the tropical North Atlantic. Dipole variability, even where optimal, explains only a small fraction of the total variance in tropical Atlantic SSTA (<7%).

Enfield, D.B., A.M. Mestas-Nunez, D.A. Mayer, and L. Cid-Serrano. The dipole in tropical Atlantic SST: Common? Random? Intrinsic? Proceedings, 23rd Annual Climate Diagnostics and Prediction Workshop, Miami, Florida, October 26-30, 1998. National Weather Service, 223-226 (1999).

In this paper we clarify the confusing and apparently contradictory views regarding tropical Atlantic dipole variability. The issue is revisited by using a recently reconstructed 136-year SST anomaly (SSTA) analysis for the globe (Kaplan et al., 1998; henceforth, K98). An expanded analysis will appear in the Journal of Geophysical Research-Oceans (Enfield et al., 1999).

Esenkov, O.E., and B. Cushman-Roisin. Modeling of two-layer eddies and coastal flows with a particle method. Journal of Geophysical Research, 104(C5):10,959-10,980 (1999).

An existing particle-in-cell (PIC) numerical code is applied to lens-like anticyclonic vortices and buoyant coastal currents. A first series of experiments with initially elongated eddies reveals that motions induced in the lower layer act to increase the rate of rotation of the structure; eccentricity reduction, if any, produces a final vortex of aspect ratio between 1.8 and 1.9, in accordance with a theoretical prediction. A second series of experiments determines the maximal separation distance that can exist between two identical and circular vortices before they spontaneously merge; this distance is a function of the vortex size and ambient stratification. In a third series of experiments, vortex interactions across layers are considered; results similar to those obtained with two-layer point vortices (hetons) are obtained. Finally, the PIC method is generalized to simulate the finite-amplitude instability of a buoyant geostrophic current flowing a long a vertical coastal wall.

Etcheto, J., J. Boutin, Y. Dandonneau, D.C.E. Bakker, R.A. Feely, R.D. Ling, P.D. Nightingale, and R.H. Wanninkhof. Air-sea CO₂ flux variability in the equatorial Pacific Ocean near 100°W. Tellus B, 51(3):734-747 (1999).

The interannual variability of the CO₂ partial pressure (pCO₂) in the surface layer of the east equatorial Pacific Ocean near 100°W is studied and compared with the sea surface temperature (SST) monitored from satellites. This variability is shown to be correlated with the SST anomaly rather than with the temperature itself. The pCO_2OC variability is related to the variability of the upwelling systems (the equatorial upwelling and the upwelling along the American coast), the main influence being from the coastal upwelling via the surface water advected from the east. A method is derived to interpolate the pCO_2OC measurements using the SST satellite measurements. By combining the result with the exchange coefficient (K) deduced from the wind speed provided by satellite-borne instruments, we deduce the air-sea CO₂ flux and, for the first time, we continuously monitor its temporal variation. The variability of this flux is mainly due to the variability of K, with a clear seasonal variation. The flux obtained using the Liss and Merlivat (1986) relationship averaged from April 1985 to June 1997 in the region 97.5°-107.5°W, 0-5°S is 1.67 mole m^-2 yr^-1 of CO₂, leaving the ocean with an estimated accuracy of 30%.

Etcheto, J., J. Boutin, D.C.E. Bakker, Y. Dandonneau, R.A. Feely, H.Y. Inoue, M. Ishii, R.D. Ling, L. Merlivat, P.D. Nightingale, N.Metzl, and R.H. Wanninkhof. pCO₂ in the equatorial Pacific and Atlantic Oceans: Determination of air-sea CO₂ flux using satellite-borne instruments. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 119-125 (1999).

No abstract.

Feely, R.A., M.F. Lamb, D.J. Greeley, and R.H. Wanninkhof. Comparison of the carbon system parameters at the global CO₂ survey crossover locations in the North and South Pacific Ocean between 1990-1996. Technical Report, ORNL/CDIAC-115, Oak Ridge National Laboratory/Carbon Dioxide Information Analysis Center, 73 pp. (1999).

As a collaborative program to measure global ocean carbon inventories and provide estimates of the anthropogenic carbon dioxide (CO₂) uptake by the oceans, the National Oceanic and Atmospheric Administration and the U.S. Department of Energy have sponsored the collection of ocean carbon measurements as part of the World Ocean Circulation Experiment and Ocean-Atmosphere Carbon Exchange Study cruises. The cruises discussed here occurred in the North and South Pacific from 1990 through 1996. The carbon parameters from these 30 crossover locations have been compared to ensure a consistent global data set emerges from the survey cruises. The results indicate that for dissolved inorganic carbon, fugacity of CO₂, and pH, the agreement at most crossover locations are well within the design specifications for the global CO₂ survey, whereas in the case of total alkalinity, the agreement between crossover locations is not as close.

Feely, R.A., C.L. Sabine, R.M. Key, and T.-H. Peng. CO₂ survey synthesis results: Estimating the anthropogenic carbon dioxide sink in the Pacific Ocean. U.S. JGOFS News, 9(4):1-4 (1999).

Our results to date suggest that the cumulative amount of anthropogenic CO₂ in the global ocean is somewhere between 105 and 118 PgC through the year 1996. These results can be utilized as a constraint on other global carbon model simulations, similar to Princeton/Geophysical Fluid Dynamics Laboratory Ocean Biogeochemical Model and National Center for Atmospheric Research model simulations. As we refined and complete the estimates of the oceanic uptake of anthropogenic CO₂, the results will be compared to CO₂ uptake estimates for the atmosphere and terrestrial biosphere.

Feely, R.A., R.H. Wanninkhof, T. Takahashi, and P. Tans. Influence of El Niño on the equatorial Pacific contribution to atmospheric CO₂ accumulation. Nature, 398:597-601 (1999).

The equatorial ocean is an important CO₂ source to the atmosphere, contributing annually 0.7-1.5 Pg of carbon as CO₂, as much as 80% of which is attributed to the equatorial Pacific. This source is known to change significantly by ENSO events. To better understand the regional and interannual variability of CO₂ fluxes from the equatorial Pacific, field measurements of the partial pressure of CO₂ (pCO₂) have been made in the equatorial Pacific region since 1992. Here, we report that during the 1991-1994 ENSO period the net annual sea-to-air flux of CO₂ was 0.3 PgC from the fall of 1991 to the fall of 1992, 0.6 PgC in 1993, and 0.7 PgC in 1994. These fluxes are 30%-80% of the 0.9 PgC observed during the non-El Niño year of 1996. The total reduction of the sea-to-air CO₂ flux during the 1991-1994 El Niño is estimated to be 0.8-1.2 PgC, which accounts for 16-36% of the atmospheric anomaly (the difference between the annual atmospheric CO₂ increase in PgC yr^-1 and the long-term average increase of 3.18 PgC yr^-1) observed over the same period.

Feely, R.A., C.L. Sabine, R.M. Key, T.-H. Peng, and R.H. Wanninkhof. The U.S. global CO₂ survey in the North and South Pacific Ocean. Preliminary synthesis results. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 193-198 (1999).

As a collaborative program to measure global ocean carbon inventories and provide estimates of the anthropogenic CO₂ uptake in the oceans, the National Oceanic and Atmospheric Administration, the U.S. Department of Energy, and the National Science Foundation have co-sponsored the collection of ocean carbon measurements as part of the World Ocean Circulation Experiment (WOCE) and Ocean-Atmospheric Carbon Exchange Study (OACES). The cruises discussed here occurred in the North and South Pacific from 1990 through 1996. The new estimates for anthropogenic CO₂, employing the DELTA-C* method of Gruber et al. (1996), indicate that the largest buildup of anthropogenic CO₂ occurs in subtropical waters. Along 155°W, anthropogenic CO₂ penetrates to a maximum depth of 900 m at about 37°N in the North Pacific and 1300 m at about 48°S in the South Pacific. Strong shoaling of anthropogenic CO₂ occurs southward of 50°S and northward of 48°N. The anthropogenic CO₂ inventories from the observations are smaller than the Princeton Ocean Biogeochemical Model (POBM) model estimates, primarily because the Princeton model produces too much deep convective mixing of anthropogenic CO₂ in the Southern Ocean. The NCAR Climate System Ocean model, which has very different physics and biological parameterizations, appears to do a better job of reproducing the general patterns in the data-based section.

Feely, R.A., R.H. Wanninkhof, D. Hansell, M.F. Lamb, K. Lee, and R.D. Castle. Water column CO₂ measurements during the GasEx 98 cruise. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S46, A31C-11 (1999).

During the recent GasEx 98 cruise in the North Atlantic aboard the NOAA Ship Ronald H. Brown, carbon measurements were performed in the area of 46°N, 20.5°W. This process study followed a warm core ring tagged with the deliberately-introduced tracer, SF6. Continuous surface water measurements were combined with vertical profiles sampled twice daily to depths up to 1000 m for carbon mass balance studies. Dissolved inorganic carbon (DIC) and fCO₂ measurements were conducted onboard in both underway and discrete analysis modes. During the 25-day experiment in the tagged patch, surface water fCO₂ values averaged 275 ± 9 µatm, providing a constant condition of undersaturation and flux of CO₂ into the ocean. Using the Wanninkhof (1992) exchange coefficient, the estimated CO₂ flux ranged from 2-10 moles m^-2 yr^-1. The largest CO₂ flux occurred during a large storm beginning on June 6. After the storm, DIC and fCO₂ values decreased for a few days as a result of increased productivity associated with the strong mixing event. The DIC were combined with the DOC, oxygen, and nutrient data to provide a mass balance for carbon within the patch. The mass balance of CO₂ can be reconciled with the gas transfer velocities determined during the cruise.

Franklin, J.F., M.L. Black, and S.E. Feuer. Wind profiles in hurricanes determined by GPS dropwindsondes. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 167-168 (1999).

No abstract.

Fratantoni, D.M., P.L. Richardson, W.E. Johns, C.I. Fleurant, R.H. Smith, S.L. Garzoli, W.D. Wilson, and G.J. Goñi. The North Brazil Current Rings Experiment. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S179, OS31B-10 (1999).

North Brazil Current rings are large (400 km diameter) anticyclonic vortices shed from the retroflecting North Brazil Current (NBC) in the low-latitude western Atlantic Ocean. NBC rings carry a large volume of South Atlantic water northwestward along the coast of South America towards the islands of the southeastern Caribbean. These rings are thought to be one of several processes responsible for the northward transport of upper-ocean water across the equatorial-tropical gyre boundary and into the North Atlantic subtropical gyre. Such transport is required to close the Atlantic meridional overturning cell (MOC) forced by the high-latitude production and southward export of North Atlantic Deep Water. The objective of this multi-institutional study is to obtain, for the first time, comprehensive observations of the NBC retroflection, the NBC ring formation process, and the physical structure and evolution of NBC rings as they translate along the low-latitude western boundary. We seek to understand the process of NBC ring generation and to quantify the role of NBC rings as a component of the Atlantic MOC. To accomplish our objectives we used several complementary measurement techniques including detailed shipboard CTD/ADCP/XBT surveys, surface drifter and subsurface RAFOS float observations, moored velocity and temperature-salinity measurements, and a moored array of inverted echo sounders. We will present results obtained during the first two NBC rings cruises in November-December 1998 and February-March 1999. A total of three rings were surveyed in detail, each differing substantially from the others in intensity and vertical structure. Maximum azimuthal surface velocities were typically of order 150 cm/s at a radius of 120-150 km from the ring center. In one ring, coherent swirl velocities of 20 cm/s were observed to extend as deep as 2000 m. Two of the three rings exhibited subsurface velocity maxima near 100 m depth. We will present a summary of our shipboard and surface drifter observations and share some initial conclusions regarding the physical structure and watermass composition of NBC rings.

Gamache, J.F. Airborne Doppler observations of intensity change in eastern Pacific Hurricane Guillermo. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 325-328 (1999).

No abstract.

Garzoli, S.L., and R.L. Molinari. Ageostrophic currents in the tropical Atlantic. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S179, OS31B-09 (1999).

Between 23 June 1997 and 12 August 1997, the R/V Seward Johnson completed two basin-wide transects in the Atlantic along 6°N and 6°S and a partial transect along the equator. During this time, the vessel occupied 81 oceanographic stations at which hydrographic, CTD, and lowered acoustic Doppler current profiler (LADCP) measurements were acquired. Hull-mounted ADCP data were collected continuously along the transects. In this paper, the data collected along 6°N and 6°S are analyzed and discussed. Direct measurement of the ageostrophic transport are obtained and compared with estimates of the Ekman transports derived from wind measurements. Estimates of divergence are compared with other results in terms of upwelling. From the present analysis it may be concluded that in the tropical Atlantic, the Ekman drift plays an important role in the upper layer (<300 m) transports but does not account totally for the ageostrophic ones. At 6°N, instability waves and inertial currents are dominant. At 6°S, most of the ageostrophic transport can be attributed to Ekman with the difference explained by inertial waves.

Garzoli, S.L., P.L. Richardson, C.M. Dumcombe Rae, D.M. Fratantoni, G.J. Goni, and A.J. Roubicek. Three Agulhas rings observed during the Benguela Current Experiment. Journal of Geophysical Research, 104(C9):20,971-20,986 (1999).

A field program to study the circulation of the Benguela Current and its extension into the southeastern Atlantic Ocean has completed the survey and instrument deployment phase. We report here new observations of three Agulhas rings north and west of Cape Town, South Africa. Three mesoscale anticyclonic rings initially identified by means of TOPEX/POSEIDON altimetry were surveyed with expendable bathythermographs (XBTs), conductivity-temperature-depth-oxygen (CTDO) profiles, direct current measurements from a lowered acoustic Doppler current profiler (LADCP), a hull-mounted acoustic Doppler current profiler (ADCP), and satellite-tracked surface drifters. Characteristics of the rings are presented and their origins are discussed. Two are typical Agulhas rings surveyed at different times after their generation; the third Agulhas ring has an anomalous watermass structure whose most likely origin is the Subtropical Front.

Godin, O.A., D. Yu. Mikhin, and D.R. Palmer. Ocean current monitoring in the coastal zone. Oceanologia, 13:174 (1999).

A new technique has recently been put forward for real-time monitoring of ocean currents in the coastal zone. The acoustic technique, called matched non-reciprocity tomography (MNT), is being developed to extend traditional ocean acoustic tomography to the coastal zone. It should provide maps of the current field extending out tens of kilometers in range and throughout the water column. These maps will have applications to several important scientific problems such as measuring ocean circulation and upwelling and monitoring global climate change. Alternative approaches for monitoring currents in the coastal zone are surveyed and their limitations when compared with the MNT approach are discussed. Non-reciprocity tomography is based on recent progress in the theory of acoustic propagation in moving media and in the use of matched-field processing to solve tomographic inverse problems. The MNT technique can be viewed as an application of matched-field processing to a judiciously selected acoustic observable that is sensitive to flow velocity, but insensitive to sound speed and bathymetric variations, and leads to robust inversions for the depth-dependence of the velocity. The development of non-reciprocity tomography is reviewed in this article in the context of extended opportunities the technique offers in monitoring ocean dynamics in the coastal zone by acoustic means. Applications of the MNT technique to problems not directly related to coastal current monitoring are also noted.

Goldenberg, S.B., and C.W. Landsea. Relationships between decadal-scale fluctuations in vertical shear from NCEP/NCAR reanalysis data and Atlantic basin tropical cyclone activity. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 1089-1091 (1999).

No abstract.

Goni, G.J. Transport estimates of the Kuroshio Current from satellite altimeter data. In Ecosystem Dynamics of the Kuroshio Oyashio Transition Region, M. Terazaki, K. Ohtani, T. Sugimoto, and Y. Watanabe (eds.). Japan Marine Science Foundation, Tokyo, 1-8 (1999).

The Kuroshio, together with the Gulf Stream, its counterpart in the North Atlantic, are the two major western boundary currents in the northern hemisphere. These currents have been viewed as the principal channel of water exchange between the equatorial regions, where heat is added to the oceans to be later removed in the polar regions. The transport of the Kursohio current remains one of the largest uncertainties in the meridional heat flux estimate across the North Pacific subtropical gyre. Estimates of the Kuroshio mean transports vary from 21 Sv to 33 Sv (1 S v =10⁶ m³ s^-1). Some characteristics of the dynamics of this current and its variability will be also briefly addressed in this work. One very important issue in ocean dynamics is to constantly monitor the subsurface thermal structure and transport of a western boundary current. This work presents a methodology that uses a combination of satellite altimetry-derived sea height anomaly and inverted echosounder-derived hydrographic data to estimate the thickness of the ocean upper layer and baroclinic transport. The estimates reveal that during the end of 1996 and beginning of 1997 the Kuroshio Current presents an anomalous behavior.

Goni, G.J., and W.E. Johns. Synoptic study of North Brazil Current rings from altimeter data. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S179, OS31B-12 (1999).

TOPEX/POSEIDON-derived sea height anomaly fields from 1993 to 1998 are used to study the mesoscale variability off northeastern South America between 0 to 15°N and 40 to 65°W. The North Brazil Current (NBC) and the anticyclonic rings generated at this current's retroflection are the major sources of mesoscale variability in the region. Space-time diagrams show a very pronounced annual cycle of the sea height anomaly field. Once this annual cycle is removed, the sea height residuals clearly show the northwest translation of the North Brazil Current rings generated at the retroflection. Using a two-layer model, the sea height anomaly field is converted into an upper layer thickness field using parameters derived from historical hydrographic data, where the base of the upper layer is defined by the 20° isotherm. The maps of the upper layer thickness are used to find the trajectory of each ring, their velocities, length scales, and mass transport. These maps also show that 5 to 8 rings are formed every year, with the greatest frequency of formation being in boreal spring. The rings translation velocities range between 7 and 18 km/day. These rings seem to have preferred trajectories which are closely related to changes in bathymetry. Estimates of the baroclinic transport of the North Brazil Current from a T/P groundtrack across the upstream part of the retroflection show that peaks in the transport are usually followed by the formation of rings.

Goni, G.J., M.M. Huber, and L.K. Shay. TOPEX/POSEIDON-derived Atlantic Ocean hurricane heat content estimates. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, American Meteorological Society 79th Annual Meeting, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 1037-1042 (1999).

No abstract.

Goodwin, K.D., R.A. Varner, P.M. Crill, and R.S. Oremland. Uptake of near-ambient levels of methyl bromide by strain IMB-1, a facultative methylotrophic bacterium. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S64, A42C-06 (1999).

A bacterium isolated from agricultural soils, Strain IMB-1, is a facultative methylotroph able to grow on high levels (500 µM) of the agricultural fumigant, methyl bromide (CH₃Br). Agricultural and structural fumigation can release 20 to 80% of the gas that is applied, creating a potential source of stratospheric-ozone-destroying Br radicals. Investigation of Strain IMB-1 has focused on harnessing its ability to consume high levels of CH₃Br (ppmv) in order to decrease the amounts of CH₃Br released during the soil fumigation process. However, agricultural soils have also been determined to irreversibly break down ambient levels of CH₃Br (pptv). Strain IMB-1 was thus tested for its ability to consume near-ambient levels of CH3Br with the use of a permeation tube/dynamic dilution system during dynamic flow-through incubations. Strain IMB-1 grown in the presence of 0.3% CH₃Br was able to consume CH₃Br supplied at 12 parts per trillion by volume (pptv). The presence of glucose or methylamine did not inhibit CH₃Br consumption. Glucose-grown cells were induced to uptake 12 pptv CH₃Br by exposure to 0.3% CH₃Br during either exponential or stationary phases of growth. Glucose-grown cells were induced to uptake 12 pptv by exposure to 100 pptv CH₃Br only during exponential growth. The uptake rate of CH₃Br by IMB-1 grown on glucose was linearly related to concentration in the range from 12 to 19,430 pptv.

Graber, H.C., M.A. Donelan, S. Atakturk, W.M. Drennan, and K.B. Katsaros. Marine flux-profile relations from an air-sea interaction spar buoy. Proceedings, Symposium on the Wind-Driven, Air-Sea Interface, Sydney, Australia, January 10-15, 1999, M. Banner (ed.). The University of New South Wales, 317-324 (1999).

The Air-Sea Interaction Spar (ASIS) is a new autonomous spar buoy designed to permit long-term measurements of processes at the air-sea interface. During a two-month deployment in the Gulf of Mexico in April/May 1997, the buoy recorded waves as high as 3.5 m and wind speeds up to 20 m/s. The ASIS buoy was instrumented to measure high resolution wave directional properties, wind stress, and four level profiles of wind speed, temperature, and humidity. These data are used to examine marine flux-profile relations and to explore the effect of a thick wave boundary layer on the validity of Monin-Obukhov similarity theory.

Gray, J. National Oceanic and Atmospheric Administration research and operation priorities. In Proceedings, South Florida Measurement Center Workshop: Establishment of a Center for Innovative Oceanography in the 21st Century, Dania, FL, February 24-26, 1999. National Science Foundation, 207-213 (1999).

No abstract.

Grima, N., A. Bentamy, K.B. Katsaros, Y. Quilfen, P. Delecluse, and C. Levy. Sensitivity of an oceanic general circulation model forced by satellite wind stress fields. Journal of Geophysical Research, 104(C4):7967-7989 (1999).

Satellite wind and wind stress fields at the sea surface, derived from the scatterometers on European Remote Sensing satellites 1 and 2 (ERS-1 and ERS-2) are used to drive the ocean general circulation model (OGCM) "OPA" in the tropical oceans. The results of the impact of ERS winds are discussed in terms of the resulting thermocline, current structures, and sea level anomalies. Their adequacy is evaluated on the one hand by comparison with simulations forced by the Arpege-Climat model and on the other hand by comparison with measurements of the Tropical Atmosphere-Ocean (TAO) buoy network and of the TOPEX/Poseidon altimeter. Regarding annual mean values, the thermal and current responses of the OGCM forced by ERS winds are in good agreement with the TAO buoy observations, especially in the central and eastern Pacific Ocean. In these regions the South Equatorial Current, the Equatorial Undercurrent, and the thermocline features simulated by the OGCM forced by scatterometer wind fields are described. The impact of the ERS-1 winds is particularly significant to the description of the main oceanic variability. Compared to the TAO buoy observations, the high-frequency (a few weeks) and the low-frequency of the thermocline and zonal current variations are described. The correlation coefficients between the time series of the thermocline simulated by ERS winds and that observed by the TAO buoy network are highly significant; their mean value is 0.73, over the whole basin width, while it is 0.58 between Arpege model simulation and buoy observations. At the equator the time series of the zonal current simulated by the ERS winds, at three locations (110°W, 140°W, and 165°E) and at two depths, are compared to the TAO current meter and acoustic Doppler current profiler (ADCP) measurements. The mean value of the significant correlation coefficients computed with the in-situ measurements in 0.72 for ERS, while it is 0.51 for the Arpege-Climat model. Thus, ERS wind fields through the OGCM generate more realistic current variations than those obtained with Arpege climate winds, and they are particularly efficient in capturing abrupt changes ("wind bursts") which may be important regarding ocean dynamics.

Hansen, D.V., and W.C. Thacker. Estimation of salinity profiles in the upper ocean. Journal of Geophysical Research, 104(C4):7921-7934 (1999).

A new algorithm is presented for estimating salinity profiles in the upper ocean from measurements of temperature profiles and surface salinity. In application to the eastern tropical Pacific the method replicates a large fraction of the variability of salinity in the upper few tens of meters and provides modest to substantial improvement at nearly all levels. Estimated salinity profiles are able to characterize barrier layers, regions formed by a halocline within the thermal mixed layer. The rms error of geopotential-height calculations based on estimated salinity profiles is reduced more than 50 percent by this method relative to methods not using surface salinity. Even without the surface salinity measurement some reduction of error in geopotential heights can be obtained relative to previous methods.

Hellin, J., M. Haig, and F.D. Marks. Rainfall characteristics of Hurricane Mitch. Nature, 399:316 (1999).

No abstract.

Hendee, J.C. An environmental information synthesizer for expert systems. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 217 (1999).

As an enhancement to the SEAKEYS environmental monitoring network, software called the Environmental Information Synthesizer for Expert Systems (EISES) has been constructed which synthesizes knowledge from near real-time acquired meteorological and oceanographic data. This knowledge is acquired in the form of facts which can be used by expert systems designed to monitor and match environmental parameters as they meet criteria generally thought to be conducive to certain biological events. The initial expert system constructed to use the facts from EISES, which we have dubbed the Coral Reef Early Warning System (CREWS), represents a first step in the construction of a larger coral reef specific expert system. When environmental conditions are conducive to coral bleaching, according to different bleaching theories or models, CREWS produces alerts which are automatically posted to the Web and emailed to researchers so they can verify and study bleaching events as they might happen. The models are refined using feedback from field data on bleaching recorded after alerts from the expert system. CREWS has now been implemented not only for the Florida Keys National Marine Sanctuary, but also for the Great Barrier Reef Marine Park Authority, and will hopefully be developed in the future for other coral reef sanctuaries or parks throughout the world. In addition to CREWS, expert systems for Florida Bay are being developed with collaborators to model juvenile pink shrimp and fish spawning migrations (with UM/RSMAS and NOAA/NMFS) and conditions conducive to harmful algal blooms (with NOAA/NESDIS). Some other example events that might be monitored or predicted from EISES expert systems include good diving and/or fishing conditions (e.g., clear water, low winds), at remote locations, phytoplankton blooms, hypo- or hypersaline influxes from Florida Bay, and excessive dissolved nutrient encroachment (inferred from high fluorometry values).

Hood, M., R.H. Wanninkhof, and L. Merlivat. The effects of wind-induced mixing on short timescale surface variability of fCO₂ and fluorescence: Results from the GasEx-98 CARIOCA buoy data. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S47, A31C-12 (1999).

During the Lagrangian deliberate tracer study in the North Atlantic, GasEx-98, hourly measurements of wind speed, sea surface temperature, fCO₂, and fluorescence were made from two CARIOCA drifting buoys near 46°N and 21.5°W over a period of approximately 20 days. Shipboard measurements of fCO₂ were used to calibrate the buoy data, and the hourly time series of the two buoys and the ship were in good agreement. Using these data, we investigated the air-sea flux of CO₂, the importance of short-term wind-induced mixing events for longer-term estimates of flux, and the physical versus biological processes controlling surface variability of fluorescence. The air-sea flux estimate for the ~20 day experiment using the Wanninkhof (1992) gas transfer velocity formulation was -0.012 mol m^-2 d^-1, and using the Liss and Merlivat (1986) formulation was -0.007 mol m^-2 d^-1. A storm with wind speeds reaching as high as 16-17 m s^-1 led to a sharp decrease in sea surface temperature and an increase in fCO₂ of approximately 30 µatm. The magnitude of this sudden change in fCO₂ is equal to approximately half of the annual range of fCO₂ in this area and accounted for approximately 38% of the flux over the 20-day period. Approximately 16 hours after the onset of the storm, there was an increase in surface fluorescence coincident with the initial increase in fCO₂. Nitrate measurements made from the ship show a sharp peak in surface concentrations about 24 hours after the increase in winds and approximately 6-8 hours after the increase in surface fluorescence. This increase in surface fluorescence that occurs in tandem with the increase in fCO₂ and decrease in SST and before the arrival of nutrients to the surface suggests an upwelling of a relatively shallow chlorophyll maximum in this area. Phaeopigment to chlorophyll ratios are consistent with this mechanism. After the upwelling of the NO₃, the fluorescence increases more sharply while the fCO₂ decreases, consistent with biological productivity.

Houston, S.H., and M.D. Powell. Hurricanes and tropical storms in Florida Bay. Florida Sea Grant College Program, FLSGP-G-99-016, 2 pp. (1999).

No abstract.

Houston, S.H., W.A. Shaffer, M.D. Powell, and J. Chen. Comparisons of HRD and SLOSH surface wind fields in hurricanes: Implications for storm surge modeling. Weather and Forecasting, 14(5):671-686 (1999).

Surface wind observations analyzed by the Hurricane Research Division (HRD) were compared to those computed by the parametric wind model used in the National Weather Service Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model's storm surge computations for seven cases in five recent hurricanes. In six cases, the differences between the SLOSH and HRD surface peak wind speeds were 6% or less, but in one case (Hurricane Emily of 1993) the SLOSH computed peak wind speeds were 15% less than the HRD. In all seven cases, statistics for the modeled and analyzed wind fields showed that for the region of strongest winds, the mean SLOSH wind speed was 14% greater than that of the HRD and the mean inflow angle for SLOSH was 19° less than that of the HRD. The radii beyond the region of strongest winds in the seven cases had mean wind speed and inflow angle differences that were very small. The SLOSH computed peak storm surges usually compared closely to the observed values of storm surge in the region of the maximum wind speeds, except Hurricane Emily where SLOSH underestimated the peak surge. HRD's observation-based wind fields were input to SLOSH for storm surge hindcasts of Hurricanes Emily and Opal (1995). In Opal, the HRD input produced nearly the same computed storm surges as those computed from the SLOSH parametric wind model, and the calculated surge was insensitive to perturbations in the HRD wind field. For Emily, observation-based winds produced a computed storm surge that was closer to the peak observed surge, confirming that the computed surge in Pamlico Sound was sensitive to atmospheric forcing. Using real-time, observation-based winds in SLOSH would likely improve storm surge computations in landfalling hurricanes affected by synoptic and mesoscale factors that are not accounted for in parametric models (e.g., a strongly sheared environment, convective asymmetries, and stably stratified boundary layers). An accurate diagnosis of storm surge flooding, based on the actual track and wind fields, could be supplied to emergency management agencies, government officials, and utilities to help with damage assessment and recovery efforts.

Houston, S.H., G. Forbes, A. Chiu, W.-C. Lee, and P.P. Dodge. Super Typhoon Paka's (1997) surface winds. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 1032-1033 (1999).

No abstract.

Huang, H., R.E. Fergen, J.J. Tsai, and J.R. Proni. Evaluation of mixing zone models: CORMIX, PLUMES, and OMZA with field data from two Florida ocean outfalls. Proceedings, Second International Symposium on Environmental Hydraulics, Hong Kong, China, December 16-18, 1998. Environmental Hydraulics, pp. 249-254 (1999).

This paper presents an evaluation of three mixing zone models: CORMIX, PLUMES, and OMZA using field data from two Florida ocean outfalls: Hollywood and Miami-Central outfalls. The hollywood outfall has a single port outlet and the Miami-Central outfall has a multiport diffuser. Both outfalls discharge secondary effluent. For the nearfield, all of the three models predict realistic initial dilutions for the tests at the outfall except three cases in CORMIX predictions and two cases in PLUMES predictions (out of 20 cases). For the nearfield and farfield combined, CORMIX significantly overestimates dye concentrations for the tests at the Hollywood outfall but underestimates dye concentrations within the 300 m to 400 m range for the tests at the Miami-Central outfall. PLUMES predictions agree reasonably well with the filed data for the range from 300 m to 800 m but do not agree well within the 300 m range for the tests at both outfalls. OMZA predictions agree well with the field data within the 800 m range for the test at both outfalls.

Huber, M.M., L.K. Shay, and G.J. Goni. The Atlantic Ocean's role on intensity change. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, American Meteorological Society 79th Annual Meeting, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 36-39 (1999).

No abstract.

Humphrey, J.C., S.L. Vargo, J.C. Ogden, and J.C. Hendee. SEAKEYS 1999: Florida Keys monitoring initiative. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Program and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 240-241 (1999).

The Sustained Ecological Research Related to the Management of the Florida Keys Seascape (SEAKEYS) program was organized in 1991 by the Florida Institute of Oceanography (FIO) with initial funding from the John D. and Catherine T. MacArthur Foundation, and continuing funding from the South Florida Ecosystem Restoration, Prediction and Monitoring (SFERPM) program, administered by the National Oceanic and Atmospheric Administration (NOAA). The SEAKEYS environmental monitoring program, which is basically an oceanographic extension to the meteorologically-oriented Coastal-Marine Automated Network of NOAA, has accumulated an unparalleled long-term database of meteorological and oceanographic data from the Florida Straits and Florida Bay. During 1998, the SEAKEYS network was upgraded with more precise oceanographic sensors, and selected stations were augmented with fluorometers, transmissometers, and water-level sensing equipment. A seventh monitoring station, a cooperative effort between FIO and the University of South Florida's Department of Marine Science (USF/DMS), was completed in Northwest Florida Bay at 25°05'00"N, 81°05'30"W during summer, 1998. This station also contains a full suite of meteorological and oceanographic instrumentation and also transmits its data hourly via a NOAA GOES satellite. The Northwest Florida Bay station is the northwestern most station in the SEAKEYS network, as well as the southernmost link in the West Florida Coastal Ocean Monitoring and Prediction System of USF/DMS. Turbulent weather was prominent during 1998 in the Florida Keys. Severe conditions reported by the SEAKEYS stations included the Ground Hog Day Storm, Hurricane Georges, and Tropical Storm Mitch. In most cases the SEAKEYS stations contained the only instruments to measure the meteorological and oceanographic measurements accompanying these events in the Florida Keys. The Long Key station measured the highest winds (119 mph) in South Florida during the Ground Hog Day Storm of February 2, 1998. On September 25, 1998 the eye of Hurricane Georges passed over Key West at 1150 EDT as wind speeds dropped from 85.2 mph to 9.6 mph. The eye moved across the Dry Tortugas station at 1610 EDT with barometric pressures dropping to 974.4 mb. Winds gusted to hurricane force only after the eye passed at 2100 EDT. Georges' most severe winds in the Florida Keys gusted to 113 mph at Sombrero Reef, with a sustained wind speed of 94 mph. Long Key, Molasses Reef, and Fowey Rocks received gusts of tropical storm force. The tide station at Sombrero Reef reported a storm water level of 2.87 feet above mean lower low water. This contrasted with below normal levels reported at a station on Florida Bay. Hurricane Mitch passed northwest of the Florida Keys on the evening of November 4, 1998, bringing peak winds of 62.4 mph at Molasses Reef and sustained gale force winds until the following afternoon. Numerous localized tornadoes spawned by this storm caused extensive damage in the Upper Keys. Daily near real-time SEAKEYS data are available to researchers via NOAA's Coral Health and Monitoring Program (CHAMP) Web site at http://www.coral.noaa.gov, while historical data are available at http://www.neptune.noaa.gov. The Coral Reef Early Warning System (CREWS), which utilizes the near real-time data from six SEAKEYS stations, is an online expert system which monitors environmental conditions on the reef that are theoretically conducive to coral bleaching. If these conditions occur, alerts are sent via email to researchers and posted to the Web at http://www.coral.noaa.gov/sferpm/seakeys/es.

Johns, E., W.D. Wilson, and T.N. Lee. Surface salinity variability of Florida Bay and southwest Florida coastal waters. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 169-171 (1999).

No abstract.

Johns, E., W.D. Wilson, and R.L. Molinari. Direct observations of velocity and transport in the passages between the Intra-Americas Sea and the Atlantic Ocean, 1984-1996. Journal of Geophysical Research, 104(C11):25,805-25,820 (1999).

Shipboard acoustic Doppler current profiler observations of the velocity in the upper 200 m of the water column collected during 1984-1996 using the National Oceanic and Atmospheric Administration R/V Malcolm Baldrige are used to examine the velocity structure and transport in the passages between the Atlantic Ocean and the Intra-Americas Sea (IAS). Data were colected during 23 cruises along the following sections: across the Straits of Florida, in the Northwest Providence Channel (NWPC), across the northern passages into the Caribbean Sea (Windward, Mona, and Anegada), across the eastern Caribbean along 63°30'W, thereby forming a closed quadrangle, and in the Grenada Passage. The Florida Current, the eastern Caribbean, and the Grenada Passage share a similar mean velocity structure characterized by high-velocity, surface intensified flows with strong vertical and horizontal shears. The northern Caribbean passages (NWPC, Windward, Mona, and Anegada) share a different common mean velocity structure, with subsurface velocity maxima directed into the IAS, and surface-intensified counterflows along one side of each paassage. On average, there is a transport balance in the upper 200 m between waters entering and exiting the IAS, with the 16.5 ± 2.4 Sv (1 Sv = 10⁶ m³ s^-1) transport of the Florida Current at 27°N comprised of 0.4 ± 0.8 Sv from the NWPC, 2.2 ± 1.5 Sv from the Windward Passage, 2.8 ± 2.1 and 2.4 ± 2.8 Sv from the Mona and Anegada passages, respectively, and 9.5 ± 4.7 Sv across the eastern Caribbean, for a total of 17.3 Sv. The four passages north of 17°N (from NWPC to Anegada Passage) have a combined transport of 7.8 Sv, nearly half of the transport of the Florida Current in the upper 200 m. Of the 9.5 Sv flowing through the eastern Caribbean between 11°N and 17°N, 4.9 ± 2.6 Sv, or more than half, come from the Grenada Passage. This is significant to the subject of cross-equatorial exchange of mass, heat, and salt, as the Grenada Passage is where the highest transport of waters originating in the southern hemisphere is thought to enter the Caribbean.

Jones, R.W., and M. DeMaria. Further studies of the optimization of a hurricane track prediction model using the adjoint equations. Monthly Weather Review, 127(7):1586-1598 (1999).

The method of model fitting, or adjoint method, is applied to a barotropic hurricane track forecast model described by DeMaria and Jones using a large sample of forecast cases. The sample includes all Atlantic tropical cyclones that reached hurricane intensity during the 1989-1993 hurricane seasons (141 72-h forecasts of 17 storms). The cases considered by DeMaria and Jones are a subset of the present sample. Model-fitting calculations using strong, weak, strong followed by weak, or weak followed by strong model constraints are discussed for data assimilation periods varying from 6 to 72 h. Generally, the best track forecasts occur for shorter assimilation periods and for weak constraints, although only the 12-h assimilation with the weak constraint has less track error than the control forecast without assimilation, and only for the 12-h forecast. The principle reason for this lack of improvement is that the fit of the model to the observed track is good at the middle of the assimilation period, but not very good at the end where the forecast begins. When a future track position at 6 h is included in the assimilation, in order to improve the track fit at the synoptic data time, the resulting track errors average about 10% smaller than the control forecast. The control forecast may also be improved in the same way. In that case, the best assimilation forecasts have 2.5% smaller track errors than the modified control forecasts.

Jones, R.W., and H.E. Willoughby. Results of generalizing a semispectral shallow-water barotropic hurricane tracking model into a two-layer baroclinic model. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 747-750 (1999).

No abstract.

Kaplan, J., and M. DeMaria. Climatological and synoptic characteristics of rapidly intensifying tropical cyclones in the North Atlantic basin. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 592-595 (1999).

No abstract.

Kelly, P.S., K.M. Lwiza, R.K. Cowen, and G.J. Goni. Low-salinity lenses at Barbados, West Indies: Their origin, frequency, and variability. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S185, OS42C-01 (1999).

A vertical array of conductivity-temperature sensors moored west of Barbados, West Indies, from May 1996 to November 1997 revealed a heterogeneous and variable salinity pattern punctuated by six intrusions of low-salinity water (less than 34.5 psu). A typical intrusion extended to 30 m depth and lasted ~25 days, although one intrusion extended to 47 m and lasted 94 days. Water samples taken during an intrusion in May 1997 have Radium 228/226 activity ratios of approximately 1, consistent with previous measurements in Barbados of water that originated in the Amazon River mixing zone. The Amazon water likely was translated to Barbados in rings spawned from the North Brazil Current (NBC). Analysis of sea height anomaly derived from the TOPEX/Poseidon satellite altimeter supports this conclusion and reveals that, contrary to previous studies, rings are shed throughout the year, mostly during spring. The intrusions of low-salinity water and their associated velocities dramatically changed the already variable flow in our study area. The complex salinity and flow we observed represented the effects of NBC rings passing the island, perhaps disrupted by the relatively shallow Tobago-Barbados ridge. The complex velocity and water structure are interesting in their own right as evidence of the Barbados region as a mixing zone and for their influence on recruitment of larval fishes to the reef along the island's west coast.

Landsea, C.W., and J.A. Knaff. Application of the El Niño-Southern Oscillation CLImatology and PERsistence (CLIPER) forecasting scheme. Experimental Long-Lead Forecast Bulletin, 8(4):34-36 (1999).

No abstract.

Landsea, C.W., and J.F. Knaff. How much "skill" did the various forecasting methods available have for the 1997-1998 El Niño event? Preprints, Second Hayes Symposium on Seasonal to Interannual Climate Variability--The 1997/1998 ENSO Cycle, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 73 (1999).

No abstract.

Landsea, C.W., R.A. Pielke, A.M. Mestas-Nunez, and J.A. Knaff. Atlantic basin hurricanes: Indices of climatic changes. Climatic Change, 42:89-129 (1999).

Accurate records of basin-wide Atlantic and U.S. landfalling hurricanes extend back to the mid 1940s and the turn of the century, respectively, as a result of aircraft reconnaissance and instrumented weather stations along the U.S. coasts. Such long-term records are not exceeded elsewhere in the tropics. The Atlantic hurricanes, U.S. landfalling hurricanes, and U.S. normalized damage time series are examined for interannual trends and multidecadal variability. It is found that only weak linear trends can be ascribed to the hurricane activity and that multidecadal variability is more characteristic of the region. Various environmental factors including Caribbean sea level pressures and 200 mb zonal winds, the stratospheric Quasi-Biennial Oscillation, the El Niño-Southern Oscillation, African West Sahel rainfall, and Atlantic sea surface temperatures, are analyzed for interannual links to the Atlantic hurricane activity. All show significant, concurrent relationships to the frequency, intensity, and duration of Atlantic hurricanes. Additionally, variations in the El Niño-Southern Oscillation are significantly linked to changes in U.S. tropical cyclone-caused damages. Finally, much of the multidecadal hurricane activity can be linked to the Atlantic Multidecadal Mode, an empirical orthogonal function pattern derived from a global sea surface temperature record. Such linkages may allow for prediction of Atlantic hurricane activity on a multidecadal basis. These results are placed into the context of climate change and natural hazards policy.

Landsea, C.W., C.A. Anderson, G. Clark, J. Fernandez-Partagas, P. Hungerford, C. Neumann, and M. Zimmer. The Atlantic hurricane database re-analysis project. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 394-397 (1999).

No abstract.

Lapitan, R.L., R.H. Wanninkhof, and A.R. Mosier. Methods for stable gas flux determination in aquatic and terrestrial systems. In Approaches to Scaling of Trace Gas Fluxes in Ecosystems, A.F. Bouwman (ed.), Elsevier, Amsterdam, 27-66 (1999).

A general description of the current approaches for measuring trace gas fluxes in aquatic and terrestrial systems is presented in this paper. Our aim is to provide an overview of the current methodologies employed in trace gas flux measurements and the most recent advancements made; with emphasis on the uncertainties observed and potential areas for future developments required to further minimize these uncertainties brought about by spatial and temporal variabilities of fluxes in the field. The increase in sensitivity and improved response time of analytical devices for measuring trace gases within the last five years, such as advancements in laser spectroscopy, have significantly improved the effectiveness of the current methods of measuring these gases in aquatic and terrestrial systems. Systematic errors in trace gas flux estimates have also been reduced with the refinements in estimates of the gas transfer velocity,k, through the use of tracers in the two systems. Footprint corrections of micrometeorological flux measurements in terrestrial systems have provided a better means of identifying the spatial sources of trace gases, and thus, have increased the scope of inference from trace gas flux measurements. Despite these improvements, however, flux measurement errors still remain high. Experimental and sampling designs that can efficiently and effectively deal with the spatial and temporal variabilities in trace gas flux measurements to the minimum are of utmost priority. The same can be said of the modeling procedures; that is, there is a need for an effective method that can reduce instead of propagate potential errors in scaling from field plot to regional or global scales.

Lee, K., R.H. Wanninkhof, R.A. Feely, F.J. Millero, and T.-H. Peng. Global distribution of total inorganic carbon in surface water. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 493-496 (1999).

No abstract.

Lee, K., R.H. Wanninkhof, T. Takahashi, S.C. Doney, and R.A. Feely. Interannual variations in oceanic uptake of anthropogenic carbon dioxide for the period of 1982-1995. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 31-34 (1999).

No abstract.

Lee, T.N., E. Williams, E. Johns, and W.D. Wilson. First year results from enhanced observations of circulation and exchange processes in western Florida Bay and connecting coastal waters, including effects of El Niño and Hurricane Georges. 1999 Florida Bay and Adjacent Marine System Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 145-147 (1999).

No abstract.

Majumdar, S.J., S.D. Aberson, C.H. Bishop, and Z. Toth. Real time hurricane track targeting using a VICBAR ensemble. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 755-756 (1999).

No abstract.

Marks, F.D., and H.A. Friedman. 1999 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami Florida (published for limited distribution), 142 pp. (1999).

No abstract.

Marks, F.D., P.P. Dodge, and C. Sandin. WSR-88D observations of hurricane atmospheric boundary layer structure at landfall. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 1051-1054 (1999).

No abstract.

McGillis, W., J. Edson, and R.H. Wanninkhof. Direct air-sea flux measurements of carbon dioxide over the North Atlantic Ocean and the comparison to indirect methods. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22,1999. Center for Global Environmental Research (CGER-I037-99), 367-377 (1999).

To date, large uncertainties in the extent of the CO₂ flux between the atmosphere and ocean have prevented us from accurately quantifying how the increasing atmospheric CO₂ burden partitions between the ocean and the terrestrial biosphere. This limits our ability to accurately predict future atmospheric CO₂ levels. We have recently designed a direct CO₂ flux measurement system that considerably improves our estimates of air-sea gas exchange. The system measures the direct air-sea flux of CO₂ in the atmospheric boundary layer using eddy correlation (direct covariance). It was successfully deployed during the large scale experiment to study air-sea gas fixes, GASES98, which was conducted in the CO₂ sink region of the North Atlantic during May/June of 1998. The seasonal algal bloom caused air-sea pCO₂ differences of between -80 to ~100 µatm. This large concentration gradient generated large signals for accurate measurement of the CO₂ flux using a close path CO₂ sensor. In addition to the CO₂ gas flux, the comprehensive atmospheric flux measurement suite included momentum, heat, and moisture fluxes. Atmospheric flux and air-sea gas concentration measurements were performed for over 500 hours, providing more than 1000 observations. Wind speeds between 1 and 16 m/s were experienced over the range of these observations. Preliminary flux estimates from our system compare extremely well with previous estimates of the gas transfer velocity for wind speeds below 7 m/s. At higher wind speeds, the transfer velocities obtained from our system are as much as 20-50% higher than those estimated by empirical relationships. Based on accurate air-sea CO₂ coefficients obtained by our investigation and atmospheric and surface ocean pCO₂ data obtained to date, estimates of the global ocean CO₂ sink are now feasible. Our findings will also provide better predictions of the seasonal and interannual variability of sea-air CO₂ flux observed in various global regions.

McTaggart, K.E., G.C. Johnson, C.I. Fleurant, and M.O. Baringer. CTD/O₂ measurements collected on a Climate and Global Change cruise along 24°N in the Atlantic Ocean (WOCE section A6) during January-February 1998. NOAA Data Report, ERL PMEL-68 (PB99-155194), 368 pp. (1999).

Summaries of CTD/O₂ measurements and hydrographic data acquired on a Climate and Global Change cruise during the winter of 1998 aboard the NOAA ship Ronald H. Brown are presented. The majority of these data were collected along 24.5°N from 23.5°W to 69°W. Completing the transatlantic section are data collected along a northeast-southwest dogleg off the coast of Africa, and along a second, short, zonal section along 26.5°N off the coast of Abaco Island from 69°W to 77°W, jogging north along 27°N in the Straits of Florida to 80°W. Data acquisition and processing systems are described and calibration procedures are documented. Station location, meteorological conditions, CTD/O₂ summary data listings, profiles, and potential temperature-salinity diagrams are included for each cast. Section plots of oceanographic variables and hydrographic data listings are also given.

Mestas-Nunez, A.M., and D.B. Enfield. Rotated global modes of non-ENSO sea surface temperature variability. Journal of Climate, 12(9):2734-2746 (1999).

A varimax rotation was applied to the EOF modes of global SST derived by Enfield and Mestas-Nuñez (1999). The SST anomaly record is more than a century long, with a global complex EOF representation of ENSO and a linear trend removed at every grid point. The rotated EOF modes capture localized centers of variability that contribute to the larger scale spatial patterns of the unrotated modes. The first rotated EOF represents a multidecadal signal with larger response in the North Atlantic. The second rotated EOF represents an interdecadal uctuation with larger response in the eastern North Pacific and out of phase fluctuations of smaller amplitude in the central North Pacific. The third rotated EOF captures interdecadal fluctuations in the eastern tropical Pacific with a dominant peak that coincides with the 1982-83 ENSO. The fourth rotated EOF has an interdecadal to multidecadal nature with larger response in the central equatorial Pacific and quasi-symmetric out of phase response in the western North and South Pacific. The fifth mode represents multidecadal fluctuations with large response at about 40°N in the North Pacific. The sixth mode has interannual to interdecadal time scales with largest response confined to the South Atlantic. Our rotated modes are dominated by intra- rather than interocean uctuations supporting the hypothesis that the non-ENSO variability is more regional than global in nature. Analyses of sea level pressure and surface wind stress show that in general the non-ENSO rotated EOFs are consistent with an ocean response to local atmospheric forcing. An exception is the eastern tropical Pacific mode which is more consistent with an atmospheric response to changes in the ocean SST.

Mestas-Nunez, A.M., and D.B. Enfield. Rotated global modes of non-ENSO sea surface temperature. Proceedings, 23rd Annual Climate Diagnostics and Prediction Workshop, Miami, Florida, October 26-30, 1998. National Weather Service, 162-165 (1999).

No abstract.

Molinari, R.L. Lessons learned from operating global ocean observing networks. Bulletin of the American Meteorological Society, 80(7):1413-1420 (1999).

The Global Ocean Observing System Center (GOOSC) at the National Oceanic and Atmospheric Administration's (NOAA) Atlantic Oceanographic and Meteorological Laboratory operates two global observing networks, a drifting buoy array, and a Voluntary Observing Ship network. The arrays provide in real time surface atmospheric and subsurface oceanographic data needed by NOAA weather and climate forecasters. The data are used in delayed mode to verify model simulations of the ocean and atmosphere, to provide in situ calibration/validation data for remote sensing observations, and to increase understanding of the dynamics of the ocean and atmosphere. The operational and research lessons learned in the operation of the GOOSC are reviewed. Operationally, it was learned that, because of costs, international participation is required to maintain global networks; data management methodology is a critical component of operations; and integrated observing systems using multiple platforms provide more accurate products. Scientifically, it was learned, for example, that accurate characterizations of the salinity field must be available in model simulations. As more data become available it is found that scales of important phenomena such as equatorial upwelling are smaller, and high-frequency signals can impact on the mean structure of the upper ocean. These findings must be considered when designing effective sampling strategies.

Molinari, R.L., S.L. Garzoli, and R.W. Schmitt. Equatorial currents at 1000 m in the Atlantic Ocean. Geophysical Research Letters, 26(3):361-364 (1999).

Twenty-seven Profiling ALACE (PALACE) floats were deployed in the equatorial Atlantic during July-August 1997. The floats were ballasted to drift at 1000 m for 10 to 14 days, return to the surface while obtaining a temperature profile, transmit data via satellite, and then after one day return to 1000 m. One-year float paths are now available. Floats deployed on the equator were launched into a deep westward jet. The jet extends some 1-2° north of the equator, with eastward motion observed in floats to the north of 2°N. The equatorial current reverses in the central basin to the east in mid-October and then back to the west in mid-February. Flow to the north also reverses. The short space and time scales contrast with earlier work based on fewer floats that inferred space scales of some 5 -10 in latitude and time scales greater than one year. The new results are consistent with models that indicate that equatorial Rossby waves are the cause of the reversing currents.

Morisseau-Leroy, N., M.K. Solomon, G.P. Momplaisir, T. Kurian, and E. Griffin. Oracle 8I SQLJ Programming. Osborne McGraw-Hill (ISBN 0072121602), 557 pp. (1999).

No abstract.

Murillo, S.T., and J.J. O'Brien. The influence of ENSO on eastern Pacific tropical cyclones. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 437-438 (1999).

No abstract.

Murillo, S.T., W.-C. Lee, K. Hondl, P.P. Dodge, C. McAdie, and F.D. Marks. Implementation of the GBVTD technique in nowcasting hurricane wind fields using the WSR-88D. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 311-312 (1999).

No abstract.

Nelsen, T.A., and J.R. Proni. Detecting, mapping, sampling, and analyzing oceanic suspended particulate matter: Methods complementary to acoustic detection of environmentally sensitive ocean outfall and dumped materials. Joint Meeting, 137th Regular Meeting of the Acoustical Society of America and 2nd Convention of the European Acoustics Association: Forum Acousticum 99, Berlin, Germany, March 15-19, 1999. Journal of the Acoustical Society of America, 105(2):1322 (1999).

Natural systems such as lakes, rivers, and oceans can be described by dissolved and particulate components. Particulate sources in coastal oceanic environments include natural materials from seaward riverine and estuarine flows and anthropogenic sources such as ocean dumping and outfalls. Plumes of suspended particulate matter (SPM) can be natural (lithogenic and biogenic), anthropogenic, and any mixture of these. Because SPM can range from environmentally neutral (i.e.,lithogenic and biogenic) to hazardous (heavy metals, bacteria), detecting, tracking, sampling, and sourcing SPM plumes can be beneficial for the environment and human health. Acoustic methods have proven successful in detecting and mapping oceanic SPM over large spatial areas but are limited in resolving internal fine structure, estimating relative contributions of merged plumes from various sources (e.g., river outflow vs. dumping), and differentiating between introduced and in-situ SPM. To complement acoustics, CTD/optical/water survey tools have been employed for guided sampling of plumes. Water samples for total suspended matter (TSM) and particle size distributions have proven useful to both calibrate acoustic measurements and provide insight into signatures provided by particle size distributions. Signatures, determined by factor and component analyses, allows mapping of SPM components, as well as estimating their dilution and long-termed budgets.

Nelsen, T.A., and J.R. Proni. Distribution and movement of discharged dredged material at the San Juan Ocean Disposal site. Final Report to the U.S. Army Corps of Engineers, MIPR No. W32CS580843181, 57 pp. (1999).

No abstract.

Nelsen, T.A., and J.R. Proni. Signatures contained in suspended particulate matter with application to coastal-ocean environmental studies. In Coastal Engineering and Marine Developments, C. Brebbia and P Anagnostopoulos (eds.). WIT Press, Southampton, 328-346 (1999).

Suspended particulate matter (SPM) samples from the New York Bight Apex collected during a sewage-dump experiment were analyzed for chemical as well as physical parameters such as particle-size distributions. The latter provided a signature of the SPMs' sewage component that allowed differentiation from other components. These results were applied to a series of eight Water Column Characterization (WCC) cruises in this area. Co-analysis of WCC and sewage dump particle-size distributions by factor analysis and Distribution Component Analysis revealed patterns that allowed differentiation of sewage-derived components for all WCC samples. From this, a long-termed budget of SPM components, including sewage-derived materials, was constructed. Given this, we conclude that useful tools are available for developing signatures of anthropogenic components of SPM plumes which are independent of study sites or subject materials. These signatures can be applied to understand the sources, pathways, and sinks of such materials in the coastal ocean, as well as constructing long-termed budgets thereof. Ultimately such estimates can be critical to waste management strategies and decisions in an ever more anthropogenically-impacted coastal ocean.

Nelsen, T.A., G. Garte, C.M. Featherstone, P.L. Blackwelder, T. Hood, C. Alvarez-Zarikian, P. Swart, H.R. Wanless, L. Tedesco, C. Souch, J. Pachut, and J. Arthur. Understanding long-term rainfall, freshwater flow, and salinity patterns with concomitant responses of benthic microfauna, stable isotopes, and pollen in Oyster and Florida Bays. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 189-190 (1999).

Salinity records exhibited variability from the decadal scale to the monthly scale that can be accounted for by changing patterns in regional rainfall. Changes in salinity, both near the outflow of the Shart River Slough at Oyster Bay, and in central Florida Bay near Jimmy Key, show a direct response to regional rainfall on these time scales. Moreover, regional rainfall, represented by the 80+ year record at Homestead, Florida, proved representative of the study area and indicated high correlation with flow into Shark River Slough prior to major watershed construction instigated in the early 1960s. During subsequent periods of water management strategies, enacted from the mid-1960s to present, results indicate essentially no correlation between regional ranfall and flow during the Monthly Allocation Plan. In contrast, correlations most closely paralleled pre-construction, apparently more natural condtions, during the Rainfall Plan. Investigated characteristics for the benthic microfaunal community (foraminifers and ostracods) such as stable isotopes, abundance, and community diversity, exhibited changes and trends that apparently more closely paralleled natural rather than anthropogenic influences over the whole period of record. At both Jimmy Key and Oyster Bay, foraminifer and ostracod data indicate direct correlation to rainfall patterns for temporal scales ranging from decadal down to the limit-of-resolution of our geochronology. An exception to this natural influence was observed from the late-1940s to mid-1950s during which time a dual transition occurred in the sediments adjacent to the Shark River Slough in Oyster Bay. Organic carbon content permanently declined from above- to below-average with concurrent onset of major increases in foraminifer and ostracod abundances. These events temporally conicided with the construction of the Everglades Agricultural Area, which impounded 700,000 acres of organic-rich swampland. These effects were not observed for sediments representing the same time period at Jimmy Key. Stable isotope (delta ¹⁸O, delta ¹³O) trends alone for ostracods and foraminifers at Oyster Bay and Jimmy Key showed mixed signals, with most data suggesting upcore trends to less fresh, more marine conditions. However, when long-term trends for relative abundance of salinity-sensitive species were examined, for the same time periods and locations, they confirmed a statistically valid upcore trend toward less fresh, more marine conditions at both Oyster and Florida Bay study sites. This trend was coincident with a weak decline in regional rainfall over the same time span. Changes in the stable isotopic values of these microfauna indicated, to the limits of our geochronology, direct responses to regional rainfall. Such responses more closely paralleled rainfall than freshwater runoff, even adjacent to the outflow of the Shark River Slough. At Oyster Bay, istracod stable isotope (delta¹⁸O) trends correlated better with variabions in regional rainfall than with freshwater outflow from the adjacent Shark River Slough. Crashes in microfaunal abundances at Oyster Bay and more gradual declines at Jimmy Key were salinity related. This abundance drop was concurrent with an equally dramatic drop in community diversity. The latter was characterized by survivor-mode dominance by two microfaunal species and occurred over a period of drought at both sites and the related reduced flow from Shart River Slough. A non-traditional use of pollen allowed evaluation of the degree of paleo-flushing from Shark River Slough that not only correlated well with existing flow and rainfall records but suggests validity as a flushing proxy for pre-record eras. Analysis of regional pollen indicated taxa associations that allowed discrimination of pollen zonations from coastal mangrove to upland slough environments. This, in turn, allowed reconstruction in the sediment record of historical periods of major to minor flushing from Shark River Slough.

Ooyama, K.V. Boundary-layer parameterization in a cloud-resolving model using the radical thermodynamic formulation. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 150-152 (1999).

No abstract.

Ortner, P.B., L.B. Crowder, and D.E. Hoss. The South Atlantic Bight Recruitment Experiment: Introduction and overview. Fisheries Oceanography, 8:1-6 (1999).

The South Atlantic Bight Recruitment Experiment (SABRE) brought together an interdisciplinary team of scientists to conduct research to enhance our understanding of the relationship between variation in environmental factors and the variable recruitment of "estuarine dependent" fishes within the South Atlantic Bight. The project sought to develop a new fusion of government and academic scientists, each possessing unique skills, to address the difficult problem of recruitment variability in fishes. This fusion required the development of appropriate and, at that time, novel management and administrative strategies. SABRE initially focused on recruitment dynamics of Atlantic menhaden, Brevoortia tyrannus, in the South Atlantic Bight, but expanded over time to include several estuarine-dependent species and much of the Middle Atlantic Bight as well. The project was conducted from 1991 to 1997 and resulted in a substantial improvement in our understanding of the life history and ecology of Atlantic menhaden and the potential constraints upon its recruitment. SABRE also contributed to our understanding of the physical oceanography of the western North Atlantic shelf and adjacent coastal inlets and the implications of physical dynamics upon the potential pathways for larval transport.

Ortner, P.B., M.J. Dagg, G.S. Kleppel, and C.R. Tomas. Grazing by zooplankton in Florida Bay waters. Florida Sea Grant College Program, FLSGP-G-99-012, 2 pp. (1999).

No abstract.

Palmer, D.R. Parabolic approximations for global acoustic propagation modeling. NOAA Technical Memorandum, ERL AOML-94 (PB99-171571), 54 pp. (1999).

Motivated by the difficulty in using the splitting matrix method to obtain parabolic approximations to complicated wave equations, we have developed an alternative method. It is three-dimensional, does not a priori assume a preferred direction or path of propagation in the horizontal, determines spreading factors, and results in equations that are energy conserving. It is an extension of previous work by several authors relating parabolic equations to the horizontal ray acoustics approximation. Unlike previous work, it applies the horizontal ray acoustics approximation to the propagator rather than to the Green's function or the homogenous field. The propagator is related to the Green's function by an integral over the famous "fifth parameter" of Fock and Feynman. Methods for evaluating this integral are equivalent to narrow-angle approximations and their wide-angle improvements. When this new method is applied to simple problems, it gives the standard results. In this paper, it is described by applying it to a problem of current interest: the development of a parabolic approximation for modeling global underwater and atmospheric acoustic propagation. The oceanic or atmospheric waveguide is on an Earth (or other heavenly body) that is modeled as an arbitrary convex solid of revolution. The method results in a parabolic equation that is energy conserving and has a spreading factor that describes field intensification for antipodal propagation. Significantly, it does not have the singularities in its range-sliced version possessed by many parabolic equations developed for global propagation. The work is generalized to allow for refracted geodetics and the possibility that the depth dependence of the pressure field can be described by adiabatic normal modes.

Peng, T.-H., and F. Chai. Modeling the carbon cycle in the equatorial Pacific Ocean. Proceedings, Second International Symposium on CO₂ in the Ocean, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 183-189 (1999).

As part of the U.S. JGOFS SMP program, we have developed an ocean ecosystem model of the equatorial Pacific Ocean with new and export productivity regulated by Si and Fe to synthesize and to analyze data collected during the process-study-oriented survey cruises in 1992. The circulation model is based on the Modular Ocean Model of the NOAA/GFDL ocean general circulation model. The ecosystem model consists of nine components describing two size phytoplankton, two size zooplankton, two detritus pool, and three dissolved nutrients: silicate, nitrate, and ammonium. The carbonate chemistry is parameterized in the model to evaluate the variations of pCO₂, and hence the CO₂ flux across the air-sea interface. At this initial stage, a test case by using a 1D model is performed to simulate low-silicate, high-nitrate, and low-chlorophyll conditions in the equatorial Pacific, and to investigate how the carbon system behaves in this ecosystem structure. The model includes the vertical upwelling and diffusion processes. The upwelling rate and vertical diffusivity were initially averaged for the region 5°S to 5°N, 180°W to 90°W, the "cold tongue" of the equatorial Pacific from the parameter values of 3D model simulations. Temperature is used to calibrate model upwelling and vertical diffusion rates. Comparison of model results with the observations made during the NOAA/OACES EqPac 1992 expeditions indicates that the vertical profiles of DIC, NO₃ and Si(OH)₄ are consistent with the measurements made in the fall season when the ocean was in a normal non-El Niño condition. A tight fit of profiles between model and observation is not possible because of spatial variations of the observed values. A 3D simulation is required, which is in progress. The 1D model CO₂ evasion rate is estimated to be 2.9 mol/m²/yr, which is within the range of estimates from measurements made during non-El Niño conditions.

Peng, T.-H., and R.H. Wanninkhof. Re-evaluation of historical carbon data based on recent high-quality measurements. AGU 1999 Fall Meeting, San Francisco, CA, December 13-17, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(46):F579, OS51E-15 (1999).

In the Indian Ocean, crossover stations between GEOSECS and recent NOAA/DOE CO₂ survey sampling cruises are selected. Measurements of temperature, salinity, oxygen, TCO₂, and alkalinity for samples taken below 2000 m depth at these crossover stations are compared. Because water masses below this depth are relatively stable with respect to anthropogenic disturbances, the carbon chemistry and hydrographic properties should remain unchanged in the last three decades. Hence, comparison of deep water properties between new and old data will provide information regarding the need for correction or adjustment in the older data sets. Systematic differences between the two data sets reflect the need for such correction. We apply "Linear Least-Squares Multiple Regression" of TCO₂ against salinity, potential temperature, oxygen, and alkalinity of deep waters in new data sets. Using this relationship, TCO₂ is predicted from these parameters measured during GEOSECS at the crossover station. The difference between the predicted TCO2 and the GEOSECS observed TCO₂ is the adjustment needed for this historical data. The overall average is 21.6 ± 4.1 mol/kg, which is the mean adjustment needs to be made to all GEOSECS TCO2 measurements in the Indian Ocean.

Peng, T.-H., J.-J. Hung, R.H. Wanninkhof, and F.J. Millero. Carbon budget in the East China Sea in spring. Tellus B, 51(2):531-540 (1999).

Results of total dissolved inorganic carbon (DIC) and total alkalinity (TA) measurements made in the East China Sea (ECS) during a geochemical expedition of KEEP (Kuroshio Edge Exchange Processes) program in May of 1996 show that ECS is a CO₂ sink during the spring season. The mean difference of fCO₂ (fugacity of CO₂) between the atmosphere and surface water is calculated to be 28 µatm, and the resulting net CO₂ invasion flux is 2.1 mol/m²/yr, which gives about 0.03 GtC/yr of CO₂ uptake in this continental shelf in spring. This study supports the notion that shelf regions can be a significant CO₂ sink. The riverine alkalinity, which discharges into ECS, is estimated to be 1,743 µmol/kg on the basis of a linear relationship between TA and salinity. The observed salinity-normalized alkalinity in ECS is higher than that in the open sea, and this excess alkalinity is estimated to be 42 µmol/kg. With the known rate of the Changjiang discharge, this excess TA gives a mean residence time of 1.2 years for the continental shelf water in the ECS. The DIC in the ECS is also found to be higher than that in the open sea. This excess DIC is estimated to be about 76 ± 70 µmol/kg, which is equal to a net carbon input to ECS of 3.9 ± 3.6 mol/m²/yr. Based on the riverine alkalinity input, the equivalent riverine carbon flux from Changjiang discharge is estimated to be about 1.8 mol/m²/yr. With net CO₂ invasion flux of 2.1 ± 2.8 mol/m²/yr, the remaining 0 ± 4.6 mol/m²/yr could come from remineralization of organic matter derived from biological pump in the shelf or terrestrial sources. Although this preliminary carbon budget implies that gas exchange and riverine input are the main sources of excess carbon in ECS, the contribution of biological carbon flux can not be ruled out because of the large uncertainty associated with these estimates.

Pielke, R.A., and C.W. Landsea. La Niña, El Niño, and Atlantic hurricane damages in the United States. Bulletin of the American Meteorological Society, 80(10):2027-2034 (1999).

Hurricanes result in considerable damage in the United States. Previous work has shown that Atlantic hurricane landfalls in the United States have a strong relationship with the El Niño-Southern Oscillation phenomena. This paper compares the historical record of La Niña and El Niño events defined by eastern Pacific sea surface temperature with a data set of hurricane losses normalized to 1997 values. A significant relationship is found between the ENSO cycle and U.S. hurricane losses, with La Niña years exhibiting much more damage. Used appropriately, this relationship is of potential value to decision makers who are able to manage risk based on probabilistic information.

Pielke, R.A., C.W. Landsea, R.T. Musulin, and M. Downton. Evaluation of catastrophe models using a normalized historical record: Why it is needed and how to do it. Journal of Risk and Insurance, 18:177-194 (1999).

No abstract.

Powell, M.D. Hurricanes at landfall. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 107-108 (1999).

No abstract.

Powell, M.D., and S.H. Houston. Comments on "A multiscale numerical study of Hurricane Andrew (1992). Part I: Explicit simulation and verification." Monthly Weather Review, 127(7):1706-1710 (1999).

No abstract.

Powell, M.D., T.A. Reinhold, and R.D. Marshall. GPS sonde insights on boundary layer wind structure in hurricanes. Proceedings, 10th Conference on Wind Engineering, Copenhagen, Denmark, June 21-24, 1999. ICWE, 307-314 (1999).

No abstract.

Powell, M.D., P.G. Black, S.H. Houston, and T.A. Reinhold. GPS sonde insights on boundary layer structure in hurricanes. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 881-884 (1999).

No abstract.

Proni, J.R., and T.A. Nelsen. Integrated measurements of sewage effluent and dredged material discharges. In Coastal Engineering and Marine Developments, C. Brebbia and P Anagnostopoulos (eds.). WIT Press, Southampton, 368-379 (1999).

A series of measurements to characterize sewage effluent discharge plumes and dredged material discharge plumes were carried out in coastal ocean waters off the coast of Puerto Rico in April 1998. A multiple sensor suite including an acoustic backscatter profiler, a towed optical backscatter containing CTD device, a vertical cast CTD having an optical transmissometer and oxygen sensors, and an acoustic Doppler current profiler (ADCP) was utilized to determine the subsurface plume spatial distribution and dilution. The sewage effluent plumes resulted from discharges at several diffusers located approximately one or more miles from the coastline. Using the multiple sensor systems listed above, it was possible to relate measurements made at water locations distant from the diffuser to plumes emanating from various parts of the diffuser under study. That is, a "connectivity" was established so that quantities inherent in the effluent discharge could be used for dilution calculations. Typical "initial" dilutions observed were on the order of 60:1. Using inherent tracers, such as plume salinity, effluent plume distributions were determined out to several hundred meters from the diffuser. "Macro" scale comparisons of multiple sensor outputs were carried out with good general agreement on plume distributions. Comparisons between in-situ "contact" sensors, e.g., temperature and salinity probes, and in-situ remote sensor probes, e.g., optical and acoustic backscatter, optical transmissivity (transmissometry), were made with good agreement resulting.

Proni, J.R., and T.A. Nelsen. Puerto Rico outfall/dredged material disposal studies: April 13-26, 1998. Contract EPA/IAG DW13937869-01-04 (Final report). U.S. Environmental Protection Agency, 74 pp. (1999).

No abstract.

Proni, J.R., and T.A. Nelsen. Recent advances in coastal ocean pollution research and monitoring. Joint Meeting, 137th Regular Meeting of the Acoustical Society of America and 2nd Convention of the European Acoustics Association: Forum Acousticum 99, Berlin, Germany, March 15-19, 1999. Journal of the Acoustic Society of America, 105(2):1323 (1999).

Design of both real-time studies of oceanic discharges of potential pollutants such as sewage effluent, and long-term monitoring of same, are complicated by a number of factors. These factors include lack of knowledge of the space and time distribution of the discharge plume, proper placement sites for sample gathering, and lack of knowledge of the space-time distribution of "interfering" plumes (plumes from sources other than the discharge plume under study). Progress has been made in the development of "integrated sensor suites" which produce data with substantial synergistic benefits. Ocean acoustics plays a key role in integrated sensor suite data unification. In a recent study in the coastal waters off San Juan, Puerto Rico, the ability of acoustics systems to view essentially the complete oceanic water enabled a connection to be made between salinity, temperature, and turbidity measurements gathered in the upper 5 m in the water column to a specific port of a sewage effluent diffuser. Having established the "connectivity" of the distal field measurement to a specific port, a dilution value at the distal point could confidently be calculated. This example is but one of many of the synergies available from utilization of multiple sensor suites unified through acoustics.

Quilfen, Y., A. Bentamy, K.B. Katsaros, and G. Lorand. Estimation of ocean-atmosphere turbulent fluxes from satellite measurements. Proceedings, 1999 International Geoscience and Remote Sensing Symposium (IGARSS '99), Hamburg, Germany, June 28-July 2, 1999. Institute of Electrical and Electronic Engineers, 2 pp. (1999).

No abstract.

Reasor, P.D., M.T. Montgomery, and F.D. Marks. The asymmetric structure of Hurricane Olivia's inner core. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 301-304 (1999).

No abstract.

Rodbell, D.T., G.O. Seltzer, D.M. Anderson, M.B. Abbott, D.B. Enfield, and J.H. Newman. A high-resolution ~15,000 year record of El Niño driven alluviation in southwestern Ecuador. Science, 283:516-520 (1999).

Debris flows have deposited inorganic laminae in an alpine lake 75 kilometers east of the Pacific Ocean, in Ecuador. These storm-induced events are dated by radiocarbon, and the age of laminae that are less than 200 years old matches the historic record of El Niño events. From about 15,000 to about 7,000 calendar years before the present, the periodicity of clastic deposition is greater than or equal to 15 years; thereafter, there is a progressive increase in frequency to periodicities of 2-8.5 years. This is the modern El Niño periodicity, which was established about 5,000 calendar years before present. This may reflect the onset of a steeper zonal sea surface temperature gradient, which was driven by enhanced trade winds.

Rogers, R.F. Amplification of warm-core vortices by convective redevelopment: A key component of tropical cyclogenesis. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 929-932 (1999).

No abstract.

Rogers, R.F., and J.M. Fritsch. Amplification of warm-core vortices by convective redevelopment: A key component of tropical cyclogenesis. Preprints, Eighth Conference on Mesoscale Processes, Boulder, CO, June 28-July 1, 1999. American Meteorological Society, Boston, 55-60 (1999).

Theories explaining the transition of a relatively disorganized area of convection into a coherent, self-sustaining system (i.e., tropical cyclogenesis) have traditionally relied upon the presence of a vortex before genesis can occur. Observations have confirmed the need for these vortices, often detecting them in radar and satellite imagery several days prior to the formation of a tropical depression. However, observational, theoretical, and numerical studies of similar systems over land have found that the initial vortices are often confined to the mid-troposphere. Therefore, an important question to address is how these vortices grow down to the surface in maritime tropical environments, for it is not until the vortex is reflected at the surface that intensification can begin, provided the large-scale environment is not unfavorable. This study investigates how midlevel vorticity within mesoscale convective vortices (MCVs) can amplify and grow downward to the surface by the redevelopment of deep convection. It is shown that the diabatic heating within the convection can increase the magnitude of the balanced warm core of the vortex, further lowering heights beneath the warm core and causing a cyclonic circulation closer to the surface. This cyclonic vorticity can develop in the lower troposphere even in the presence of the anomalously cold air of the low-level cold pool, given a sufficiently strong warm core aloft. The factors that play a key role in governing the downward penetration of vorticity to the surface are 1) onset of deep moist convection; 2) local reduction of the Rossby radius of deformation; and 3) weakening of the surface-based cold pool. These concepts are explored by performing a 48-hour numerical simulation of an observed MCV that underwent multiple cycles of convective redevelopment, amplifying after each cycle. The model was successful in reproducing the creation and evolution of the MCV. The amplitude of the midlevel vortex increased considerably after each convective cycle, as cyclonic vorticity reached the surface during the third cycle. Conditions prior to the third cycle showed a strong southwesterly low-level jet that was transporting warm, moist air over an outflow boundary left from the previous convective cycle and underneath the existing MCV. Deep convection developed within the existing cyclonic circulation and intense latent heat release amplified the warm core. As a result of this warming, lower-tropospheric geopotential heights lowered, creating low-level convergence which increased cyclonic vorticity under the amplifying vortex. This convergence led to an intense vortex in the lower troposphere during the strongest periods of the convective cycle, despite the fact that the lower troposphere was anomalously cold during the entire period. A conceptual model incorporating these ideas is presented.

Schmid, C. On the circulation in the tropical Atlantic. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S179, OS31B-08 (1999).

The circulation in the tropical Atlantic is studied using recent and historical Lagrangian observations. The measurements of the Lagrangian velocities were performed at two levels: near the surface and at intermediate depth. The surface measurements were collected with surface drifters whose drogues were centered at 15 m depth. The intermediate layer measurements derive from an array of 17 PALACE floats deployed in the tropical Atlantic during the summer of 1997. They cycle between about 1000 m and the surface to take a temperature profile every 11 days. Between the two profiles, the PALACE floats drift at depth for 10 days. The presentation will focus on the description of the velocity field and the analysis of the seasonal variability. The available surface drifter data allow the estimation of the mean monthly circulation patterns over large parts of the tropical Atlantic. The resulting fields show the seasonal reversal of the North Equatorial Countercurrent with predominantly westward velocities in the first half of the year and eastward velocities during the second half of the year. The PALACE floats also indicate the existence of a seasonal variability at about 1000 m.

Smith, R.H. IASlinks.org: Online management and distribution of oceanographic and meteorological data for the Gulf of Mexico and Caribbean Sea. Proceedings, First Biennial Intra-Americas Sea Initiative (IASI) Science Meeting, Panama City, Panama, November 9-11, 1999. University of Miami (1999).

There is a growing recognition of the connectivity among oceanic processes within the Gulf of Mexico and Caribbean Sea region (Intra-Americas Sea). Recent technological breakthroughs in communication, specifically the Internet, provide a common denominator for scientific collaboration and data exchange among the region's institutions and government agencies that collect data and utilize data products. The growing need for regional scale models requires that interaction between research endeavors take place, enabling the creation of larger, regional data sets and a more unified approach to understanding the oceanography, climate, and ecology of the Intra-Americas Sea. The Internet web site, http://IASlinks.org, hosted by NOAA/AOML in Miami, Florida, has been developed to facilitate the sharing of resources, results, and data sets relevant to research conducted throughout the Intra-Americas Sea region. The site is presently designed with indices describing the different types of research and the different institutions, agencies, and personnel involved, with regular highlights of specific regional research topics; it is our hope that the site will continue to expand, becoming a more complete representation of observational programs presently underway in and around the Gulf of Mexico and Caribbean Sea. The usefulness of a venue such as IASlinks.org will continue to be realized as scientists and operational observing systems throughout the Intra-Americas Sea make more of their data available over the Internet. In particular, the Internet as a medium for data exchange will play a pivotal role in the forthcoming IOCARIBE-GOOS regional observing system. IASlinks will complement the IASI web site, which will emphasize research programs, education, and training. This collaborative atmosphere, where scientific information and resources are shared with one another, will provide investigators working in the region the ability to tackle larger questions regarding climate, circulation, the propagation of species, and the connectivity of regional marine environments.

Swenson, M.S., and D.V. Hansen. Tropical Pacific Ocean mixed-layer budget: The Pacific cold tongue. Journal of Physical Oceanography, 29(1):69-82 (1999).

Data from satellite-tracked drifting buoys and VOS/XBT profiles for the years 1979-1995 were used to evaluate the seasonal cycle of how major oceanic processes redistribute heat in the cold tongue region of the tropical Pacific. The most active processes for the annual cycle are local heat storage and heat export by entrainment of upwelling and by mean meridional advection. Heat export by zonal advection, however, is not negligible, and meridional eddy heat fluxes associated with tropical instability waves effect a negative feedback that offsets a considerable fraction of that produced by the mean meridional advection. All of these processes mimic the essentially one cycle per year of the surface wind stress, as do those of the depths of both the bottom of the surface mixed layer and the thermocline. Because it is associated with poleward Ekman transports, upwelling, and baroclinic adjustment near the equator, the zonal wind stress component appears to be the more important. The meridional wind stress, while weaker in the annual mean, has a larger annual variation and, therefore, has equal influence on the annual variation of the scalar stress and perhaps the mixed layer thickness. The Monin-Obukov length is found to underestimate the mixed layer thickness very considerably. Finally, we produce the first estimates of the seasonal cycle of eddy heat flux convergence, which plays a significant role in the evolution of the cold tongue, and show that the eddy heat flux convergence can be quantitatively modeled as eddy diffusion with a diffusivity derived from single-particle buoy statistics.

Takahashi, T., R.H. Wanninkhof, R.A. Feely, R.F. Weiss, D.W. Chipman, N. Bates, J. Olafsson, C.Sabine, and S.C. Sutherland. Net sea-air CO₂ flux over the global oceans: An improved estimate based on the sea-air pCO₂ difference. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 9-15 (1999).

No abstract.

Tedesco, L.P., C. Souch, J. Pachut, J.A. Arthur, H.R. Wanless, P.L. Blackwelder, T. Hood, C. Alvarez-Zarikian, J. Trefry, W.J. Kang, S. Metz, and T.A. Nelsen. The signature of hurricane sedimentation in the lower Everglades/Florida Bay ecosystem: Recognition of sedimentologic, geochemical, and microfaunal indicators. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 194-195 (1999).

Winter storm and hurricane resuspension and transport processes are responsible for building the bulk of the sediment sequence in the accreting bank flanks in both northwest Oyster Bay (Whitewater Bay) and Florida Bay. Repetitive resuspension by winter storms provides fine silt-sized carbonate, siliceous and organic laminae as thin event laminae, mostly a millimeter or less in thickness. As these repetitive winter storms produce similar wind and transport sequences in an area, the constituent composition and mineralogy of the laminae are similar. Vertical profiles of excess ²¹⁰Pb activity in sediments from northwest Oyster Bay, Jimmy Key, and First National Bank showed that sedimentation at these sites has been in steady state during the last 40 years. However, two to three discontinuities of short duration (<2 years) in the decay profiles of excess ²¹⁰Pb activities were observed in the sedimentary records from northwest Oyster Bay, Jimmy Key, and First National Bank. Based on excess 210Pb-based ages, the discontinuities occurred at about 1960, 1948, and 1935, dates coincident with major hurricanes passing through Florida Bay: Donna in September 1960 (category 4); an unnamed hurricane in September 1948 (category 3); and the Great Labor Day Hurricane in September 1935 (category 5). Hurricane layers from 1935, 1948, 1960 (Donna), and 1992 (Andrew) in Oyster Bay are identified by a sharp surface on which sand-sized shell, carbonate peloids, and organic detritus are concentrated and overlain by a white, fine sand to silt layer, 0.5-2 cm in thickness. Sedimentologic and geochemical data on discontinuity surfaces show that the base of each hurricane layer is an erosional surface from which several centimeters of sediment was eroded. This is expected as the upper 3-10 cm of the sediment in these accreting flanks is a very soft zone with as much as 80% water content that could easily be removed. Discontinuities of ²¹⁰Pb profiles and, therefore, erosion were more pronounced in open water sites such as Jimmy Key and First National Bank (3-20 cm thick) relative to the more protected, mangrove coastline surrounded environment of northwest Oyster Bay (~2 cm thick). Major hurricanes (categories 4 and 5) are devastating to the red and black mangrove communities, causing destruction to 50-100% of the forest in the eye wall of the storm. This loss is reflected in the organic detritus content of sediments in cores from northwest Oyster Bay and other areas surrounded by extensive mangrove coastlines. Prior to a major hurricane, the macro-organic detritus is mainly partly decayed fragments of mangrove leaves released from the adjacent forests. Defoliation, uprooting, and death of the forest during and following the storm result in a change in the amount and composition of organic detritus in sediments. Organic detritus is composed of fine root hairs for a period of 5-10 years following the event. This reflects an extended period of erosion and release of root-hair detritus from the disrupted and decaying mangrove peat substrate. Organic detritus gradually decreases and becomes dominated by leaf detritus as the forest recovers. Hurricane-related signals in the microfaunal assemblage data (benthic ostracods and foraminifers) are both site- and event-specific. The two hurricanes that significantly modified the microfaunal assemblages from Jimmy Key and northwest Oyster Bay are the Labor Day Hurricane of 1935 and Hurricane Donna (1960). Hurricane Donna resulted in peaks in relative abundance of atypical benthic foraminifer species at both sites. At Jimmy Key, the species comprising this peak were derived from elsewhere within Florida Bay. In contrast, in northwest Oyster Bay, species were comprised of continental shelf species transported from the Gulf of Mexico by Donna's last winds. An example of hurricane-specific effects can be seen in the differing signals recorded by the 1935 and 1960 hurricanes at Jimmy Key. The 1960 hurricane left a distinct lag-type deposit, whereas the 1935 hurricane sediments were essentially barren of microfauna. High organic carbon influx and subsequent oxygen depletion associated with these hurricane events appear to be recorded in the microfaunal assemblages as well.

Thacker, W.C. Principal predictors. International Journal of Climatology, 19:821-834 (1999).

Principal predictors are linear combinations of variables from one set that efficiently describe the collective variability of those from a second set. Their defining eigenproblem is similar to that of canonical-correlation analysis, and when the two sets are taken to be the same, principal predictors reduce to principal components. Within the context of a forecast model for the circulation in the Gulf of St. Lawrence, they are shown to be capable of providing a low-dimensional characterization of high-resolution model dynamics.

Uhlhorn, E.W., P.G. Black, and A.F. Hasler. Evolution of mesoscale flow in a mature tropical cyclone as determined from satellite imagery. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 200-203 (1999).

No abstract.

Vachon, P.W., and K.B. Katsaros. Atmospheric cyclones from spaceborne SAR. Backscatter, 10(4):14-19 (1999).

No abstract.

Vachon, P.W., K.B. Katsaros, P.G. Black, and P.P. Dodge. RADARSAT synthetic aperture radar measurements of some 1998 hurricanes. Proceedings, 1999 International Geoscience and Remote Sensing Symposium (IGARSS '99), Hamburg, Germany, June 28-July 2, 1999. Institute of Electrical and Electronic Engineers, 1631-1633 (1999).

The RADARSAT synthetic aperture radar (SAR) acquired C-band and HH polarization images over four 1998 hurricanes: Bonnie, Danielle, Georges, and Mitch. We present the SAR images and discuss their quantitative use in understanding hurricane morphology. The SAR provides a complementary "view from below" that is most beneficial when considered in the context of more conventional hurricane observations.

Wang, C., R.H. Weisberg, and J.I. Virmani. Western Pacific interannual variability associated with the El Niño-Southern Oscillation. Journal of Geophysical Research, 104(C3):5131-5149 (1999).

Observations of sea surface temperature (SST), sea level pressure (SLP), surface wind, and outgoing longwave radiation (OLR) show that the El Niño-Southern Oscillation (ENSO) displays western Pacific anomaly patterns in addition to eastern Pacific anomaly patterns. During the warm phase of ENSO, warm SST and low SLP anomalies in the equatorial eastern Pacific and low OLR anomalies in the equatorial central Pacific are accompanied by cold SST and high SLP anomalies in the off-equatorial western Pacific and high OLR anomalies in the off-equatorial far western Pacific. Also, while the zonal wind anomalies over the equatorial central Pacific are westerly, those over the equatorial far western Pacific are easterly. The nearly out-of-phase behavior between the eastern and western tropical Pacific is also observed during the cold phase of ENSO, but with anomalies of opposite sign. These western Pacific interannual anomaly patterns are robust features of ENSO, independent of data sets. It is argued that equatorial easterly (westerly) wind anomalies over the far western Pacific during the warm (cold) phase of ENSO are initiated by off-equatorial western Pacific cold (warm) SST anomalies, and that these winds are important for the evolution of ENSO. An atmosphere model is employed to demonstrate that small off-equatorial western Pacific cold (warm) SST anomalies (compared to those in the east) are sufficient to produce equatorial easterly (westerly) wind anomalies as observed over the far western Pacific. The coupled ocean-atmosphere model of Zebiak and Cane is then modified to investigate the evolution of the western Pacific interannual anomaly patterns in a coupled ocean-atmosphere system, by including a meridional structure to the subsurface temperature parameterization in the western Pacific. The modified model produces both western and eastern Pacific interannual anomaly patterns.

Wang, C., R.H. Weisberg, and H. Yang. Effects of the wind speed-evaporation-SST feedback on the El Niño-Southern Oscillation. Journal of the Atmospheric Sciences, 56(10):1391-1403 (1999).

The thermodynamical process of latent heat flux is added to an analogical delayed oscillator model of the El Niño-Southern Oscillation (ENSO) that mainly considers equatorial ocean dynamics and produces regular, non-phase-locked oscillations. Latent heat flux affects the model sea surface temperature (SST) variations by a positive feedback between the surface wind speed and SST operating through evaporation which is called the wind speed-evaporation-SST feedback. The wind speed-evaporation-SST feedback in which the atmosphere interacts thermodynamically with the ocean through surface heat flux differs from the conventional zonal wind stress-SST feedback in which the atmosphere interacts dynamically with the ocean through momentum flux. The combination of equatorial ocean dynamics and thermodynamics produces relatively more realistic model oscillations. When the annual cycle amplitude of the zonal wind in the wind speed-evaporation-SST feedback is gradually increased, the model solution undergoes a transition from periodic to chaotic and then to periodic oscillations for some ranges of the parameters, whereas for other ranges of the parameters the transition goes from periodic to quasi-periodic and then to periodic oscillations. The route to chaos is the intermittency route. Along with such irregularity, the nonlinear interactions between the annual and interannual cycles operating through the wind speed-evaporation-SST feedback also produce a phase-locking of ENSO to the seasonal cycle. The model ENSO onset and peak occur in the boreal winter and spring, respectively, consistent with the observed phase-locking of ENSO in the far eastern Pacific. It is shown that ENSO decadal or interdecadal variability may result from the nonlinear interactions between the annual and interannual cycles in the tropics.

Wanninkhof, R.H. An overview of GAS EX-98. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S49, A32A-01 (1999).

The gas experiment in the North Atlantic (GAS EX-98) had as its main objective to improve our knowledge of air-sea CO₂ fluxes. Understanding of the physics controlling the gas transfer in the field necessitates measuring gas transfer on the time scales of the environmental forcing (sub-hour). Conventional waterside mass balance methods have a response time of at least a day such that we must rely on micrometeorological measurements, or proxies of CO₂ such as heat, along with assumption of similarities. Since micrometeorological measurements have yielded too high fluxes compared to mass balance approaches in the past, the first step was to reconcile the measurements. Micrometeorological CO₂ flux estimates were obtained from gradients of CO₂ and dimethyl sulfide in the (air) marine boundary layer, and by CO₂ co-variance measurements. Gas transfer velocities were measured using the dual-deliberate tracer technique with 3He and SF6 in the water column. Changes of CO₂ in the water column were used as overall constraints for the gas fluxes after accounting for changes of CO₂ concentrations due to biology. The selection of study location was based on the site being a constrained watermass in an eddy in a large CO₂ sink region. The anticyclonic (warm core) eddy inhibited dispersion of the deliberate tracers, thereby extending the duration of the experiment, and SF6 concentrations were measurable for the duration of the 24-day process study. The large CO₂ sink, averaging -85 µatm during the study, improved the signal to noise for the direct flux measurements. The post-bloom environment was thought to minimize the biological signal compared to the change due to CO₂ invasion in the water column mass balance. However, despite the near absence of major nutrients, several lines of evidence suggest rapid biological cycling. The independent estimates of gas transfer velocities agreed well with each other. This is the first time that such concordance is observed between the micrometeorological-based measurements and the water column mass balance based observations. The results from the co-variance data of McGillis and Edson (see abstract in this session) can be fit with a cubic dependence with wind speed. Such a relationship can be reconciled with global flux constraints based on bomb ¹⁴C. If such a relationship holds universally over the ocean, the net global CO₂ uptake would increase by a half based on the monthly pCO2 climatology of Takahashi (1997).

Wanninkhof, R.H. Recent advances in determining air-sea CO₂ fluxes. Proceedings, Second International Symposium on CO₂ in the Oceans, Tsukuba, Japan, January 18-22, 1999. Center for Global Environmental Research (CGER-I037-99), 101-104 (1999).

Uncertainties in inverse calculations to determine regional carbon fluxes between the atmospheric, oceanic, and terrestrial reservoirs (Fan et al., 1998) have clearly indicated the need to improve our oceanic carbon flux estimate. There have been significant advances in several aspects of air-sea flux determinations to address this question, including direct estimates of fluxes by co-variance and gradient measurements in the air-boundary layer, extrapolation routines using remote sensing products, and a rapidly increasing observational database of air-sea partial pressure differences. The gas fluxes are commonly expressed as F = k s DELTA-pCO₂ where F is the air-sea flux CO₂ (mol m^-2 day^-1), k is the gas transfer velocity (m day^-1), s is the solubility (mol m³ µatm^-1) and DELTA-pCO₂ is the air-water partial pressure difference (µatm). This overview discusses recent research aimed at improving estimates of F, k, and DELTA-pCO₂.

Wanninkhof, R.H., and W.M. McGillis. A cubic relationship between air-sea CO₂ and wind speed. Geophysical Research Letters, 26(13):1889-1892 (1999).

Using recent laboratory and field results we explore the possibility of a cubic relationship between gas exchange and instantaneous (or short-term) wind speed, and its impact on global air-sea fluxes. The theoretical foundation for such a dependency is based on retardation of gas transfer at low to intermediate winds by surfactants, which are ubiquitous in the world's oceans, and bubble-enhanced transfer at higher winds. The proposed cubic relationship shows a weaker dependence of gas transfer at low wind speed and a significantly stronger dependence at high wind speed than previous relationships. A long-term relationship derived from such a dependence, combined with the monthly CO₂ climatology of Takahashi (1997), leads to an increase in the global annual oceanic CO₂ uptake from 1.4 Gigaton C yr^-1 to 2.2 Gigaton C yr^-1. Although a cubic relationship fits within global bomb-¹⁴C oceanic uptake constraints, additional checks are warranted, particularly at high wind speeds where the enhancement is most pronounced.

Wanninkhof, R.H., E. Lewis, R.A. Feely, and F.J. Millero. The optimal carbonate dissociation constants for determining pCO₂ from alkalinity and total inorganic carbon. Marine Chemistry, 65(3-4):291-301 (1999).

In many numerical ocean chemistry models total dissolved inorganic carbon (DIC) and total alkalinity (TA) are transported between subsurface boxes, and partial pressure pCO₂ is calculated from TA and DIC in the surface box in order to account for air-sea exchange of carbon dioxide. The conversion is commonly performed by solving the thermodynamic relationships for equilibria between carbonate, bicarbonate, and aqueous CO₂ using apparent carbonate dissociation constants. Four independent determinations of the constants have been performed for seawater in the past 50 years. These results have been corrected, refit, and combined by others, creating a virtual cottage industry of laboratory and field verification and cross checks. Here we show that, based on extensive field observations in three major ocean basins, the calculated surface pCO₂ from TA and DIC corresponds best with the measured pCO₂ of the constants proposed by Mehrbach et al.

Wanninkhof, R.H., S. Doney, T.-H. Peng, J.L. Bullister, K. Lee, and R.A. Feely. Comparison of methods to determine the anthropogenic CO₂ invasion into the Atlantic Ocean. Tellus B, 51(2):511-530 (1999).

A comparison of different methods of estimating anthropogenic CO₂ into the Atlantic Ocean through the center of the basin between 62°N and 42°S is performed using referenced high quality total dissolved inorganic carbon (DIC) data. The specific anthropogenic input is determined utilizing analytical procedures as described in Gruber et al. (1996), and Chen and Millero (1979) to correct for remineralization and to estimate preanthropogenic endmembers. These estimates are compared with results of the Princeton ocean biogeochemical model (OBM). The results show the specific inventories of anthropogenic carbon agreeing to within 20% but with different uptake patterns. The differences are largely caused by differing assumptions about mixing and winter outcrop endmembers. The same photosynthetic quotients (Redfield ratios) were used each methods. Varying these constants within the range of literature values causes changes in specific inventories of similar magnitude as the different methodologies. Comparison of anthropogenic CO₂ uptake and chlorofluorocarbon ages, and preanthropogenic photosynthetic quotients utilizing the analytical methods suggest that anthropogenic CO₂ penetration is too shallow following the procedure according to Gruber et al. (1996), and too deep using those of Chen and Millero (1979) in the North Atlantic. The results support previous observations that the uptake of CO₂ in the North Atlantic is disproportionate to its surface area. This is caused by a combination of deep water formation and deep winter mixed layers.

Whung, P.-Y., C.J. Fischer, and T. Meyers. Atmospheric deposition of nitrogen and phosphorous to the South Florida Bay ecosystems. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 87 (1999).

The monitoring nutrient deposition to South Florida Bay is now underway. A 10-m meteorological tower was installed at the Keys Marine Laboratory at Long Key in April 1998. Air samples, both dry and wet deposition such as gaseous ammonia (NH₃), particulate ammonium (NH₄⁺), particulate nitrate (NO₃^-), organic phosphorous (org-PO₄), and total phosphorous (PO₄), are measured. Meteorological parameters such as wind speed, wind direction, air temperature, relative humidity, and solar radiation are also collected at the sampling site. Atmosphere nitrogen, which includes NH₃, NH₄⁺, and NO₃^-, was sampled using treated filter packs. The preliminary results for the gaseous nitrogen species during the period of April 1998 and March 1999 showed that the NH₃ concentrations varied greatly (between 0.034 and 0.76 ug/m³), with relatively higher concentrations in the summer season. The averaged particulate NH₄⁺ and NO₃^- concentrations were 1.20 ug/m³ and 2.17 ug/m³, respectively. The observed atmospheric NH₃ concentrations in South Florida Bay were similar to the averaged NH₃ concentrations in other coastal regions (such as Tampa Bay and Chesapeake Bay). Since late October 1998, aerosol monitoring of phosphorous and wet deposition of nitrogen has been underway. The sampling protocol, sample analysis, and shipping logistics have been worked out in collaboration with the laboratory at the Illinois State Water Survey who conducted the analysis for the National Atmospheric Deposition Program (NADP). Samples collected through mid-February have been analyzed. For this period, the average dry deposition rate of ammonium aerosol was estimated to be about 0.18 mg/m²/wk, compared to an average wet deposition rate of 0.1 mg/m²/wk. The averaged weekly wet deposition rate of nitrate was on the order of 0.7 mg/m²/wk. For phosphorous, there has only been one week in which the wet deposition data were above the detectable limit. However, measurable air concentrations have been obtained each week in order to obtain a dry deposition rate. At this time, the averaged weekly PO₄^- deposition rate was estimated to be about 0.1 mg/m²/wk. The analysis for organic contributions (that do not show up as PO₄) (which includes the organic fraction) have been 30% higher than the inorganic fractions. Further analyses of elemental ratios will be used to determine the possible origin of this organic fraction.

Wilkerson, J.C., J.R. McCollum, and J.R. Proni. A methodology for validating satellite estimates of rainfall over the ocean using underwater acoustic techniques. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S99, H21A-05 (1999).

Current methods for validating satellite estimates of precipitation over the open ocean use rain gauge or radar data. The rain gauge data come from low-lying islands and atolls or from moored buoys. The intercomparison of satellite and rain gauge estimates leads to uncertainties in the satellite error estimates due largely to the differences in spatial coverage. Satellite rainfall estimates cover tens to hundreds of km² while the representative area measured by a rain gauge is only several cm². In addition to sampling uncertainties, most of these gauges are in the tropical Pacific, while satellite estimation errors depend upon location on the globe. Radar rainfall estimates have sufficient spatial resolution for comparisons with satellite estimates, but the amount of radar data from coastal sites or ships is scarce. In addition, satellite rainfall estimation techniques based on passive microwave emission cannot be applied to grid boxes containing coast, which further limits the amount of comparison data. Due to the current difficulties in validation of oceanic rainfall estimates, we have examined the possibility of utilizing underwater acoustics for oceanic rainfall estimation. It has subsequently been shown that underwater sound can, in fact, be used to detect and classify rainfall in coastal ocean regions and that rainfall estimation to useful accuracy appears feasible. The acoustic technique is now being tested in the deep ocean at the U.S. Navy Atlantic Undersea Test and Evaluation Center located in the Tongue of the Ocean, Bahamas. A 12-hydrophone array tethered to the ocean floor at a depth of 1.5 km has been made available to NOAA for investigation. Acoustic data from the array, covering a 500 km² area of the ocean surface, is sampled continuously once every 12 seconds giving temporal and spatial data coverage comparable to that of satellite rainfall estimates. This paper presents results of an initial comparison of four satellite rainfall products for the acoustic site with concurrent estimates of rainfall from the underwater array made at comparable time and space scales. These data are supported by independent measurements of rainfall over the array from a WR 74C weather radar located at Nassau, 60 km distant. Products from the Geostationary Operational Environmental Satellite (GOES) include estimates from the Global Precipitation Index (GPI), the GOES Multi-Spectral Rainfall Algorithm (GMSRA), and the Auto Estimator. Rainfall observations from the Special Sensor Microwave Imager (SSM/I) on the Defense Meteorological Satellite Program (DMSP) polar orbiting satellites are also examined.

Willis, P.T. An evaluation of NEXRAD (WSR88D) data as a measure of fresh water flux into the Florida Bay/Everglades system. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 153 (1999).

The radar measurement of rain provides excellent spatial and temporal resolution over a large area. This is true even over water areas, where a dense gauge network may be impossible or prohibitively expensive. But, since the radar does not measure rainfall rate directly, but measures the sixth moment of the raindrop size distribution (dsd), the measurement requires a definitive relation between rainfall rate and the shape of the drop size distribution. The shape of the dsd is not uniquely related to the rainfall rate. This is a source of error, and scatter, in the radar rainfall rate measurements. A major thrust of the project has been to characterize the shape of raindrop size distributions in south Florida. The project described herein involves the measurement of dsd's at a site at the ENP Research Center, and a comparison of the radar rain measurements to the gauge measurements from the extensive gauge network associated with the Florida Bay/Everglades Restoration project. The raw radar data has a spatial scale of approximately 1 x 1 km and a time resolution of 5-6 min. The NEXRAD hydrologic product (dpa) has been smoothed to a spatial scale of 4 x 4 km and a time resolution of 1 hr. This can be easily averaged to larger scales, and longer times to provide desired products. The radar data are empirically related to the gauge data using a probability matching methodology (PMM) which forces the overall match of the radar mean rainfall rate and the mean gauge rainfall and also forces an empirical match in data bin intervals. From extensive data comparisons between the dpa and 1-hr gauge data it is found that the radar significantly underestimates the higher rainfall rates, and overestimates the lower rainfall rates. This is true even from a smaller sample of the full resolution radar data, and high-resolution gauge and disdrometer data. The match provided by the PMM is virtually the same as that from the 4 km/1 hr data. The stability of this relation is being checked with an additional year of radar and gauge data, and the result will be reported. A single gauge/radar rainfall product that retains the best features of each data type is being developed using a cokriging methodology. Sample one-month mean radar data, and combined products using the empirical calibrations, are presented. Planned improvements and future work are also presented.

Willis, P.T. The WSR-88D tropical Z-R relationship in south Florida. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 237-240 (1999).

No abstract.

Willoughby, H.E. Hurricane heat engines. Nature, 401:649-650 (1999).

No abstract.

Willoughby, H.E. Vortex tracking semispectral hurricane models. Preprints, 23rd Conference on Hurricanes and Tropical Meteorology, Dallas, TX, January 10-15, 1999. American Meteorological Society, Boston, 662-665 (1999).

No abstract.

Wilson, W.D. Atlantic western boundary currents. Proceedings, South Florida Measurement Center Workshop: Establishment of a Center for Innovative Oceanography in the 21st Century, Dania, FL, February 24-26, 1999. National Science Foundation, 131-140 (1999).

No abstract.

Wilson, W.D., E. Johns, R.H. Smith, T.N. Lee, and E. Williams. Interaction of freshwater riverine discharges from the Everglades with the Gulf of Mexico and Florida Bay: Preliminary results from a moored array and shipboard surveys. 1999 Florida Bay and Adjacent Marine Systems Science Conference, Programs and Abstracts, Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 175-177 (1999).

No abstract.

Wilson, W.D., S.L. Garzoli, G.J. Goni, W.E. Johns, R.H. Smith, C.I. Fleurant, P.L. Richardson, and D.M. Fratantoni. The North Brazil Current Retroflection: Two recent surveys. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union,80(17):S179, OS31B-11 (1999).

The North Brazil Current is the low-latitude western boundary current that flows northward across the equator in the western Atlantic along the coast of Brazil. The NBC is the main source of inter-hemispheric warm water transport in the Atlantic. Its retroflection supplies water to equatorial zonal currents at various latitudes and depths, and rings separate from the retroflection at irregular intervals and propagate into the western tropical Atlantic. Because of its broad spatial extent, and non-linear and rapidly changing nature, synoptic surveys that adequately describe the NBC are difficult to perform. Two such surveys, by far the most complete to date, were conducted as part of the North Brazil Current Rings Experiment in November/December 1998 and February/March 1999. Surveys contain data from XBT, CTD, and shipboard and lowered ADCP data sources, providing water properties and current velocities to 2000 m. Continuity between cruises is provided by satellite altimetry. In November/December, 1998, the near-surface currents of the retroflection reached to nearly 9°N, 52°W, and a closed recirculation center was evident, which separated shortly thereafter to form an NBC ring. At sub-thermocline level, only the closed circulation of the ring was seen, with the subsurface retroflection completely turning eastward near 4° to 5°N, east of 48°W. During the February/March 1999 survey, the retroflection was found further to the south, its northernmost tip extending to only 7°N, 51°W, with a newly formed NBC ring found just northwest of the retroflection.

Yvon-Lewis, S.A., J.H. Butler, D.B. King, S.A. Montzka, J. Rodriguez, J.M. Lobert, and M. Ko. The oceanic contribution to organic bromine in the atmosphere. International Union of Geodesy and Geophysics, XXII General Assembly, Birmingham, England, July 18-30, July 1999. IUGG99 Abstracts, A110 (1999).

The ocean delivers considerable organic bromine into the troposphere. Although many of the oceanic, bromine-containing compounds are short-lived in the troposphere, they can be convected periodically into the stratosphere, where they contribute to the destruction of stratospheric ozone. Methyl bromide (CH₃Br) and the halons are recognized as being the primary carriers of bromine into the stratosphere, but contributions from other compounds may be significant. Some of these other trace gases include CH₂Br₂, CHBr₃, CH₂BrCl, CHBr₂Cl, and CHBrCl₂. All of these gases are produced to some extent in the ocean and their collective sea-air flux is of the same order as the total flux of CH₃Br from all sources. We have been measuring CH₃Br, CH₂Br₂, CHBr₃, and other bromine-containing compounds in air and surface seawater samples on research cruises in the Pacific, Atlantic, and Southern Oceans since 1994. Results show CH₃Br undersaturations throughout much of the ocean, suggesting that the ocean is a net sink for this brominated trace gas. However, results for CH₂Br₂, CHBr₃, and the other bromine-containing compounds show these trace gases to be supersaturated throughout much of the ocean, often with higher degrees of saturation in the tropics and subtropics. These data are presented here and will be used in conjunction with a two-dimensional model to examine the role that the oceans play in the cycling of atmospheric organic bromine.

Zhang, J.-Z. Ship determination of nM nitrite and nitrate by gas-segmented continuous flow analysis with a liquid waveguide capillary flow cell. AGU 1999 Fall Meeting, San Francisco, CA, December 13-17, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(46):F46, B12B-09 (1999).

Incorporation of a 2-m long liquid waveguide capillary flow cell to a gas-segmented continuous flow auto-analyzer significantly enhances the sensitivity of automated colorimetric analysis. Nanomolar concentrations of nitrite and nitrate in oligotrophic surface seawater can be accurately determined. Using this technique the diel cycle of nitrate at nM level in oligotrophic water was observed. The advantages of this technique are low detection limit, high precision, and automation for rapid analysis of a large numbers of samples. This technique has been successfully used on shipboard measurements of about 1000 seawater samples during a one-month cruise in North Atlantic.

Zhang, J.-Z., C.J. Fischer, and P.B. Ortner. Laboratory glassware as a contaminant in silicate analysis of natural water samples. Water Research, 33(12):2879-2883 (1999).

When glassware is used for the storage of water samples, reagents, and standard solutions, dissolution of silicate from the glass containers can contaminate the samples. Experimental results demonstrate that dissolution from glassware can introduce micromolar silicate within a few hours. The extent of dissolution depends upon contact time, salinity, and pH of the solution, and the size and shape of the containers.

Zhang, J.-Z., C.J. Fischer, and P.B. Ortner. Optimization of performance and minimization of silicate interference in continuous flow phosphate analysis. Talanta, 49(2):293-304 (1999).

Specific reaction conditions for automated continuous flow analysis of phosphate are optimized in regard to minimizing coating and silicate interference, while maintaining high sensitivity. Use of Sb in the reagent increases sensitivity and yields absorbances with little temperature dependence. Coating can be minimized by using a final solution at a pH >0.5. At final pH of 0.78, there is maximum interference from silicate in the sample. We recommend, therefore, as an optimal reaction condition with minimal silicate interference, the use of Sb, a final solution pH of 1.00, room temperature for the reaction, and a [H+]/Mo ratio of 70. An equation is provided to correct silicate interference in high precision phosphate determination.

Zhang, J-Z., R.H. Wanninkhof, and K. Lee. New production estimated from diel cycle of nutrient and oxygen in the mixed layer. AGU 1999 Spring Meeting, Boston, MA, June 1-4, 1999. Supplement to EOS, Transactions, American Geophysical Union, 80(17):S50, A32A-03 (1999).

New production can be estimated from accurate measurement of inventory change in nutrient at nM level in the mixed layer. A strong diel cycle was observed in nutrient concentration in response to photosynthesis in an anticyclonic eddy in North Atlantic during the GASEX-98 cruise. During a diel study, nitrate concentration was about 92 nM in the morning and decreased to 12 nM at 6 p.m. Nitrate concentration increased after dark, presumably due to the diffusive flux from the nitracline. Oxygen data in the mixed layer also showed a similar diel cycle. The oxygen production during the day caused concentrations to increase by about 2 uM. Under steady state conditions, eddy diffusion is a dominant process for transportation of nutrient to the euphotic zone to sustain the new production. The vertical eddy diffusion coefficients were derived from temporal changes in concentrations of a deliberate tracer, SF6, in the upper thermocline. Together with vertical nitrate distributions, the nitrate flux from nitracline could be estimated. Such a diffusive flux throughout the night can account for a nitrate concentration of 102 nM by morning, which is in good agreement with measured nitrate of 92 nM at 6 a.m. The new production estimated from changes of nitrate inventory in the mixed layer during the day was 28 mmole C/m², which is in good agreement with 31 mmole C/m² estimated from the oxygen inventory change. Increases in mixed layer nutrients were observed during a storm event that deepened the mixed layer and brought the nutrient to the surface (1.2 uM nitrate). A good correlation between wind speed and the concentrations of nitrate and nitrite is observed. Addition of nitrate to the mixed layer by the storm disappeared within two days, indicating a rapid nutrient cycle by marine organisms. The relative importance of sporadic storm events versus daily diffusive flux in supply nutrient to new production can be estimated from accurate measurement of inventory change of nutrient and oxygen in the mixed layer.

Zhang, J.-Z., C.J. Fischer, C.R. Kelble, and F.J. Millero. Phosphate distribution coefficients for suspended sediments in Florida Bay. 1999 Florida Bay and Adjacent Marine System Science Conference, Programs and Abstracts Key Largo, FL, November 1-5, 1999. University of Florida Sea Grant Program, 77 (1999).

The distribution coefficient Kd (Kd = Cs/Cw, where Cs is concentration of phosphorus on particle surface and Cw in seawater) is a key parameter that governs phosphorus partitioning between seawater and particle surface. To estimate the distribution coefficient for phosphorus partitioning between suspended sediments and seawater, surface sediments were collected from Florida Bay at various locations with different environmental conditions. The sediments were equilibrated with low nutrient seawater for 24 hours at constant temperature. The particles were then separated from seawater by filtration. The phosphate concentrations in equilibrated seawater were determined by spectrophotometric method using an autoanalyzer. The sediments were then equilibrated with a 1 M MgCl₂ solution at pH of 8 for 4 hours. The sorbed and desorbable phosphorus was then extracted into the solution by a complexing reaction with MgCl₂. The extracted phosphate was determined after separation from the suspended sediments. The results showed a linear correlation between phosphate concentrations in seawater and exchangeable phosphate on the sediments surface. Preliminary estimated Kd is of 100 L/kg. Further experiments are underway to study the effect of salinity and temperature on the Kd. A fitted equation of Kd as a function of salinity and temperature can be used in a water quality model to predict the fate of input phosphorus in Florida Bay. **1998**

Aberson, S.D. Five-day tropical cyclone track forecasts in the North Atlantic basin. Weather and Forecasting, 13(4):1005-1015 (1998).

Statistical analyses of the most recent 40 years of hurricane tracks (1956-1995) are presented, leading to a version of the North Atlantic climatology and persistence (CLIPER) model that exhibits much smaller forecast biases but similar forecast errors compared to the previously used version. Changes to the model involve the inclusion of more accurate historical tropical cyclone track data and a simpler derivation of the regression equations. Nonlinear systems analysis shows that the predictability timescale in which the average errors increase by a factor e is approximately 2.5 days in the Atlantic basin, which is larger than that found by similar methods near Australia. This suggests that five-day tropical cyclone track forecasts may have some benefit, and, therefore, a version of CLIPER extended to five days to be used as a baseline to measure this skill is needed.

Aberson, S.D. Impact of the Gulfstream-IV jet aircraft on hurricane forecasts. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C. (paper was mistakenly omitted from the Minutes) (1998).

No abstract.

Aberson, S.D. Targeted observations to improve tropical cyclone forecasts. Scientific Programme, XXIII General Assembly, European Geophysical Society, Nice, France, April 20-24, 1998. European Geophysical Society, 256 (1998).

No abstract.

Aberson, S.D., M.A. Bender, and R.E. Tuleya. Ensemble forecasting of tropical cyclone intensity. Preprints, Symposium on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 150-153 (1998).

No abstract.

Aberson, S.D., M.A. Bender, and R.E. Tuleya. Ensemble forecasting of tropical cyclone tracks. Preprints, 12th Conference on Numerical Weather Prediction, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 290-292 (1998).

No abstract.

Aberson, S.D., M.A. Bender, and R.E. Tuleya. Ensemble forecasting of tropical cyclone tracks and intensity. Scientific Programme, XXIII General Assembly, European Geophysical Society, Nice, France, April 20-24, 1998. European Geophysical Society, 255 (1998).

No abstract.

Aberson, S.D., R.E. Tuleya, and M.A. Bender. Ensemble forecasting of hurricane track and intensity using the GFDL model during 1997. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C.,143-145 (1998).

Tropical cyclone track predictions have shown considerable skill past three days, and intensity predictions are beginning to show some skill. While most forecasts are good, great variability in the utility of individual forecasts occurs. Ensemble forecasting provides a mechanism by which the inherent uncertainty in model forecasts can be assessed. During the 1996 and 1997 hurricane seasons, more than 100 sets of ensemble forecasts using a two-mesh version of the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model have been run, based upon the bred growing modes produced operationally at the National Centers for Environmental Prediction (NCEP). Results of these track and intensity forecasts will be presented, including information as to how well the models conform to the "perfect model" scenario, whether the forecasts envelope the evolution of the atmosphere, and whether information on the utility of individual model forecasts can be obtained from the ensembles. Plans to continue ensemble forecasting runs during the 1998 hurricane season will be presented.

Aberson, S.D., R.E. Tuleya, and J. Heming. Five-day forecasts of tropical cyclone tracks in the Atlantic basin. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C. (paper was mistakenly omitted from the Minutes) (1998).

Tropical cyclone track predictions have improved so that skill, as assessed by the improvement of forecasts over a forecast provided by a simple statistical model based upon climatology and persistence, averages more than 30% at 72 h, the current standard length of forecasts. Because of the possibility of such skill levels at longer forecast times during the 1997 Atlantic hurricane season, four tropical cyclone track models produced quasi-operational 120 h forecasts. The models were a new version of CLIPER, with which to assess skill, and extensions of the currently run VICBAR, GFDL, and UKMO models. Individual track forecasts and skill assessments for the various models will be shown, and recommendations for future work in this area, both operationally and for research, will be made.

Alfaro, E., L. Cid, and D.B. Enfield. Relationships between the start and end date of the rainy season in Central America and the tropical Atlantic and Pacific Oceans. Investigaciones Marinas, 26:59-69 (1998).

In recent years, several studies have shown that anomalies in the sea surface temperature of the tropical Atlantic and Pacific Oceans are related to variations in the intensity and timing of the rainy season in Central America. In order to study anomalous behavior of the rainy season over Central America, tropical Atlantic and Pacific Oceans indices are used to produce correlation series with the starting and ending date (IELL and TELL) of the rainy season. The North Atlantic (ATN) and SOI-Niño3 indices show the main correlations with the IELL and the TELL respectively.

Amat, L.R., M.D. Powell, and S.H. Houston. WANDA: HRD's real-time tropical cyclone "Wind Analysis Distributed Application." Preprints, 16th Conference on Weather Analysis and Forecasting, Symposium on the Research Foci of the U.S. Weather Research Program, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, J29-J31 (1998).

No abstract.

Asher, W.E., and R.H. Wanninkhof. The effect of bubble-mediated gas transfer on purposeful dual gaseous-tracer experiments. Journal of Geophysical Research, 103(C5):10,555-10,560 (1998).

For air-water gas exchange across unbroken surfaces, the only gas-dependent parameter affecting the transfer velocity is the molecular diffusivity of the transferring species. In contrast, bubble-mediated transfer processes can cause the transfer velocity to depend on both molecular diffusivity and aqueous-phase solubility. This can complicate the analysis of data from dual-gaseous tracer gas transfer experiments. Bubble effects also complicate the estimation of transfer velocities for other gases from the transfer velocity calculated using the dual-tracer data. Herein, a method for incorporating the effects of bubble-mediated gas transfer processes on the transfer velocity is presented. This new procedure is used to analyze the data from two recent dual-tracer gas transfer experiments. Transfer velocities that include the effect of bubbles are calculated using the data from two previous oceanic dual-gaseous tracer experiments. Comparing these transfer velocities with transfer velocities calculated by neglecting the effect of bubbles shows that bubble-mediated transfer increased the transfer velocity of helium 3 by 5% at a wind speed of 10.6 m s^-1. However, when using the transfer velocities form helium 3 to calculate transfer velocities for carbon dioxide under the same conditions, including the effect of bubbles, decreases the transfer velocity of carbon dioxide by 18%. This shows that bubble-mediated transfer does not have a large effect on the analysis of dual-tracer data, but it is important in relating transfer velocities determined using helium 3 and sulfur hexafluoride to transfer velocities of more soluble gases at wind speeds above 10 m s^-1.

Asher, W.E., and R.H. Wanninkhof. Transient tracers and air-sea gas transfer. Journal of Geophysical Research, 103(C8):15,9393-15,958 (1998).

This paper provides a review of the physics and chemistry associated with air-sea gas transfer of transient atmospheric trace gases and the available laboratory and field measurement techniques used to study air-water gas transfer. The mechanistic principals and their relation to the measurement techniques are used to show that the error associated with estimating air-sea transfer velocities of transient tracers from transfer velocities measured using proxy tracers can be significant if an incorrect dependence of the transfer velocity on molecular diffusivity is assumed. Bubble-mediated transfer processes are also demonstrated to have a significant effect on the parameterization of the transfer velocity.

Atakturk, S.S., and K.B. Katsaros. Estimates of surface humidity and wind speed obtained from satellite data in the stratocumulus regime in the Azores region. In Remote Sensing of the Pacific Ocean by Satellites, R.A. Brown (ed.). Southwood Press, Marrickville, Australia, 16-22 (1998).

No abstract.

Bauer, S., M.S. Swenson, A. Griffa, A.J. Mariano, and K. Owens. Eddy-mean flow decomposition and eddy-diffusivity estimates in the equatorial Pacific. Journal of Geophysical Research, 103(C13):30,855-30,872 (1998).

The ocean-atmospheric dynamics of the tropical Pacific Ocean create longitudinally coherent zonal flow () with strong meridional shear () in the large-scale mean and energetic mesoscale (O(100 km)) component. Parameterization of the effects of the mesoscale field depends on the separation of the large-scale mean and mesoscale eddy components in order to compute meaningful eddy diffusivity estimates in flow regimes that demonstrate strong currents and strong shear. Large gradients in the large-scale mean have precluded diffusivity estimation by traditional binning techniques. In this first of two publications, a method is developed for using Lagrangian data to estimate the diffusivity addressing the inhomogeneity of the mean flow. The spatially dependent estimate of the mean field is computed with a least squares bicubic smoothing spline interpolation scheme with an optimized roughness parameter which guarantees minimum energy in the fluctuation field at low frequencies. Numerical simulations based on a stochastic model of a turbulent shear flow are used to validate our approach in a conceptually simple but realistic scenario. The technique is applied to near-surface drifter observations obtained from 1979-1996 from two dynamically distinct time-space regions of the tropical Pacific Ocean. The first region, in the SEC, is characterized by a linear zonal shear mean flow and an approximately exponential autocovariance structure in the residuals. The residual velocity variance is s² ~ 130 cm² s^-2 for both components and horizontal diffusivities are 7 × 10⁷ cm² s^-1, and 3 × 10 cm² s^-1. The second region, in the NECC and the NEC, has a mean flow with a strong zonal shear and a weak northward velocity. The autocovariance is approximately exponential for the zonal component while the meridional component has a negative lobe at about 10 days probably due to the presence of instability waves. The variance is approximately tripled compared to the SEC region estimate while the meridional diffusivity estmate is nearly the same magnitude. The zonal diffusivity is estimated to be 15 × 10⁷ cm² s^-1.

Black, M.L., S.H. Houston, and G. Carter. AFRES-NOAA flight-level data comparisons. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C. (paper was mistakenly omitted from the Minutes) (1998).

A coordinated flight between an Air Force Reserve (AFRES) C-130 aircraft and both National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft was conducted on 12 July 1997. This mission was the third in recent years and resulted from a recommendation made at the 49th Interdepartmental Hurricane Conference. The AFRES and NOAA aircraft each recorded, at 1-sec intervals, the standard suite of flight-level meteorological data (winds, temperature, dew point, pressure) and navigational information (e.g., position, true air speed, heading, etc.). The data were collected during clear and moderate-wind conditions along the Florida west coast, about 100 miles north of Tampa. The NOAA and AFRES aircraft conducted "fly-bys" adjacent to an Air Force Aerostat balloon which was carrying a NOAA calibrated instrument package. The balloon approaches were at altitudes ranging from 1,000 to 10,000 feet and provide the basis for the intercomparisons. A GPS dropwindsonde was released along the coast to supply another set of independent measurements. Comparisons between the flight-level data collected from the balloon, the dropsonde, and the NOAA and AFRES aircraft will be presented. Recommendations, if any, will be made to improve the data collection, processing, and strategies for future intercomparison flights. Additionally, the calibration information gained from this flight will be used to investigate the data quality from concurrent flights into tropical cyclones by both the NOAA and AFRES aircraft this past hurricane season.

Black, P.G., and L.K. Shay. Observations of tropical cyclone intensity change due to air-sea interaction processes. Preprints, Symposium on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 161-168 (1998).

No abstract.

Black, P.G., F.D. Marks, P. Dodge, I. Popstefanija and R. Pauwl. First observations from the vertically scanning Doppler radar (VSDR): A key to G-IV reconnaissance operations. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A236-A256 (1998).

No abstract.

Boebel, O., C. Duncombe Rae, S.L. Garzoli, J. Lutjeharms, P. Richardson, T. Rossby, C. Schmid, and W. Zenk. Float experiment studies interocean exchanges at the tip of Africa. EOS, Transactions, American Geophysical Union, 79(1):7-8 (1998).

No abstract.

Bosart, L.F., W.E. Bracken, J. Molinari, C.S. Velden, and P.G. Black. Environmental influences on the rapid intensification stage of Hurricane Opal (1995) over the Gulf of Mexico. Preprints, Symposium on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 105-112 (1998).

No abstract.

Bove, M.C., J.J. O'Brien, J.B. Eisner, C.W. Landsea, and X. Niu. Effect of El Niño on U.S. landfalling hurricanes, revisited. Bulletin of the American Meteorological Society, 79(11):2477-2482 (1998).

Changes in the frequency of U.S. landfalling hurricanes with respect to the El Niño-Southern Oscillation (ENSO) cycle are assessed. Ninety-eight years (1900-1997) of U.S. landfalling hurricanes are classified, using sea surface temperature anomaly data from the equatorial Pacific Ocean, as occurring during an El Niño (anomalously warm tropical Pacific waters), La Niña (anomalously cold tropical Pacific waters), or neither (neutral). The mean and variance of U.S. landfalling hurricanes are determined for each ENSO phase. Each grouping is then tested for Poisson distribution using a chi-squared test. Resampling using a "bootstrap" technique is then used to determine the 5% and 95% confidence limits of the results. Last, the frequency of major U.S. landfalling hurricanes (sustained winds of 96 kt or more) with respect to ENSO phase is assessed empirically. The results indicated that El Niño events show a reduction in the probability of a U.S. landfalling hurricane, while La Niña shows an increase in the chance of a U.S. hurricane strike. Quantitatively, the probability of two or more landfalling U.S. hurricanes during an El Niño is 28%, of two or more landfalls during neutral conditions is 48%, and of two or more landfalls during La Niña is 66%. The frequencies of landfalling major hurricanes show similar results. The probability of one or more major hurricane landfall during El Niño is 23% but is 58% during neutral conditions and 63% during La Niña.

Broecker, W.S., and T.-H. Peng. Greenhouse Puzzles, Part I, Keeling's World: Is CO₂ Greening the Earth? Eldigio Press, Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, 111 pp. (1998).

This section's hero is Charles David Keeling. In the late 1950s, he had the wisdom to establish two stations for the continuous precise measurement of atmospheric carbon dioxide, one high on Hawaii's extinct volcano Mauna Loa and the other at the South Pole. The records from these stations provide the foundation upon which all studies of man's perturbation of the Earth's carbon cycle rest. Not only did Keeling have the foresight to establish these stations but also the tenacity to make sure that year in and year out they produced accurate results. Keeling took on this task as part of a career-long effort to understand the flux of CO₂ gas through the atmosphere, into the ocean and into and out of the terrestrial biosphere. He was the first to realize the wealth of information contained in the spatial and seasonal texture of the atmosphere's CO₂ content. In addition to his direct scientific contribution, he fostered a secondary one. Son, Ralph, is doing for atmospheric O₂ all the kinds of things papa did for atmospheric CO₂.

Broecker, W.S., and T.-H. Peng. Greenhouse Puzzles, Part II, Martin's World: CO₂'s Glacial Hideout? Eldigio Press, Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, 73 pp. (1998).

The selection of the hero of this section has proven difficult. Under consideration were those who first measured the low CO₂ contents of air trapped in glacial age ice, those who used carbon isotope ratios and cadmium contents in foraminifera to set constraints on scenarios designed to explain this drop, and those who demonstrated that the high latitude outcrops of the deep sea dictated the CO₂ content of the entire surface ocean and, in turn, that of the atmosphere. But in the end, we initially selected a dark horse, David Archer, who at the time this book was being written, put his finger on what appeared to be the mechanism responsible for the atmosphere's glacial to interglacial CO₂ cycle. He obtained microelectrode O₂ and pH data from the upper few centimeters of deep sea sediments which clearly demonstrated the importance of bacterial respiration as a driver of calcite dissolution. Encouraged by preliminary boron-isotope-based paleo pH measurements which suggested large deep sea CO⁼₃ concentrations during glacial time, Archer showed that an increase in the rain rate of organic matter could generate the required CO⁼₃ ion change with little or no change in lysocline depth. But alas, now five years later, Archer's hypothesis has like its predecessors fallen on hard times. Danny Sigman, while a graduate student at Woods Hole, demonstrated that the requisite large separation between the saturation horizon and the lysocline could not be sustained. So in this second edition, we replace David Archer with the late John Martin who pioneered the concept that the availability of iron limits plant productivity in many parts of the oceans. He also pointed out that the large excess of iron carried to the sea during glacial time by the several-fold higher dust rain may have been responsible for the CO₂ drawdown.

Broecker, W.S., and T.-H. Peng. Greenhouse Puzzles, Part III, Walker's World: CO₂ , Chemical Traffic Controller? Eldigio Press, Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, 93 pp. (1998).

This section's hero is James C.G. Walker, a space physicist at the University of Michigan. In 1981, together with his colleagues P.B. Hays and J.F. Kasting, he published a paper which lays out in beautiful simplicity the role of atmospheric CO₂ as the chemical policeman controlling the flow of continental weathering products to the sea, and thereby maintaining a balance between the rate of outgassing of CO₂ gas from our planet's interior and the rate of CO₂ removal to sea floor sediments as calcite. The important consequence of this police action is its influence on Earth climate. Walker and his colleagues pointed out that early in the Earth's history the tendency toward cooler temperatures related to the faintness of the young Sun was mostly likely compensated by higher atmospheric CO₂ contents. In an attempt to explain the cooling of the Earth over the last 100 million years, the role of Walker's mechanism was subsequently expanded by Berner, Lasaga and Garrels, who postulated that the cooling was driven by a decrease in the planetary outgassing rate related to a progressive slowing of plate motions. This suggestion was met with wide interest and became known as the BLAG hypothesis in honor of its creators. In the enthusiasm to explore all the aspects of BLAG, the earlier contribution of Walker tended to be forgotten. Hopefully, in naming this section, we will help to return the credit for the CO₂ policing concept to its originator, James C.G. Walker.

Broecker, W.S., S.L. Peacock, S. Walker. R. Weiss, E. Fahrbach, M. Schroeder, U. Mikolajewicz, C. Heinze, R. Key, T.-H. Peng, and S. Rubin. How much deep water is formed in the Southern Ocean? Journal of Geophysical Research, 103(C8):15,833-15,843 (1998).

Three tracers are used to place constraints on the production rate of ventilated deep water in the Southern Ocean. The distribution of the water mass tracer PO₄* ("phosphate star") in the deep sea suggests that the amount of ventilated deep water produced in the Southern Ocean is equal to or greater than the outflow of North Atlantic Deep Water from the Atlantic. Radiocarbon distributions yield an export flux of water from the North Atlantic which has averaged about 15 Sv over the last several hundred years. CFC inventories are used as a direct indicator of the current production rate of ventilated deep water in the Southern Ocean. Although coverage is as yet sparse, it appears that the CFC inventory is not inconsistent with the deep water production rate required by the distributions of PO₄* and radiocarbon. It has been widely accepted that the major part of the deep water production in the Southern Ocean takes place in the Weddell Sea. However, our estimate of the Southern Ocean ventilated deep water flux is in conflict with previous estimates of the flux of ventilated deep water from the Weddell Sea, which lie in the range 1-5 Sv. Possible reasons for this difference are discussed.

Bryan, G.H., R.F. Rogers, and J.M. Fritsch. Cloud-scale resolution simulations in moist absolutely unstable layers. Preprints, Eighth Pennsylvania State University/National Center for Atmospheric Research's Mesoscale Model Users Workshop, Boulder, CO. National Center for Atmospheric Research, 59-62 (1998).

No abstract.

Butler, J.H., J.W. Elkins, S.A. Montzka, T.M. Thompson, T.H. Swanson, A.D. Clarke, F.L. Moore, D.F. Hurst, P.A. Romashkin, S.A. Yvon-Lewis, J.M. Lobert, M. Dicorleto, G.S. Dutton, L.T. Lock, D.B. King, R.E. Dunn, E.A Ray, M. Pender, P.R. Wamsley, and C. M. Volk. Nitrous oxide and halocompounds. In Climate Monitoring and Diagnostics Laboratory Summary Report No. 24, D.J. Hofmann, J.T. Peterson, and R.M. Rosson (eds.). National Technical Information Services, Springfield, VA, 91-121 (1998).

No abstract.

Castle, R.D., R.H. Wanninkhof, J.L. Bullister, S.C. Doney, R.A. Feely, B.E. Huss, E. Johns, F.J. Millero, K. Lee, D. Frazel, D. Wisegarver, D. Greeley, F. Menzia, M. Lamb, G. Berberian, and L.D. Moore. Chemical and hydrographic profiles and underway measurements from the eastern North Atlantic during July and August of 1993. NOAA Data Report, ERL AOML-32 (PB98-131865), 82 pp. (1998).

From July 4-August 30, 1993, the National Oceanic and Atmospheric Administration's (NOAA) Ocean-Atmosphere Carbon Exchange Study (OACES) and Radiatively Important Trace Species (RITS) programs participated in an oceanographic research cruise aboard the NOAA ship Malcolm Baldrige. The objectives of the OACES component were to determine the source and sink regions of CO₂ in the equatorial and North Atlantic during the summer and to establish a baseline of total carbon inventory in the region. Data were collected from 5°S to Iceland along a nominal longitude of 20°W. This report presents only the OACES-related data from legs 1, 2A, and 2B, including hydrography, nutrients, carbon species, dissolved oxygen, total inorganic carbon, chlorofluorocarbons, total alkalinity, pH, and salinity. Included are contour plots of the various parameters and descriptions of the sampling techniques and analytical methods used in data collection.

Chen, G., B. Chapron, J. Tournadre, K.B. Katsaros, and D. Vandemark. A new look at the diurnal variation of global oceanic precipitation from the ocean TOPography EXperiment (TOPEX) and the TOPEX Microwave Radiometer (TMR). International Journal of Remote Sensing, 19(1):171-180 (1998).

New results on the diurnal variation of global oceanic precipitation are obtained by using one year's TOPEX (ocean TOPography EXperiment) and TMR (TOPEX Microwave Radiometer) data, derived from the dual-frequency (Ku and C band) capacity of the altimeter and the non-Sun-synchronous orbit of the satellite. The diurnal variation is characterized by a three-maximum structure which peaks at 00:00, 08:00, and 16:00 local time. The midnight-morning-afternoon maxima and dawn-noon-evening minima pattern seems to correlate with the results of most previous studies and to offer a unified picture of the diurnal variation of oceanic rainfall. A slight daytime (06:00-18:00) preference of oceanic precipitation appears to be significant in all seasons with the day/night ratio varying from 1.032 to 1.141 and the annual mean being 1.082. Examination of the geographical distribution of the timing of diurnal variation shows that the majority of the world oceans favor an afternoon maximum and an evening minimum. Moreover, the northern hemisphere is more coherent in reaching its maximum, while the southern hemisphere in reaching its minimum. In addition, the mechanisms responsible for the diurnal variations are discussed.

Chen, G., B. Chapron, J. Tournadre, K.B. Katsaros, and D. Vandemark. Identification of possible wave damping by rain using TOPEX and TMR data. Remote Sensing of Environment, 63(1):40-48 (1998).

A global picture of wave damping by rain (WDBR), a phenomenon familiar to seafarers for centuries, has been so far unavailable owing to the fact that neither rules nor tools exist for its systematic measurement. The situation has changed following the launch of the first dual-frequency (5.3 GHz and 13.6 GHz) radar altimeter TOPEX, along with the three-frequency (18 GHz, 21 GHz, and 37 GHz) radiometer TMR (TOPEX Microwave Radiometer). In this study, a scheme for detecting possible WDBR using TOPEX/TMR data is proposed. The geographical distribution of identified WDBR is consistent with the simultaneous presence of high sea state and intensive rainfall. Frequent occurrences of WDBR are observed in the midlatitude of the two hemispheres, particularly in the Pacific Ocean. In contrast, WDBR rarely occurs in the majority of the tropical and subtropical oceans. The global seasonality of WDBR is found to be weak as a result of the hemispheric phase opposition of sea state and rainfall in their annual variations. Knowledge of spatial distribution and temporal variation of WDBR is useful in dealing with potential systematic biases in satellite wind and wave measurements due to rain/sea interaction. It would have been interesting to compare the WDBR with coincident estimates of global rainfall from the SSM/I (Special Sensor Microwave/Imager).

Cione, J.J., and P.G. Black. Surface thermodynamic observations within the tropical cyclone inner core. Preprints, Symposium on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 141-145 (1998).

No abstract.

Cione, J.J., S. Raman, L.J. Pietrafesa, R.A. Neuherz, K. Keeter, and X. Li. The use of pre-storm low-level baroclinicity in determining and implementing the Atlantic surface cyclone intensification index. Boundary Layer Meteorology, 89:211-224 (1998).

The lateral motion of the Gulf Stream off the eastern seaboard of the United States during the winter season can act to dramatically enhance the low level baroclinicity within the coastal zone during periods of offshore cold advection. The relative close proximity of the Gulf Stream current off the mid-Atlantic coast can result in the rapid and intense destabilization of the marine atmospheric boundary layer directly above and shoreward of the Gulf Stream within this region. This airmass modification period oftentimes precedes either wintertime coastal cyclogenesis or the cyclonic re-development of existing mid-latitude cyclones. A climatological study investigating the relationship between the severity of the pre-storm, cold advective period, and subsequent cyclogenic intensification was undertaken by Cione et al. in 1993. Findings from this study illustrate that the thermal structure of the continental airmass, as well as the position of the Gulf Stream front relative to land during the pre-storm period (i.e., 24-48 h prior to the initial cyclonic intensification), are linked to the observed rate of surface cyclonic deepening for storms that either advected into or initially developed within the Carolina-southeast Virginia offshore coastal zone. It is a major objective of this research to test the potential operational utility of this pre-storm low level baroclinic linkage to subsequent cyclogenesis in an actual National Weather Service (NWS) coastal winter storm forecast setting. The ability to produce coastal surface cyclone intensity forecasts recently became available to North Carolina State University researchers and NWS forecasters. This statistical forecast guidance utilizes regression relationships derived from a nine-season (January 1982- April 1990), 116-storm study conducted by Cione et al. (1993). During the period between February 1994 and February 1996, the Atlantic Surface Cyclone Intensification Index (ASCII) was successfully implemented in an operational setting by the NWS at the Raleigh-Durham forecast office for 10 winter storms. Analysis of these ASCII forecasts will be presented.

Crane, M.L. Project ACCESS: Community coastal monitoring for year 2007. Earth System Monitor, 8(4):12-16 (1998).

No abstract.

Donelan, M.A., H.C. Graber, S. Ataktürk, W.M. Drennan,, E.A. Terray, and K.B. Katsaros. Marine flux-profile relations from an air-sea interaction spar buoy. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS99, OS31J-09 (1998).

During the Spring of 1997, the Air Sea Interaction Spar (ASIS) buoy was deployed in the northeastern Gulf of Mexico. Continuous data on profiles of wind speed, temperature, and humidity were obtained with concurrent wind stress, heat flux, and wave directional properties. This paper examines the flux-profile relations and the effect of non-local or non-equilibrium wave fields on them.

Doney, S.C., J.L. Bullister, and R.H. Wanninkhof. Climatic variability in upper ocean ventilation rates diagnosed using chlorofluorocarbons. Geophysical Research Letters, 25(9):1399-1402 (1998).

The chlorofluorocarbon CFC-12 (CCl₂-F₂) distributions from two occupations of a meridional hydrographic section in the eastern North Atlantic are used to describe the oceanic penetration of CFCs and change in the integrated ventilation patterns over the five years from 1988 to 1993. The CFC-12 water-column inventories increased by 30-40%, despite a slowing atmospheric growth rate (14%), because of continuing uptake by undersaturated subsurface water masses whose response is lagged by the ventilation time-scales. After removing the long-term CFC temporal trend using a tracer age based normalization technique, we observe a distinct dipole pattern in upper ocean ventilation, with reduced convection in the subpolar gyre and enhanced production of saline subtropical underwater in 1993. These differences are discussed in relation to interannual variability in atmospheric surface forcing, upper ocean anomalies, and convection patterns associated with the North Atlantic Oscillation.

Duncombe Rae, C., S.L. Garzoli, P. Richardson, and D. Fratantoni. Hydrography of some rings in the southeast Atlantic. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS131, OS41D-02 (1998).

Mesoscale rings and eddies in the southeast Atlantic Ocean have three potential sources: the Brazil-Malvinas Current Confluence, the Agulhas Current Retroflection, and the South Atlantic Subtropical Front. Previous hydrographic surveys have identified Agulhas rings and Brazil eddies in the region of the Cape Basin. During a component cruise of KAPEX (Cape of Good Hope Experiment), an experiment to track the flow of intermediate water around the southern tip of Africa and through the Benguela Current, three large eddies were encountered in the Cape Basin and east of the Mid-Atlantic Ridge during September 1997. The eddies were detected in satellite altimetry before the cruise and surveyed with XBT, CTD and LADCP profiles. One of the rings, closest to the Agulhas retroflection, appeared a typical Agulhas ring in its first year after shedding, with a single surface isothermal stad of 16.1°C down to 280 m. The ring furthest from the supposed shedding point exhibited two lenses, 130-210 m and 320-420 m depth, at 15.27°C and 14.45°C, respectively, in addition to the surface mixed layer, 17.6°C, suggesting an Agulhas ring which had experienced two winter mixing periods since leaving the retroflection. The middle ring had a stad of 12.22°C between 440 and 600 m and showed little evidence of convective overturning events above that level, apart from a surface mixed layer (160 m, 16.7-16.8°C) which was evident also in the background water column. The origin, structure, and temperature-salinity characteristics of these three eddies are examined. It is surmised that these eddies were shed from the Agulhas retroflection and subsequently modified by atmospheric cooling, convective overturning during winter, and possibly interaction with the Subtropical Front.

Dunion, J., S.H. Houston, C. Velden, M.D. Powell, and P.G. Black. Use of GOES high-density low-level VIS winds to improve the estimation of tropical cyclone outer wind radii. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A72-A87 (1998).

UW-CIMSS recently began providing real-time GOES low-level VIS winds in the vicinity of tropical cyclones on a demonstrational basis to NOAA's Hurricane Research Division (HRD). These data were included in many of HRD's real-time tropical cyclone surface wind analyses which were sent to NHC forecasters on an experimental basis during 1997. These wind analyses are used as guidance in their tropical cyclone advisories and warnings. The satellite observations provide essential coverage in the periphery of hurricanes where conventional in-situ observations (e.g., ships, buoys, etc.) are often widely spaced or non-existent and reconnaissance aircraft do not normally fly. The GOES VIS winds were adjusted to the surface using a PBL model. These adjusted data were used in real-time surface wind analyses for Hurricanes Danny and Erika of 1997 and were available for post-storm analyses in 1996 Hurricanes Edouard, Fran, Hortense, and Lili. The satellite observations improved the estimation of the 34 kt wind radii in many cases and also helped place the 50 kt wind radii for some cases. Examples of the impact of these data on hurricane surface wind analyses will be shown. Statistics on comparisons (>100 cases) of the adjusted and unadjusted GOES VIS winds with in-situ surface measurements will be presented. Also, in some cases GPS-sonde profiles were available in the vicinity of the GOES VIS winds. Comparisons of these highly detailed soundings with the satellite winds and their height assignments will be shown. The potential for further improvement of outer wind radii estimation through joint use of GOES VIS winds and satellite-based scatterometer surface winds will be discussed.

Durand, P., H. Dupuis, D. Lambert, B. Bénech, A. Druilhet, K.B. Katsaros, P.K. Taylor, and A. Weill. Comparison of sea surface flux measured by instrumented aircraft and ship during SOFIA and SEMAPHORE experiments. Journal of Geophysical Research, 103(C11):25,125-25,136 (1998).

Two major campaigns (Surface of the Oceans, Fluxes and Interactions with the Atmosphere (SOFIA) and Structure des Echanges Mer-Atmosphére, Propriétés des Hétérogénéités Océaniques: Recherche Expérimentale (SEMAPHORE)) devoted to the study of ocean-atmosphere interaction were conducted in 1992 and 1993, respectively, in the Azores region. Among the various platforms deployed, instrumented aircraft and ship allowed the measurement of the turbulent flux of sensible heat, latent heat, and momentum. From coordinated missions we can evaluate the sea surface fluxes from (1) bulk relations and mean measurements performed aboard the ship in the atmosphere surface layer and (2) turbulence measurements aboard aircraft, which allowed the flux profiles to be estimated through the whole atmospheric boundary layer and therefore to be extrapolated toward the sea surface level. Continuous ship fluxes were calculated with bulk coefficients deduced from inertial-dissipation measurements in the same experiments, whereas aircraft fluxes were calculated with eddy-correlation technique. We present a comparison between these two estimations. Although momentum flux agrees quite well, aircraft estimations of sensible and latent heat flux are lower than those of the ship. This result is surprising, since aircraft momentum flux estimates are often considered as much less accurate than scalar flux estimates. The various sources of errors on the aircraft and ship flux estimates are discussed. For sensible and latent heat flux, random errors on aircraft estimates, as well as variability of ship flux estimates, are lower than the discrepancy between the two platforms, whereas the momentum flux estimates cannot be considered as significantly different. Furthermore, the consequence of the high-pass filtering of the aircraft signals on the flux values is analyzed; it is weak at the lowest altitudes flown and cannot therefore explain the discrepancies between the two platforms but becomes considerable at upper levels in the boundary layer. From arguments linked to the imbalance of the surface energy budget, established during previous campaigns performed over land surfaces with aircraft, we conclude that aircraft heat fluxes are probably also underestimated over the sea.

Eads, L.J., H.A. Friedman, and D.J. Garcia. From humble beginnings as the Inner City Marine Project to selection as a National School of Excellence. Preprints, Seventh Symposium on Education, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 162-165 (1998).

The evolution of the MAST Academy (Maritime and Science Technology High School), a Dade County Magnet School of Choice, from its predecessor, the Inner City Marine Project (ICMP), is described. ICMP originated after Dade County experienced civil unrest in the Black community in 1984. At that time, Dr. Linda J. Eads, currently MAST Academy's principal, was assigned to design a program in maritime education which emphasized career exploration for minorities. The ICMP operated from the District Office of the Dade County Public Schools and targeted elementary and middle schools in the inner city with high minority populations. When the MAST Academy opened its doors in 1991, the ICMP became the MAST Academy Outreach Department which continued to provide programs for the targeted schools. The MAST Academy presently carries on the tradition of the ICMP by providing high school students with specialized marine-theme science and technology courses. In 1996, the MAST Academy was selected as a U.S. Department of Education National Blue Ribbon School of Excellence.

Ellis, G., P. Swart, M. Lutz, C. Alvarez-Zarikian, P. Blackwelder, T.A. Nelsen, H. Wanless, and J. Trefry. The stable isotope composition of foraminifera, ostracods, and organic material in a dated core from Whitewater Bay. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 2 pp. (1998).

No abstract.

Ellsberry, R.L., and F.D. Marks. U.S. Weather Research Program Hurricane Landfall Workshop Report. Technical Note, NCAR/TN-442, 40 pp. (1998).

No abstract.

Feely, R.A., R.H. Wanninkhof, C.D. Cosca, and K. Lee. The impact of the 1997-1998 El Niño on the air-sea exchange flux of CO₂ in the oceans. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F507, OS41H-08 (1998).

As part of the NOAA Ocean Atmosphere Carbon Exchange Study (OACES), measurements of CO₂ partial pressure were made in the atmosphere and in the surface waters of the central and eastern equatorial Pacific from 1992 to 1998. Surface water pCO₂ data indicate significant diurnal, seasonal, and interannual variations. The largest variations were associated with the 1997-98 ENSO event, which reached maximum intensity in the winter of 1997-1998. The lower surface pCO₂ values during the 1997-98 ENSO period were the result of the combined effects of both remotely and locally forced physical processes: (1) development of a low-salinity surface cap as part of the formation of the warm pool in the western and central equatorial Pacific; and (2) deepening of the thermocline by propagating Kelvin waves in the eastern Pacific. Both these processes serve to reduce pCO₂ values towards near equilibrium values at the height of the warm phase of ENSO. These changes resulted in a lower-than-normal CO₂ flux to the atmosphere. The annual average fluxes indicate that strong ENSOs exchange about 0.3-0.4 GtC/yr to the atmosphere; whereas, during non-El Niño years the equatorial Pacific exchanges about 0.9-1.0 GtC/yr to the atmosphere. This difference is enough to account for approximately one-third of the atmospheric anomaly during an El Niño. Our models suggest that this effect occurs in temperate and polar regions as well. Thus, the ENSO process is the major controlling factor of the interannual variability of the air-sea exchange of CO₂ in the oceans. During decades dominated by strong ENSO events, such as this one, as much as 2-3 Gt more C are retained by the oceans compared with normal decades. Clearly, the equatorial Pacific is a very important region for studying climate feedbacks of greenhouse warming.

Feely, R.A., R.H. Wanninkhof, H.B. Milburn, C.E. Cosca, M. Stapp, and P.P. Murphy. A new automated underway system for making high precision pCO₂ measurements onboard ships of opportunity. Analytica Chimica Acta, 377:185-191 (1998).

We have developed a new temperature-controlled, automated underway system for making atmospheric and surface ocean pCO₂ measurements onboard research vessels equipped with an uncontaminated seawater intake system. Uncontaminated seawater is supplied to a showerhead plexiglass equilibrator at the rate of approximately 50 liters/minute. After about 3 minutes, the air trapped in the equilibrator is equilibrated with seawater. This air is sampled six times per hour. In addition, atmospheric air is sampled three times per hour from the intake on the bow flagstaff through 3/8" Dekabon^TM tubing to the underway system. The CO₂ measurements are made with a differential, non-dispersive, infrared analyzer LiCor^TM (model 6252). The underway system operates on an hourly cycle with the first quarter of each hour devoted to calibration with three CO₂ standards, each measured for 5 minutes. A second order polynomial calibration curve is calculated from the voltage values of the standards. The remaining time in each hour is used to measure equilibrator air (15 min), bow air (15 min), and equilibrator air once again (15 min). To date, we have successfully used the underway pCO₂ system on 12 cruises of the NOAA Ship Ka'imimoana in the equatorial Pacific. The analytical precision of the system is approximately 0.3-0.4 ppm for seawater and for air.

Ffield, A., C.I. Fleurant, R.L. Molinari, and W.D. Wilson. NOAA Ship Malcolm Baldrige 1995 cruises: MB95-02, MB95-04, and MB95-07 hydrographic data. LDEO-98-1, Technical Report, 310 pp. (1998).

No abstract.

Fleurant, C.I., and R.L. Molinari. Comparison of bottle salinity and bottle oxygen values from WHP repeat lines I7N, I1W, I8N, and I8S. International WOCE Newsletter, 33:27-29 (1998).

No abstract.

Franklin, J.L., and M.L. Black. GPS dropwindsonde data in hurricanes. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A111-A142 (1998).

The 1997 hurricane season was the first with both NOAA WP-3D aircraft equipped with the new NCAR GPS dropwindsonde system. The GPS sonde replaces the old Omega-based ODW, in use since the early 80's on the P-3s. During the season, the first successful dropwindsonde releases (of any kind) were made in a hurricane eyewall (Guillermo). These were followed by additional eyewall releases in Hurricane Erika. The wind profiles show that surface winds in the eyewall may be much higher than what is typically inferred from flight-level reconnaissance data. Very strong jets resolved by the GPS dropsondes in and just above the boundary layer may be indicative of peak surface gusts.

Fratantoni, D.M., P.L. Richardson, C.M. Duncombe Rae, and S.L. Garzoli. Three warm-core rings in the eastern south Atlantic. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS131, OS41D-04 (1998).

During the September 1997 Benguela Current Experiment, three large (300 km) anticyclonic rings were identified and surveyed near 30°S in the eastern South Atlantic. Preliminary analysis suggests that these rings were formed from the retroflecting Agulhas Current south of Africa. Two of the rings were observed west of the Walvis Ridge and appear to have been freely translating for nearly two years. The transport of intermediate water (approximate depth range 400-1000 m) within Agulhas rings is thought to be an important interbasin transport pathway associated with the global-scale thermohaline circulation. Employing an array of Lagrangian floats and drifters, this experiment and others associated with the U.S., German, and South African KAPEX (Cape of Good Hope Experiment) program constitute the first direct examination of this pathway. In-situ hydrographic and direct velocity measurements were performed aboard the R/V Seward Johnson. Nominal ring positions were estimated prior to departure using satellite altimetry. During the cruise intensive shipboard XBT and ADCP surveys revealed the three-dimensional structure of temperature and velocity associated with each ring and facilitated a determination of the ring center. Multiple acoustically-tracked subsurface RAFOS floats (at 700 m depth) and satellite-tracked surface drifters were then launched near the center of each ring to measure ring translation and the evolution of core properties over a two-year period. Additional floats and drifters were deployed along 30°S and 7°W to characterize the background flow of surface and intermediate water in the Benguela Current and the eastern South Atlantic subtropical gyre. In this poster we describe the horizontal structure of these large (300 km diameter) and energetic (40 cm/s) warm-core rings using both in-situ and Lagrangian measurements. We present synoptic plan-view depictions of thermocline depth, upper-ocean velocity, and integrated heat content for each ring. The scale and intensity of each ring is discussed in the context of a translation history compiled from archived TOPEX/Poseidon altimetry. Finally, surface drifter trajectories are used to assess ring translation and to describe the temporal evolution of azimuthal velocity structure and intensity.

Friedman, H.A., and D.J. Garcia. Tropical cyclone public awareness programmes: Preparing for the twenty-first century. Preprints, Seventh Symposium on Education, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 166-168 (1998).

During the period from 1969 to 1993, a total of 1551 tropical cyclones, typhoons, and hurricanes occurred worldwide. Literally millions of lives are affected each year, and billions of dollars are lost as a result of these storms. At present, we can do little, if anything, to lessen the occurrence, frequency, or intensity of tropical cyclones, or to influence their paths. But over the past three decades, significant advances have been made in mankind's capability to prepare for and mitigate their damaging effects. Concerted international scientific efforts have resulted in better understanding the phenomenon of tropical cyclones, their formation, characteristics, path of movement, and effects. Technical advances in weather monitoring equipment satellites, computers, improved radar systems, and other space age meteorological tools enable scientists today to vigilantly monitor cyclones as they form, track them as they move, and predict with some accuracy where they are likely to impact on land and people. Correspondingly, meteorological services in many countries have been substantially improved in recent years. Cyclone monitoring equipment has been installed in most cyclone-prone regions of the world. National systems have been linked to regional and international networks through which meteorological data is shared and warnings of approaching cyclones conveyed. In many localities, local communication systems and administrative procedures have been strengthened to ensure that information about approaching cyclones is passed to communities most at risk. While great strides have been made in our ability to understand and live with cyclones, still more must be done. We must strive to further expand our basic knowledge about tropical cyclones, upgrade tools needed for weather monitoring and prediction, improve the warning and communications network, and strengthen meteorological services. It is a useful reminder that the primary objectives of these varied activities is to prevent the loss of lives and prevent or minimize property damage from cyclones. The need for continued effort is reconfirmed by the deaths and destruction left in the wake of each tropical cyclone that affects populated areas today; a problem that is likely to continue and increase in seriousness as coastal populations enlarge. The goal of preventing loss of life and reducing property damage from tropical cyclones, however, can not be achieved simply through improved technical and meteorological services. Accurate prediction and timely notice are critically important, but loss of life and property can only be minimized if officials and the general public are knowledgeable of the hazards faced, understand the warnings provided, and take the proper actions to protect life and property before, during, and after a cyclone. The process required to achieve a public state of readiness is commonly referred to as an awareness program. A resource guide, designed to provide a framework for the development and implementation of local tropical cyclone awareness programs, will be discussed. The Internet was used extensively to obtain up-to-date information on worldwide issues concerning tropical cyclones. The guide's design encourages interactive use by disaster preparedness officials and educators at the local level. Questionnaires and community-specific checklists are provided to elicit local participation in the process of creating tropical cyclone awareness.

Garcia, D.J., H.A. Friedman, and L.J. Eads. MAST Academy outreach: Serving the community with marine theme programs. Preprints, Seventh Symposium on Education, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 169-171 (1998).

The MAST Academy's Outreach Department provides marine theme enrichment programs which emphasize career opportunities for targeted schools with high minority enrollments. Enrichment programs include the Land SHARC (Science Hands-on and Related Careers) and WOW (Weather On Wheels) mobile laboratories, environmental field trips, internships, and the MAST Mariners Program, a middle school summer course focused on, but not exclusively for, minority students. The role of NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) and other outside agencies in providing school year and summer internships for MAST Academy students is discussed. Meteorologists from AOML's Hurricane Research Division serve as advisory board members for the WOW; their contributions to the program are presented.

Garzoli, S.L., C. Duncombe Rae, D. Fratantoni, G.J. Goni, J. Mantel, A. Roubicek, P. Fratantoni, and C. Whittle. Benguela Current Experiment. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS131, OS41D-01 (1998).

Although intermediate water is an important component of the northward-flowing meridional circulation cell in the Atlantic, the pathways, velocity, and variability of this water are poorly known. In order to study the northward flow of intermediate water in the Benguela Current and its extension, a program was initiated by scientists of WHOI, NOAA/AOML, and Sea Fisheries (South Africa). The main objective was to obtain the first subsurface Lagrangian float measurements of the northward flow of intermediate water in t he eastern South Atlantic and to measure the characteristics of this water. This program is a component of KAPEX (Cape of Good Hope Experiment), a joint U.S., Germany, and South Africa effort. During September 1997, we participated in a cruise aboard the RV Seward Johnson from Cape Town to Recife. The main objectives of this cruise were: to launch an array of RAFOS floats and surface drifters; to perform an intensive survey to determine the characteristics of the flow; and to search for and study Agulhas rings in the area. Agulhas rings are considered to be one of the main carriers of Indian Ocean waters into the Atlantic. Hydrographic casts (CTD-O₂) and direct measurements of currents (ADCP/LADCP) were performed along 30°S (between 14°E and 7°W) and along 7°W (between 33°S and 18°S) to study the characteristics and paths of the intermediate water flow at the time of deployments. Three anticyclonic rings were identified through intensive XBT surveys guided by satellite images of sea surface height. CTD/LADCP stations were performed and RAFOS floats and drifters launched in a radial from the center of the rings. The eddies are tentatively identified as being Agulhas rings, although a deep (600 m), cold (12.2°C), mixed layer in one ring raises questions about its origin. Thirty-two RAFOS floats and 11 surface drifters were launched along the sections and in the rings. This poster will provide an overview of the Benguela Current Experiment and the preliminary results from the September 1997 cruise.

Goni, G.J., and S.L. Garzoli. Origin and evolution of the Benguela Current Experiment rings by altimetry. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS131, OS41D-03 (1998).

Historical hydrographic data is used to compute the mean upper layer thickness and reduced gravity in the southeastern Atlantic. These parameters, along with the altimeter-derived sea surface height anomaly, are used to derive the upper layer thickness of the ocean. This product proved to be an efficient means to identify and track anticyclonic rings. In September 1997, as part of the Benguela Current Experiment, a cruise on the R/V Seward Johnson guided by the TOPEX/POSEIDON product identified and surveyed three rings. The water mass characteristics of these rings indicate that at least two of them could have their origin in the Agulhas retroflection. The third ring has hydrographic characteristics that raise questions about its origin. This poster shows the results of a study of these rings based on altimetry. Synoptic maps of the upper layer thickness are analyzed to determine the trajectories of the rings in the region for a period of two years previous to the Benguela Current Experiment. The origins and evolution of the three rings observed during the September 1997 cruise are established and discussed. The translation velocity, available potential energy, and heat content are calculated from the altimeter data. A comparison between the shipboard and altimeter-derived values of the upper layer thickness is also presented.

Graber, H.C., M.A. Donelan, S. Atakturk, W.M. Drennan, and K.B. Katsaros. Evaluation of NSCAT scatterometer winds with wind stress measurements in the Gulf of Mexico. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F417, OS72G-03 (1998).

Wind vectors and radar backscatter observed by the NASA scatterometer (NSCAT) are compared with wind and wind stress measurements from an air-sea interaction spar (ASIS) buoy and wind measurements from a nearby NDBC discus buoy. ASIS is a new autonomous spar buoy designed to permit long-term measurements of interfacial processes. During a two-month deployment in the Gulf of Mexico in April 1997, the buoy experienced several fronts associated with rapid changes in wind speed and direction. The ASIS buoy was equipped for motion-corrected measurements of the wind stress vector, as well as high resolution wave directional properties. These are used to explore wind and backscatter measurements of scatterometers. Time difference and spatial separation between NSCAT and buoy observations were limited to less than 30 minutes and 25 km, respectively.

Gray, W.M., C.W. Landsea, J.A. Knaff, P.W. Mielke, and K.J. Berry. Verification of the 1997 seasonal hurricane forecasts and a prediction for 1998. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A331-A338 (1998).

No abstract.

Hacker, E., E. Firing, W.D. Wilson, and J.C. Kindle. Evidence for a North Equatorial Countercurrent in the eastern Indian Ocean during the northeast monsoon. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS75, OS21J-02 (1998).

Data collected during February and March 1995 as part of the WOCE Hydrographic Program Expedition in the Indian Ocean provide evidence for an eastward-flowing countercurrent, a possible North Equatorial Countercurrent (NECC), extending from 80°E south of Sri Lanka to about 92°E. The current is associated with a local surface salinity maximum (34.5 psu) representing its probable northwest Indian Ocean source. At 80°E, the combination of shipboard and lowered acoustic Doppler current profiler (ADCP) data shows weak flow to the east between 2°N and 2.8°N near the surface, with flow to the east extending from 1.5°N to 4°N at a depth of 100 m. The eastward flow is imbedded in a westward flow of lower salinity water extending from 3°S to 6°N. The westward flow represents a combination of the outflow of fresher, surface Bay of Bengal water and westward return flow of the eastward-flowing South Equatorial Countercurrent water. At 92°E, the NECC is part of an intense circulation feature with eastward flow extending from 3°N to 6°N and peak speed of 0.8 m/s. NOAA data from the repeat hydrographic line along 80°E during late October 1995, during the monsoon transition period, show evidence of a weak eastward flow in the upper 100 m between 4°N to 5°N imbedded in a broader westward flow between 1°N and 6°N. The observations are compared to model circulation features from the NRL high-resolution, three-layer, non-linear, model forced by ECMWF winds. Although the NRL model does not show an NECC south of Sri Lanka, it does show a weak countercurrent trough further to the east between 4°N and 7°N. The temporal and spatial smoothing of historical data products may be the reason that the NECC has not been reported previously.

Hansen, D.V., and M.S. Swenson. Application of oceanic heat budgets to evaluation of surface heat flux climatologies. Proceedings, First International Conference on Reanalyses, Washington, D.C., October 27-31, 1997. World Climate Research Programme, 40 (1998).

We are using the extensive WOCE/TOGA data sets from drifting buoys and VOS/XBT measurements for quantification of climatological heat budget processes in the equatorial cold tongue and NECC regions of the eastern tropical Pacific Ocean. One interesting application of the results is in their implication for the net surface heat flux. Early results suggest that the heat flux climatology generated from the NCEP/NCAR Reanalysis Project is superior to other popular climatologies. A major factor in the improvement appears to be the annual cycle of downward shortwave radiation.

Hasler, A.F., K. Palaniappan, C. Kambhammetu, P.G. Black, E.W. Uhlhorn, and D. Chesters. High-resolution wind fields within the inner core and eye of a mature tropical cyclone from GOES 1-min images. Bulletin of the American Meteorological Society, 79(11):2483-2496 (1998).

Mesoscale wind fields have been determined for a mature hurricane with high spatial and temporal resolution, continuity, and coherency. These wind fields, near the tropopause in the inner core and at low levels inside the eye, allow the evolution of mesoscale storm features to be observed. Previously, satellite-derived winds near hurricanes have been determined only at some distance from the eye over a typical time period of 1V2 h. Hurricane reconnaissance aircraft take 30 min to 1 h to complete an inner-core pattern. With the long observation periods of these previous methods, steady-state conditions must be assumed to give a complete description of the observed region. With the advent of 1-min interval imagery, and fourfold improvement of image dynamic range from NOAA's current generation of GOES satellites, there is a new capability to measure inner-core tropical cyclone wind fields near the tropopause and within the eye, enabling mesoscale dynamical processes to be inferred. These measurements give insights into the general magnitude and structure of the hurricane vortex, along with very detailed measurements of the cloud-top wind's variations in response to convective outbursts. This paper describes the new techniques used to take advantage of the GOES satellite improvements that, in turn, allowed the above innovations to occur. The source of data for this study is a nearly continuous 12-h sequence of 1-min visible images from NOAA GOES-9 on 6 September 1995. These images are centered on Hurricane Luis with maximum winds of 120 kt (CAT4) when it was 250 km northeast of Puerto Rico. A uniform distribution of long-lived cirrus debris with detailed structure is observed in the central dense overcast (CDO), which has been tracked using the 1-min images. The derived wind field near the tropopause at approximately 15 km in the CDO region has a strong closed circulation with speeds up to 25 m s^-1, which pulses in response to the convective outbursts in the eyewall. Cloud displacements are computed at every pixel in every image, resulting in a quarter-million uVv winds in each of 488 hurricane images observed at 1- to 4-min intervals over 12 h. For analysis and presentation, these ultradense wind fields are reduced to 8- or 16-km grids using a 7-min time base by smoothing displacement vectors in space and time. Cloud structures were tracked automatically on a massively parallel processing computer, but with manual spot-checking. Manual tracking has been used to follow CDO structure over long time periods, up to 90 min for a small test sample. Cloud tracking for the wind fields presented here is accomplished using a Massively Parallel Semi-Fluid Motion Analysis (MPSMA) automatic technique. This robust deformable surface-matching algorithm has been implemented on the massively parallel Maspar supercomputer. MPSMA automatic tracking typically follows a feature for 7 min. For this time base the error of these winds is estimated to be 1.5 m s^-1. However, systematic navigation and height assignment errors in the moderately sheared hurricane environment must still be considered. Spatial and temporal smoothing of the wind field have been performed to reduce systematic navigation errors and small-scale turbulent noise. The synthesis used here to compute the wind fields gives an order of magnitude reduction in the amount of data presented compared to the amount of data processed. Longer tracking could give higher accuracy but would smooth out the smaller-scale spatial and temporal features that appear dynamically significant. The authors believe that the techniques described in this paper have great potential for further research on tropical cyclones and severe weather as well as in operational use for nowcasting and forecasting. United States and foreign policymakers are urged to augment the GOES, GMS, FY2, and Meteosat geostationary satellite systems with dual imaging systems such that 1-min observations are routinely taken.

Hendee, J.C. An expert system for marine environmental monitoring in the Florida Keys National Marine Sanctuary and Florida Bay. Proceedings, 2nd International Conference on the Coastal Environment, Cancun, Mexico, September 8-10, 1998. Computational Mechanics Publications/WIT Press, Southampton, 57-66 (1998).

The National Oceanic and Atmospheric Administration's (NOAA, U.S. Department of Commerce) Atlantic Oceanographic and Meteorological Laboratory (AOML) works cooperatively with the Florida Institute of Oceanography (FIO) in the implementation of the SEAKEYS (Sustained Ecological Research Related to Management of the Florida Keys Seascape) network, which is situated along 220 miles of coral reef tract within the Florida Keys National Marine Sanctuary (FKNMS). This network is itself actually an enhanced framework of seven Coastal-Marine Automated Network (C-MAN) stations for long-term monitoring of meteorological parameters (wind speed, wind gusts, air temperature, barometric pressure, relative humidity). To the C-MAN network, SEAKEYS adds oceanographic parameters (sea temperature, photosynthetically active radiation, salinity, fluorometry, optical density) to the stations. As a recent enhancement to the SEAKEYS network, an expert system shell is being employed to provide daily interpretations of near real-time acquired data for the benefit of scientists, fishermen, and skin divers. These interpretations are designed to be automatically emailed to Sanctuary managers and to the FIO maintainers of the network. The first set of interpretations include those dealing with environmental conditions conducive to coral bleaching. Other marine environmental interpretations are slated to follow.

Hendee, J.C., C. Humphrey, and T. Moore. A data-driven expert system for producing coral bleaching alerts. Proceedings, 7th International Conference on the Development and Application of Computer Techniques to Environmental Studies, Las Vegas, Nevada, November 10-12, 1998. Computational Mechanics Publications/WIT Press, Southampton, 139-147 (1998).

As a recent enhancement to the SEAKEYS (Sustained Ecological Research Related to Management of the Florida Keys Seascape) environmental monitoring network, an expert system shell was employed to provide daily interpretations of near real-time acquired combinations of meteorological and oceanographic parameters as they meet criteria generally thought to be conducive to coral bleaching. These interpretations were automatically posted to the World-Wide Web and emailed to Florida Keys National Marine Sanctuary managers and scientists so they could witness and study bleaching events as they might happen, and so that a model could be developed with greater precision in identifying physical factors conducive to coral bleaching. The expert system, as a model, was successful in showing that certain assumptions by experts regarding coral bleaching apparently do not hold at Sombrero Reef.

Henderson-Sellers, A., H. Zhang, G. Berz, K. Emanuel, W. Gray, C.W. Landsea, G. Holland, J. Lighthill, S.-L. Shieh, P. Webster, and K. McGuffie. Tropical cyclones and global climate change: A post-IPCC assessment. Bulletin of the American Meteorological Society, 79(1):19-38 (1998).

The very limited instrumental record makes extensive analyses of the natural variability of global tropical cyclone activities difficult in most of the tropical cyclone basins. However, in the two regions where reasonably reliable records exist (the North Atlantic and the western North Pacific), substantial multidecadal variability (particularly for intense Atlantic hurricanes) is found, but there is no clear evidence of long-term trends. Efforts have been initiated to use geological and geomorphological records and analysis of oxygen isotope ratios in rainfall recorded in cave stalactites to establish a paleoclimate of tropical cyclones, but these have not yet produced definitive results. Recent thermodynamical estimation of the maximum potential intensities (MPI) of tropical cyclones shows good agreement with observations. Although there are some uncertainties in these MPI approaches, such as their sensitivity to variations in parameters and failure to include some potentially important interactions such as ocean spray feedbacks, the response of upper-oceanic thermal structure and eye and eyewall dynamics do appear to be an objective tool with which to predict present and future maxima of tropical cyclone intensity. Recent studies indicate the MPI of cyclones will remain the same or undergo a modest increase of up to 10%-20%. These predicted changes are small compared with the observed natural variations and fall within the uncertainty range in current studies. Furthermore, the known omissions (ocean spray, momentum restriction, and possibly also surface to 300-hPa lapse rate changes) could all operate to mitigate the predicted intensification. A strong caveat must be placed on analysis of results from current GCM simulations of the "tropical-cyclone-like" vortices. Their realism, and hence prediction skills (and also that of "embedded" mesoscale models), is greatly limited by the coarse resolution of current GCMs and the failure to capture environmental factors that govern cyclone intensity. Little, therefore, can be said about the potential changes of the distribution of intensities as opposed to maximum achievable intensity. Current knowledge and available techniques are too rudimentary for quantitative indications of potential changes in tropical cyclone frequency. The broad geographic regions of cyclogenesis and, therefore, also the regions affected by tropical cyclones are not expected to change significantly. It is emphasized that the popular belief that the region of cyclogenesis will expand with the 26 C SST isotherm is a fallacy. The very modest available evidence points to an expectation of little or no change in global frequency. Regional and local frequencies could change substantially in either direction, because of the dependence of cyclone genesis and track on other phenomena (e.g., ENSO) that are not yet predictable. Greatly improved skills from coupled global ocean-atmosphere models are required before improved predictions are possible.

Hitchcock, G.L., C. Wiebinga, and P.B. Ortner. CTD hydrographic data from the Global Ocean Ecosystem Dynamics (GLOBEC) Indian Ocean cruises. University of Miami Technical Report, 97-006, 69 pp. (1998).

No abstract.

Hitchcock, G., G.A. Vargo, T. Lee, E. Johns, E. Williams, and J. Jurado. The influence of circulation on nutrient distributions in western Florida Bay. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 98-99 (1998).

No abstract.

Hood, T., C. Alvarez-Zarikian, P. Blackwelder, P. Swart, T.A. Nelsen, H.R. Wanless, J.H. Trefry, and L. Tedesco. The sediment record as a monitor of natural and anthropogenic changes in the lower Everglades/Florida Bay ecosystem. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 33-34 (1998).

No abstract.

Houston, S.H., and M.D. Powell. Reconstruction of surface wind fields for hurricanes affecting Florida Bay. Preprints, Second Conference on Coastal Atmospheric and Oceanic Prediction and Processes, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 241-244 (1998).

Hurricanes constitute episodic events which affect the physical and oceanographic processes within Florida Bay. These effects are manifested by significant changes in water-levels, waves, currents, and sediment transport processes. In addition, these storms impact plant and animal life in the Bay and the surrounding areas. Hurricane wind fields are now being made available to researchers, such as oceanographers and biologists, on a Hurricane Research Division World Wide Web site (http://www.aoml.noaa.gov/hrd). Researchers can use the wind fields to estimate the potential impacts of future tropical cyclones on the south Florida ecosystem and especially on Florida Bay. The hurricanes used in this study were the Labor Day Hurricane of 1935, Donna of 1960, Betsy of 1965, Felix of 1987, and Andrew of 1992. These tropical cyclones represented vastly different scenarios for the type of event that might be expected over extreme south Florida. The 1935 hurricane was a category 5 storm and is the most intense hurricane known to have struck the USA. This hurricane had a relatively small, concentrated wind field when it crossed the Florida Keys and Florida Bay. Hurricane Donna (1960) was a category 4 hurricane with a much broader wind field that crossed the Keys and Bay on a similar track to the 1935 Hurricane. Hurricane Andrew was a fast moving category 4 hurricane when it struck south Florida recently. However, its strongest winds covered only a very small area, especially to the south of the storm track. The direct impact of Andrew on Florida Bay appears to have been minimal, but decomposing organic storm debris in the Everglades likely contributed to water quality problems in the Bay.

Houston, S.H., and M.D. Powell. Surface wind field in Florida Bay hurricanes. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 35 (1998).

No abstract.

Houston, S.H., and M.D. Powell. Surface wind fields in hurricanes. Proceedings, Third International Symposium, Waves '97, Virginia Beach, VA, November 3-7, 1997. American Society of Civil Engineers (ASCE), 1391-1399 (1998).

No abstract.

Houston, S.H., and M. D. Powell. The potential impact of GPS sondes in real-time surface wind analyses for hurricanes. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 26-30, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-110 (1998).

During the 1996 and 1997 hurricane seasons, GPS sondes were dropped within the inner core of some tropical cyclones (i.e., Josephine of 1996; Danny, Erika, Guillermo, and Linda of 1997). The data from these sondes provided some highly detailed boundary layer profiles and surface measurements of each tropical cyclone's wind and thermodynamic properties after the fact. During the upcoming 1998 hurricane season, two potential developments may make the GPS sonde data useful for defining the hurricane's surface wind structure in real-time: (1) The GPS sonde "temp drop message" sent from AFRES and NOAA missions in and near hurricanes (including drops from the NOAA G-IV) may include additional essential information that will likely enhance the real-time use of these sondes. For example, the splash location and time are two additional parameters that may be available in the drop messages. (2) When it is deemed necessary by NHC for the issuance of warnings and (or) other critical factors, GPS sondes may be dropped along the flight-track of tasked reconnaissance flights. These drops have the potential to provide estimates of the peak surface winds and may help define some of the wind radii (i.e., 34, 50, and/or 64 kt wind radii) in those quadrants where the drops are made. This study examines the potential impacts additional wind and thermodynamic observations from sondes might have on surface wind analyses in hurricanes, which are currently provided to NHC's forecasters in real-time by HRD on an experimental basis. Some examples of post-storm analyses in 1997 hurricanes utilizing these new data in addition to conventional data sources will be presented and the potential impacts will be assessed. In addition, some preliminary comparisons of the boundary layer measurements from GPS sondes with reliable in-situ surface observations (e.g., buoys, C-MAN's, etc.) of wind, temperature, and pressure in the vicinity of tropical cyclones will be shown.

Houston, S.H., M. Lawrence, S. Spisak, and S.T. Murillo. A verification of National Hurricane Center forecasts of surface wind speed radii in hurricanes. Preprints, Symposium on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 139-140 (1998).

The National Hurricane Center (NHC) issues a position and intensity forecast every six hours on all tropical cyclones in the Atlantic and eastern Pacific basins. This forecast is contained in the forecast/advisory product and includes a forecast of the horizontal distribution of the surface wind field. This distribution is given as radii in four quadrants from the center of the tropical cyclone to three wind speed values: 17.5, 25.7, and 32.9 m s^-1 (i.e., 34, 50, and 64 kt, respectively). A set of opportunistic marine observations w ere collected to determine the wind speed radii from the center of each tropical cyclone to the observation site. This can be done when a tropical cyclone's wind field affects a measurement platform with the required wind speeds. The wind speed radii based on the marine platform data were used to verify the official NHC radii forecasts described above. The preliminary results are for 17.5 m s^-1 wind speeds and are based on only 25 cases. Statistics will be presented showing that the mean absolute error of the 25 cases of verification is about 83 km (45 nm) at the initial (i.e., 0 h) forecast period and decreases about 25% by the 36 h forecast. There is a positive bias (the forecasts were larger than observed) of about 37 km (20 nm) for these cases, which also appears to decrease with longer forecast periods. The small number of cases limits our analysis to simple averages. This is the first time that such a data set has been prepared and that forecasts of tropical cyclone intensity in terms of wind speed radii have been verified. Details on the method of verification will be given along with the final statistics of the study, including 17.5 and 25.7 m s^-1 radii verification.

Huang, H., R.E. Fergen, J.R. Proni, and J.J. Tsai. Initial dilution equations for buoyancy-dominated jets in currents. Journal of Hydraulic Engineering, 124:105-108 (1998).

Initial dilution of submerged, single, round, buoyancy-dominated jets in a current is considered. Two simple semi-empirical equations, one for centerline dilution and the other for minimum surface dilution, are presented. These equations are derived based on the continuity equation for the buoyant jet flow with a hypothesis that shear entrainment and forced entrainment can be added. Available laboratory and field data are used to determine the constants in the equations. Unlike asymptotic equations which apply for the limiting flow regimes, the proposed equations span all flow regimes, from the buoyancy-dominated near field (BDNF), to the transition, and to the buoyancy-dominated far field (BDFF), providing continuous predictions for dilutions.

Jameson, A.R., A.B. Kostinski, and R.A. Black. The texture of clouds. Journal of Geophysical Research-Atmospheres, 103(D6):6211-6220 (1998).

Using a precise definition of clustering, it is shown that in two tropical cumulus clouds, droplets appear to be bunched over distances ranging from at least a kilometer or more down to several centimeters. A statistical framework is proposed for quantifying clustering in terms of a Poisson probability mixture. While these observations require further substantiation in many different clouds, droplet clustering may play a role in diverse phenomena from the coalescence growth of raindrops to the scattering of radiation by clouds.

Johns, E., and W.D. Wilson. Direct observations of velocity structure in the passages between the Intra-Americas Sea and the Atlantic Ocean, 1984-1996. Proceedings, Conference on the Transports and Linkages of the Intra-Americas Sea (IAS), Cozumel, Mexico, November 1-5, 1997. IOC/IOCARIBE/MMS, 36 (1998).

Shipboard acoustic Doppler current profiler (ADCP) velocity data collected between 1984 and 1996 in connection with several NOAA research programs have been used to examine the mean and variability of the velocity structure within the Straits of Florida, the Northwest Providence Channel, a northern approach to the Windward Passage, the Mona and Anegada Passages, and across the eastern Caribbean Sea. Historically, direct velocity data collection in these important passages between the Gulf of Mexico, the Caribbean Sea, and the Atlantic Ocean has been very sparse. Herein, we examine the transport and velocity structure in the passages using a more complete data set than previously available. This newer data set allows computation of statistically significant mean and standard deviations of the transport and velocity fields, and examination of the temporal (seasonal to interannual) variability of these fields. Comparison will be made of the mean and varying flow fields with the results of previous studies and with available time series of regional forcing functions such as the COADS wind stress data set. Most importantly, the mean transports should prove useful to numerical modelers of the Intra-Americas Sea for calibration and refinement of model boundary conditions.

Johns, E., W.D. Wilson, and T.N. Lee. Interaction of Florida Bay waters with the Gulf of Mexico and the Atlantic Ocean. Proceedings, 1998 Meeting of the Oceanography Society and the Intergovernmental Oceanographic Commission on Coastal and Marginal Seas, Paris, France, June 1-4, 1998. Oceanography, 11, No. 2 supplement, 38 (1998).

As part of the South Florida Ecosystem Restoration program, an observational study of the circulation of Florida Bay and its connection with the surrounding waters of the Gulf of Mexico, the southwest Florida shelf, and the Atlantic Ocean is presently underway. Measurement systems include moored arrays equipped with current meters, bottom pressure sensors and conductivity-temperature sensors, satellite-tracked surface drifters, and shipboard ADCP. Bimonthly interdisciplinary surveys include continuous thermosalinograph observations of surface salinity, temperature, and fluorescence. Early results show that there is a net southeastward flow of 1 to 4 cm/s which transports waters from the Gulf of Mexico and the Everglades across western Florida Bay and through the channels of the Florida Keys, on a time scale of 1 to 3 months depending on local wind forcing. This net flow, with a volume transport of 1000 to 2000 m³/s, has the potential to deliver harmful algal blooms and excess nutrients out to the environmentally sensitive coral reefs of the Florida Keys National Marine Sanctuary. The ongoing study now focuses on refining and quantifying the flow between the Gulf of Mexico, Florida Bay, and the Atlantic and its response to seasonal and episodic meteorological forcing. In addition, new emphasis is placed on examining the fate of the freshwater river discharges from the Everglades into the Gulf of Mexico, and the relation of the river plume dispersion to regional wind and rainfall distributions.

Kaplan, J., and M. DeMaria. Climatological and synoptic characteristics of rapidly intensifying tropical cyclones in the North Atlantic basin. Preprints, Symposiuim on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 119-123 (1998).

No abstract.

Katsaros, K.B. Microwave remote sensing with radiometers. In Remote Sensing of the Pacific Ocean by Satellites, R.A. Brown (ed.). Southwood Press, Marrickville, Australia, 13-15 (1998).

No abstract.

Katsaros, K.B. Turbulent flux of water vapor in relation to the wave field and atmospheric stratification. In Physical Processes in Lakes and Oceans, J. Imberger (ed.). Coastal and Estuarine Studies, Volume 54, American Geophysical Union, 37-46 (1998).

Field measurements of evaporation rate, momentum, and heat flux together with mean meteorological quantities allow inferences to be drawn concerning the sheltering of air in the troughs of large waves and the possible differences between moisture and heat fluxes in very stable regimes over water. Interpretation of the measurements in terms of the processes near the surface are based on the Monin-Obukhov similarity theory. The results presented indicate that in the presence of water waves and under strong atmospheric stable stratification further detailed measurements are needed to fully explain the processes at work and that Monin-Obukhov theory may need modification.

King, D.B., S.A. Yvon-Lewis, S.A. Montzka, and J.H. Butler. Dependence of trace halocarbon saturation anomalies on sea-surface properties. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F429, OS11F-02 (1998).

If global warming results in an increase in sea surface temperature, the saturations and air-sea fluxes of trace gases in the surface ocean are also likely to change. Since many of these gases are involved in tropospheric chemistry, global warming, and even the destruction of stratospheric ozone, it would be useful to predict how their fluxes into and out of the oceans might be altered as a result of climate change. Although such an effort requires an intricate examination of biological and chemical activity, a first step in understanding the nature of this behavior is mapping their degree of saturation in waters of different temperature, location, and chemical properties. As part of a joint expedition to the Atlantic and Pacific Oceans, we have measured the saturation anomalies of a number of trace gases in surface waters in an effort to evaluate the dependence of their air-sea fluxes upon sea-surface properties. Data collected on this cruise demonstrate that the fates of some compounds may be easier to predict than others. Some gases are conservative in seawater, and their integrated fluxes over a year are small. Other gases are consumed by chemical reaction. For example, methyl chloroform, an anthropogenic trace gas that is no longer emitted in significant amounts to the atmosphere, was undersaturated in warm surface waters, but not in cooler waters, which is consistent with enhanced hydrolysis in warmer water. Other compounds, such as the methyl halides, are produced and consumed by a variety of processes. Methyl bromide was generally undersaturated at sea surface temperatures above 25°C, becoming supersaturated at colder temperatures. Yet, there were several regions where it was supersaturated in the warmer waters, indicating that the concentration of this gas in the surface ocean is controlled by more than just chemical removal. Methyl chloride and methyl iodide were supersaturated for the duration of the cruise, with the degree of saturation decreasing with surface water temperature. If the saturation of these compounds were controlled solely by chemical removal, the trend would have been the opposite of what was observed. We relate the measured saturation anomalies to pertinent sea-surface properties, including those measurable by satellite (e.g., SeaWiFS), to see if any useful correlations can be derived.

Landsea, C.W., and R.A. Pielke. Trends in U.S. hurricane losses, 1925 1995. Preprints, Ninth Symposium on Global Change Studies, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 210-212 (1998).

No abstract.

Landsea, C.W., J. Kaplan, and M. DeMaria. The differing roles of the large-scale environment in the intensity changes of recent Atlantic hurricanes. Preprints, Symposium on Tropical Cyclone Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 113-114 (1998).

No abstract.

Landsea, C.W., N. Nicholls, and J. Gill. Australian region tropical cyclones: Recent trend and interannual predictions. Preprints, Ninth Conference on Interaction of the Sea and Atmosphere, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 1-4 (1998).

No abstract.

Landsea, C.W., G.D. Bell, W.M. Gray, and S.B. Goldenberg. The extremely active 1995 Atlantic hurricane season: Environmental conditions and verification of seasonal forecasts. Monthly Weather Review, 126(5):1174-1193 (1998).

The 1995 Atlantic hurricane season was a year of near-record hurricane activity with a total of 19 named storms (average is 9.3 for the base period 1950-1990) and 11 hurricanes (average is 5.8), which persisted for a total of 121 named storm days (average is 46.6) and 60 hurricane days (average is 23.9), respectively. There were five intense (or major) Saffir-Simpson category 3, 4, or 5 hurricanes (average is 2.3 intense hurricanes) with 11.75 intense hurricane days (average is 4.7). The net tropical cyclone activity, based upon the combined values of named storms, hurricanes, intense hurricanes and their days present, was 229% of the average. Additionally, 1995 saw the return of hurricane activity to the deep tropical latitudes: seven hurricanes developed south of 25°N (excluding all of the Gulf of Mexico) compared with just one during all of 1991-1994. Interestingly, all seven storms that formed south of 20°N in August and September recurved to the northeast without making landfall in the United States. The sharply increased hurricane activity during 1995 is attributed to the juxtaposition of virtually all of the large-scale features over the tropical North Atlantic that favor tropical cyclogenesis and development. These include extremely low vertical wind shear, below-normal sea level pressure, abnormally warm ocean waters, higher than average amounts of total precipitable water, and a strong west phase of the stratospheric quasi-biennial oscillation. These various environmental factors were in strong contrast to those of the very unfavorable conditions that accompanied the extremely quiet 1994 hurricane season. The favorable conditions for the 1995 hurricane season began to develop as far back as the previous winter. Their onset well ahead of the start of the hurricane season indicates that they are a cause of the increased hurricane activity, and not an effect. The extreme duration of the atmospheric circulation anomalies over the tropical North Atlantic is partly attributed to a transition in the equatorial Pacific from warm episode conditions (El Niño) to cold episode conditions (La Niña) prior to the onset of the hurricane season. Though the season as a whole was extremely active, 1995's Atlantic tropical cyclogenesis showed a strong intraseasonal variability with above-normal storm frequency during August and October and below normal for September. This variability is likely attributed to changes in the upper-tropospheric circulation across the tropical North Atlantic, which resulted in a return to near-normal vertical shear during September. Another contributing factor to the reduction in tropical cyclogenesis during September may have been a temporary return to the near-normal SSTs across the tropical and subtropical North Atlantic, caused by the enhanced tropical cyclone activity during August. Seasonal hurricane forecasts for 1995 issued at Colorado State University on 30 November 1994, 5 June 1995, and 4 August 1995 correctly anticipated an above-average season, but underforecast the extent of the extreme hurricane activity.

Landsea, C.W., W.M. Gray, J.A. Knaff, P.W. Mielke, and K.J. Berry. Verification of the 1997 seasonal hurricane forecast and a prediction for 1998. Minutes, 52nd Interdepartmental Hurricane Conference, Clearwater, FL, January 27, 1998. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-331-A-338 (1998).

The forecast for the 1998 Atlantic hurricane season issued by Dr. Bill Gray and collaborators (including myself) will be discussed. This prediction, to be issued in early December 1997, will be updated in early April, early June, and early August. Uncertainties in the predictors, especially in El Niño, Atlantic sea surface temperatures, and Sahel rainfall, will be discussed in how they may impact the number and intensity of tropical cyclones this year. I will also analyze and discuss the performance of the 1997 forecasts.

Lee, K., R.H. Wanninkhof, T. Takahashi, S.C. Doney, and R.A. Feely. Low interannual variability in recent oceanic uptake of atmospheric carbon dioxide. Nature, 396(12):155-158 (1998).

An improved understanding of the partitioning of carbon between the atmosphere, terrestrial biosphere, and ocean allows for more accurate predictions of future atmospheric CO₂ concentrations under various fossil-fuel CO₂ emission scenarios. One of the more poorly quantified relevant processes is the interannual variability in the uptake of fossil-fuel CO₂ from the atmosphere by the terrestrial biosphere and ocean. Existing estimates, based on atmospheric measurements, indicate that the oceanic variability is large. Here we estimate the interannual variability in global net air-sea CO₂ flux using changes in the observed wind speeds and the partial pressure of CO₂ (pCO₂) in surface seawater and the overlying air. Changes in seawater pCO₂ are deduced from interannual anomalies in sea surface temperature and the regionally and seasonally varying temperature-dependence of seawater pCO₂, assuming that variations in sea surface temperature reflect seawater pCO₂ changes caused by thermodynamics, biological processes, and water mixing. The calculated interannual variability in oceanic CO₂ uptake of 0.4 Gt C yr^-1(2 sigma) is much less than that inferred from the analysis of atmospheric measurements. Our results suggest that variable sequestration of carbon by the terrestrial biosphere is the main cause of observed year-to-year variations in the rate of atmospheric CO₂ accumulation.

Lee, T.N., E. Johns, W.D. Wilson, and E. Williams. Florida Bay circulation and exchange study. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 43-44 (1998).

No abstract.

Marks, F.D., and H.A. Friedman. 1998 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 144 pp. (1998).

The objective of the National Oceanic and Atmospheric Administration (NOAA) hurricane research field program is the collection of descriptive data that are required to support analytical and theoretical hurricane studies. These studies are designed to improve the understanding of the structure and behavior of hurricanes. The ultimate purpose is to develop improved methods of hurricane prediction. Ten major experiments have been planned, by principal investigators at the Hurricane Research Division (HRD)/Atlantic Oceanographic and Meteorological Laboratory (AOML) of NOAA and the Mission Planning Committee for the National Aeronautics and Space Administration (NASA) Third Convection and Moisture Experiment (CAMEX-3), for the 1998 Hurricane Field Program. These experiments will be conducted with the NOAA/Aircraft Operations Center (AOC) WP-3D and Gulfstream IV-SP aircraft and the NASA DC-8 and ER-2 aircraft.

Marks, F.D., and L.K. Shay. Landfalling tropical cyclones: Forecast problems and associated research opportunities. Preprints, 16th Conference on Weather Analysis and Forecasting, Symposium on the Research Foci of the U.S. Weather Research Program, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 520-523 (1998).

No abstract.

Marks, F.D., L.K. Shay, and PDT-5 (Fifth Prospectus Development Team). Landfalling tropical cyclones: Forecast problems and associated research opportunities. Report of the Fifth Prospectus Development Team to the U.S. Weather Research Program. Bulletin of the American Meteorological Society, 79(8):305-323 (1998).

The Fifth Prospectus Development Team of the U.S. Weather Research Program was charged to identify and delineate emerging research opportunities relevant to the prediction of local weather, flooding, and coastal ocean currents associated with landfalling U.S. hurricanes specifically, and tropical cyclones in general. Central to this theme are basic and applied research topics, including rapid intensity change, initialization of and parameterization in dynamical models, coupling of atmospheric and oceanic models, quantitative use of satellite information, and mobile observing strategies to acquire observations to evaluate and validate predictive models. To improve the necessary understanding of physical processes and provide the initial conditions for realistic predictions, a focused, comprehensive mobile observing system in a translating storm-coordinate system is required. Given the development of proven instrumentation and improvement of existing systems, three-dimensional atmospheric and oceanic data sets need to be acquired whenever major hurricanes threaten the United States. The spatial context of these focused three-dimensional data sets over the storm scales is provided by satellites, aircraft, expendable probes released from aircraft, and coastal (both fixed and mobile), moored, and drifting surface platforms. To take full advantage of these new observations, techniques need to be developed to objectively analyze these observations, and initialize models aimed at improving prediction of hurricane track and intensity from global-scale to mesoscale dynamical models. Multinested models allow prediction of all scales from the global, which determine long-term hurricane motion to the convective scale, which affect intensity. Development of an integrated analysis and model forecast system optimizing the use of three-dimensional observations and providing the necessary forecast skill on all relevant spatial scales is required. Detailed diagnostic analyses of these data sets will lead to improved understanding of the physical processes of hurricane motion, intensity change, the atmospheric and oceanic boundary layers, and the air-sea coupling mechanisms. The ultimate aim of this effort is the construction of real-time analyses of storm surge, winds, and rain, prior to and during landfall, to improve warnings and provide local officials with the comprehensive information required for recovery efforts in the hardest hit areas as quickly as possible.

Masters, J.C., and R.H. Wanninkhof. Continuous pCO₂ measurements as a method to characterize upwelling along the northwestern Arabian Sea boundary. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS52, OS21G-11 (1998).

Upwelling zones are identified using surface water pCO₂ and other biogeochemical parameters in the northwestern Arabian Sea based on observations from May through August 1995. This time frame encompasses the beginning of the southwest monsoon through the first monsoonal break. The Ekman dynamics associated with the wind stress create an upwelling structure along the northwestern boundary of the Arabian Sea. The characteristics of upwelled water are low temperature, high nutrients, high dissolved inorganic carbon (DIC), and high pCO₂ relative to the surrounding waters. Each parameter has a unique response time and can be used to characterize the upwelling zone. An underway monitoring system collected pCO₂ data from the surface water and the marine boundary air. The pCO₂ measurements, taken at 4-minute intervals, were plotted against the ship track and produced a high-resolution representation of the upwelling structure, boundaries, and water mass movement though time. Temperature, salinity, fluorescence, and nitrate values were used to further define the water mass and upwelling zones. Satellite sea surface temperature images were used to produce a more complete two-dimensional picture of the water mass movement on the surface. When upwelled water reaches the surface, the physical and chemical characteristics of the water are affected by incident radiation, wind stress, and photosynthesis. As the primary production consumes nutrients, the concentration of chlorophyll a increases and pCO₂ decreases. The parameters change as a function of the time the water mass spends on the surface. By the time the upwelled water warms to adjacent conditions, the pCO₂ has decreased but remains elevated compared to the surrounding waters. The nutrients are depleted and there are high chlorophyll a concentrations. Thus, in conjunction with concentrations of chlorophyll a and nutrients, pCO₂ can be used as a non-conservative tracer of an upwelled water mass. The results show that coastal upwelling took place during the entire five-month period at approximately 10°N, 51°E, 19°N, 58°E, and 22°N, 59.5°E. During the southwest monsoon, the upwelling in these areas strengthened, as manifested by lower sea surface temperatures (29°C in May to 20°C in August) and higher pCO₂ (430 ppm to 720 ppm). The mass transport of upwelled water moves offshore in "squirts" or "jets" as shown by large changes in pCO₂ over approximately 20 km scales. These narrow jets diffuse offshore into a larger surface area and their pCO₂ decreases as a function of time, slower than the time it takes for the water temperature to equilibrate with its surroundings.

Mayer, D.A., and R.H. Weisberg. El Niño-Southern Oscillation-related ocean-atmosphere coupling in the western equatorial Pacific. Journal of Geophysical Research, 103(C9):18,635-18,648 (1998).

Using 43 years of Comprehensive Ocean-Atmosphere Data Set (COADS) and related data for the period 1950-1992, an examination is made into the regional dependence of ocean-atmosphere coupling in relation to the El Niño-Southern Oscillation (ENSO). The cross correlation between sea surface temperature (SST) and sea level pressure (SLP) anomalies over the global tropics shows two patterns of significant negative correlation consistent with a local hydrostatic response of SLP to SST: (1) the eastern Pacific, where the correlation is symmetric about and largest on the equator; and (2) the western Pacific, where symmetric regions of negative correlation are found off the equator, separated by a region of positive correlation on the equator. Anomalies within these two patterns vary out of phase with each other. While the SLP anomalies on both sides of the basin are of similar magnitude, the SST anomalies in the east are much larger than those in the west. Despite this disparity in the SST anomaly magnitudes between the eastern and western Pacific, we argue that the ocean-atmosphere couplings in the western and west-central Pacific are important for ENSO. The off-equator SST anomalies in the west enhance the SLP anomalies there and they appear to initiate easterly wind anomalies over the far western Pacific during the peak El Niño phase of ENSO. As these easterlies evolve, their effect upon the ocean tends to oppose that of the westerly wind anomalies found over the west-central Pacific. These competing effects suggest a mechanism that may contribute to coupled ocean-atmosphere system oscillations. The west-central equatorial Pacific (the region separating the eastern and western patterns), while exhibiting large momentum and heat flux exchanges, shows minimum correlation between SST and SLP. Thus, neither the SST and SLP anomaly magnitudes nor the correlation between them are alone indicative of ocean-atmosphere coupling, and the regional dependence for such coupling in relation to ENSO appears more complicated than mechanistic interpretations of ENSO would suggest.

Mayer, D.A., G.J. Goni, and R.L. Molinari. Comparison of hydrographic and altimetric estimates of sea level height variability in the Atlantic Ocean. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10,1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F432, OS12A-06 (1998).

Hydrographic estimates of dynamic height (DH) derived from expendable bathythermograph (XBT) data and average temperature salinity (TS) relationships are compared to sea height anomalies (SHA) derived from TOPEX/Poseidon (T/P) altimeter data along two sections of the Atlantic Ocean. Our inquiry examines the relationship between the variability of dynamic effects in the upper 500 m of the water column and SHA over seasonal to interannual time scales for the period 1993 through 1997. Our spatial domain extends from 30°S to 50°N. Emphasis is on two well sampled sections representative of the western and eastern regions of the Atlantic. Both the XBT and T/P data are matched by time and location within 2° of latitude by 4° of longitude quadrangles and then binned by month. The SHA signal is compared to DH derived with respect to reference depths ranging from 50 m to 500 m. DH is estimated from T/P data by computing their linear correlations along both sections. The subtropics show correlations that remain relatively constant throughout most of the water column. This reveals the dominant effects of seasonal heating on SHA due to surface fluxes. In contrast, correlations in the tropics can be sharply depth dependent, suggesting the effects of ocean dynamics (thermocline depth) on SHA due to the seasonal cycle of the zonal currents and their system of ridges and troughs. Correlations are generally significant at the 90% significance level (SL). With a few exceptions, most of the relationship between SHA and DH is a consequence of the annual cycle. Correlations degrade well below the 90% SL if the annual cycle is removed before the correlations are computed. In both the tropics and subtropics, most of the dynamic height signal can be accounted for by using reference depths of 500 m. However, the DH does not fully account for the SHA by a factor of 2 or more in some instances. This discrepancy can be attributed to factors such as the use of average historical TS relationships, the spatial averaging within each 2° by 4° quadrangle, reference depths to only 500 m, and barotropic effects.

Mayer, D.A., R.L. Molinari, and J.F. Festa. The mean and annual cycle of upper layer temperature fields in relation to Sverdrup dynamics within the gyres of the Atlantic Ocean. Journal of Geophysical Research, 103(C9):18,545-18,566 (1998).

Using 28 years of expendable bathythermograph data (1967-1994), we describe the mean and annual cycle of the upper ocean temperature fields in the Atlantic from 30°S to 50°N in the context of the basin-scale wind-driven gyres (Sverdrup stream function field) which provide a framework for describing the oceanographic measurements. We examine the circulation field implied by the temperature distributions which are used as a proxy for the field of mass. Similarities between the temperature and stream function fields increase with depth. In the lower to subthermocline depths of the tropical and equatorial gyres, the zonal currents form a closed circulation. A Southeastward Boundary Current is suggested near and below 150 m that provides closure for the tropical gyre, and the equatorial gyre axis is southward of that suggested by the stream function field. Higher in the water column, the North Equatorial Countercurrent (NECC) may be a surface manifestation of the North Equatorial Undercurrent (NEUC) where the latter can be interpreted as the southern limb of the tropical gyre. Because there are large vertical shears in the tropics, the equatorial gyre is not clearly indicated in the vertically integrated temperature field but appears below about 200 m. Here, the South Equatorial Undercurrent (SEUC) can be interpreted as the eastward flowing northern limb of the equatorial gyre and is opposite in direction to the westward flowing South Equatorial Current above. Both the NEUC and SEUC are analagous to currents in the Pacific that are governed by non-Sverdrup dynamics. Despite the shortcomings of the data, the mean annual cycle appears to be relatively stable, and we have discounted the possibility that in regions where it represents a significant percentage of the total variance, it is changing slowly over the 28 years of record. The wind-forcing fields, which undergo large meridional movements (5-6 of latitude) during their annual cycle, with some exceptions, have essentially no counterpart in gyre movements between their seasonal extremes. Most of the variability associated with the annual cycle is confined to the upper 300 m. Greatest variability, where ranges exceed 6°C, occurs in the northwestern Atlantic in late winter and early spring. During this time of year south of the Gulf Stream and below about 100 m, water temperatures exhibit a systematic phase lag with depth. The next largest area of variability, where ranges can also exceed 6°C, resides in the tropical western basin between the equator and 10°N just below 100 m. In the eastern basin, ranges decrease and shoal. Additionally, the phase fields are consistent with the intensification and relaxation of the tropical ridge-trough system where the NECC disappears in March in the west but the NECC/NEUC complex is strongest in September.

McElligott, S., R.H. Byrne, K. Lee, R.H. Wanninkhof, F.J. Millero, and R.A. Feely. Discrete water column measurements of CO₂ fugacity and pHT in seawater: A comparison of direct measurements and thermodynamic calculations. Marine Chemistry, 60(1-2):63-73 (1998).

The NOAA Equatorial Pacific CO₂ system data set (~2500 water samples) has been evaluated to assess the internal consistency of measurements and calculations involving CO₂ fugacity and pH_T. This assessment represents the first large scale field comparison of pH_T and fCO₂ data. Comparisons of direct discrete CO₂ fugacity (fCO₂) measurements with CO₂ fugacity calculated from total inorganic carbon (C_T), total alkalinity (A_T), and spectrophotometric pH (pH_T = -log[H⁺]_T) indicate that a variety of improvements are needed in the parameter measurements and thermodynamic relationships used to relate fCO₂, C_T, A_T, and pH_T in seawater. CO₂ fugacity calculated from C_T and pH_T or A_T and pH_T agree with direct measurements to no better than 1%. Comparisons of measured fugacity, fCO₂ (measured), and CO₂ fugacity calculated from C_T and pH_T, fCO₂ (C_T, pH_T), indicate that the precision of fCO₂ calculations is good relative to direct measurements. In contrast, due to the extreme sensitivity of fCO₂ and [H⁺]_T calculations to relatively small errors in both C_T and A_T, CO₂ fugacity, as well as [H⁺]_T, calculated from C_T and A_T are very imprecise and render comparisons with direct measurements of little use. Consequently, precise calculations of fCO₂ require the use of direct pH_T measurements.

Mestas-Nunez, A.M., and D.B. Enfield. Rotated global modes of multiyear sea surface temperature variability. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS75, OS22H-04 (1998).

El Niño-Southern Oscillation (ENSO) is a global phenomenon with significant phase propagation which we capture in the first mode of a complex empirical orthogonal function (EOF) analysis of sea surface temperature anomaly (SSTA) from the mid-19th century through 1991. We subsequently remove the global ENSO from the SSTA data, plus a linear trend everywhere, in order to consider other global modes of variability uncontaminated by the effects of ENSO. An ordinary EOF analysis of the SSTA residuals reveals three non-ENSO modes that are related to slow oceanic and climate signals described in the literature. The first two modes both have an interdecadal time scale with high loadings in the Pacific. The third mode is a multidecadal signal with maximal realization in the extratropical North Atlantic southeast of Greenland. It also has high loadings in the tropical Atlantic, anticorrelated across the intertropical convergence zone, and strong variability of opposite sign in the eastern tropical Pacific. Unlike ENSO and the secular global warming, it is not known if the variability at intermediate (decadal to multidecadal) time scales is global or regional in nature. To investigate the presence of localized centers of variability, we perform a varimax rotation of the ordinary non-ENSO EOFs. The first rotated mode has multidecadal scales with maximal realization in the North Atlantic. The second rotated mode has interdecadal scales with maximal realization in the western tropical Pacific and captures the interdecadal warm anomaly that contributed to the strong ENSO of 1983. These first two rotated modes capture the Atlantic and western tropical Pacific counterparts of the third Atlantic multidecadal unrotated mode. The third rotated mode is a multidecadal signal with maximal realization in the mid-latitude eastern North Pacific. The relation of these and higher order rotated modes to the unrotated modes and to published climatic signals are discussed.

Millero, F.J., and J.-Z. Zhang. Adsorption of phosphate on calcium carbonate. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 115 (1998).

No abstract.

Millero, F.J., W. Yao, K. Lee, J.-Z. Zhang, and D.M. Campbell. Carbonate system in the waters near the Galapagos Islands. Deep-Sea Research II, 45(6):1115-1134 (1998).

During the IRONEX cruise in the equatorial Pacific Ocean, the carbonate parameters TA (total alkalinity), TCO₂ (total inorganic carbon), pH, and fCO₂ (fugacity of CO₂), were determined both in a small (8 × 8 km) patch of water fertilized with Fe and in the waters around the Galapagos Islands. The CO₂ parameters, along with hydrographic properties, were found to be uniform in the surface waters of the study area before the addition of iron. A significant decrease of the surface TCO₂ (7 µmol kg^-1) and fCO₂ (11 µatm) in the patch was detected within 48 h of the iron release. This decrease, however, did not continue and was lower than expected from the complete utilization of NO₃^- due to the addition of iron. The shipboard iron a ddition experiments (3 nM fe) resulted in a continual decrease of TCO₂ (up to 48 µmol kg^-1) and complete consumption of the nutrients. A good correlation was found between TCO₂, pH, and fCO₂ with temperature in the surface waters around the Galapagos Islands. The salinity (S = 35) normalized alkalinities were quite uniform (NTA = 2310 ± 9 mol kg^-1) throughout the region. The effect of high primary production on the CO₂ system in the downstream plume is overshadowed by the upwelling waters with high CO₂.

Millero, F.J., D.G. Purkerson, P. Steinberg, E. Peltola, K. Lee C. Edwards, J. Goen, and M.P. Roche. The carbon dioxide system in the Ross Sea during the JGOFS Southern Ocean Process Study. University of Miami Technical Report, RSMAS-98-001, 159 pp. (1998).

In the austral summer of 1996 and austral fall of 1997, we participated in the Joint Global Ocean Flux Study (JGOFS) supported by the National Science Foundation (NSF) in the Southern Ocean aboard the R/V Nathaniel B. Palmer. The first cruise was a survey across the Antarctic Convergence Zone from Port Lyttelton, New Zealand to the Ross Sea and back. The Process 1 and 3 cruises were in the Ross Sea. The first process cruise originated in Port Lyttelton, New Zealand and ended in McMurdo Station, Antarctica. The third process cruise originated and ended in Port Lyttelton, New Zealand. This report gives the results of our pH, total alkalinity (TA), and total inorganic carbon dioxide (TCO₂) measurements made during these cruises. The pH, TCO₂, and TA results were obtained by potentiometric titration of seawater samples with hydrochloric acid (HCl), while the TCO₂ was determined by coulometry. Spectroscopic pH measurements were also made. Measurements of pH, TA, and TCO₂ were made on certified reference material (CRM) throughout the cruises to assess the quality of the measurements. The reproducibility of these CRM measurements by potentiometric titration were ±1.6 µmol kg^-1 in TA, ±2.2 µmol kg^-1 in TCO₂, and ±0.005 in pH. The reproducibility in TCO₂ by coulometry were ±1 µmol kg^-1 and ±0.001 in the spectroscopic values of pH. The at sea measurements agreed with the assigned values of ±2 µmol kg^-1 in TA, ±5 µmol kg^-1 in TCO₂, and ±0.002 in pH. All the measurements done at sea were adjusted for these differences. The values of pH, TA, and TCO₂ for the measurements in the Ross Sea are examined for the process studies along with surface nutrients and pCO₂.

Molinari, J., S. Skubis, D. Vollaro, F. Alsheimer, and H.E. Willoughby. Potential vorticity analysis of tropical cyclone intensification. Journal of the Atmospheric Sciences, 55(6):2632-2644 (1998).

The interaction of marginal Tropical Storm Danny (1985) with an upper-tropospheric positive potential vorticity anomaly was examined. The intensification mechanism proposed earlier for mature Hurricane Elena appears to be valid for Danny as well, despite significant differences in the synoptic-scale environment and in the stage of the tropical cyclone prior to the interaction. Both storms experienced rapid pressure falls as a relatively small-scale positive upper potential vorticity anomaly began to superpose with the low-level tropical cyclone center. The interaction is described in terms of a complex interplay between vertical wind shear, diabatic heating, and mutual advection among vortices at and below the level of the outflow anticyclone. Despite this complexity, the superposition principle appears to be conceptually useful to describe the intensification of tropical cyclones during such interactions.

Molinari, R.L., H.F. Bezdek, M. Latif, and A. Groetzner. A comparison of modeled and observed mean and decadal time-scale Atlantic air-sea structure. Proceedings, Atlantic Climate Variability Meeting, Palisades, New York, September 24-26, 1997. University Corporation for Atmospheric Research, 78-79 (1998).

No abstract.

Molinari, R.L., R.A. Fine, W.D. Wilson, J. Abell, M. McCartney, and R. Curry. A fast-track for recently formed Labrador Sea Water: The Deep Western Boundary Current of the North Atlantic. Proceedings, Atlantic Climate Variability Meeting, Palisades, New York, September 24-26, 1997. University Corporation for Atmospheric Research, 80 (1998).

No abstract.

Molinari, R.L., R.A. Fine, W.D. Wilson, R.G. Curry, J. Abell, and M.S. McCartney. The arrival of recently formed Labrador Sea Water in the Deep Western Boundary Current at 26.5°N. Geophysical Research Letters, 25(13):2249-2252 (1998).

The Deep Western Boundary Current (DWBC) of the North Atlantic is a principal conduit between the formation region for Labrador Sea Water (LSW) and the oceanic interior to the south. Time series (1985-1997) of hydrographic properties obtained in the DWBC at 26.5°N show that prior to 1994, temperature, salinity, and transient tracer properties within the LSW density range showed little indication of recently formed parcels. Properties characteristic of a newer version of LSW (cooler, fresher, and higher tracer concentrations) were observed beginning in 1994 and continuing through 1997. Longer time series of temperature and salinity, developed from a regional data base, show both the 1994 and a 1980-1981 event in the Abaco region. Both events are consistent with anomalies in the Labrador Sea that occurred some 10 years earlier. The 10-year transit time from the Labrador Sea to 26.5°N is less than the 18-year transit time inferred from earlier studies.

Murphy, P.P., R.A. Feely, and R.H. Wanninkhof. On obtaining high-precision measurements of oceanic pCO₂ using infrared analyzers. Marine Chemistry, 62(1-2):103-115 (1998).

Assessments of ocean carbon uptake using the air-sea disequilibrium of CO₂ require very high quality measurements of pCO₂ in the atmosphere and in surface seawater. These measurements are often collected and analyzed using infrared detectors. Laboratory data are presented here which suggest that errors of the order of several parts per million in xCO₂ can result if the analyzer temperature and pressure are not carefully matched during calibration and sampling. Field data were examined to address questions about the importance of measuring analysis temperature and pressure under more extreme conditions, sample averaging, and calibration frequency. The results indicate that calibration frequency can be minimized without significant compromises in data quality if the analyzer temperatures and pressures are suitably monitored and/or controlled. Daily calibrations gave results to within 0.4 ppm of the results obtained by hourly calibration when the temperature of the analyzer was controlled to ±0.2°C and the voltages were corrected for pressure differences between calibration and sampling.

Nelsen, T.A., H. Wanless, P. Blackwelder, T. Hood, C. Alvarez-Zarikian, P. Swart, J. Trefry, W.-J. Kang, L. Tedesco, and M. O'Neil. The sediment record as a monitor of anthropogenic changes in the lower Everglades/Florida Bay ecosystem. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program (1998).

Florida Bay is a shallow subtropical estuary (~2200 km², mean depth ~2 m) that lies at the southern end of peninsular Florida and is subject to both natural and anthropogenically-induced changes. Nearshore areas receive not only atmospheric input but also freshwater input from natural sheetflow, major and minor creeks (Shark River and Taylor Sloughs respectively), an unquantified input from groundwater and direct precipitation, as well as anthropogenic sources (c-111 canal). A paleoecological evaluation of this region was instigated using high-resolution retrospective analysis of regional sediments. It integrated sedimentology, geochronology (PB²¹⁰, Cs¹³⁷), biology (foraminifera and ostracods), chemistry (organic carbon, heavy metals, stable isotopes), and palynology to allow a broad scope of characterization. These data were complemented with an analysis of historical rainfall, freshwater flow, and limited nearshore salinity data. Placed within a temporal context by geochronology, sediment accumulation rates of ~1 cm per year in recovered sequences permitted evaluation back to about the turn of the century, thus allowing high-resolution evaluation of other co-sampled parameters over a time period that encompasses both natural and anthropogenic changes. Results from geochronology that were supported by other co-sampled parameters indicated disburbed horizons that temporarily correlate with major hurricanes. Moreover, foraminifera and ostracod community structures showed changes that temporally correlated with both natural rainfall patterns and anthropogenic effects such as water management practices. Sediment burdens of heavy metals also showed time-based changes that temporally correlated with documented anthropogenic usage patterns.

Nelsen, T.A., H.R. Wanless, P. Blackwelder, T. Hood, C. Alvarez-Zarikian, P. Swart, J.H. Trefry, W.-J. Kang, L. Tedesco, and M. O'Neal. The sediment record as a monitor of natural and anthropogenic changes in the lower Everglades/Florida Bay ecosystem. Proceedings, ASLO/ESA Land-Water Interface: Science for a Sustainable Biosphere, St. Louis, Missouri, June 8-13, 1998. American Society of Limnology and Oceanography, A-64 (1998).

Florida Bay is a shallow subtropical estuary (~2200 km², mean depth ~2 m) that lies at the southern end of peninsular Florida and is subject to both natural and anthropogenically-induced changes. Nearshore areas receive not only atmospheric input but also freshwater input from natural sheetflow, major and minor creeks (Shark River and Taylor Sloughs respectively), an unquantified input from groundwater and direct precipitation, as well as anthropogenic sources (c-111 canal). A paleoecological evaluation of this region was instigated using high-resolution retrospective analysis of regional sediments. It integrated sedimentology, geochronology (Pb²¹⁰, Cs¹³⁷), biology (foraminifera and ostracods), chemistry (organic carbon, heavy metals, stable isotopes) and palynology to allow a broad scope of characterization. These data were complemented with an analysis of historical rainfall, freshwater flow, and limited near-shore salinity data. Placed within a temporal context by geochronology, sediment accumulation rates of ~1 cm per year in recovered sequences permitted evaluation back to about the turn of the century, thus allowing high-resolution evaluation of other co-sampled parameters over a time period that encompasses both natural and anthropogenic changes. Results from geochronology, that were supported by other co-sampled parameters, indicated disturbed horizons that temporally correlate with major hurricanes. Moreover, foraminifera and ostracod community structures showed changes that temporally correlated with both natural rainfall patterns and anthropogenic effects such as water management practices. Sediment burdens of heavy metals also showed time-based changes that temporally correlated with documented anthropogenic usage patterns.

Nicholls, N., C.W. Landsea, and J. Gill. Recent trends in Australian region tropical cyclone activity. Meteorology and Atmospheric Physics, 65:197-205 (1998).

No abstract.

Niyogi, D.S., J.J. Cione, and S. Raman. Gulf Stream influence on the North Carolina mesoclimate. Preprints, 2nd Conference on Coastal Atmospheric and Oceanic Prediction, American Meteorological Society 78th Meeting, Phoenix, AZ, January 12-16, 1998. American Meteorological Society, Boston, 421-424 (1998).

No abstract.

Ogden, J.C., S.L. Vargo, J.C. Hendee, R. Timko, J.C. Humphrey, and T.C. Moore. SEAKEYS 1998: An enhanced Florida Bay monitoring initiative. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 118 (1998).

No abstract.

Ortner, P.B., M.J. Dagg, G.S. Kleppel, R. Brenner, and C. Tomas. Trophic pathways in the pelagic environment of Florida Bay. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 143-145 (1998).

No abstract.

Ozgokmen, T.M., and O.E. Esenkov. Asymmetric fingers induced by the nonlinear-equation of state. Phys. Fluids, 10(8):1882-1890 (1998).

No abstract.

Ozgokmen, T.M., O.E. Esenkov, and D.B. Olsen. A numerical study of layer formation due to fingers in double-diffusive convection in a vertically-bounded domain. Journal of Marine Research, 56:463-487 (1998).

No abstract.

Peltola, E., R. Wanninkhof, R. Molinari, B.E. Huss, R. Feely, J. Bullister, J.-Z. Zhang, F. Chavez, A. Dickson, A. Ffield, D. Hansell, F. Millero, P. Quay, R. Castle, G. Thomas, R. Roddy, T. Landry, M. Roberts, H. Chen, D. Greeley, K. Lee, M. Roche, J.A. Goen, F. Millero, K. Buck, M. Kelly, F. Menzia, A. Huston, T. Waterhouse, S. Becker, and C. Mordy. Chemical and hydrographic measurements during the Indian Ocean I8 repeat cruise (IR8N) in September and October 1995. NOAA Data Report, ERL AOML-34 (PB99-126948), 176 pp. (1998).

This document contains data and metadata from the I8 repeat cruise in the Indian Ocean cruise in 1995 from Fremantle, Australia to Male in the Maldives. From September 22 to October 25, 1995, the National Oceanic and Atmospheric Administration (NOAA) sponsored an oceanographic research cruise conducted aboard the NOAA Ship Malcolm Baldrige. This report presents the analytical and quality control procedures and data from the cruise that was conducted for the Ocean-Atmosphere Carbon Exchange Study (OACES). Samples were taken at 101 stations. The data presented in this report includes hydrography, nutrients, total dissolved inorganic carbon dioxide (DIC), fugacity of carbon dioxide (fCO₂), total alkalinity (TA), pH, total organic carbon and nitrogen data (TOC/TON), chlorofluorocarbons, ¹³C, and biological parameters.

Peng, T.-H., and F. Chai. Modeling of the carbon cycle in the equatorial Pacific Ocean. AGU 1998 Western Pacific Geophysics Meeting, Taipei, Taiwan, July 21-24, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(24):W41, OS41A-10 (1998).

As a part of the U.S. JGOFS program, field data relating to hydrographic, chemical, and biological properties in the equatorial Pacific have been collected during the process-study-oriented survey cruises in 1992. To synthesize and analyze these data for a better understanding of the carbon cycle dynamics, an ocean ecosystem model of the equatorial Pacific Ocean has been developed. The circulation model is based on the Modular Ocean Model of the NOAA/GFDL ocean general circulation model. It consists of five components describing phytoplankton, zooplankton, detritus, and two forms of dissolved inorganic nitrogen: nitrate and ammonium. The carbonate chemistry is parameterized in the model to evaluate the variations of pCO₂, and hence the CO₂ flux across the air-sea interface. At this initial stage, a test case by using a one-dimensional model is performed to investigate how the carbon system behaves in the ecosystem structure. The model includes the vertical upwelling and diffusion processes. The upwelling rate and the diffusivity were averaged for the region 5°S to 5°N, 180° to 90°W, the "cold tongue" of the equatorial Pacific. Results of this one-dimensional testing model and comparison with the observed data collected in 1992 will be presented.

Peng, T.-H., R. Key, and H.G. Ostlund. Temporal variations of bomb radiocarbon in the Pacific Ocean. Marine Chemistry, 60:3-14 (1998).

The natural and anthropogenic components of the radiocarbon measurements from seawater samples can be successfully separated by an improved method, which is based on a very well-defined relationship between natural radiocarbon and dissolved silica observed mainly during the GEOSECS survey for waters beneath 1000 m depth. This relationship is further reconfirmed by the ¹⁴C measurements from large volume samples taken in the deep waters in the Pacific Ocean during the recent WOCE survey program. Analysis of upper ocean ¹⁴C measurements made along 152°W, and north of 20°'N, in the northeastern Pacific Ocean during the NOAA's CGC91 cruise, which is a part of the WOCE survey program, indicates that the bomb ¹⁴C inventory in this part of the ocean has increased by 22% since the GEOSECS measurements made in 1974. This increase is consistent with the model prediction of 25% for the northern hemisphere ocean. Change of the surface water bomb ¹⁴C values during this period is insignificant. This feature is also consistent with the model simulation. Results of this new analysis will provide useful information of the temporal variations of bomb ¹⁴C inventory in the ocean, in addition to the spatial distribution, which can be used as powerful constraints in calibrating the global ocean carbon cycle models, especially those based on three dimensional ocean general circulation models, for estimating the uptake of CO₂ by the ocean.

Peng, T.-H., R.H. Wanninkhof, J.L. Bullister, R.A. Feely, and T. Takahashi. Quantification of decadal anthropogenic CO₂ uptake in the Indian Ocean based on dissolved inorganic carbon measurements. Nature, 396(10):560-563 (1998).

The increase of total dissolved inorganic carbon (DIC) in the ocean caused by the uptake of fossil fuel CO₂ is estimated mostly by ocean models. These model estimates need to be verified using field measurements. However, the direct detection of the anthropogenic CO₂ signal in the ocean has been hampered by the relatively small annual increase in DIC in seawater (~1 µmol/kg/yr, as compared with background DIC of ~2000 µmol/kg) and by lack of high-precision measurements in the past. With the recent improvement in DIC analyses techniques, it has now become possible to detect the anthropogenic CO₂ signal on decadal time scales. Here we report a significant increase in DIC between the GEOSECS survey in 1978 and the recent NOAA-OACES survey in 1995 in the Indian Ocean. The anthropogenic CO₂ signal is 12 ± 4.5 µmol/kg at ~300 m (potential density, sigma_theta = 26.6) and the signal decreases on denser isopycnal horizons down to undetectable near ~1000 m (sigma_theta = 27.2). The data are used to illustrate the isopycnal analysis and corrections necessary to determine the anthropogenic CO₂ increase over time. The work can be used as a guide for future observational strategies to assess uptake of anthropogenic CO₂.

Pielke, R.A., and C.W. Landsea. Normalized hurricane damages in the United States: 1925-1995. Weather and Forecasting, 13(3):621-631 (1998).

Hurricanes are the costliest natural disasters in the United States. Understanding how both hurricane frequencies and intensities vary from year to year, as well as how this is manifested in changes in damages that occur, is a topic of great interest to meteorologists, public and private decision makers, and the general public alike. Previous research into long-term trends in hurricane-caused damage along the U.S. coast has suggested that damage has been quickly increasing within the last two decades, even after considering inflation. However, to best capture the year-to-year variability in tropical cyclone damage, consideration must also be given toward two additional factors: coastal population changes and changes in wealth. Both population and wealth have increased dramatically over the last several decades and act to enhance the recent hurricane damages preferentially over those occurring previously. More appropriate trends in the United States hurricane damages can be calculated when a normalization of the damages are done to take into account inflation and changes in coastal population and wealth. With this normalization, the trend of increasing damage amounts in recent decades disappears. Instead, substantial multidecadal variations in normalized damages are observed: the 1970s and 1980s actually incurred less damages than in the preceding few decades. Only during the early 1990s does damage approach the high level of impact seen back in the 1940s through the 1960s, showing that what has been observed recently is not unprecedented. Over the long term, the average annual impact of damages in the continental United States is about $4.8 billion (1995 $), substantially more than previous estimates. Of these damages, over 83% are accounted for by the intense hurricanes (Saffir-Simpson categories 3, 4, and 5), yet these make up only 21% of the U.S.-landfalling tropical cyclones.

Powell, M.D., and S.D. Aberson. How well do we forecast the position and time of hurricane landfall? Preprints, 16th Conference on Weather Analysis and Forecasting, Symposium on the Research Foci of the U.S. Weather Research Program, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 9-12 (1998).

No abstract.

Powell, M.D., and S.H. Houston. Surface wind fields of 1995 Hurricanes Erin, Opal, Luis, Marilyn, and Roxanne at landfall. Monthly Weather Review, 126(5):1259-1273 (1998).

Hurricanes Erin, Opal, Luis, Marilyn, and Roxanne were the most destructive hurricanes of 1995. At landfall, Luis and Marilyn contained maximum sustained winds (marine exposure) estimated at near 60 and 46 m s^-1, respectively. The strongest landfalling storm of the 1995 season, Luis, decreased in intensity from a category 4 to 3 on the Saffir-Simpson scale shortly before the eyewall crossed the Islands of Antigua, Barbuda, St. Kitts-Nevis, St. Barthelemy, St. Martin, and Anguilla. Hurricane Marilyn strengthened as it approached the U.S. Virgin Islands, with St. Thomas bearing the brunt of the north and south eyewall winds of 46 m s^-1 (marine exposure) and St. Croix being affected by the relatively weak western eyewall peak winds of 35-40 m s^-1 (marine exposure). For Luis and Marilyn, only surface winds with marine exposures were analyzed because of unknown small-scale interactions associated with complex island terrain with 500-1000-m elevations. Wind engineering studies suggest that wind acceleration over blunt ridges can increase or "speed up" winds by 20%-80%. Topographic effects were evident in damage debris analyses and suggest that an operational method of assessing terrain-induced wind gusts (such as a scaled down mesoscale model) is needed. After landfall as a marginal hurricane over central Florida, Hurricane Erin regained strength over the Gulf of Mexico with a well-defined radar reflectivity structure. Erin struck the Florida panhandle near Navarre Beach with maximum sustained surface winds of 35-40 m s^-1 affecting the Destin-Ft. Walton area. Hurricane Opal made landfall in nearly the identical area as Erin, with maximum sustained surface winds of 40-45 m s-1, having weakened from an intensity of nearly 60 m s-1 only 10 h earlier. Opal was characterized by an asymmetric structure that was likely related to cold front interaction and an associated midlevel southwesterly jet. Roxanne struck Cozumel, Mexico, with sustained surface winds (marine exposure) of 46 s^-1, crossed the Yucatan, and meandered in the southwest Gulf of Mexico for several days. While in the Bay of Campeche, Roxanne's large area of hurricane-force winds disabled a vessel, which led to the drowning deaths of five oil industry workers. High-resolution wind records are critical to preserving an accurate extreme wind climatology required for assessment of realistic building code risks. Unfortunately, power interruptions to Automated Surface Observing Stations (ASOS) on the U.S. Virgin Islands (St. Croix, St. Thomas) and Destin, Florida, prevented complete wind records of the eyewall passages of Marilyn and Opal, respectively.

Powell, M.D., and S.K. Rinard. Marine forecasting at the 1996 centennial olympic games. Weather and Forecasting, 13(3):764-782 (1998).

A team of meteorologists from the United States, Canada, and Australia provided marine weather support to the sailing events of the 1996 Centennial Olympic Games, held in Wassaw Sound near Savannah, Georgia. The team conducted research on the weather and climate and developed a set of forecast products designed to inform athletes, volunteers, and race managers of the wind, tidal current, wave, and weather behavior expected each day during the pre-Olympic and Olympic periods. The Olympic period proved to be a challenge with thunderstorms delaying, abandoning, or postponing races on half of the days. Thunderstorm development and movement was linked to the timing and strength of the sea breeze as well as the direction and speed of the gradient wind. Numerous thunderstorm warnings were issued with the assistance of the WSR-88D radar and the Warning Decision Support System. Frequent lightning was a legitimate safety concern due to the long distances between race courses and lack of suitable shelter; fortunately no one was injured during the lightning episodes. Forecasters benefited from access to a variety of monitoring tools and models including real-time Olympic buoy wind and current time series displays; satellite and radar imagery animation; 2-, 8-, and 10-km resolution mesoscale models; a live video feed of race coverage; and communications with forecasters aboard patrol craft offshore. Official wind forecasts, mesoscale models, and a simple vector addition model performed better than climatology and persistence as defined by mean vector error and rms wind direction error. Climatology was difficult to beat on the basis of wind speed error.

Powell, M.D., S.H. Houston, L.R. Amat, and N. Morisseau-Leroy. The HRD real-time hurricane wind analysis system. Journal of Wind Engineering and Industrial Aerodynamics, 77&78:53-64 (1998).

The HRD real-time wind analysis system is currently undergoing evaluation in the operational forecasting environment of the National Hurricane Center. The system is an object-oriented, distributed, three-tiered client-server application that assimilates disparate observations and processes the data into a common framework for exposure, height, and averaging time. The data are then examined collectively or by type, quality controlled, and passed on to a scale-controlled objective analysis algorithm. Several products are derived from the analysis wind field and storm track, yielding effective tools for disaster assessment, emergency management, and recovery.

Proni, J.R., and J.C. Wilkerson. Underwater acoustic monitoring for satellite rainfall estimation validation. Proceedings, 6th International Conference for Precipitation, Mauna Lani Bay, Hawaii, June 29-July 1, 1998. NASA/NOAA, 2-10 (1998).

Application of underwater acoustic techniques to the monitoring of rainfall over water is demonstrated at four acoustically distinct ocean sites based on information in the 4-30 kHz frequency band. Rainfall detection and classification as to type (convective or stratiform) are possible because underwater sound spectral characteristics of rain are different from the normally prevailing underwater background noise in the ocean, and because there are distinct differences in the sound levels and spectral shapes of the acoustic signature of the two rain types. Rain type classification is determined by an acoustic discriminant, D_R, which is defined as the difference in the average spectral levels between the 10-30 and 4-10 kHz bands. Rainfall estimation potential is based on the high correlation between sound spectral levels in decibels (in the 4-10 kHz frequency band) and radar reflectivity dBz. Data obtained from a spatially distributed 12-hydrophone array on the ocean floor, at a depth of 1.5 km, demonstrates the potential of monitoring rainfall at the sea surface on spatial (420 km²) and temporal (five samples/minute) scales suitable for validating precipitation estimates from remote sensors carried on geostationary and polar orbiting satellites.

Proni, J.R., and J.C. Wilkerson. Wind-generated acoustic spectral effects in the surf zone in the presence and absence of rainfall at Duck, North Carolina. Proceedings, 16th International Congress on Acoustics and 135th Meeting of the Acoustical Society of America, Seattle, Washington, June 20-26, 1998. Journal of the Acoustical Society of America, 103(5):2865-2866 (1998).

Concurrent underwater sound, wind, radar, and rainfall measurements were made on November 5, 1992, off Duck, North Carolina. A wind speed increment from 5 m/s to 13 m/s in 90 seconds resulted in a reduction in the rainfall sound spectrum level beginning at about 50 kHz and extending downward in frequency with time to about 10 kHz. The reduction in rainfall-generated sound spectrum level with time is thought to be due to sound absorption by the evolving wind-generated bubble field.

Proni, J.R., C. McArthur, and G. Schuster. Adaptive dredged material discharge for the Port of Miami. Proceedings, Ports '98, Long Beach, California, March 8-11, 1998. American Society of Civil Engineers, 1249-1257 (1998).

In a joint effort of the U.S. Army Corps of Engineers, the U.S. Environmental Protection Agency, the National Oceanic and Atmospheric Administration, the State of Florida, the Port of Miami, and the University of Miami, a novel, environmentally adaptively controlled procedure was developed, wherein a vital port expansion and maintenance dredging operation was carried out while affording maximum protection to sensitive coral reefs. After establishing the existence and spatial disposition of a residual water column discharge plume, via acoustic backscattering methods, a real-time current measurement system was established at the offshore dredged material disposal site to be utilized. Dredged material discharges then proceeded on a schedule in conformity with the ambient currents, so that material transport to the coral reefs of concern was minimized.

Quilfen, Y., B. Chapron, T. Elfouhaily, K.B. Katsaros, and J. Tournadre. Observations of tropical cyclones by high-resolution scatterometry. Journal of Geophysical Research, 103(C4):7767-7786 (1998).

Unprecedented views of surface wind fields in tropical cyclones (hereafter TCs) are provided by the European Remote Sensing Satellite (ERS) C-band scatterometer. Scatterometer measurements at C band are able to penetrate convective storms clouds, observing the surface wind fields with good accuracy. However, the resolution of the measurements (50 × 50 km²) limits the interpretation of the scatterometer signals in such mesoscale events. The strong gradients of the surface wind existing at scales of a few kilometers are smoothed in the measured features such as the intensity and location of the wind maxima and the position of the center. Beyond the ERS systems, the scatterometers on-board the ADEOS and METOP satellites, designed by the Jet Propulsion Laboratory and by the European Space Agency, respectively, will be able to produce measurements of the backscattering coefficient at about 25 × 25 km² resolution. A few sets of ERS-1 orbits sampling TC events were produced with an experimental 25 × 25 km² resolution. Enhancing the resolution by a factor of 2 allows location of the wind maxima and minima in a TC with a much better accuracy than at 50 km resolution. In addition, a better resolution reduces the geophysical noise (variability of wind speed within the cell and effect of rain) that dominates the radiometric noise and, hence, improves the definition of the backscattering measurements. A comprehensive analysis of the backscattering measurements in the case of high winds and high sea states obtained within TCs is proposed in order to refine the interpretation of the wind vector derived from a backscattering model that is currently only calibrated up to moderate winds (<20 m/s) in neutral conditions. Observations of the TOPEX-POSEIDON dual-frequency altimeter are also used for that purpose. Patterns of the surface winds in TCs are described and characteristic features concerning asymmetries in the maximum winds and in the divergence field are discussed.

Roubicek, A.J., S.L. Garzoli, P.L. Richardson, C.M. Dumcombe Rae, and D.M. Fratantoni. Benguela Current Experiment, R/V Seward Johnson Cruise SJ9705, Cape Town, September 4, 1997-Recife, September 30, 1997. NOAA Data Report, ERL AOML-33 (PB98-164775), 215 pp. (1998).

The main objective of this program is to study the pathways, velocity, transport, and variability of the Benguela Current and its extension with emphasis on tracking floats in the intermediate water. It is expected that the results of this program will make a significant contribution towards the understanding of inter-ocean (Indian to Atlantic) and inter-basin (South and North Atlantic) exchange of intermediate water and its role in heat and mass exchanges. This program is a component of KAPEX (Cape of Good Hope Experiment), a joint U.S., German, and South African experiment. In March 1997, a German cruise on the Polarstern led by W. Zenk and O. Boebel launched 35 RAFOS floats and five sound sources (including one of the U.S. sources near 20°S, 4°E) in the general area west and southwest of Cape Town. During August 1997, a U.S. cruise on the R/V Seward Johnson led by T. Rossby launched three sound sources east and southeast of Cape Town; 50 RAFOS floats will be launched in the Agulhas Current starting in November 1997. During the Benguela Current Experiment cruise on the RV Seward Johnson in September 1997, 32 RAFOS floats and two sound sources were launched in the general area west and northwest of Cape Town. During KAPEX, over 100 RAFOS floats and nine sound sources will measure ocean trajectories for the first time in the Agulhas Current, in its rings which enter the South Atlantic, and in the Benguela Current and its extension, which is the source of water moving northward through the Atlantic in the meridional overturning circulation cell. In addition, temperature, salinity, and velocity profiles will document the water mass and velocity structure of the Benguela Current, its extension, and several Agulhas rings.

Shapiro, L.J., and S.B. Goldenberg. Atlantic sea surface temperatures and tropical cyclone formation. Journal of Climate, 11(4):578-590 (1998).

It has long been accepted that interannual fluctuations in sea surface temperature (SST) in the Atlantic are associated with fluctuations in seasonal Atlantic basin tropical cyclone frequency. To isolate the physical mechanism responsible for this relationship, a singular value decomposition (SVD) is used to establish the dominant covarying modes of tropospheric wind shear and SST, as well as horizontal SST gradients. The dominant SVD mode of covarying vertical shear and SST gradients, which comprises equatorially confined near-zonal vertical wind shear fluctuations across the Atlantic basin, is highly correlated with both equatorial eastern Pacific SST anomalies (associated with El Niño) and west African Sahel rainfall. While this mode is strongly related to tropical storms, hurricanes, and major hurricane frequency in the Atlantic, it is not associated with any appreciable Atlantic SST signal. By contrast, the second SVD mode of covarying vertical shear and horizontal SST gradient variability, which is effectively uncorrelated with the dominant mode, is associated with SST fluctuations concentrated in the main tropical cyclone development region between 10°N and 20°N. This mode is significantly correlated with tropical storm and hurricane frequency but not with major hurricane frequency. Statistical tests confirm the robustness of the mode, and lag correlations and physical reasoning demonstrate that the SST anomalies are not due to the developing tropical cyclones themselves. Anomalies of SST and vertical shear during years where the mode has substantial amplitude confirm the resemblance of the individual fields to the modal structure, as well as the association of hurricane development with the warmer SSTs. Although SSTs are of secondary importance to vertical shear in modulating hurricane formation, explaining only 10% of the interannual variability in hurricane frequency over the 50% explained by vertical shear, the results support the conclusion that warmer SSTs directly enhance development. The lack of correlation with major hurricanes implies that the underlying SSTs are not a significant factor in the development of these stronger systems.

Shay, L., G.J. Goni, F.D. Marks, J.J. Cione, and P.G. Black. Role of warm ocean features on intensity change: Hurricane Opal. Preprints, Symposium on Tropical Intensity Change, American Meteorological Society 78th Annual Meeting, Phoenix, AZ, January 11-16, 1998. American Meteorological Society, Boston, 131-138 (1998).

No abstract.

Sheinbaum, J., J. Candela, W.D. WILSON, J. Ochoa, and A. Badan. Shipboard ADCP and lower ADCP observations in the Yucatan Channel. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS125, OS32P-01 (1998).

Observations obtained during two cruises in December 1996 and in May/June 1997 within the CANEK Project are discussed. The cruises were onboard the R/V Justo Sierra, equipped with a ship-mounted RDI 75 kHz ADCP, usually measuring up to 400 m depth, and covered the area around the Yucatan Channel within 20° to 22.5°N. Both cruises show a persistent and swift Yucatan Current flowing towards the Gulf of Mexico, on the western side of the Channel, with surface magnitudes as large as 2 m/s. Transport estimates in the upper 300 m indicate that this current was transporting around 8 Sv into the Gulf during both cruises, for an equivalent cross-shelf section about 50 km in length at around 22°N and oriented nearly in west-east direction. A complete cross-Channel section between Isla Contoy, Yucatan and Cabo San Antonio, Cuba, during the May cruise, gives a total transport of 19 Sv into the Gulf in the upper 300 m. Ship-mounted ADCP velocities from the top 300 m are used to reference velocity measurements from a Lower-ADCP (LADCP), an RDI 300 kHz acoustic Doppler current profiler attached to a CTD-rosette frame which samples the whole water column. Total and deep transport estimates, together with methods to filter out tidal transports, are also discussed.

Sheinbaum, J., J. Candela, J. Ochoa, A. Badan, I. Gonzalez, W.D. Wilson, and R.H. Smith. Velocity and transport measurements with a lower-acoustic Doppler current profile in the Yucatan Channel: Some preliminary results. Proceedings, Conference on the Transports and Linkages of the Intra-Americas Sea (IAS), Cozumel, Mexico, November 1-5, 1997. IOC/IOCARIBE/MMS, 57 (1998).

We present preliminary results from the extensive surveys carried out onboard UNAM'S R/V Justo Sierra using a shipboard ADCP and a CTD/LADCP during December 1996 and May 1997 in the Yucatan Channel. These cruises were part of the CANEK Project, a collaborative effort between CICESE, ICMyL-UNAM, UAM (Mexico), NOAA (USA), and IOC (Cuba), to measure the exchange between the Carribean Sea and the Gulf of Mexico. Velocity measurements and transport estimates from both instruments are analyzed and compared. The May 1997 cruise had a standard GPS instrument to fix ship positions, which were recorded almost continuously (every second) during the whole cruise. These data were filtered before velocity and transport calculations were carried out. Details of the data processing and sensitivity of absolute velocity estimates from the LADCP instrument to the ship's position are discussed.

Swart, P., K.S. White, D.B. Enfield, P. Milne, and R.E. Dodge. Stable oxygen isotopic composition of corals from the Gulf of Guinea as indicators of periods of extreme precipitation conditions in the sub-Sahara. Journal of Geophysical Research, 103(C12):27,885-27,891 (1998).

Analyses of scleractinian coral skeletons from the Gulf of Guinea in the eastern Atlantic reveal that the corals from this region can be used to identify periods of severe drought and above average precipitation in the Subsahara. Data presented in this paper show a positive correlation between the magnitude of the Sahel drought and the d18O values of the Principe coral skeleton. The explanation for this positive correlation is that the salinity of the Gulf of Guinea is strongly influenced by the outflow of the Niger and Zaire Rivers. The outflow of these rivers is also correlated with the fluorescence of the Principe coral. These periods of high freshwater input correlate with periods of higher rainfall in the Subsahara and have affected the d18O values of the coral skeleton. The correlations between Principe coral d18O values and Atlantic NATL (r = -0.34), the dipole (r = -0.45), and the latitudinal position of the ITCZ (r = -0.37) illustrate that the d18O values in the Principe coral reflect climate dynamics of the region that affect the precipitation patterns in the Subsahara.

Swenson, M.S., and D.V. Hansen. Drifter-based estimates of the seasonal cycle of heat advection in the NECC of the eastern tropical Pacific. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F431, OS12A-05 (1998).

Drifter-based estimates of the seasonal cycle of heat advection in the NECC of the eastern tropical Pacific is based on over 2500 estimates of weekly averaged velocity and DT/Dt from drifting buoys and over 2100 XBT casts in the region 4°N-11°N, 145°W-115°W from the historical data base in the Pacific for 1979-1996. This is the region of the North Equatorial Countercurrent (NECC) over which the Intertropical Convergence Zone is usually found. The NECC exhibits a strong seasonal cycle in zonal velocity and mixed-layer depth structure. We estimate the contribution to the mixed layer heat budget in this region arising from horizontal advection and diffusion during the march of the seasonal cycle. These contributions are compared with estimates of the remaining terms in an attempt to close the budget and identify the mechanisms which dominate during different seasons. The estimates will include eddy heat flux estimates. Finally, we will attempt to evaluate existent surface flux climatologies based on the balances we find.

Swenson, M.S., and H.F. Bezdek. On ocean-atmosphere coupling in the North Atlantic. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS77, OS22I-08 (1998).

We explore the geographical variability of the structure of the cross correlation function between sea surface temperature anomalies (SSTA) and anomalies of the sum of the latent and sensible heat fluxes (LSHFA) in the North Atlantic based on summaries from the Comprehensive Ocean Atmosphere Data Set (COADS) summaries from 1947-1990. Two distinct cross correlation structures emerge, one of which dominates in the open ocean at midlatitudes and the other of which dominates in the western boundary current and in the tropics. The former is characterized by a strong antisymmetry, while the latter is one-sided with a peak at zero-lag. A simple stochastic model (vector first-order auto-regressive model) is proposed to account for the observed structure. This is the simplest auto-regressive model that can produce the antisymmetric aspect in the cross correlation found in the open ocean midlatitude region. The model reproduces the results with great fidelity, but requires essential mutual coupling between SSTA and LSHFA to reproduce the open ocean midlatitudes result. The residuals from the fit contain low-frequency behavior with decadal time scales.

Thomas, G.G., R. Benway, S. Cook, Y.-H. Daneshzadeh, and W.S. Krug. Surface salinity and temperature from ships of opportunity. Proceedings, Ocean Community Conference '98, Baltimore, MD, November 16-19, 1998. Marine Technology Society, 160-165 (1998).

Thermosalinograph (TSG) data collected aboard both NOAA research vessels and ships participating in the National Oceanic and Atmospheric Administration's (NOAA) Volunteer Observing Ship (VOS) program plays an important role in the study of meridional circulation in the world's oceans. Sea surface temperature (SST) and sea surface salinity (SSS) are valuable measurements in our attempt to understand the interaction between the world's oceans and global climate. The ability to collect and calibrate these data sets to insure a high standard of data quality is necessary to validate their use in NOAA's Global Ocean Observing System (GOOS) Center data base at the Atlantic Oceanographic and Meteorological Laboratory (AOML) located in Miami, Florida.

Wang, C., and R.H. Weisberg. Climate variability of the coupled tropical-extratropical ocean atmosphere system. Geophysical Research Letters, 25(21):3979-3982 (1998).

Observations show that tropical and extratropical Pacific SST anomalies vary out-of-phase, and that the atmospheric meridional Hadley and zonal Walker Circulations are related to these variations. A tropical-extratropical model is constructed to show oscillations consistent with observations. The positive feedback introduced by the Walker Circulation causes tropical warming so that the air rises and flows toward the subtropics where it sinks. When the sinking air approaches the sea surface, it flows both equatorward and poleward enhancing tropical easterly and extratropical westerly winds, respectively. Enhanced extratropical westerlies increases wind speed and hence evaporation, resulting in extratropical cooling. The Walker and Hadley Circulations thus result in tropical warming and extratropical cooling, respectively. The tropical warming and extratropical cooling increase the meridional SST difference and hence the meridional heat transport which erodes the tropical warming and extratropical cooling. Enhanced tropical easterlies due to the Hadley Circulation cools the tropical ocean through ocean dynamics. These negative feedbacks help the system to switch from warm to cold phases, and vice versa.

Wang, C., and R. H. Weisberg. Observations of meridional scale frequency dependence in the coupled tropical ocean-atmosphere system. Journal of Geophysical Research, 103(C2):2811-2816 (1998).

It is generally observed in models of the coupled tropical ocean-atmosphere system that the meridional scales for oscillations at interannual periods are larger than an oceanic equatorial Rossby radius of deformation. Using nine years of the high-resolution Optimum Interpolation sea surface temperature (SST) product of the NOAA/NCEP, analyses are made on the frequency dependence of the observed meridional scales, with emphasis on the latitudinal structures in the central Pacific at 140°W. On the relatively short intraseasonal and seasonal time scales the SST variations are found to occur over a meridional scale of the oceanic equatorial Rossby radius of deformation suggested by conventional equatorially trapped wave theory. In contrast to this, on the longer annual and interannual time scales the meridional scales are found to increase beyond the oceanic equatorial Rossby radius of deformation. A physical explanation for this meridional scale increase with decreasing frequency in the coupled tropical ocean-atmosphere system is discussed.

Wanninkhof, R.H., and R.A. Feely. fCO₂ dynamics in the Atlantic, Pacific, and South Indian Oceans. Marine Chemistry, 60(1-2):15-31 (1998).

Subsurface fugacities of CO₂ (fCO₂(20)) can be used in combination with total dissolved inorganic carbon (DIC) to precisely calculate total alkalinity. Thus, it can be used to determine dissolution of calcium carbonate (hard tissue) and remineralization of organic material (soft tissue), to quantify saturation constants of calcite and aragonite in seawater, and to characterize water masses. fCO₂(20) is a good tracer of biological transformation since it is thermodynamically related to the other inorganic carbon system parameters and it has a dynamic range from 200 to 2000 µatm in the world's ocean. Precision of fCO₂ measurements is better than 0.3% and the values are well calibrated using compressed gas reference standards. Increases of fCO₂(20) are observed as the water masses age during movement from the Atlantic to the Indian and South Pacific Oceans. As an example of the determination of the ratio of soft tissue remineralization to hard tissue dissolution from fCO₂(20) and DIC, the trends along the 27.2 isopyncal for the subtropical gyres of the three basins are investigated. Little CaCO₃ dissolves along this isopycnal in the Atlantic and the South Pacific while the soft tissue remineralization to hard tissue dissolution ratio in the Indian Ocean is 4.5:1. The difference in this ratio along the 27.2 isopycnal appears to be a combination of the calcite and aragonite saturation levels and the supply of aragonite tests.

Weisberg, R.H., and D.A. Mayer. Interhemisphere and intergyre exchange processes. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F484, OS31F-10 (1998).

Given that tropical ocean and atmosphere property fields have large annual cycles, intergyre and interhemisphere exchanges are likely to be seasonally dependent. Using COADS, we describe the annual variability of the tropical Atlantic Ocean wind-driven circulation and its implications for property exchanges. Focus is on three gyres: the anticyclonic northern hemisphere subtropical gyre, the cyclonic tropical gyre north of the equator, and the clockwise equatorial gyre. In the tropical gyre, the Sverdrup circulation argues against a continuous western boundary current for transporting water between the equatorial region and the Caribbean in boreal winter. Instead, the Sverdrup circulation implies a southeastward flowing boundary current, bringing to question the mechanisms for the interhemisphere and intergyre exchanges of heat and mass. A conceptual model is proposed involving two stages. First, the western boundary current closing the clockwise equatorial gyre is instrumental in transporting heat across the equator and storing warm water mass between the North Equatorial Countercurrent ridge and the North Equatorial Current trough in boreal summer. Transport farther north into the subtropical gyre in boreal winter is then accomplished by Ekman transport, as the seasonal change in wind stress deepens the thermocline, allowing for northward Sverdrup transport over the region of warmest waters. Once in the subtropical gyre, the Ekman transport continues to be northward despite the Sverdrup transport reversing to be southward. These stages constitute a rectification of the annual cycle wherein different regions play additive roles during different times of year. With Ekman and geostrophic transports being important, we also look at how they combine to form divergence on the equator. We use vertical velocity estimates from an equatorial central Pacific array of moorings deployed during TIWE. Upwelling (downwelling) is observed above (below) the EUC core, and while the divergence is centered on the equator, poleward surface and equatorward subsurface flows are larger at 1°S than at 1°N. The results are consistent with interior fluid pathways to the equator in the central Pacific. These gyre and vertical velocity analyses demonstrate that three-dimensional and time dependent processes are at work in transporting properties across hemispheres and gyres.

Whung, P.-Y., and C.J. Fischer. Input of atmospheric nitrogen species in the Florida Bay area: Its role in the nitrogen budget of Florida Bay. Proceedings, 1998 Florida Bay Science Conference, Miami, Florida, May 12-14, 1998. Florida Sea Grant College Program, 71 (1998).

No abstract.

Willoughby, H.E. Tropical cyclone eye thermodynamics. Monthly Weather Review, 126(12):3053-3067 (1998).

In intense tropical cyclones, sea level pressures at the center are 50-100 hPa lower than outside the vortex, but only 10-30 hPa of the total pressure fall occurs inside the eye between the eyewall and the center. Warming by dry subsidence accounts for this fraction of the total hydrostatic pressure fall. Convection in the eyewall causes the warming by doing work on the eye to force the thermally indirect subsidence. Soundings inside hurricane eyes show warm and dry air aloft, separated by an inversion from cloudy air below. Dewpoint depressions at the inversion level, typically 850-500 hPa, are 10-30 K rather than the 100 K that would occur if the air descended from tropopause level without dilution by the surrounding cloud. The observed temperature and dewpoint distribution above the inversion can, however, be derived by 100 hPa of undilute dry subsidence from an initial sounding that is somewhat more stable than a moist adiabat. It is hypothesized that the air above the inversion has remained in the eye since it was enclosed when the eyewall formed and that it has subsided at most a few kilometers. The cause of the subsidence is the enclosed air's being drawn downward toward the inversion level as the air below it flows outward into the eyewall. Shrinkage of the eye's volume is more than adequate to supply the volume lost as dry air is incorporated into the eyewall or converted to moist air by turbulent mixing across the eye boundary. The moist air below the inversion is in thermodynamic contact with the sea surface. Its moisture derives from evaporation of seawater inside the eye, frictional inflow of moist air under the eyewall, and from moist downdrafts induced as condensate mixes into the eye. The moist air's residence time in the eye is much shorter than that of the dry air above the inversion. The height of the inversion is determined by the balance between evaporation, inflow, and inward mixing on one hand and loss to the eyewall updrafts on the other.

Wilson, W.D. Constructing an IAS regional Global Ocean Observing System. Proceedings, Conference on the Transports and Linkages of the Intra-Americas Sea (IAS), Cozumel, Mexico, November 1-5, 1997. IOC/IOCARIBE/ MMS, 66 (1998).

The Global Ocean Observing System (GOOS) was established as an international program in 1993 by the IOC, WMO, UNEP, and ICSU. The main elements are the collection and timely distribution of oceanic data and products, including assessments, assimilation of data into numerical prediction models, the development and transfer of technology, and capacity building within participating member states to develop analysis and application capability. To date, national GOOS operational activities worldwide are primarily split between global programs (supported almost entirely by a small number of highly developed countries) and regional networks of linked coastal and nearshore programs, such as EURO-GOOS in the EU and NEAR-GOOS in northeastern Asia. The IOC suggests that "...In regions having existing IOC Sub-Commissions (e.g., IOCARIBE), countries organizing regional GOOS activities will do so in consultation with the Sub-Commission." Subsequently, both IOC and IOCARIBE have expressed support for the development of an IAS regional GOOS. Because of the nature of the IOCARIBE member states, which contain far fewer autonomous national oceanographic programs than eastern Asia or western Europe, the IAS GOOS paradigm will have a somewhat different structure than NEAR-GOOS or EURO-GOOS. It is hoped that this talk will promote a dialogue about planning for the implementation of an IAS regional GOOS. For discussion purposes, some important issues to be addressed in planning an IAS GOOS include: (1) identification of customer concerns, e.g., fisheries, climate studies, pollution management, etc., in keeping with the primary GOOS goal of providing practical benefits to society; (2) Design of a scientifically sound, expandable pilot observing system for continual monitoring; (3) model development to provide a framework for data synthesis and program expansion; (4) utilization of existing and planned regional programs and regional parts of global programs as components for cost-efficiency; and (5) regional dispersal of technology and capacity building for synoptic data acquisition, management, and utilization.

Wilson, W.D., and W.E. Johns. Measurements of transport and water mass exchange in the passages to the Caribbean Sea. AGU 1998 Ocean Sciences Meeting, San Diego, CA, February 9-13, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(1):OS125, OS32P-03 (1998).

Physical oceanographic measurements from 14 cruises during 1991-1997 in the Antilles island passages have been analyzed to study water exchange between the Atlantic Ocean and the Caribbean Sea. This region is generally thought to be an important site for the entrainment of upper ocean waters of South Atlantic origin into the North Atlantic circulation system, a process necessary to balance southward North Atlantic outflow in deeper layers. The magnitude of this exchange, comprising the North Atlantic thermohaline Meridional Overturning Circulation (MOC), is thought to be around 15 Sv. While earlier cruises were concentrated on passages south of 15°N (Wilson and Johns, 1997, DSR, 44[3]), recent results also include five occupations of the more northern passages of the Lesser Antilles, allowing estimation of significant mean transports through all the passages. Net transport above 800 m in the passages south of Dominica (15°N) is estimated to be 12.2 Sv, partitioned among Grenada (6.1), St. Vincent (2.8), St. Lucia (2.0), and Dominica (1.3). The northern passages, Guadeloupe (1.0), Antigua (2.9), and Anegada (2.8), account for an additional 6.7 Sv. Allowing a maximum of 1 Sv of unresolved inflow, approximately 20 Sv of the 32 Sv that leaves the Straits of Florida at 27°N enters through the passages of the Lesser Antilles. This is quite consistent in total and in spatial distribution with geostrophic transports relative to 800 m calculated from high-resolution historical T-S data at 60°W. Too few sections in the Mona and Windward passages are available to estimate mean transports there. Consideration of these data, historical data, Sverdrup theory, and numerical model results suggests that very little of the mean inflow through the southern passages can be attributed to wind-driven circulation, and that most of that transport is derived from South Atlantic waters crossing the equator in the upper limb of the Atlantic thermohaline cell. The remainder of the upper ocean thermohaline likely follows a different route into the subtropical gyre, possibly flowing northward in the interior and entering the Caribbean through the northern passages.

Wilson, W.D., W. Johns, and E. Johns. Atlantic-Caribbean water exchange: A quantitative summary of observations. Proceedings, Conference on the Transports and Linkages of the Intra-Americas Sea (IAS), Cozumel, Mexico, November 1-5, 1997. IOC/IOCARIBE/MMS, 65 (1998).

The need for good models of IAS circulation is growing as regional researchers seek input for studies of air-ocean-land interaction, climate variability, fisheries management, and pollution control. Proper boundary conditions will be essential to the operation and validation of these models. The water masses that enter, transit, and exit the IAS are determined by interaction between the Atlantic thermohaline and wind-driven circulations as well as regional modifications within the IAS itself. Existing data on transports into, within, and out of the IAS are quantitatively summarized to aid understanding of the IAS general circulation, provide initial conditions, and serve as benchmarks for model evaluation. Passages are categorized as inflows (passages of the Antilles and Bahamas), internal (Pedro Banks, Yucatan Channel, western Straits of Florida), or outflows (northern Straits of Florida). Inflow passages are further subdivided by geographic location (southern/northern); transport and water mass characteristics vary markedly between northern and southern due to their location relative to the western Atlantic gyre and wind field structure. Range of variability as well as mean flow values are estimated when possible, as this is important to evaluation of model dynamics. A significant result of this summary is a "best estimate" of mean transport distribution and variability by region, passage, and depth levels. These values are compared to transports derived from mean hydrographic and wind fields.

Wilson, W.D., D. Wallace, R. Olivacce, R.A. Watlington, and W.E. Johns. Monitoring the pulse of the DWBC in the Anegada Passage. Proceedings, Conference on the Transports and Linkages of the Intra-Americas Sea (IAS), Cozumel, Mexico, November 1-5, 1997. IOC/IOCARIBE/MMS, 63 (1998).

A serial station in the Anegada Passage, site of significant surface transport and of the deepest exchange between the Atlantic Ocean and the Caribbean Sea, is contributing to earlier observations at this location to provide a useful background against which variability of the Deep Western Boundary Current (DWBC) can be contrasted. Profiles of dissolved inorganic carbon, dissolved oxygen, chlorofluorocarbons, and standard hydrographic variables have successfully portrayed the several water masses transiting this location at depths down to 1900 m. Significantly, the southward advance of the prodigious flow Labrador Sea Water observed at Abaco is expected to manifest itself at this station within the coming year. ACTS is a project of the University of the Virgin Islands conducted in partnership with Brookhaven National Laboratory and the NOAA Atlantic Oceanographic and Meteorological Laboratory. The study, in itself, represents a successful collaborative model whereby long-term oceanic observations are conducted at minimal expense.

Yvon-Lewis, S.A., J.H. Butler, P.A. Matrai, E.S. Saltzman, D.B. King, R. Tokarczyk, K. Sullivan, B. Yocis, W. Grosko, and H. Wright. An investigation into the use of SeaWiFS data to study the biogeochemical cycling of methyl bromide. AGU 1998 Fall Meeting, San Francisco, CA, December 6-10, 1998. Supplement to EOS, Transactions, American Geophysical Union, 79(45):F429, OS11F-01 (1998).

The objectives of this study are to evaluate the effects of oceanic biological degradation and production of methyl bromide (CH₃Br) on its uptake by and emission from the ocean, to relate the derived parameters to satellite measurements of oceanic and atmospheric properties, and to evaluate the use of satellite data in modeling oceanic fluxes of this gas. Results of this study will have a direct, and likely significant, impact upon our understanding of the lifetime and budget of atmospheric methyl bromide and may be useful in future assessments of the budget of atmospheric CH₃Br as anthropogenic emissions decrease. The first step in this investigation was completed during a cruise in the North Atlantic in May and June 1998, where in-situ measurements of CH₃Br saturation anomalies and measurements of biological degradation and production rates for CH₃Br were made. Results from these measurements will be included in a global model if the production rates, degradation rates, and/or saturation anomalies can be linked to a property or properties that are recorded by satellite, particularly ocean color from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Here, we will present the preliminary results from the field measurements described above and results from our initial efforts to correlate these measurements with a SeaWiFS data product.

Zegowitz, V., and S.K. Cook. World Meteorological Organization-Volunteer Observing Ship Program. Proceedings, Ocean Community Conference '98, Baltimore, MD, November 16-19, 1998. Marine Technology Society, 6 pp. (1998).

As one of our astute, well-informed political figures said recently, "What do we need the Weather Service for, we have the Weather Channel!" Just where DOES the data come from to make a good marine forecast? Even those of you who have wandered here by mistake are about to be exposed to a little bit of information about a big contributor to this process, the World Meteorological Organization (WMO) Voluntary Observing Ship (VOS) program.

Zhang, J.-Z., and P.B. Ortner. Effect of thawing conditions on the recovery of reactive silicic acid from frozen natural water samples. Water Research, 32(8):2553-2555 (1998).

A method for thawing frozen samples for silicic acid analysis is recommended. The maximum recovery of silicic acid is achieved by thawing the frozen samples in a refrigerator (at 4°C) in the dark for at least four days. This method significantly improves the recovery of silicic acid from frozen fresh water samples. It also permits close to 100% recovery of reactive silicic acid from frozen seawater samples even after three months storage. **1997**

Aberson, S.D. Adaptive observations in a hurricane environment. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 308-309 (1997).

No abstract.

Aberson, S.D. Five-day statistical hurricane track forecasts. Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL, March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Support Research, Washington, D.C., A-3 (1997).

A dimensional analysis of five-day hurricane tracks is presented to calculate the number of predictors necessary to accurately predict tracks. While the dimensions of the hurricane tracks are large, statistical analyses can still be used as a benchmark by which other methods can be assessed. A new version of CLIPER is developed which eliminates problems with the original dependent data sets and extends the forecasts to five days. The new version updates the original CLIPER, which used data from 1930 through 1970, a time during which many tracks are conjecture and many are missed completely. The new version eliminates the Gulf of Mexico tropical cyclones from the Atlantic basin, and corrects for problems in the original Gulf of Mexico data. The new version also eliminates non-physical cross-terms in the multiple linear regression. Independent forecasts are made for the 1996 hurricane season and compared to the older version of the model. Model biases of the two versions are compared.

Aberson, S.D. The prediction of the performance of a nested barotropic hurricane track forecast model. Weather and Forecasting, 12(1):24-30 (1997).

Linear multiple regression and discriminant analyses provide estimates of the errors of track forecasts from a nested barotropic hurricane track forecast model (VICBAR), which was run in the North Atlantic Basin during the 1989-94 hurricane seasons. Predictors are determined from the synoptic situation, the magnitude of atmospheric changes in the environment of the tropical cyclone, the consistency between current and past predictions, and the past performance of the model for each particular storm. This technique distinguishes cases in which VICBAR performs well from those for which it performs poorly and can provide skillful operational predictions of model performance to forecasts.

Acero-Schertzer, C.E., D.V. Hansen, and M.S. Swenson. Evaluation and diagnosis of surface currents in the NCEP ocean analyses. Journal of Geophysical Research, 102(C9):21,037- 21,048 (1997).

Ensemble average currents from the 15 m depth level of the NCEP analyses of the tropical Pacific Ocean are evaluated against surface mixed layer current observations obtained from an extensive set of satellite-tracked drifting buoys. These averages display many climatological characteristics of the region, but are not intended to serve as a climatology because the data from the analyses are trimmed to match the time-space distribution of the observations. Substantial discrepancies between the analyses and the observations are revealed. First, the near-equatorial meridional currents and divergence have approximately twice the magnitude in the analyses as in the observations. This discrepancy is largely independent of whether temperature profile data are assimilated or not, and is attributed to the parameterization of vertical viscosity. Second, the zonal flow in both the NECC and the SEC is much stronger in the analyses than in the observations, especially in the western Pacific. This discrepancy is associated with assimilation of temperature profile data. It arises because salinity is an active variable in the underlying analysis model, but is not controlled by boundary fluxes or other observations. Under the uncontrolled influence of advection and strong horizontal diffusion, the salinity distribution becomes nearly homogeneous. Consequently, the analyses do not account for observed temperature-salinity correlations when density is computed following assimilation of temperature profile data. This leads to erroneous pressure gradients that drive excessively strong geostrophic currents and force large accelerations near the western boundary. Our results indicate that it is important to consider the consequences on the density structure of neglecting salinity during the assimilation of temperature data. We recommend that surface salinity observations from drifting buoys and volunteer observing ships be initiated to improve the ocean analyses.

Baringer, M.O., and J.F. Price. Mixing and spreading of the Mediterranean Outflow. Journal of Physical Oceanography, 27(8):1654-1677 (1997).

Hydrographic and expendable current profiler (XCP) data taken during the Gulf of Cadiz Expedition on September 21-27, 1988 were analyzed to diagnose the mixing, spreading, and descent of the Mediterranean Outflow. The theta/S properties and the thickness and width of the outflow were very similar to that seen in earlier surveys (for example, by Heezen and Johnson, 1969). The transport of pure Mediterranean water (S=38.4) was estimated to be about half a Sv, which is considerably lower than historical estimates, most of which were indirect, but comparable to other recent estimates made from direct velocity observations. The total outflow transport was about 0.7 Sv at the west end of the Strait of Gibraltar, and increased to about 1.9 Sv within the western Gulf of Cadiz. This increase in transport occurred by entrainment of fresher North Atlantic Central Water (NACW), and the salinity anomaly of the outflow was rapidly eroded. The velocity-weighted salinity decreased to 36.7 within 60 km of the Strait, during the initial descent of the continental slope, and decreased by about another 0.1 before the deeper portion of the outflow began to float off of the bottom near Cape St. Vincent. Entrainment appears to have been correlated with the occurrence of bulk Froude numbers slightly greater than 1. In the western Gulf of Cadiz, where entrainment was much weaker, Froude numbers were well below 1. The outflow began in the eastern Strait of Gibraltar as a narrow (10 km wide) current having a very narrow range of theta/S properties (theta varies by < 0.5°C). The outflow broadened as it descended the continental slope of the northern Gulf of Cadiz, and reached a maximum width of 90 km in the western Gulf of Cadiz. The descent of the outflow was very asymmetric: the offshore and downslope edge of the flow descends rapidly, while the onshore and shallower edge of the outflow descends slowly. The northern, nearshore side remained considerably higher in the water column and thus entrained relatively warm and salty NACW. This caused the outflow to develop horizontal theta/S variability and, by about 100 km downstream, the across-stream variation in temperature on an isopycnal was more than 2°C. Much of the volume transport in the western Gulf of Cadiz was contained in two preferred modes, often called cores, apparently because of topographic steering effects. The deeper, offshore core had a central sigma_theta = 27.8, and the shallower nearshore core, which was still in contact with the bottom in the Gulf of Cadiz, had a central sigma_theta = 27.5.

Baringer, M.O., and J.F. Price. Momentum and energy balance of the Mediterranean Outflow. Journal of Physical Oceanography, 27(8):1678-1692 (1997).

Hydrographic and expendable current profiler (XCP) data taken during the Gulf of Cadiz Expedition in September 1988 were analyzed to describe some aspects of the dynamics of the Mediterranean Outflow. During the initial descent of the continental slope, the outflow current executes a 90 degrees right turn that appears to be approximately inertial. The estimated geostrophic velocity greatly underestimated the actual current, and the estimated curvature Rossby number is about 0.5. A form of the Bernoulli function was evaluated to infer the total stress (entrainment stress and bottom drag) acting on the outflow. Total stress was as large as 5 Pa where the outflow begins to descend the continental slope and where currents were in excess of 1 m/s. The entrainment stress, estimated independently from property fluxes, reached a maximum of only about 1 Pa, which was less than the inferred bottom stress. By about 100 km downstream, the current was aligned approximately along the topography. The current amplitude and the estimated stress were much less, about 0.3 m/s and less than 0.5 Pa. The entrainment stress was very small in the region well downstream of the Strait. Bottom stress thus appears to be the crucial element in the dynamics of the Mediterranean Outflow, allowing or causing the outflow to descend some 1000 m into the North Atlantic. In the regions of strongest bottom stress the inferred drag coefficient was about 3 × 10^{- 3}. Entrainment stress was much smaller by comparison, but the entrainment effect upon the density anomaly was crucial in eroding the density anomaly of the outflow.

Black, M.L., and J.R. Parrish. The structure of the hurricane eyewall at altitudes reached by the NOAA Gulfstream-IV aircraft. Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL, March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-16 (1997).

Starting with the 1997 Atlantic hurricane season, the recently acquired and specially instrumented NOAA Gulfstream-IV (G-IV) jet aircraft will conduct synoptic reconnaissance missions in the periphery of tropical cyclones. The missions are designed to sample, via dropsondes, vertical profiles of the environmental air from flight altitudes of 40,000-45,000 ft. The flights are intended to avoid the convectively active eyewall and rainband regions of the storms. In future seasons, however, research and reconnaissance needs may warrant high altitude penetrations of the hurricane core. Before conducting flights directly into tropical cyclones, the structure of the deep convection, especially in the eyewall, needs to be assessed to determine the types of flight conditions the G-IV might experience. The purpose of this report is to use the remote-sensing capabilities of the NOAA WP-3D aircraft to document and describe the structure of the hurricane eyewall at high altitudes. Vertcally-pointing Doppler radials from the tail radars on the NOAA P-3 aircraft yield estimates of the two-dimensional (radius-height plane) reflectivity and vertical velocity structure. Observations from more than 200 radial legs through the eyewalls of tropical cyclones have shown that vertical velocity extrema with magnitudes >10 m/s can occur at heights up to 15 km, well above the maximum attainable altitude of the G-IV. These extrema occur infrequently (<10% chance) but can contain steep vertical velocity gradients that may produce moderate to severe turbulence, similar to that experienced by the P-3 aircraft at lower altitudes. Examples of the various types of vertical velocity structures that the G-IV may encounter in eyewall penetrations will be presented.

Black, M.L., R.W. Burpee, and F.D. Marks. The asymmetric distribution of vertical motions and precipitation in the hurricane eyewall. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 100-101 (1997).

No abstract.

Black, M.L., J.F. Gamache, H.E. Willoughby, C.E. Samsury, F.D. Marks, and R.W. Burpee. Airborne radar observations of shear-induced asymmetries in the convective structure of Hurricane Olivia (1994). Proceedings, 28th Conference on Radar Meteorology, September 9-12, 1997, Austin, TX. American Meteorological Society, Boston, 577-578 (1997).

The Hurricane Research Division of NOAA conducted dual aircraft experiments on successive days in eastern Pacific Hurricane Olivia. The flights occurred on 24 September 1994 while Olivia was intensifying and 25 September when the hurricane was initially at maximum intensity followed by a period of rapid filling. The data collected from the flights into Hurricane Olivia provide a unique opportunity to investigate and describe the interplay between environmental wind shear, eye-wall convection, and intensity changes. Radar systems on the WP-3D research aircraft recorded radar reflectivity from the horizontally-scanning, lower-fuselage (LF) radar (5-cm), and reflectivity and Doppler radials from the tail radar (3-cm) which scans in a plane perpendicular to the aircraft track. On September 24th, the hurricane was embedded in weak easterly shear and observations from the LF radar showed that the convection in Olivia's eyewall was highly asymmetric. The deepest convection and highest reflectivities were concentrated in the south and southeast portions of the eyewall, while the northern portions contained a stratiform-like precipitation structure. Vertical profiles of reflectivity and vertical velocity derived from vertically-pointing radials from the tail Doppler radar further describe the nature of these asymmetries. Large and strong updrafts were located just upwind of the heaviest precipitation while downward motion dominated in the eyewall region slightly downwind of the precipitation maximum. Much weaker and smaller up- and downdrafts existed in the low-reflectivity region of the northern eyewall. Olivia intensified during the 24-hour period between flights while the environmental shear was weak, ahead of a mid-tropospheric trough. On the 25th, when the aircraft first arrived near the center, Olivia's eyewall appeared on LF radar images as a highly symmetric, nearly continuous ring of high reflectivities (>40 dBZ). Doppler radar observations of the vertical velocity structure, however, still showed an asymmetric structure, albeit not as pronounced as the previous day. During the flight, westerly shear increased dramatically, Olivia's central pressure rose, and large asymmetries in the eyewall reflectivity field developed in an apparent response to the changing vertical wind shear. Olivia's weakening may also have been partially due to the storm moving over a region of cooler sea-surface temperatures. Convective cells with strong updrafts formed in the eastern eyewall (downshear), and advected around to the high-reflectivity region of the northern eyewall. Strong downdrafts appeared to form at high altitudes, adjacent to and slightly downwind of the large and strong updrafts, and rotated around the eyewall to the weak-reflectivity region of the western eyewall (upshear). Near the end of the flight, the magnitude of the updrafts decreased and the convective tops were lower in altitude, conditions that are consistent with a weakening hurricane.

Black, R.A. Giant raindrops observed from large aircraft. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 494-495 (1997).

No abstract.

Boebel, O., C. Schmid, and W. Zenk. Flow and recirculation of Antarctic Intermediate Water across the Rio Grande Rise. Journal of Geophysical Research, 102(C9):20,967-20,986 (1997).

The flow of the low-salinity Antarctic Intermediate Water (AAIW) at 700-1150 m depth across the Rio Grande Rise and the lower Santos Plateau is studied under the auspices of the World Ocean Circulation Experiment (WOCE) in the context of the Deep Basin Experiment. Our data set consists of several hydrographic sections, a collection of 15 RAFOS float trajectories, and records from 14 moored current meters. The data were gathered during different intervals between 1990 and 1994. The inferred flow field strongly supports a basinwide anticyclonic recirculation cell in the subtropical South Atlantic underneath the wind-driven gyre. Its center, which appears to be southeast of the Rio Grande Rise, separates the eastward advection of AAIW below the South Atlantic Current from the westward flowing, recirculating AAIW. The two near-shelf limbs closing the circumference of AAIW flow are formed in the east by the deep Benguela Current, potentially modulated by salty inflow of Indian Ocean Intermediate Water, and in the west by the Brazil Current system. Further important circulation elements are the Brazil-Falkland (Malvinas) Confluence Zone at 40°S and an unnamed divergence at 28°S close to the 1000 m isobath. The resulting broad southward flow of AAIW augments the share of modified, i.e., saltier, intermediate water in the source region of the South Atlantic Current, while the smaller northward flow marks the source of a narrow equatorward Western Intermediate Boundary Current, ultimately leaving the South Atlantic. This shelf-trapped jet is clearly documented in hydrographic data from 19°S and in nearby current meter records. The jet contrasts a sluggish flow across this latitude east of 35°W. A continuous flow of AAIW from its subpolar region in the southwestern Argentine Basin all along the western slope toward the equator appears unlikely between 35°S and 25°S.

Bringi, V.N., K.Knupp, A. Detwiler, L. Liu, I.J. Caylor, and R.A. Black. Evolution of a Florida thunderstorm during the Convection and Precipitation Experiment: The case of August 9, 1991. Monthly Weather Review, 125(9):2131-2160 (1997).

The relationships among kinematic, microphysical, and electric field properties within a multicell Florida thunderstorm are investigated using observations from three Doppler radar (one with multiple wavelength and polarization diversity capabilities), four instrumented penetrating aircraft, a surface-based electric field mill network, and other observation facilities. The storm was convectively active for about 1 h and at least five primary cells developed within the storm during this time, one of which went through three consecutive development cycles. The updrafts in this storm were 2-4 km wide, exhibited bubble-like evolution, and had lifetimes of 10-20 min. The maximum updraft determined by the multiple Doppler analysis was about
20 m s^-1. A differential reflectivity (Z_DR) "column," indicating regions containing millimeter-size raindrops, extending above the freezing level, was associated with each cell during its developing stages. This column reached altitudes exceeding 6 km (-8°C) in the stronger updrafts. As the Z_DR columns reached maximum altitude, a "cap" of enhanced linear depolarization ratio (LDR) and enhanced 3-cm wavelength attenuation (A3) formed, overlapping the upper regions of the Z_DR column. These parameters indicate rapid development of mixed-phase conditions initiated by freezing of supercooled raindrops. Lightning was observed only in the central and strongest convective cell. Electric fields exceeding 10 k V m^-1 were noted during aircraft penetrations in this as well as several other cells that did not produce lightning. Fields exceeding 1 k V m^-1 were noted by the instrumented aircraft at midcloud levels within a few minutes of development of mixed-phase conditions at these levels or aloft. The first intracloud lightning was detected by the surface field mill network within 5 min of development of mixed-phase conditions aloft in the first cycle of development in the central cell, and the first cloud-to-ground event was noted within 9 min of this development. Lightning continued through two additional cycles of updraft growth in this central region and diminished as the convection subsided after about 30 min. Aircraft-measured electric fields and lightning retrievals from the surface field meter network are consistent with a tendency for negative charge to accumulate above the 6.5 km (-12°C) level within regions of radar reflectivity maxima and for positive charge to accumulate in the anvil region well above 9 km (-30°C).

Butler, J.H., and S.A. Yvon-Lewis. Estimating lifetimes of atmospheric trace gases with respect to oceanic loss: Two approaches. AGU 1997 Spring Meeting, Baltimore, MD, May 27-30, 1997. Supplement to EOS,Transactions, American Geophysical Union, 78(17):S90, A42E-12 (1997).

The flux of a gas across the air-sea interface typically is estimated as the product of the air-sea, gas-transfer coefficient and the difference in the partial pressure of the gas between the water and the air. Although there is some uncertainty in the value and mechanism selected for the transfer coefficient, this approach is generally considered a reasonable way to evaluate the rate at which a gas passes between the ocean and the atmosphere. Problems can arise, however, when one tries to compute the partial lifetime of this gas in the atmosphere with respect to its loss in the ocean. So long as the gas is not produced in the ocean, this calculated flux can be used to derive a partial lifetime. However, if the gas is simultaneously produced and consumed in the ocean, the lifetime estimate calculated in this way will be too long. This can be accounted for if one considers that the calculated flux from the atmosphere to the ocean is a net flux and that it will change in opposition to changes in the atmospheric burden of the gas. In this sense, the ocean acts as a "buffer" for the gas in the atmosphere, yet the effect is calculable. An alternative approach, involving the separation of inward and outward fluxes, gets past the lifetime and emission problem and allows for an accurate calculation of the partial atmospheric lifetime. This approach also provides for the computation of emissions from undersaturated waters or uptake by supersaturated waters. Each approach is internally consistent and both can be used, along with information on other non-oceanic fluxes, to describe the budgets of atmospheric trace gases. However, each carries with it certain caveats and limitations that must be considered in constructing these budgets. This talk will address these issues, with specific emphasis on methyl bromide and other trace gases of interest in ozone depletion and global warming.

Carsey, T.P., D.D. Churchill, M.L. Farmer, C.J. Fischer, A.A. Pszenny, V.B. Ross, E.S. Saltzman, M. Springer-Young, and B. Bonsang. Nitrogen oxides and ozone production in the North Atlantic marine boundary layer. Journal of Geophysical Research, 102(D9):10,653-10,665 (1997).

Measurements of reactive nitrogen gases (NO, NO₂, NOy), as well as related chemical (O₃, CO, aerosol black carbon, radon, selected nonmethane hydrocarbons) and meteorological parameters, were made on board the R/V Malcolm Baldrige prior to and subsequent to the 1992 ASTEX (Atlantic Stratocumulus Transition Experiment) in the North Atlantic Ocean during June and July 1992. Results showed indications of well-defined plumes from North America and Europe from both chemistry and back trajectory data. Elevated ozone concentrations were also observed in air masses from uninhabited continental regions. Chemical and meteorological data were incorporated into a simple photochemical model in which ozone destruction predominated over generation. The principal reaction leading to ozone destruction was O(¹D) + H₂O - 2OH.

Checkley, D.M., P.B. Ortner, L.R. Settle, and S.R. Cummings. A continuous, underway fish egg sampler (CUFES). Fisheries Oceanography, 6(2):58-73 (1997).

We describe a method to sample the highly contagious distribution of pelagic fish eggs. CUFES, the continuous, underway fish egg sampler, consists of a submersible pump, concentrator, electronics, and sample collector. This system operates continuously and under nearly all sea conditions, providing a real-time estimate of the volumetric abundance of pelagic fish eggs at pump depth, usually 3 m. CUFES-derived estimates of volumetric abundance agree well with those from nets towed at pump depth and with a real abundance estimated from vertically-integrated plankton tows. CUFES has been used successfully to sample the eggs of menhaden, pinfish, sardine, and anchovy off the coasts of the eastern and western United States and South Africa. Two large patches of eggs of the Atlantic menhaden were sampled off North Carolina in winter 1993-1994, had a linear scale of 5-10 km, and were found in waters between the Gulf Stream and mid-shelf front. Spawning location may be related to bathymetry. CUFES is now being used to estimate spawner biomass by the Daily Egg Production Method. An optical plankton counter provided accurate estimates of the number of Atlantic menhaden eggs sampled by CUFES. Automation of egg counting in CUFES is under development.

Chelton, D.B., and A.M. Mestas-Nunez. The large-scale, wind-driven response of the North Pacific. International WOCE Newsletter, 25:3-6 (1997).

In this note, we present the results of an investigation of the validity of the time-varying Sverdrup balance in the North Pacific based on analysis of three years of: (1) a simple flat bottom Sverdrup model; (2) the primitive equation global ocean circulation model developed by the Parallel Ocean Program (POP) at the Los Alamos National Laboratory; and (3) observations of sea surface height (SSH) by the TOPEX/POSEIDON (T/P) altimeter. The three-year period considered here is October 1992 through November 1995. We conclude that much of the large-scale, low-frequency variability in the North Pacific can be accounted for by simple Sverdrup dynamics.

Chen, G., B. Chapron, J. Tournadre, K.B. Katsaros, and D. Vandemark. Global oceanic precipitation: A joint view by TOPEX and the TOPEX microwave radiometer. Journal of Geophysical Research, 102(C5):10,457-10,471 (1997).

The TOPEX/POSEIDEN mission offers the first opportunity to observe rain cells over the ocean by a dual-frequency radar altimeter (TOPEX) and simultaneously observe their natural radiative properties by a three-frequency radiometer (TOPEX microwave radiometer (TMR)). This work is a feasibility study aimed at understanding the capability and potential of the active/passive TOPEX/TMR system for oceanic rainfall detection. On the basis of past experiences in rain flagging, a joint TOPEX/TMR rain probability index is proposed. This index integrates several advantages of the two sensors and provides a more reliable rain estimate than the radiometer alone. One year's TOPEX/TMR data are used to test the performance of the index. The resulting rain frequency statistics show quantitative agreement with those obtained from the Comprehensive Ocean-Atmosphere Data Set (COADS) in the Intertropical Convergence Zone (ITCZ), while qualitative agreement is found for other regions of the world ocean. A recent finding that the latitudinal frequency of precipitation over the Southern Ocean increases steadily towards the Antarctic continent is confirmed by our result. Annual and seasonal precipitation maps are derived from the index. Notable features revealed include an overall similarity in rainfall pattern from the Pacific, the Atlantic, and the Indian Oceans and a general phase reversal between the two hemispheres, as well as a number of regional anomalies in terms of rain intensity. Comparisons with simultaneous Global Precipitation Climatology Project (GPCP) multisatellite precipitation rates and COADS rain climatology suggest that systematic differences also exist. One example is that the maximum rainfall in the ITCZ of the Indian Ocean appears to be more intensive and concentrated in our result compared to that of the GPCP. Another example is that the annual precipitation produced by TOPEX/TMR is constantly higher than those from GPCP and COADS in the extratropical regions of the northern hemisphere, especially in the northwest Pacific Ocean. Analyses of the seasonal variations of prominent rainy and dry zones in the tropics and subtropics show various behaviors such as systematic migration, expansion, and contraction, merging and breakup, and pure intensity variations. The seasonality of regional features is largely influenced by local atmospheric events such as monsoon, storm, or snow activities. The results of this study suggest that TOPEX and its follow-on may serve as a complementary sensor to the special sensor microwave/imager in observing global oceanic precipitation.

Chereskin, T.K., W.D. Wilson, H.L. Bryden, A. Ffield, and J. Morrison. Observations of the Ekman balance at 8°30'N in the Arabian Sea during the 1995 southwest monsoon. Geophysical Research Letters, 24(21):2541-2544 (1997).

The Ekman transport is estimated from two sets of hydrographic and shipboard acoustic Doppler current profiler (ADCP) velocity observations made during June and September 1995, during the southwest monsoon in the Arabian Sea. Both sets of measurements were made along latitude 8°30'N, designated as World Ocean Circulation Experiment (WOCE) line I1W, from Somalia to Sri Lanka. The Ekman transport estimates calculated from ageostrophic velocity were southward: 17.6 ± 2.4 10⁶ m³ s^-1 in June and 7.9 ± 2.7 10⁶ m³ s^-1 in September. These direct estimates were in good agreement with those predicted by the Ekman balance using both shipboard and climatological winds. The vertical structure of the ageostrophic velocity and the stratification were quite different between the two occupations of the transect. The wind-driven momentum was confined to a very shallow layer in June (about 50 m) and the surface layer was strongly stratified, with a maximum salinity layer at depths between 50 and 70 m. The ageostrophic velocity penetrated much deeper in September (to about 160 m) and the pycnocline was correspondingly deeper. In both cases, the Ekman transport penetrated beneath the mixed layer, to the top of the pycnocline.

Cione, J.J., and S. Raman. The impact of SST gradients on propagating low-level mesovortices near the Gulf Stream. Preprints, Conference on Coastal Oceanic and Atmospheric Prediction, Atlanta, GA, January 28- February 2, 1996. American Meteorological Society, Boston, 204-211 (1997).

No abstract.

DeMaria, M., and J. Kaplan. An operational evaluation of a statistical intensity prediction scheme (SHIPS). Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 280-281 (1997).

No abstract.

Dietrich, D.E., C.A. Lin, A.M. Mestas-Nunez, and D.-S. Ko. A high resolution numerical study of Gulf of Mexico fronts and eddies. Meteorology and Atmospheric Physics, 64:187-201 (1997).

The Gulf of Mexico (GOM) circulation is simulated using the DieCAST ocean model, with a horizontal resolution of 1/12 degree and 20 vertical layers. The results compare well with observations of both large and small scale features, including Loop Current frontal occlusions associated with frontal eddies. The simulation is carried out without any data assimilation. The frontal eddies tend to be spaced at about 90 degree intervals around the Loop Current, leading to a Loop Current head shaped like a square with rounded corners. The pattern rotates as eddies circle the Loop, and frontal eddies elongate as they squeeze through the Florida Strait. Major warm core eddies separate regularly from the Loop Current and propagate to the western GOM. Old warm core eddies in the western Gulf dissipate through bottom drag effects, which also generate cyclonic parasitic eddies. Newly arrived warm core eddies merge with old ones in the western GOM. Recently separated elongated Loop Current eddies can rotate and reattach temporarily to the Loop Current. The barotropic flow component develops eddies between the main separated warm core eddy and the Loop Current due to eastward dispersion, as the main eddy itself propagates westward into the Gulf.

Dodge, P.P., S.H. Houston, and J.F. Gamache. Three-dimensional windfields in Hurricane Fran (1996) at landfall. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 115-116 (1997).

No abstract.

Dodge, P.P., S.H. Houston, and J.F. Gamache. Windfields in Hurricane Fran (1996) at landfall from combined WSR-88D and airborne Doppler radar data. Proceedings, 28th Conference on Radar Meteorology, Austin, TX, September 9-12, 1997. American Meteorological Society, Boston, 575-576 (1997).

The Hurricane Research Division's (HRD) Tropical Cyclone Windfields at Landfall Experiment collects data in landfalling tropical cyclones from NOAA aircraft to improve real-time and post- storm surface wind analyses that are prepared by HRD. The real-time analyses are provided to forecasters at the Tropical Prediction Center. Airborne Doppler radar data are combined with National Weather Service WSR-88D radar data in three-dimensional analyses to document the evolution of tropical cyclones at landfall, and to provide corroborating data for testing WSR-88D tropical cyclone algorithms. From 2056 UTC, 5 September 1996, to 0348, 6 September 1996, the NOAA research aircraft RF42 flew in Hurricane Fran as it moved ashore in North Carolina. A "figure 4" pattern at 5,000 ft, overflights of marine and coastal surface platforms, and several passes along radials from the Wilmington and Morehead City WSR-88D radars in North Carolina provided flight-level wind data that were included in HRD's surface wind analyses. The research flight concluded with an overland "figure 4" pattern at 14,000 ft that passed near the Raleigh WSR-88D, and then through Fran's center when it was 70 km north-northwest of the Wilmington WSR-88D. The portable Doppler radar on wheels from the University of Oklahoma also recorded data at the Wilmington airport during the landfall, so there is a rich data set to describe convective and mesoscale features in Hurricane Fran. At the conference, we will present windfields synthesized from the airborne and WSR-88D radars that describe the kinematic structure as Fran moved over the coast. The comparison of vertical structure of the wind fields near the coast and 200 km inland should be particularly interesting. We will also discuss the problems of combining airborne and ground-based Doppler radar data.

Donelan, M.A., W.M. Drennan, and K.B. Katsaros. The air-sea momentum flux conditions of wind sea and swell. Journal of Physical Oceanography, 27(10):2087-2099 (1997).

During the Surface Wave Dynamics Experiment, direct measurements of momentum, heat, and water vapor fluxes were obtained from a mast on the foredeck of a SWATH (small water-plane area, twin hull) ship in deep water off the state of Virginia. Directional wave spectra were obtained simultaneously from a six or three-wire wave-staff array mounted at the bow of the ship. One hundred and twenty-six 17-minute runs of flux and wave data obtained with the ship steaming slowly into the wind are examined for the effects of the relative direction of the wind sea and background swell on the momentum transfer. The adequacy of the inertial dissipation method, which depends on the high-frequency turbulent fluctuations for evaluating the wind stress, is also examined for any effects of swell. The results show that the presence of counter- and cross-swells can result in drag coefficients that are much larger than the value for a pure wind sea. The eddy correlation and inertial dissipation methods for measuring wind stress are found to diverge during the complex sea conditions. The authors interpret the latter observations as an indication that the traditional inertial dissipation method, in which the pressure and transport terms in the kinetic energy balance equation are assumed to be in balance, may be unsuitable for use in a marine boundary layer disturbed by swell.

Drennan, W.M., M.A. Donelan, E.A. Terray, and K.B. Katsaros. On waves, oceanic turbulence, and their interaction. Geophysica, 33:17-28 (1997).

No abstract.

Dupuis, H., P.K. Taylor, A. Weill, and K.B. Katsaros. Inertial dissipation method applied to derive turbulent fluxes over the ocean during the Surface of the Fluxes and Interactions with the Atmosphere/Atlantic Stratocumulus Transition Experiment (SOFIA/ASTEX) and Structure des Echanges Mer-Atmosphere, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) experiments with low to moderate wind speeds. Journal of Geophysical Research, 102(C9):21,115-21,129 (1997).

The transfer coefficients for momentum and heat have been determined for 10 m neutral wind speeds (U_10n) between 0 and 12 m/s using data from the Surface of the Ocean, Fluxes and Interactions with the Atmosphere (SOFIA) and Structure des Echanges Mer-Atmosphere, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) experiments. The inertial dissipation method was applied to wind and pseudo virtual temperature spectra from a sonic anemometer, mounted on a platform (ship) which was moving through the turbulence field. Under unstable conditions the assumptions concerning the turbulent kinetic energy (TKE) budget appeared incorrect. Using a bulk estimate for the stability parameter, Z/L (where Z is the height and L is the Obukhov length), this resulted in anomalously low drag coefficients compared to neutral conditions. Determining Z/L iteratively, a low rate of convergence was achieved. It was concluded that the divergence of the turbulent transport of TKE was not negligible under unstable conditions. By minimizing the dependence of the calculated neutral drag coefficient on stability, this term was estimated at about -0.65 Z/L. The resulting turbulent fluxes were then in close agreement with other studies at moderate wind speed. The drag and exchange coefficients for low wind speeds were found to be C_en × 10³ = 2.79 U_10n^-1 + 0.66 (U_10n < 5.2 m/s), C_en × 10³ = C_hn × 10³ = 1.2 (U_10n > 5.2 m/s), and C_dn × 10³ = 11.7 U_10n^-2 + 0.668 (U_10n < 5.5 m/s), which imply a rapid increase of the coefficient values as the wind decreased within the smooth flow regime. The frozen turbulence hypothesis and the assumptions of isotropy and an inertial subrange were found to remain valid at these low wind speeds for these shipboard measurements. Incorporation of a free convection parameterization had little effect.

Elfouhaily, T., B. Chapron, K.B. Katsaros, and D. Vandemark. A unified directional spectrum for long and short wind-driven waves. Journal of Geophysical Research, 102(C7):15,781-15,796 (1997).

Review of several recent ocean surface wave models finds that while comprehensive in many regards, these spectral models do not satisfy certain additional, but fundamental, criteria. We propose that these criteria include the ability to properly describe diverse fetch conditions and to provide agreement with in-situ observations of Cox and Munk (1954), Jahne and Riemer (1990), and Hara et al. (1994) data in the high-wavenumber regime. Moreover, we find numerous analytically undesirable aspects such as discontinuities across wavenumber limits, nonphysical tuning or adjustment parameters, and noncentrosymmetric directional spreading functions. This paper describes a two-dimensional wavenumber spectrum valid over all wavenumbers and analytically amenable to usage in electromagnetic models. The two regime model is formulated based on the Joint North Sea Wave Project (JONSWAP) in the long-wave regime and on the work of Phillips (1985) and Kitaigorodskii (1973) at the high wavenumbers. The omnidirectional and wind-dependent spectrum is constructed to agree with past and recent observations including the criteria mentioned above. The key feature of this model is the similarity of description for the high- and low-wavenumber regimes; both forms are posed to stress that the air-sea interaction process of friction between wind and waves (i.e., generalized wave age, u/c) is occurring at all wavelengths simultaneously. This wave age parameterization is the unifying feature of the spectrum. The spectrum's directional spreading function is symmetric about the wind direction and has both wavenumber and wind speed dependence. A ratio method is described that enables comparison of this spreading function with previous noncentrosymmetric forms. Radar data are purposefully excluded from this spectral development. Finally, a test of the spectrum is made by deriving roughness length using the boundary layer model of Kitaigorodskii. Our inference of drag coefficient versus wind speed and wave age shows encouraging agreement with Humidity Exchange Over the Sea (HEXOS) campaign results.

Enfield, D.B., and D.A. Mayer. Tropical Atlantic sea surface temperature variability and its relation to El Niño-Southern Oscillation. Journal of Geophysical Research, 102(C1):929-945 (1997).

Past analyses of tropical Atlantic sea surface temperature variability have suggested a dipole behavior between the northern and southern tropics, across the Intertropical Convergence Zone (ITCZ). By analyzing an improved 43-year (1950-1992) record of SST (Smith et al., 1996) and other data derived from the Comprehensive Ocean-Atmosphere Data Set (COADS), it is shown that the regions north and south of the ITCZ are statistically independent of each other at the seasonal to interannual time scales dominating the data, confirming the conclusions of Houghton and Tourre (1992). Some dipole behavior does develop weakly during the boreal spring season, when there is a tendency for SST anomaly west of Angola to be opposite of that in the tropical North Atlantic. It is further shown that tropical Atlantic SST variability is correlated with Pacific El Niño-Southern Oscillation (ENSO) variability in several regions. The major region affected is the North Atlantic area of northeast trades west of 40°W along 10°N-20°N and extending into the Caribbean. There, about 50-80% of the anomalous SST variability is associated with the Pacific ENSO, with Atlantic warmings occurring 4-5 months after the mature phases of Pacific warm events. An analysis of local surface flux fields derived from COADS data show that the ENSO-related Atlantic warmings occur as a result of reductions in the surface northeast trade wind speeds, which in turn reduce latent and sensible heat losses over the region in question, as well as cooling due to entrainment. This ENSO connection is best developed during the boreal spring following the most frequent season of maximum ENSO anomalies in the Pacific. A region of secondary covariability with ENSO occurs along the northern edge of the mean ITCZ position and appears to be associated with northward migrations of the ITCZ when the North Atlantic warmings occur. Although easterly winds are intensified in the western equatorial Atlantic in response to Pacific warm events, they do not produce strong local changes in SST. Contrary to expectations from studies based on equatorial dynamics, these teleconnected wind anomalies do not give rise to significant correlations of SST in the Gulf of Guinea with the Pacific ENSO. As the teleconnection sequence matures, strong southeast trades at low southern latitudes follow the development of the North Atlantic SST anomaly and precede by several months the appearance of weak negative SST anomalies off Angola and stronger positive anomalies extending eastward from southern Brazil along 15°-30°S.

Enfield, D.B., and A.M. Mestas-Nunez. Global modes of ENSO and non-ENSO sea surface temperature variability. AGU 1997 Fall Meeting, San Francisco, CA, December 8-12, 1997. Supplement to EOS, Transactions, American Geophysical Union, 78(46):F349, OS21D-05 (1997).

El Niño-Southern Oscillation (ENSO) is a global phenomenon with significant phase propagation within and between basins, which we capture and describe in the first mode of a complex empirical orthogonal function (CEOF) analysis of sea surface temperature anomaly (SSTA) from the mid-19th century through 1992. We subsequently remove the global ENSO from the SSTA data, plus a linear trend everywhere, in order to consider other global modes of variability uncontaminated by the intra- and inter-basin effects of ENSO. An ordinary EOF analysis of the SSTA residuals reveals three non-ENSO modes of low-frequency variability that are related to slow oceanic and climate signals described in the literature. The first two modes both have an interdecadal time scale with high loadings in the Pacific; they bear some spatial similarities to the ENSO pattern but are broader and differ in the time domain. A CEOF analysis confirms that they are not merely the phase-related components of a single mode and that all three modes are without significant phase propagation. The third mode is a multidecadal signal with maximal realization in the extratropical North Atlantic southeast of Greenland. It also has high loadings in the tropical Atlantic, anticorrelated across the intertropical convergence zone (ITCZ), and strong variability of opposite sign in the eastern tropical Pacific. All three modes have significant loadings over the central and/or eastern equatorial Pacific. Temporal extrema in the first and third modes during 1982-1983 explain the large magnitude of that ENSO event, which in the global ENSO mode is large but equalled or exceeded by four other events.

Faber, T., L.K. Shay, S.D. Jacob, S.H. Houston, and P.G. Black. Observed air-sea interactions during Hurricane Emily. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 433-434 (1997).

No abstract.

Feely, R.A., R.H. Wanninkhof, C. Goyet, D.E. Archer, and T. Takahashi. Variability of CO₂ distributions and sea- air fluxes in the central and eastern equatorial Pacific during the 1991-1994 El Niño. Deep-Sea Research II, 44(9-10):1851-1867 (1997).

As part of the U.S. JGOFS Program and the NOAA Ocean-Atmosphere Carbon Exchange Study (OACES), measurements of CO₂ partial pressure were made in the atmosphere and in the surface waters of the central and eastern equatorial Pacific during the boreal spring and autumn of 1992, the spring of 1993, and the spring and autumn of 1994. Surface-water pCO₂ data indicate significant diurnal, seasonal, and interannual variations. The largest variations were associated with the 1991-1994 ENSO event, which reached maximum intensity in the spring of 1992. The lower values of surface-water DELTApCO₂ observed during the 1991-1994 ENSO period were the result of the combined effects of both remotely and locally forced physical processes. The warm pool, which reached a maximum eastward extent in January-February of 1992, began in September of 1991 as a series of westerly wind events lasting about 30 days. Each wind event initiated an eastward-propagating Kelvin wave which caused a deepening of the thermocline. By the end of January 1992 the thermocline was at its maximum depth, so that the upwelled water was warm and CO₂-depleted. In April of the same year, the local winds were weaker than normal, and the upwelling was from shallow depths. These changes resulted in a lower-than-normal CO₂ flux to the atmosphere. The results show that for the one-year period from the fall of 1991 until the fall of 1992, approximately 0.3 GtC were released to the atmosphere; 0.6 GtC were released in 1993, and 0.7 GtC in 1994, in good agreement with the model results of Ciais et al. (Science, 269, 1098-1102; J. Geophys. Res., 100, 5051-5070). The net reduction of the ocean-atmosphere CO₂ flux during the 1991-1994 El Niño was on the order of 0.8-1.2 GtC. Thus, the total amount of CO₂ sequestered in the equatorial oceans during the prolonged 1991-1994 El Niño period was about 25% higher than the severe El Niño of 1982-1983.

Festa, J.F., and R.L. Molinari. Comparison of thermal statistics derived from observational data sets in the tropical Atlantic and Pacific Oceans. NOAA Technical Memorandum, ERL AOML-91 (PB97-208177), 78 pp. (1997).

Statistical analysis of surface and subsurface temperature data in the tropical Atlantic and Pacific Oceans is presented. The statistics were estimated from the Comprehensive Ocean-Atmospheric Data Set (COADS) and the historical expendable bathythermograph (XBT) observations. Spatial structure functions (semivariograms) for the anomaly fields of sea surface temperature and the temperature at 200 m and 400 m were estimated for a 2 degree by 2 degree grid in the tropical oceans. Dominant scales of spatial variability are identified and compared with other investigations.

Ffield, A., J. Toole, and W.D. Wilson. Seasonal circulation in the South Indian Ocean. Geophysical Research Letters, 24(22):2773-2776 (1997).

Two World Ocean Circulation Experiment hydrographic cruises in March and June 1995, along with Topex-Poseidon altimeter data and National Meteorological Center wind data, are used to estimate seasonal changes in the South Indian Ocean subtropical gyre. Mean annual curves derived from the altimeter and wind data reveal strengthening of the anticyclonic gyre in March and September, and weakening in June and December. The seasonal changes correspond to variations in the wind field south of 30 S at the equinoxes and solstices. In addition, the wind-driven gyre is further north in July, and further south in March. These variations in strength and location of the South Indian Ocean gyre may influence inter-ocean transports south of Africa. Despite the inferred mean annual seasonal variations in the South Indian Ocean gyre, volume transports estimated in 1995 from the hydrographic data are close to mean values. Apparently, a mesoscale eddy in March disrupts the stronger fall gyre, whereas in June the weaker winter gyre is delayed by 1 month.

Gamache, J.F. Evaluation of a fully three-dimensional variational Doppler analysis technique. Proceedings, 28th Conference on Radar Meteorology, Austin, TX, September 9-12, 1997. American Meteorological Society, Boston, 422-423 (1997).

A method is described that deduces the three-dimensional wind field from two or more independent Doppler observations and from the continuity equation, using a simultaneous three-dimensional variational solution of the Doppler projection equations and the continuity equation. The solution minimizes a cost function that includes (1) the difference between observed Doppler radial velocities (corrected for precipitation fall speed) and the projection of the analysis velocities upon the observed Doppler pointing angles, (2) the error in the discretized continuity equation, and (3) and the difference between a velocity component and the surrounding six grid points. The third part of the cost function is included to quiet noise in the solution. A much higher weight is given to the second term since it represents the solution to the continuity equation at only one grid cell. Otherwise, when all grid cells are combined there would be substantial "leakage" in the continuity equation. Errors in the discretized continuity equation are less than 10^-6 s^-1 at individual grid points. Analytical wind fields will be resampled and the ability of the variational analysis to repeat the analytical field will be discussed at the conference. The technique has already been applied to the core of several hurricanes, convection within a developing tropical storm, and several cases in TOGA COARE. By the time of the conference it may also have been applied to a VORTEX case. Bubble-like features have been seen in several of these cases, and the bubble locations are very consistent with the radar reflectivity presentation. Several of these examples will be shown at the conference.

Gamache, J.F. Wind shear and sea surface temperature in hurricanes observed by airborne Doppler radar. Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL, March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-17-A-18 (1997).

The relationships between sea surface temperature (SST), vertical wind shear, and hurricane structure and intensity change are described for two eastern Pacific hurricanes. Two NOAA WP-3D Doppler-equipped aircraft observed Hurricane Jimena on 23 September 1991 and Hurricane Olivia on 24 and 25 September 1994. Aircraft flight tracks were coordinated for optimum Doppler wind analysis of inner core (radius <30 km) winds. Hurricane Jimena maintained virtually steady intensity for 24 hours, while Hurricane Olivia deepened 1-2 mb/hr during the mission on the 24th and filled at 3 mb/hr during the mission on the 25th. The missions yielded four wind analyses in Hurricane Jimena and seven for each of the two days in Olivia. The average interval between analyses is about 35 minutes. At the time of the mission, Jimena was located at 13.3°N, 109.6°W over warm tropical waters. The shear between 1 and 10 km was southeast at 15 m/s, and the hurricane remained at a nearly constant intensity. Hurricane Olivia intensified into a hurricane early on 24 September 1994. As the aircraft first reached Olivia, it was located near 15.2°N,118.0°W. During three hours on station the central pressure decreased by about 6 mb. The hurricane had a mean shear during the mission of east at 7 m/s between 1 and 9 km, and the asymmetric distribution of greater precipitation to the south was sustained throughout the mission. During the 24th the hurricane traveled west-northwestward and was over warm tropical water (28.2°C). As the aircraft began their penetrations on 25 September, Olivia was near its maximum intensity. The radar presentation was highly symmetric, and the shear between 1 and 9 km was 3 m/s from the west. In three hours the shear had increased to 15 m/s from west-northwest, and are highly asymmetric precipitation pattern had developed with dBZ greater than 50 seen to the north of center and nothing above 40 dBZ to the south of center. Mean winds at the 9-km level decreased by 15 m/s. The role of shear in producing this change may be confused by Olivia passing the SST front as it travelled nearly northward at 5 m/s, so the SST by the end of the mission was 27°C. Another interesting feature that may be described at the Interdepartmental Conference is a highly convective feature in the northeast eyewall late on 25 September in Olivia that had an elevated echo maximum and apparently a low-reflectivity vault where the strongest updrafts were. Analysis has just begun of this feature. Hopefully, it will be described at the next conference.

Gamache, J.F., H.E. Willoughby, M.L. Black, and C.E. Samsury. Wind shear, sea surface temperature, and convection in hurricanes observed by airborne Doppler radar. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 121-122 (1997).

No abstract.

Garzoli, S.L., G.J. Goni, A.J. Mariano, and D.B. Olson. Monitoring the upper southeastern Atlantic transports using altimeter data. Journal of Marine Research, 55(3):453-481 (1997).

A large in-situ data set, collected in the southeastern Atlantic Ocean, is merged with the TOPEX/POSEIDON altimeter observations in order to verify the use of altimeter data in monitoring the transports of the Agulhas/Benguela system. Comparisons between altimeter observations and either moored current meters or inverted echo sounder measurements shows that the sea surface elevation anomaly is significantly correlated with the thermocline depth and the surface dynamic height, respectively. Knowing the least-squares regression parameters, it is possible to calculate the transports by using geostrophy and either a two-layer or a continuously-stratified model. The transports obtained from fits of dynamic height to altimeter sea surface height are similar to the ones calculated with the moored instruments. In the southern part of the area under analysis, around 35°S, close to the Agulhas retroflection, the transports obtained from the two-layer model are overestimated. Across the Benguela Current, at 30°S, transports are still overestimated but of the same order as the measured ones. In this part of the region, the two-layer model can be successfully used to calculate the total and barotropic transports of the Benguela Current. Analysis of the three years of geostrophic transport obtained from the altimeter data indicate that the mean Benguela Current transport does not change interannually more than 20%. However, the primary interannual variability derives from the source water that forms the Benguela Current.

German, C.R., D.L. Bourles, E.T. Brown, J. Hergt, S. Colley, N.C. Higgs, E.M. Ludford, T.A. Nelsen, R.A. Feely, G. Raisbeck, and F. Yiou. Hydrothermal scavenging on the Juan de Fuca Ridge: ²³⁰Th_xs, ¹⁰Be, and REE in ridge-flank sediments. Geochimica et Cosmochimica Acta, 61(19):4067-4078 (1997).

We have investigated the geochemistry of a hydrothermally-enriched sediment core recovered from the western flank of the N.Cleft Segment, Juan de Fuca Ridge, 8 km west of the "MegaPlume" area previously identified near 45°N. The core contains varying biogenic, lithogenic, and hydrothermal components, as reflected in CaCO₃, Al, and Fe contents, respectively. Horizons of pronounced hydrothermal input, in core-top sediments and at depth, exhibit increased concentrations of Fe, Cu, Zn, Pb, and shifts in Pb isotopic compositions toward nonradiogenic (MORB/hydrothermal) values. REE concentrations co-vary with hydrothermal Fe down-core, and shale-normalized REE distributions patterns exhibit both negative Ce-anomalies and positive Eu-anomalies, indicative of input from plume-particle fall-out. Unsupported ²³⁰Th_xs activities down-core are consistent with continuous slow sediment accumulation rates of 0.54 cm/ky for 200 ky since the deposition of the deeper Fe-rich horizon. ¹⁰Be₍₀₎ and ⁹Be isotope concentrations also co-vary with hydrothermal Fe down-core and exhibit ¹⁰Be₍₀₎ ⁹Be ratios which approach that of Pacific Ocean deep water, indicative of a seawater-scavenging source. ¹⁰Be₍₀₎ ²³⁰Th_xs(0) ratios throughout most of Core GC88-6 are greater than mean Pacific Ocean values, indicating that hydrothermal scavenging can lead to significant net removal of dissolved ¹⁰Be into ridge-flank sediments.

Goldenberg, S.B., C.W. Landsea, and L.J. Shapiro. Are we seeing the beginning of a long-term upturn in Atlantic basin major hurricane activity? Proceedings, Tropical Cyclone Symposium, Melbourne, Australia, December 9-13 1996. U.S. Office of Naval Research, 10 pp. (1997).

No abstract.

Goldenberg, S.B., L.J. Shapiro, and C.W. Landsea. Are we seeing a long-term upturn in Atlantic basin major hurricane activity related to decadal-scale SST fluctuations? Preprints, 7th Conference on Climate Variations, Long Beach, CA, February 2-6, 1997. American Meteorological Society, Boston, 305-310 (1997).

No abstract.

Goldenberg, S.B., L.J. Shapiro, and C.W. Landsea. Mounting evidence for a decadal-scale upturn in Atlantic basin tropical cyclone activity. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 507-508 (1997).

No abstract.

Goldenberg, S.B., L.J. Shapiro, and C.W. Landsea. The hyperactive 1995 Atlantic hurricane season: Just a spike or a harbinger of things to come? Proceedings, 21st Climate Diagnostics and Prediction Workshop, Hunstville, AL, October 28-November 1, 1996. American Meteorological Society, Boston, 9-12 (1997).

For over 25 years the North Atlantic hurricane basin has experienced a relative lull in tropical cyclone activity, in particular, in major hurricane (maximum sustained surface winds of at least 50 m/s) activity and in overall activity in the deep tropics. After the experience of renewed "normal" activity in 1988 and 1989, it was suggested that the Atlantic basin was returning to a long-term period of higher activity such as what was experienced back in the decades of the 1950s and 1960s and some earlier periods. The renewed activity in 1988 and 1989 was followed, however, by a marked downturn in activity from 1991 to 1994. In fact, the inhabitants of the regions surrounding the Caribbean experienced no hurricanes from 1990-1994. As a result of the resumption of the below-normal activity, primarily attributed to the highly anomalous, long-lasting warm event (El Niño) in the tropical Pacific, the notion that the Atlantic basin had entered a high-activity decade was pretty much discarded. The warm event in the Pacific finally ended in early 1995 and was followed by one of the most active hurricane seasons in the Atlantic on record, including renewed activity in the Caribbean, and with almost every measure of activity over twice the long-term mean. Of particular note was that the season produced five major hurricanes for the first time since 1964. Most of the major hurricanes in the North Atlantic basin form from easterly (African) wave disturbances and are especially sensitive to fluctuations in the tropical climate on the interannual and interdecadal time scales. The chief issue that will be addressed in the current study is whether or not the activity of the 1995 season was simply an anomalous "spike" or a harbinger of longer-term climate shifts signaling the probability of greater activity over the next decade or so.

Goldenberg, S.B., L.J. Shapiro, and C.W. Landsea. The hyperactive 1995 Atlantic hurricane season: A spike or a harbinger of things to come? Workshop Proceedings, Climate Change and Climate Variability in the Atlantic, Halifax, Nova Scotia, December 3-6, 1996. American Meteorological Society, Boston, 113-119 (1997).

No abstract.

Goni, G.J., S.L. Garzoli, A.J. Roubicek, D.B. Olson, and O.B. Brown. Agulhas ring dynamics from TOPEX/POSEIDON satellite altimeter data. Journal of Marine Research, 55(5):861-883 (1997).

The transfer of warm water from the Indian Ocean into the South Atlantic subtropical gyre takes place in the form of rings and filaments formed when the Agulhas Current retroflects south of Africa between 15°E and 25°E. A survey of the rings formed from September 1992 until December 1995 in the retroflection region was carried out using TOPEX/POSEIDON altimeter data. A two-layer model was used to estimate the upper layer thickness from the altimeter-derived sea surface height anomaly data. An objective analysis scheme was used to construct a map of upper layer thickness every 10 days. Seventeen rings and their trajectories were identified using these maps. The shedding of rings from the Agulhas Current was neither continuous nor periodic, and for long periods there is no formation of rings. Several rings remained in the region for more than a year and, at any given time, two to six rings coexisted in the region east of the Walvis Ridge. The results showed that the number of rings translating simultaneously in this region is larger during the first half of each year. The upper layer transport of the Agulhas Current in the retroflection region was computed and a close association between high variations in transport and ring shedding was found. Rings translated west-northwest at translation speeds ranging from 5-16 km day^-1 following formation. The values of available potential energy computed for the rings place them among the most energetic rings observed in the world oceans, with values of up to 70 × 10¹⁵ J. Transport computations indicate that each ring contributes in the average approximately 1 Sv of Agulhas Current waters to the Benguela Current.

Gordon, A.L., S. Ma, D.B. Olson, P. Hacker, A. Ffield, L.D. Talley, W.D. Wilson, and M.O. Baringer. Advection and diffusion of Indonesian throughflow within the Indian Ocean South Equatorial Current. Geophysical Research Letters, 24(21):2573-2576 (1997).

Warm, low salinity Pacific water weaves through the Indonesian Seas into the eastern boundary of the Indian Ocean. The Indonesian Throughflow Water (ITW) adds freshwater into the Indian Ocean as it spreads by the advection and diffusion within the Indian Ocean's South Equatorial Current (SEC). The low salinity throughflow trace, centered along 12°S, stretches across the Indian Ocean, separating the monsoon dominated regime of the northern Indian Ocean from the more typical subtropical stratification to the south. ITW is well represented within the SEC thermocline, extending with concentrations above 80% of initial characteristics from the sea surface to 300-m within the eastern half of the Indian Ocean, with 60% concentration reaching well into the western Indian Ocean. The ITW transport within the SEC varies from 4 to 12 × 10⁶ m³ sec^-1, partly in response to variations of the injection rate at the eastern boundary and to the likelihood of a zonally elongated recirculation cell between the Equatorial Counter Current and the SEC within the Indian Ocean. Lateral mixing disperses the ITW plume meridionally with an effective isopycnal mixing coefficient of 1.1 to 1.6 × 10⁴ m² sec^-1.

Gray, W.M., J.D. Sheaffer, and C.W. Landsea. Climate trends associated with multi-decadal variability of Atlantic hurricane activity. In Hurricanes, Climate, and Socioeconomic Impacts, H.F. Diaz and R.S. Pulwarty (eds.). Springer, Berlin, 15-53 (1997).

No abstract.

Haddad, Z.S., D.A. Short, S.L. Durden, E. Im, S. Hensley, M.B. Grable, and R.A. Black. A new parameterization of the rain drop size distribution. IEEE, Transactions of Geoscience and Remote Sensing, 35(3):532-539 (1997).

This paper revisits the problem of finding a parametric form for rain drop size distribution (DSD) which (1) is an appropriate model for tropical rainfall, and (2) involves statistically-independent parameters. Using TOGA/COARE data, we derive a parameterization which meets these criteria. This new parameterization is an improvement on the one that was derived in [3], using TRMM ground truth data from Darwin, Australia. The new COARE data allows us to verify that the spatial variability of the two "shape" parameters is relatively small, thus confirming that this parameterization should be particularly useful for remote sensing applications. We also derive new DSD-based radar-reflectivity-rain-rate power laws, whose coefficients are directly related to the shape parameters of the DSD. Perhaps most important, since the coefficients are independent of the rain-rate itself, and very little spatially, the relations are ideally suited for rain retrieval algorithms. It should also prove straightforward to extend this method to the problems of extimating cloud hydrometeors from remote-sensing measurements.

Hasler, A.F., P.G. Black, V.M. Karyampudy, M. Jentoft-Nilsen, K. Palaniappan, and D. Chesters. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 201-202 (1997).

No abstract

Hendee, J.C. Object-oriented analysis and design of a near real-time marine environmental data acquisition and reporting system. Proceedings, 8th International Coral Reef Symposium, Panama City, Panama, June 24-28, 1996. Smithsonian Tropical Research Institute, 2:1569-1574 (1997).

The National Oceanic and Atmospheric Administration's Coral Health and Monitoring Program has cooperated with the Florida Institute of Oceanography in developing a near real-time marine environmental monitoring and reporting system. Using an object-oriented analysis technique, this report describes how data are retrieved from satellite data and archiving facilities, then reformatted for presentation via a Remote Bulletin Board system and facsimile. Using an object-oriented design technique, a new system is designed using a requirements analysis of the original system.

Hitchcock, G.L., W.J. Wiseman, W.C. Boicourt, A.J. Mariano, N. Walker, T.A. Nelsen, and E. Ryan. Property fields in an effluent plume of the Mississippi River. Journal of Marine Systems, 12:109-126 (1997).

Surface property distributions were mapped in the Mississippi River plume during May and August 1993 while following surface drifters. Prevailing winds were the primary factor controlling the orientation of the plume. In May, under typical southeasterly winds, the plume turned anticyclonically towards the coast, while in August, under anomalous westerly winds, the plume turned east. Remote imagery of sea surface temperature and suspended sediments confirmed the direction of the plume. Optimally interpolated maps of surface salinity, temperature, chlorophyll a fluorescence, and transmissivity from underway sampling, and periodic nutrient samples, reveal the plume structure. In May, concentrations of nitrate, silicate, and phosphate decreased linearly with increasing salinity. Chlorophyll a increased to peak concentrations of 10 µg 1^-1 in the plume, although higher pigment biomass was observed near the coast. In August, nitrate and silicate concentrations decreased conservatively near the mouth of Southwest Pass, except where pigment biomass was enhanced in a convergent surface front. Surface nutrient concentrations in the plume also decreased with increasing salinity. The observations provide the first Lagrangian view of surface property distributions in the Mississippi River plume, and indicate that significant temporal variability exists in physical and biological properties within a day after waters are discharged from the river delta.

Ho, D.T., L.F. Bliven, R.H. Wanninkhof, and P. Schlosser. The effect of rain on air-water gas exchange. Tellus, 49B:149-158 (1997).

The relationship between gas transfer velocity and rain rate was investigated at NASA's Rain- Sea Interaction Facility (RSIF) using several SF₆ evasion experiments. During each experiment, a water tank below the rain simulator was supersaturated with SF₆, a synthetic gas, and the gas transfer velocities were calculated from the measured decrease in SF₆ concentration with time. The results from experiments with 18 different rain rates (7 to 110 mm h^-1) and 1 of 2 dropsizes (2.8 or 4.2 mm diameter) confirm a significant and systematic enhancement of air-water gas exchange by rainfall. The gas transfer velocities derived from our experiment were related to the kinetic energy flux calculated from the rain rate and dropsize. The relationship obtained for mono-dropsize rain at the RSIF was extrapolated to natural rain using the kinetic energy flux of natural rain calculated from the Marshall-Palmer raindrop size distribution. Results of laboratory experiments at RSIF were compared to field observations made during a tropical rainstorm in Miami, Florida and show good agreement between laboratory and field data.

Ho, D.T., R.H. Wanninkhof, J.C. Masters, R.A. Feely, and C.E. Cosca. Measurement of underway fCO₂ in the eastern equatorial Pacific on NOAA ships Malcolm Baldrige and Discoverer from February to September 1994. NOAA Data Report, ERL AOML-30 (PB97-169056), 58 pp. (1997).

From February through September 1994, underway measurements of the fugacity (partial pressure) of carbon dioxide (fCO₂) were performed in the eastern equatorial Pacific as part of the Ocean Atmosphere Carbon Exchange Study (OACES) of the National Oceanic and Atmospheric Administration (NOAA). The measurements were performed with semi-autonomous instruments which measured the fugacity in the air and in the headspace of an equilibrator drawing water from the bow of the ship, from which the fCO₂ of the surface water is calculated. From the difference in fugacity in air and water, the CO₂ flux from the equatorial Pacific can be estimated. On the NOAA ship Malcolm Baldrige the system measured three reference standards, three air values, and eight water values per hour. The system on the Discoverer measured three standards, one 19-minute average air sample, and one 20-minute average water sample per hour. This report contains a description of the methodology and reduction of the fCO₂ and ancillary measurements. The results from the cruises of the Malcolm Baldrige in the equatorial Pacific in the (boreal) spring and fall of 1994 and from the Discoverer along nominally 110°W in the spring of 1994 are shown in a series of graphs with fCO₂ air and water versus latitude as top panel and temperature and salinity versus latitude as bottom panel.

Hopkins, M., M. DeMaria, and J. Kaplan. Evaluation of an empirical inland wind model for the landfall of Hurricane Fran (1996). Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-22 (1997).

A simple empirical model for predicting the winds from landfalling hurricanes has been developed for the Gulf and east coasts of the U.S. This model was originally developed to estimate the maximum sustained surface winds near the center of landfalling storms, but was generalized to predict the two-dimensional field of maximum winds (wind swath). The performance of the model during the landfall of Hurricane Fran will be evaluated by comparing the predicted winds with all available surface observations. Plans for improving the swath part of the model using a combined wind data set from several recent landfalling storms will also be described.

Houston, S.H., M.D. Powell, and P.P. Dodge. Surface wind fields for Hurricanes Bertha and Fran (1996). Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL, March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-23 (1997).

Hurricanes Bertha and Fran made landfall near Wilmington, North Carolina within two months of each other in 1996. These tropical cyclones contained maximum sustained surface winds (marine exposure at 10 m) estimated to be 46 m s^-1 and
50 m s^-1, respectively, at the time of landfall. Fran caused more loss of life and greater estimated U.S. property damage (34 deaths and $3.2 billion) than Bertha (8 deaths and $250 million). In both storms, the property losses were primarily due to storm surge and waves along the coast rather than directly from the wind. Fran also caused considerable damage due to inland flooding resulting from heavy rainfall across a large swath of the eastern U.S. as it moved northward after landfall. The Hurricane Research Division (HRD) has been providing real-time tropical cyclone surface wind fields to forecasters at the National Hurricane Center (NHC) since 1993; there were 134 of these analyses made in 1996. The analysis system contains adjustment techniques for exposure and interactive data quality control that produce a field of input observations conforming to a common framework for exposure, height, and averaging period. In Hurricane Bertha, HRD transmitted 14 real-time surface wind fields to NHC. The real-time and post-storm surface wind analyses indicate that the peak sustained surface winds in Bertha were primarily over the Atlantic Ocean at the time of landfall. The storm rapidly weakened after landfall and, based on the HRD wind fields, it is very unlikely that the peak sustained surface winds were observed at any point along the coastline of North Carolina. During Hurricane Fran, HRD produced 28 real-time surface wind fields for NHC. These, together with post-storm analyses, indicated that Fran's surface winds at landfall were stronger and spread over a larger area north and east of the center than Bertha. Unlike Bertha, the coastal areas were affected by Fran's strongest winds, especially in advance of landfall. Real-time and post-storm surface wind analyses in Hurricanes Bertha and Fran will be discussed, along with their utility for NHC's marine forecasts, emergency management, and storm surge forecasting.

Houston, S.H., M.D. Powell, and P.P. Dodge. Surface wind fields in 1996 Hurricanes Bertha and Fran at landfall. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 92-93 (1997).

No abstract.

Humphrey, J.C., T.C. Moore, J.C. Hendee, and J.C. Ogden. SEAKEYS: Real-time monitoring of the Florida Keys reef tract and Florida Bay. 28th Meeting Association of Marine Laboratories of the Caribbean (ALMC-97), San Pedro, Costa Rica, July 21-25, 1997. University of Costa Rica, 51 (1997).

No abstract.

Johns, E., R.A. Fine, and R.L. Molinari. Deep flow along the western boundary south of the Blake Bahama Outer Ridge. Journal of Physical Oceanography, 27(10):2187-2208 (1997).

In June-July 1990, hydrographic, chloroflourocarbon (CFC), and direct velocity observations were taken in the western North Atlantic between the Blake Bahama Outer Ridge (BBOR) at 30°N and San Salvador Island at 24°N. The deep flow in the region, dominated by the Deep Western Boundary Current (DWBC), forms a pattern of strong, narrow currents and cyclonic gyres close to the continental slope, with broad, weaker southward flow offshore. The CFCs reveal that in general the most recently ventilated water (i.e., having the highest CFC concentrations) is found along the western boundary as two distinct cores within the DWBC between potential temperatures 4-6°C and 1.9-2.4°C. Geostrophic transport streamlines are constructed for the DWBC layers, referenced using direct velocity observations at 26.5°N and assuming mass conservation between closed areas bounded by the hydrographic sections. The tracers and transports are used to define the spatial scales and strengths of the recirculation gyres and to examine their relationship to bottom topography and their role in ventilating the interior. Geostrophic transports for the DWBC layers which transit the region and continue equatorward along the western boundary are approximately 5 Sv for the 4-6°C layer; 14 Sv for the 2.4-4.0°C layer; 9 Sv for the 1.9-2.4°C layer; and 3 Sv below 1.9°C, for a total equatorward DWBC transport of 31 Sv below 6°C. A cyclonic gyre with one or more embedded gyres extends out to about 74°W, transporting 12 Sv of water intermediate CFC concentrations. Farther offshore, a broad band of southward flow contributes an additional 16 Sv of water with lower CFC concentration to the total equatorward transport. This flow may be connected to a much larger elongated cyclonic recirculation gyre which reaches equatorward to the Guiana Basin off northeastern Brazil. The close correspondence of the tracer distributions with the regional topography indicates that the major topographic features in this region strongly influence the circulation, particularly in the deep and bottom layers. It appears that the most recently ventilated water, between 4-6°C and 1.9-2.4°C, does not reach the southern top of the BBOR, but rather it bypasses the BBOR to the north of the study region and turns back westward following the isobaths toward the western boundary north of 30°N. Only in the coldest layer (<1.9°C) are the relatively highest CFCs observed south of 30°N on the BBOR. The layer containing the shallow CFC core (4-6°C) is apparently less constrained by the bottom topography; 3 Sv are carried westward across the axis of the BBOR forming an extended zonal high CFC and salinity distribution related to the Gulf Stream recirculation. South of the BBOR, due to the steep topography west of the Blake Basin, the DWBC is channeled into a narrow equatorward boundary flow. At the San Salvador Spur, some of the more recently ventilated water appears to be deflected northward following the isobaths in a cyclonic gyre around the extension of the Bahama Ridge. The cyclonic gyres between the BBOR and the San Salvador Spur appear to be localized features close to the western boundary that may have little impact on the larger scale deep North Atlantic circulation. Nevertheless, the gyres serve to ventilate the interior by diluting the tracer concentration carried equatorward by the DWBC.

Jones, R.W., and H.E. Willoughby. Sensitivity of a spectral shallow-water barotropic vortex to variations of domain size and spectral truncation. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 577-578 (1997).

Recent studies by Willoughby (1992, 1994, 1995) discuss the motion of a vortex on a beta plane for various environmental flows with a linear and non-linear version of the model. The domain size was 3000 km. Experiments for a 6000 km domain show small 50-km track differences by 10 days for an all cyclonic vortex with no environmental flow. Experiments with environmental flows will also be reported. The spectral truncation is wave number 3 for the non-linear model. Spectral truncations at wave numbers 2 and 4 will be reported. The purpose of these calculations is to show that highly truncated models are good enough to describe the dynamics of vortex motion on a beta plane with environmental flows. In the future, a baroclinic model will be developed for theoretical studies and for application to real-time hurricane tracking.

Kaplan, J., C.W. Landsea, M. DeMaria, and J.J. Cione. The differing roles of the large-scale environment in the intensity changes of three 1996 Atlantic hurricanes. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 358-359 (1997).

No abstract.

Knaff, J.A., and C.W. Landsea. An El Niño-Southern Oscillation CLImatology and PERsistence (CLIPER) forecasting scheme. Weather and Forecasting, 12(3):633-652 (1997).

A statistical prediction method is developed for the El Niño-Southern Oscillation (ENSO) phenomena which is based entirely on the optimal combination of persistence, month-to-month trend of initial conditions and climatology. The selection of predictors is by design intended to avoid any pretense of predictive ability based on "model physics" and the like, but rather is to specify the optimal "no-skill" forecast as a baseline comparison for more sophisticated forecast methods. Multiple least squares regression using the method of leaps and bounds is employed to test a total of fourteen possible predictors for the selection of the best predictors, based upon 1950-1994 developmental data. A range of zero to four predictors were chosen in developing twelve separate regression models, developed separately for each initial calendar month. The predictands to be forecast include the Southern Oscillation (pressure) Index (SOI) and the Niño 1+2, Niño 3, Niño 4 and Niño 3.4 SST indices for the equatorial eastern and central Pacific at lead times ranging from zero seasons (0-2 months) through seven seasons (18-20 months). Though hindcast ability is strongly seasonally dependent, substantial improvement is achieved over simple persistence wherein largest gains occur for two to seven season (6 to 21 months) lead times. For example, expected maximum forecast ability for the Niño 3.4 SST region, depending on the initial date, reaches 92, 85, 64, 41, 36, 24, 24 and 28 percent of variance for leads of zero to seven seasons. Comparable maxima of persistence only forecasts explain 92, 77, 50, 17, 6, 14, 21 and 17 percent, respectively. More sophisticated statistical and dynamical forecasting models are encouraged to utilize this ENSO-CLIPER model in place of persistence when assessing whether they have achieved forecasting skill; to this end, real-time results for this model are made available via a Web site.

Lamb, M.F., J.L. Bullister, R.A. Feely, G.C. Johnson, D.P. Wisegarver, B. Taft, R.H. Wanninkhof, K.E. McTaggart, K.A. Krogslund, C.W. Mordy, K. Hargreaves, D. Greeley, T. Lantry, H. Chen, B.E. Huss, F.J. Millero, R.H. Byrne, D.A. Hansell, F.P. Chavez, P.D. Quay, P.R. Guenther, J.-Z. Zhang, W. Gardner, M.J. Richardson, and T.-H. Peng. Chemical and hydrograph measurements in the eastern Pacific during the CGC94 expedition (WOCE section P18). NOAA Data Report, ERL PMEL-61 (PB97-158075), 235 pp. (1997).

No abstract.

Landsea, C.W. Comments on "Will greenhouse gas-induced warming over the next 50 years lead to higher frequency and greater intensity of hurricanes?" Tellus, 49A:622-623 (1997).

No abstract.

Landsea, C.W. Indices of global tropical cyclone activity. CLIVAR/GCOS/WMO Workshop on Indices and Indicators for Climate Extremes, Asheville, North Carolina, 10 pp. (1997).

No abstract.

Landsea, C.W., G.D. Bell, W.M. Gray, and S.B. Goldenberg. The hyperactive 1995 Atlantic hurricane season: A juxtaposition of favorable conditions. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 505-506 (1997).

No abstract.

Landsea, C.W., N. Nicholls, W.M. Gray, and L.A. Avilia. Reply to comment by R.W. Wilson on "Downward trend in the frequency of intense Atlantic hurricanes during the past five decades. Geophysical Research Letters, 24(17):2205-2206 (1997).

No abstract.

Landsea, C.W., W.M. Gray, P.W. Mielke, K.J. Berry, and J.A. Knaff. A seasonal hurricane forecast for 1997. Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL, March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., B-183 (1997).

The forecast for the 1997 Atlantic hurricane season issued by Dr. Bill Gray and collaborators (including myself) will be discussed. This prediction was issued in early December 1996 and will be updated in early April, early June, and early August. Uncertainties in the predictors, especially in El Niño and Sahel rainfall, will be discussed in how they may impact the number and intensity of tropical cyclones this year. I will also briefly discuss the performance of the 1996 forecasts.

Lee, K., F.J. Millero, and R.H. Wanninkhof. The carbon dioxide system in the Atlantic Ocean. Journal of Geophysical Research, 102(C7):15,693-15,708 (1997).

During the National Oceanic and Atmospheric Administration's Ocean Atmosphere Carbon Exchange Study expedition in the eastern North Atlantic in summer 1993, measurements of four CO₂ parameters, along with hydrographic properties, were made: fugacity of CO₂, fCO₂ (measured at 20°C and in situ); pH (measured at 20°C); total inorganic carbon, TCO₂; and total alkalinity, TA. The major objective of this cruise was to establish a benchmark against which future measurements of the transient invasion of CO₂ can be made. The large-scale distributions of surface water CO₂ parameters were related to temperature and salinity in this region. The subsurface TA and TCO₂ measurements were fitted to multiple linear functions of salinity, in situ temperature, apparent oxygen utilization, and silicate. The measurements of the inorganic carbon system were also used to examine the internal consistency of the carbonate system in this area. The measurements were internally consistent to ±1.3% in fCO₂, ±0.006 in pH, ±3 µmol kg^{- 1} in TCO₂, and ±3 µmol kg^-1 in TA if proper carbonic acid dissociation constants are used for different input combinations. The thermodynamic constants of Goyet and Poisson (1989), Roy et al. (1993), Millero (1995), and Lee and Millero (1995) were most consistent with the measurements of pH (at 20°C), TCO₂, and TA. However, if fCO₂ (at 20°C) is used in thermodynamic calculations, the constants of Mehrbach et al. (1973) gave the best representation of measurements. The constants of Lee and Millero (1995) were also in reasonable agreement with these measurements.

Lobert, J.M., S.A. Yvon-Lewis, J.H. Butler, S.A. Montzka, and R.C. Myers. Undersaturations of CH₃Br in the Southern Ocean. Geophysical Research Letters, 24(2):171-172 (1997).

Dry mole fractions of methyl bromide (CH₃Br) in marine boundary layer air and air equilibrated with surface seawater were measured in the Southern Ocean. Saturation anomalies were consistently negative at -36 ± 7%. The observed undersaturations do not support recently published predictions of highly supersaturated Antarctic waters, but instead suggest a net uptake of atmospheric CH₃Br by cold, productive oceans. The observations do not appear to be supported by known chemical degradation rates and present strong evidence for an unidentified, oceanic sink mechanism such as biological breakdown. Our estimate for the global, net, oceanic sink for atmospheric methyl bromide remains negative at -21 (-11 to -32) Gg y^-1.

Marks, F.D., and P.P. Dodge. Hurricane concentric eyewall characteristics as revealed by airborne Doppler radar analyses. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 102-103 (1997).

No abstract.

Marks, F.D., and H.A. Friedman. 1997 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 132 pp. (1997).

The objectives of the National Oceanic and Atmospheric Administration (NOAA) hurricane research field program is the collection of descriptive data that are required to support analytical and theoretical hurricane studies. These studies are designed to improve the understanding of the structure and behavior of hurricanes. The ultimate purpose is to develop improved methods for hurricane prediction. Ten major experiments have been planned, primarily by principal investigators at the Hurricane Research Division (HRD)/Atlantic Oceanographic and Meteorological Laboratory (AOML) of NOAA, for the 1997 hurricane field program. These experiments will be conducted with the NOAA/Aircraft Operations Center (AOC) WP-3D and Gulfstream IV-SP aircraft.

Marks, F.D., and L.N. Shay. Landfalling tropical cyclones: Forecast problems and associated research opportunities: Report of the Fifth Prospectus Development Team of the U.S. Weather Research Program. Minutes, 51st Interdepartmental Hurricane Conference, Miami, FL, March 24-28, 1997. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-26 (1997).

The Fifth Prospectus Development Team (PDT-5) of the U.S. Weather Research Program was charged to identify and delineate emerging research opportunities relevant to the prediction of local weather, flooding, and coastal ocean currents associated with landfalling U.S. hurricanes, specifically, and tropical cyclones, in general. Central to this theme are fundamental and applied issues including: rapid intensity change; initialization of and parameterization in dynamical models; coupling of atmospheric and oceanic models; quantitative use of satellite information; and optimal adaptive observing strategies to validate predictive models. To acquire the necessary understanding and provide the initial conditions for improved prediction, a focused, comprehensive observing system in a translating storm-coordinate system is required. With the development of proven instrumentation and improvement of existing systems, three-dimensional wind and thermodynamic data sets can be obtained whenever major hurricanes threaten the United States. Satellites, aircraft, expendable probes released from aircraft, and coastal, moored, and drifting surface platforms are needed to estimate the upper-ocean temperatures and currents, air-sea interactions, the distribution of storm surge, boundary layer winds, rainfall, and potential damage. In the hurricane core, airborne Doppler radar, supplemented by a suite of other instruments, would measure tropospheric winds including critical areas of the boundary layer and outflow region. Microwave systems would determine surface winds, ocean waves, and storm surge. On the hurricane periphery, dropsondes would be released from turboprop and jet aircraft to map the atmospheric temperature, humidity, and wind structure. Satellites would acquire both storm-scale and surrounding environmental data. To take full advantage of these new observations, techniques need to be developed to objectively analyze these observations, and initialize models aimed at improving prediction of hurricane track and intensity from global-scale and mesoscale dynamical models. Multi-nested models allow prediction of all scales from the global, which determine long-term hurricane motion, to the convective-scale, which affect intensity. Development of an integrated analysis and model forecast system optimizing the use of observations and providing the necessary forecast skill on all relevant spatial scales is required. Detailed diagnostic analyses of these data sets will lead to improved understanding of the physical processes of hurricane motion, intensity change, the atmospheric boundary layer, and air-sea coupling. Ultimately, the aim is on development of real-time analyses of storm surge, winds, and rain, before and during landfall, to improve warnings and provide local officials with the information needed to focus recovery efforts in the hardest hit areas as quickly as possible.

Martin, D., M. Tsivou, B. Bonsang, C. Abonnel, T.P. Carsey, M. Springer-Young, and A.A. Pszenny. Hydrogen peroxide (H₂O₂) in the marine atmospheric boundary layer during the ASTEX/MAGE experiment in the eastern subtropical North Atlantic. Journal of Geophysical Research, 102:6003-6015 (1997).

No abstract.

Masters, J.C., R.H. Wanninkhof, D.T. Ho, M. Steckley, R.A. Feely, and C. Cosca. Continuous air and surface seawater measurements of fCO₂ on board the NOAA ship Malcolm Baldrige around-the-world cruise in 1995. NOAA Data Report, ERL AOML-31 (PB98-105950), 65 pp. (1997).

From February 1995 through January 1996 the NOAA ship Malcolm Baldrige conducted scientific operations on an around-the-world tour. The majority of work occurred in the Indian Ocean. The CO₂ groups of the National Oceanic and Atmospheric Administration's (NOAA) Atlantic Oceanographic and Meteorological Laboratory (AOML) and Pacific Marine Environmental Laboratory (PMEL) operated a continuously flowing partial pressure carbon dioxide analyzer. Samples were taken from both the surface water and the overlying atmosphere to determine carbon dioxide flux across the gas/water interface. Other parameters such as salinity, barometric pressure, and temperature were used to reduce the data and calculate the fugacity of CO₂*. Total dissolved inorganic carbon (DIC) samples of surface water were also collected. Data were collected on each leg of the cruise. Leg 1 was a transit from Miami to Durban, South Africa. Leg 2 operated from Durban to Colombo, Sri Lanka. Leg 3 operated from Colombo to Muscat, Oman. Leg 4 operated from Muscat to Victoria, Seychelles. Leg 5 operated from Victoria to Muscat, Oman. Leg 6 operated from Muscat to Diego Garcia. Leg 7 consisted of a transit from Diego Garcia to Fremantle, Australia followed by the major scientific operations between Fremantle and Male, Maldive Islands. Leg 8 included another transit from Male to Darwin, Australia. Operations began after leaving Darwin and headed into the western equatorial Pacific. The ship inported in American Samoa and continued to Panama, Miami, Florida and finished in Charleston, South Carolina. Descriptions of sampling methods and graphical data summaries are given in this report.

McCarthy, M.C., L.D. Talley, and M.O. Baringer. Deep upwelling and diffusivity in the southern Central Indian Basin. Geophysical Research Letters, 24(22):2801-2804 (1997).

Transport of the deepest water westward through a gap at 28°S in the NinetyEast Ridge between the Central Indian Basin and the West Australia Basin is calculated from hydrographic data collected as part of the WOCE Hydrographic Program section I8N. Zero reference velocity levels at mid-depth were chosen through consideration of water masses. The small transport of 1.0 Sv westward through the gap of water denser than sigma₄ = 45.92 kg/m³ must all upwell in the southern Central Indian Basin. Of this, 0.7 Sv upwells between the central and western sill sections, that is, close to the sill itself. Using the areas covered by the isopycnal, we calculate an average vertical velocity of 3.3 × 10^-3 cm/s close to the sill and of 4.2 × 10^-4 cm/s west of the sill. Associated average vertical diffusivities are 10⁵ cm²/s close to the sill and 13 cm²/s west of the sill, in this very near bottom layer.

McCartney, M.S., R.G. Curry, and H.F. Bezdek. The interdecadal warming and cooling of Labrador Sea Water. ACCP Notes, 1-10 (1997).

No abstract.

McLeish, W., D.V. Hansen, and J.R. Proni. Coastal currents induced by Hurricane Andrew. Florida Scientist, 60(4):254-264 (1997).

Ocean current meters in 18 and 24 m depth water along the southeast Florida coast recorded water motions as Hurricane Andrew crossed the narrow continental shelf with the storm center 32 km from the southernmost current meter. Wind speeds up to 48 m s^-1 at the meter closest to the storm path were associated with recorded mean current speeds up to 94 cm s^-1. The greatest water speeds, however, were transient motions from the wind waves. These motions caused major changes to the bottom and to objects lying on it. Direct and remotely sensed observations showed an increasing degree of turbulence in the water as the hurricane approached, stirring both air bubbles and bottom sediment throughout the water and mixing the water so that vertical shear in the current was suppressed. Thus, beneath the strong wind stress there was not a mean water flow in the direction of the wind at the surface and a flow in the opposite direction near the bottom, as had been indicated in previous studies. Some of the water that had been forced toward shore by the strong west moving wind in the hurricane eyewall moved northward along the coast. In a region where the wind speed was less but still of hurricane force, water was displaced offshore contrary to the direction of the wind stress. At the same time that the offshore current developed, wave motions became much more severe: it appears that the new countercurrent may have induced major hurricane waves to break in this farther offshore location.

Mielke, P.W., K.J. Berry, C.W. Landsea, and W.M. Gray. A single-sample estimate of shrinkage in meteorological forecasting. Weather and Forecasting, 12(4):847-858 (1997).

An estimator of shrinkage based on information contained in a single sample is presented and the results of a simulation study are reported. The effects of sample size, amount, and severity of nonrepresentative data in the population, inclusion of noninformative predictors, and least (sum of) absolute deviations and least (sum of) squared deviations regression models are examined on the estimator. A single-sample estimator of shrinkage based on drop-one cross-validation is shown to be highly accurate under a wide variety of research conditions.

Molinari, R.L., D.A. Mayer, J.F. Festa, and H.F. Bezdek. Multi-year variability in the near surface temperature structure of the midlatitude western North Atlantic Ocean. Journal of Geophysical Research, 102(C2):3267-3278 (1997).

Between 1966 and 1995, subsurface temperature data have been collected in the western North Atlantic Ocean using expendable bathythermographs. Data coverage is sparse in both time and space, but evidence for decadal variability in the upper 400 m of the water column is found. The data were averaged by month onto a 2 degree of latitude by 4 degree of longitude grid. Thirty-one quadrangles in the region bounded by 17°N and 43°N and 78°W and 66°W have sufficient data to provide consistent results. Anomaly time series at 0, 100, 200, 300, and 400 m were estimated by subtracting a mean monthly climatology. The individual records were detrended and filtered to highlight the longer period signals. The analysis resulted in 25-year records (1969-1993) for study. Within the thermocline of the subtropical gyre and the Gulf Stream at 100 and 200 m, periods of predominately positive temperature anomaly end in 1971, 1982, and 1990, while periods of negative anomaly end in 1976 and 1985. Only the events ending in 1971, 1976, and 1990 are in the majority of the records at 300 and 400 m. Most of the events also appear in the sea surface temperature (SST) records, but are somewhat masked by significant noise at the surface. Meridional-vertical temperature sections through the subtropical gyre show that transitions from negative to positive anomaly events are characterized by a deepening of the isotherms throughout the section and transitions from positive to negative events by a rising of the isotherms. Significant lateral migration of the axis of the Gulf Stream, although possibly masked by the 2 degree averaging, is not necessary to explain either type of event. The transitions in the SST and 100 m temperature time series occur at essentially the same time as the transitions in an index of the North Atlantic Oscillation (NAO) that has also been detrended (i.e., 1971, 1976, 1980, 1984, 1988). The 1971, 1976, and 1988 NAO events are also observed at 300 and 400 m as described earlier. Periods of positive (negative) subsurface temperature anomaly are coincidental with periods of positive (negative) NAO index. Thus, earlier results showing connections between the NAO and western Atlantic SST at decadal time scales are now extended to at least 400 m in the water column. Trends were computed from the individual 25-year records. The trends at all depths are predominately negative (positive) north (south) of 38°N. Inferences from the horizontal distribution of the trends and results from earlier studies suggest that the 1969-1993 period may be a phase of a 30- to 50-year signal observed in the northern Atlantic since the beginning of the century.

Murillo, S.T., S.H. Houston, and M.D. Powell. Composites of surface marine observations for hurricanes during 1975-1996. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 78-79 (1997).

No abstract.

Ooyama, K.V. Footnotes to "conceptual evolution." Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 13-18 (1997).

No abstract.

Ooyama, K.V. The semi-implicit integration of a nested spectral model and the result of tests in squall-line simulation. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 531-532 (1997).

No abstract.

Parrish, J.R., and M.L. Black. The NOAA G-IV and the tropical cyclone environment. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 123-124 (1997).

No abstract.

Powell, M.D., and S.H. Houston. Surface wind fields of 1995 Hurricanes Erin, Opal, Luis, Marilyn, and Roxanne at landfall. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 90-91 (1997).

No abstract.

Proni, J.R., and T.A. Nelsen. Final Report: Deep Ocean Relocation Project, Phase II: Application of acoustical and tracer methodologies to the deep ocean relocation of dredge material. Contract Report ARPAC 558.AOO, Naval Research Laboratory, Washington, D.C., 37 pp. (1997).

One of the major challenges facing the United States today is disposal of contaminated dredged material. Inexorable economic and population pressures assure that this challenge will exist for the foreseeable future. One concept for dealing with this material is deep ocean disposal or deep ocean relocation (DOR). A key component of DOR concepts is monitoring of the geosynthetic fabric containers (GFCs), which will be used to contain the dredged material, during descent through the oceanic water column to the ocean bottom. The present report deals with the use of acoustical and tracer methodologies for monitoring DOR-associated plumes. Discussed herein is the feasibility of utilizing active acoustical systems to monitor both GFCs and any escaping plumes. A discussion of nepheloid layer characteristics of relevance to GFC detection is presented.

Proni, J.R., and R.G. Williams. Acoustic measurements of currents and effluent plume dilutions in the western edge of the Florida Current. In Acoustic Remote Sensing Applications, S.P. Singal (ed.). Narosa Publishing House, New Delhi, India, 537-550 (1997).

The Southeast Florida Outfall Experiment (SEFLOE), carried out in the western boundary of the Florida Current off southeast Florida, USA, between 1988 and 1993, was the most extensive application of acoustics to wastewater effluent studies performed in the United States. The objective was to provide a scientific basis for managerial regulations for effluent discharges. This article describes the acoustical measurements to map effluent plume distributions, and the three-dimensional current regime. Current meters were installed near each outfall near the top and bottom of the water column. An acoustic Doppler current profiler (ADCP) was deployed on the bottom in the vicinity of the outfalls. Research ships towed active acoustical systems over the diffusers. Examples are given of the outfall plume distribution and the principal current regimes. A conceptual three-dimensional model is developed to compare with observed data. The acoustical measurements are shown to serve as a surrogate for the effluent constituent distributions.

Rhoads, K.P., P. Kelley, R.R. Dickerson, T.P. Carsey, and M.L. Farmer. Composition of the troposphere over the Indian Ocean during the monsoonal transition. Journal of Geophysical Research, 102(D15):18,981-18,996 (1997).

The atmosphere over the equatorial Indian Ocean is a unique environment in which to study the chemical and radiative effects of an intense source of anthropogenic emissions from the northern hemisphere directly coupled to the relatively pristine background conditions present in the southern hemisphere. As an initial investigation into the role of the intertropical convergence zone (ITCZ) on interhemispheric transport of pollutants, a number of trace atmospheric species were measured aboard the National Oceanic and Atmospheric Administration (NOAA) R/V Malcolm Baldrige between Durban, South Africa, and Colombo, Sri Lanka, from March 12 to April 22, 1995. Sharp increases in the concentrations of carbon monoxide (CO), carbon dioxide (CO₂), and aerosols were associated with four distinct meteorological regimes transected by the cruise track from 33°S to 9°N. Across the ITCZ, aerosol concentrations, including non-sea-salt sulfate, nitrate, and ammonium, increased by a factor of 4. Surface zone measurements showed a latitudinal gradient with a minimum near the equator and a strong diurnal variation in the equatorial regions. The latitudinal profile of gas-phase reactive nitrogen paralleled ozone and was higher in the remote southern hemisphere than in the remote northern hemisphere. Evidence of direct anthropogenic impact on the region was observed more than 1500 km from the southern tip of India. Back trajectories, calculated with NOAA's medium range forecast data using the Hybrid Single Particle Lagrangian Integrated Trajectory (HY- SPLIT) program, identified the origin of the air mass regimes characterized by the trace gas and aerosol data. Continental emissions in the northern hemisphere were shown to have a major impact on the radiative properties and oxidizing capacity of the marine atmosphere.

Rogers, R.F. A component of tropical cyclogenesis: Convective redevelopment within a warm-core mesovortex. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Fort Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 555-556 (1997).

Theories explaining the transition of a relatively disorganized area of convection into a coherent self-sustaining system (i.e., tropical cyclogenesis) have traditionally relied upon the presence of a vortex before genesis can occur. Observations have confirmed the need for these vortices, often detecting them in radar and satellite imagery several days prior to the formation of a tropical depression. However, observational, theoretical, and numerical studies of similar systems over land have found that the initial vortices are confined to the mid-troposphere. Therefore, an important question to address is how these vortices grow down to the surface in maritime tropical environments, for it is not until the vortex is reflected at the surface that intensification can begin, provided the large-scale environment is not unfavorable. Viewing these vortices in the framework of potential vorticity (PV) allows a consideration of their penetration depth, which describes the vertical extent of the effects of the anomaly. This depth is a function of the magnitude of the PV anomaly itself--strengthening the PV anomaly will increase the penetration depth. One mechanism to explain how a vortex can grow downward is to increase the strength of the PV anomaly by initiating convection within the existing anomaly. Observations indicating successive cycles of convection before a named storm exists support this hypothesis. Understanding the mechanisms responsible for these repeated "internal" convective cycles is therefore critical to understanding whether a vortex will penetrate to the surface. Theories have been advanced in the literature as to how vortices are instrumental in initiating new convective outbreaks. However, the scale of the systems have prevented detailed observational studies which could verify or refute these hypotheses, necessitating the use of a high-resolution numerical model. In this study, a case of multiple convective regeneration by a mesoscale convective system (MCS)-generated mesovortex was investigated using the Penn State/NCAR mesoscale model MM5. The case involved a vortex that developed in an MCS in Colorado and tracked across the country over a three-day period, initiating five distinct convective cycles during its lifetime. Preliminary results of the simulation of one of the convective redevelopments will be reported, with the goal of examining and comparing to theory the processes whereby the vortex induces this redevelopment. The effect of the convective redevelopment on the vortex size and strength will also be examined.

Samsury, C.E., M.L. Black, P.P. Dodge, and R.E. Orville. Utilization of airborne and NEXRAD data in the analysis of cloud-to-ground lightning in 1995 and 1996 tropical cyclones. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 125-126 (1997).

No abstract.

Slansky, C.M., R.A. Feely, and R.H. Wanninkhof. The stepwise linear regression method for calculating anthropogenic CO₂ invasion into the North Pacific Ocean. In Biogeochemical Processes in the North Pacific, S.Tsunogai (ed.). Japan Marine Science Foundation, 70-79 (1997).

No abstract.

Takahashi, T., R.A. Feely, R.F. Weiss, R.H. Wanninkhof, D.W. Chipman, S.C. Sutherland, and T.T. Takahashi. Global air-sea flux of CO₂: An estimate based on measurements of sea-air pCO₂ difference. Proceedings, National Academy of Science, USA 94:8292-8299 (1997).

Approximately 250,000 measurements made for the pCO₂ difference between surface water and the marine atmosphere, DELTApCO₂, have been assembled for the global oceans. Observations made in the equatorial Pacific during El Niño events have been excluded from the data set. These observations are mapped on the global 4° × 5° grid for a single virtual calendar year (chosen arbitrarily to be 1990) representing a non-El Niño year. Monthly global distributions of DELTApCO₂ have been constructed using an interpolation method based on a lateral advection-diffusion transport equation. The net flux of CO₂ across the sea surface has been computed using DELTApCO₂ distributions and CO₂ gas transfer coefficients across sea surface. The annual net uptake flux of CO₂ by the global oceans thus estimated ranges from 0.60 to 1.34 Gt-C • yr^-1 depending on different formulations used for wind speed dependence on the gas transfer coefficient. These estimates are subject to an error of up to 75% resulting from the numerical interpolation method used to estimate the distribution of DELTApCO₂ over the global oceans. Temperate and polar oceans of both hemispheres are the major sinks for atmospheric CO₂, whereas the equatorial oceans are the major sources for CO₂. The Atlantic Ocean is the most important CO₂ sink, providing about 60% of the global ocean uptake, while the Pacific Ocean is neutral because of its equatorial source flux being balanced by the sink flux of the temperate oceans. The Indian and Southern Oceans take up about 20% each.

Talley, L.D., and M.O. Baringer. Preliminary results from WHP sections I8N/I5E in the central Indian Ocean. Geophysical Research Letters, 24(22):2789-2792 (1997).

The R/V Knorr departed Colombo, Sri Lanka on March 10, 1995 and arrived in Fremantle, Australia on April 15, 1995 to carry out its third WOCE hydrographic leg in the Indian Ocean. Basic technical support was provided by Scripps Institution of Oceanography's Oceanographic Data Facility. Acoustic Doppler current profiler (ADCP) operations were carried out by the University of Hawaii (Firing). The basic sampling program was accomplished very smoothly. The full cruise report can be obtained from the author. The cruise track is shown in the overview figure for this newsletter, labeled I8N and I5E. The latter portion was a nominal repeat of the 1987 section (Toole and Warren, 1993). The goals of the sampling were to obtain a section through the center of the Central Indian Basin, and to repeat the crossing of the northward flow of deep water just to the west of Australia. Particular attention was paid to a potential source of deep water for the Central Indian Basin, through a sill in the NinetyEast Ridge, located at about 28°S. It was also possible to deviate from the 32°S section, and sample in the deep water south of Broken Ridge instead of along the top of the ridge. Between Broken Ridge and Australia we chose to move the section slightly north of the original position of I5E in order to resolve whether the deep flow splits around Dirck Hartog Ridge. All stations were to within 10 m of the bottom and included a 36-bottle rosette/CTD cast with lowered ADCP. A ship-mounted ADCP was operated throughout. Basic station spacing was 30 nmi, and was reduced at the equator, Sri Lankan, and Australian coasts and crossings of the NinetyEast and Broken Ridges. The CTD data stream consisted of elapsed time, pressure, two temperature channels, conductivity, oxygen, altimeter, and transmissometer signals. Water samples were collected for analyses of salt, oxygen, silica, phosphate, nitrate, and nitrite on all stations and of CFC-11, CFC-12, carbon tetrachloride, helium-3, helium-4, tritium, AMS C14, pCO₂, total dissolved inorganic carbon, alkalinity, and barium on selected stations. Water sample results were compared with preliminary data acquired on prior WOCE legs and with earlier data. The comparisons are available in the cruise report and show that the WOCE data collected on legs 1 through 3 are a uniform data set; they also show significant differences from Geosecs salinity and phosphate which are attributable to measurement precision.

Thacker, W.C., and R. Lewandowicz. A comparison of low-dimensional representations of sea-surface temperature anomalies in the North Atlantic. International Journal of Climatology, 17:953-967 (1997).

Correlation-matrix principal components of North Atlantic sea-surface temperature anomalies for the interval 1950-1970 account for the anomalous variability observed during the interval 1972-1992 better than do similar numbers of covariance-matrix principal components, regional averages, or carefully selected local anomalies. When drift in the seasonal cycle is taken into account, local anomalies for the 127 6° × 4° longitude-by-latitude North Atlantic cells could be recovered with an average skill as high as 0.79. Surprisingly, skill increased monotonically with increasing numbers of principal components, and the maximum value was not obtained until 62 were used to characterize the field. Clearly, far more principal components carry useful information about local details than has been previously suspected.

Thacker, W.C., and R. Lewandowicz. Partitioning the North Atlantic into regions of similar seasonal sea-surface temperature anomalies. International Journal of Climatology, 17:3-23 (1997).

Mean sea-surface temperatures were computed within 127 6° × 4° longitude-by-latitude cells comprising most of the North Atlantic for 171 three-month seasons from 1950 through 1992, the mean seasonal cycle was removed, and cells with correlated seasonal anomalies were clustered into regions of coherent thermal behavior. Clustering algorithms consistently produced smaller thermal regions in the vicinity of the Gulf Stream, and while the regions were generally contiguous, a disjoint region was consistently found near the Grand Banks. Examining within-region variability as a function of the number of regions revealed no obvious "best" number of regions. For 26 regions, correlations between pairs of cells within a common region were typically 0.7; for 13 regions, a sizeable fraction were less than 0.5; and for only seven regions, within-region correlations were distributed fairly uniformly between 0.2 and 0.8.

Vaughan, S.L., and R.L. Molinari. Temperature and salinity variability in the Deep Western Boundary Current. Journal of Physical Oceanography, 27(5):749-761 (1997).

A ten-year time series (1984-1993) of repeat hydrographic sections from offshore Abaco Island, the Bahamas (26.5°N), is used to define the mean and time dependent characteristics of the Deep Western Boundary Current (DWBC). The DWBC flow is divided into four vertical layers based on chlorofluorocarbon (CFC) concentration and formations regions (upper layer, CFC core, theta ~ 3.9-5.0°C; second layer, classical Labrador Sea Water, theta ~ 3.2-3.9°C; third layer, CFC minimum, theta ~ 2.4-3.2°C; deepest layer, CFC core, theta ~ 1.85-2.4°C). Time series analysis of mean layer properties and their anomalies showed that the temperature and salinity of each layer did not increase or decrease monotonically with time. Variations in temperature and salinity were characterized by two to three-year period oscillations. Variability between years is illustrated by subtracting repeat sections of temperature and salinity along levels of both constant pressure and constant potential density. To determine an original water mass modification that could be responsible for the observed variability in the section differences, an analytical method, which uses both types of differencing schemes, was applied to the DWBC data. Variability in the upper layer between 1987 and 1993 was shown to originate primarily from an increased salinity of the source waters for this layer. Variability in the second layer was shown to arise from a combination of cooling and salinification. Variability in the two deepest layers seemed to be almost entirely due to vertical movement of the isopycnals. Increases in potential temperature and salinity observed in a sublayer of the second layer defined by sigma_1.5 ~ 34.68-34.74 (classical Labrador Sea Water) from 1991 to 1993 was shown to be mainly the result of cooling. It is suggested that this cooling may have originally occurred in the central Labrador Sea during the period of active deep water renewal in the early 1970s.

Wanninkhof, R.H., and W.E. Asher. Use of the deliberate dual-gaseous tracer method to measure gas transfer velocities. 1997 AGU Spring Meeting, Baltimore, MD, May 27-30, 1997. Supplement to EOS, Transactions, American Geophysical Union, 78(17):S89, A42E-06 (1997).

Use of the deliberate dual-gaseous tracer method to measure gas transfer velocities, the deliberately injected gases, helium-3 (³He) and sulfur hexafluoride (SF₆), have been used in the past decade to measure air-sea gas transfer velocities in coastal oceans. The method relies on knowledge of the relative exchange rates of the gases. It is successful because the exchange rates of the two gases differ by about a factor of three and because both gases can be measured at extremely low levels. Our results from two different field experiments and laboratory studies indicate that the measurements are robust and quantitative at low to intermediate wind speeds. The field results are in accordance with independently-determined gas exchange-wind speed relationships by the authors. Interpretation of the dual tracer results at higher wind speeds is problematic because of the influence of bubbles. In particular, the conversion of the 3He gas transfer results to gas transfer velocities of climate-relevant gases is uncertain. We will give an overview of the methodology, present results of two coastal gas transfer experiments, and discuss the power and shortcomings of the technique.

Wanninkhof, R.H., G. Hitchcock, W.J. Wiseman, G. Vargo, P.B. Ortner, W.E. Asher, D.T. Ho, P.Schlosser, M.-L. Dickson, R. Masserini, K. Fanning, and J.-Z. Zhang. Gas exchange, dispersion, and biological productivity on the west Florida shelf: Results from a Lagrangian tracer study. Geophysical Research Letters, 24(14):1767-1770 (1997).

A Lagrangian tracer study was performed on the west Florida shelf in April 1996 using deliberately injected trace gases. Although such studies have been performed previously, this work is the first where the deliberate tracers, in conjunction with carbon system parameters, are used to quantify changes in water column carbon inventories due to air-sea exchange and net community metabolism. The horizontal dispersion and the gas transfer velocity were determined over a period of 2 weeks from the change in both the concentrations and the concentration ratio of the two injected trace gases, sulfur hexafluoride (SF₆) and helium-3 (³He). Horizontal diffusion estimates were about an order of magnitude greater than calculated from empirical equations, and the difference is attributed to vertical shear. The second moment of the patch grew to 1.6 × 10³ km² over a period of 11 days. The gas transfer velocity, normalized to CO₂ exchange at 20°C, was 8.4 cm hr^-1 at an average wind speed, U₁₀, of 4.4 m s^-1 for the duration of the experiment, which is in good agreement with empirical estimates. Remineralization rates exceeded productivity, causing an increase in dissolved inorganic carbon of about 1 µmol kg^-1 day^-1 in the water column. During this period of senescence, 80% of the increase in inorganic carbon is attributed to community remineralization and 20% due to invasion of atmospheric CO₂. This net remineralization is in accordance with in situ and on-deck incubation experiments.

Weisberg, R.H., and C. Wang. A western Pacific oscillator paradigm for the El Niño-Southern Oscillation. Geophysical Research Letters, 24:779-782 (1997).

A data-based hypothesis is presented on the mechanism of the El Niño-Southern Oscillation (ENSO), a major determinant of interannual global climate variability. The hypothesis emphasizes the importance of off-equator sea surface temperature and sea level pressure variations west of the dateline for initiating equatorial easterly winds over the far western Pacific. These winds compete with westerly winds over the equatorial central Pacific enabling the coupled ocean-atmosphere system to oscillate. Consistent with this hypothesis, an analogical oscillator model is constructed that produces ENSO-like oscillations. The proposed mechanism differs from the delayed oscillator paradigm in that wave reflection at the western boundary is not a necessary condition for the coupled ocean-atmosphere system to oscillate.

Weisberg, R.H., and C. Wang. Slow variability in the equatorial west-central Pacific in relation to ENSO. Journal of Climate, 10(8):1998-2017 (1997).

Six years of upper ocean velocity, temperature and surface wind data collected in the west-central Pacific at 0°, 170°W reveal a slow ocean dynamical mode associated with the El Niño-Southern Oscillation (ENSO). Latent and sensible heat flux calculations using the basin-wide Tropical Atmosphere Ocean (TAO) array data show a coincident, slow ocean-atmosphere thermodynamical mode. Beginning with the La Niña conditions in 1988 through the peak El Niño conditions in 1992, the Equatorial Undercurrent (EUC) speed decreased along with the surface zonal wind stress and the zonal pressure gradient. Simultaneous with these were increasing trends in the Richardson number above the EUC core and in sea surface temperature (SST). After peak warming was achieved the variations in all of these quantities reversed in a movement toward their previous La Niña conditions. As this evolved within the ocean the sensible and latent heat fluxes increased with large values emanating eastward from the western Pacific. The largest interannual perturbations, then, for both the surface momentum and heat flux quantities during this recent ENSO cycle were within the west-central Pacific, the transition region between the warmest waters found in the western Pacific warm pool and the coldest waters found in the eastern Pacific cold tongue. The observed ocean and atmosphere variability represents a positive feedback. This raises a question about the origin of negative feedback that is necessary for the coupled system to oscillate. Arguing from the standpoint of a Gill atmosphere and observed SST/sea level pressure correlation patterns, the paper draws a connection between condensation heating in the equatorial west-central Pacific and easterly winds over the equatorial western Pacific during the mature phase of El Niño. The formation of such easterlies by ocean-atmosphere coupling over the western Pacific is hypothesized as providing a negative feedback for reversing the sign of anomalous SST in the equatorial central Pacific. This mechanism may complement, but it is different from, the delayed oscillator mechanism for ENSO.

Willis, P.T., P.P.Dodge, F.D. Marks, D. Smith, and D. Churchill. Evaluation of the accuracy of the NEXRAD radar rainfall estimates in tropical summer convective rainfall over the Everglades/Florida Bay. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, Ft. Collins, CO, May 19-23, 1997. American Meteorological Society, Boston, 679-680 (1997).

No abstract.

Willoughby, H.E. More about hurricane eye thermodynamics. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology, May 19-23, 1997, Ft. Collins, Colorado. American Meteorological Society, Boston, 96-97 (1997).

No abstract.

Wilson, W.D., and W.E. Johns. Velocity structure and transport in the Windward Islands Passages. Deep Sea Research, 44(3):487-520 (1997).

During 1991-1994, repeated measurements of current structure and water mass properties were made in the major southern passages to the Caribbean Sea between Trinidad and Dominica. A total of 10 cruises were performed in different seasons, consisting primarily of serial station occupations in the Grenada, St. Vincent, St. Lucia, and Dominica Passages. This data set is by far the most comprehensive available in these passages and better determines the mean flow and range of variability than do previous studies. The flow structure in these passages is characterized by a strong and relatively stable inflow above the thermocline (approximately the upper 100 m), and a more highly variable flow regime within and below the thermocline. Typical near-surface inflow velocities in Grenada and St. Vincent passages were 40-60 cm/s, with maximum observed currents of 90 cm/s. Frequently, counterflows were observed below this surface layer flowing out of the Caribbean, trapped to the southern side of the passages. This subsurface counterflow appeared to be strongest and most prevalent in Grenada Passage, where outflow speeds as large as 30 cm s^-1 were observed.

Yvon-Lewis, S.A., and J.H. Butler. The oceanic lifetime and budget of atmospheric methyl bromide. 1997 AGU Spring Meeting, Baltimore, MD, May 27-30, 1997. Supplement to EOS, Transactions, American Geophysical Union, 78(17):S90, A42E-12 (1997).

Methyl bromide (CH₃Br) has become of interest recently because of its involvement in the depletion of stratospheric ozone. However, unlike the chlorofluorocarbons, which are entirely anthropogenic, methyl bromide has both natural and anthropogenic sources. At ~10 parts per trillion in the troposphere, methyl bromide is believed to be the single largest contributor of stratospheric Br. Once in the stratosphere, Br is estimated to be 40 to 100 times more effective in depleting stratospheric ozone than chlorine. Known sinks for atmospheric methyl bromide include photolysis at high altitudes and reaction with OH, uptake by the oceans and loss to soils. In the ocean, dissolved methyl bromide is degraded via hydrolysis and chloride substitution. Recently, it has been shown that methyl bromide also undergoes biological degradation, which may be due to bacterial uptake. Results from field studies, showing large undersaturations in polar and sub-polar waters, also suggest an additional, perhaps biological, sink mechanism. Previous calculations of the partial atmospheric lifetime of methyl bromide with respect to oceanic degradation have only considered the chemical degradation mechanisms. We use a global, coupled ocean-atmosphere box model to examine the potential effect that biological degradation and its distribution can have on the lifetime of atmospheric methyl bromide. The results of this study show that both the value of the oceanic degradation rate constant and its global distribution are important in determining the calculated atmospheric lifetime. The "best" estimate of the partial lifetime of atmospheric methyl bromide with respect to oceanic loss now comes to 1.7-1.8 y with a full possible range of 0.85-3.7 y, which, together with other, non-oceanic losses, yields a total atmospheric lifetime of 0.7 y with a range of 0.5-0.9 y due only to uncertainty in the oceanic lifetime. A subsequent revision of the budget for atmospheric methyl bromide indicates that a source or sources of methyl bromide totaling 90 to Gg/y (1/2 of the total sink strength) has not yet been identified.

Yvon-Lewis, S.A., and J.H. Butler. The potential effect of oceanic biological degradation on the lifetime of atmospheric CH₃Br. Geophysical Research Letters, 24(10):1227-1230 (1997).

We use a global, coupled ocean-atmosphere box model to examine the potential effect that biological degradation and its distribution can have on the lifetime of atmospheric CH₃Br. The results of this study show that both the value of the oceanic degradation rate constant and its global distribution are important in determining the calculated atmospheric lifetime. The "best" estimate of the partial lifetime of atmospheric CH₃Br with respect to oceanic loss now comes to 1.7-1.8 y with a full possible range of 0.85-3.7 y, which, together with other, non-oceanic losses, yields a total atmospheric lifetime of 0.7 y (0.5-0.9 y). A subsequent revision of the budget for atmospheric CH₃Br indicates that estimated sinks of CH₃Br today exceed estimated sources by about 90 Gg y^-1.

Yvon-Lewis, S.A., and J. H. Butler. The uptake of atmospheric trace gases by the ocean. AGU 1997 Fall Meeting, San Francisco, CA, December 8-12, 1997. Supplement to EOS, Transactions, American Geophysical Union, 78(46):F93, OS21D-05 (1997).

A global ocean-atmosphere model was developed to study the uptake of CH₃Br by the oceans. With this model we significantly reduced the uncertainties in the partial atmospheric lifetime of CH₃Br with respect to its oceanic uptake (to, CH₃Br) (Yvon and Butler, Geophys. Res. Lett., 23(1), 53-56, 1996). Results from this model have also demonstrated that the distribution of the oceanic degradation term is important in caculating the partial atmospheric lifetime of a trace gas with respect to oceanic loss processes and, consequently, its total atmospheric lifetime (Yvon-Lewis and Butler, Geophys. Res. Lett., 24(10):1227-1230, 1997). It is now possible to determine the partial atmospheric lifetime with respect to oceanic degradation of any trace gas for which the oceanic degradation rate constant can be calculated. The results from model runs for several trace gases including, CH₃Br, CH₃Cl, and CH₃I, suggested that the total atmospheric lifetimes of these trace gases should be reduced by 38%, ~3%, and ~2%. These reductions are due solely to the inclusion of the oceanic chemical degradation loss process. When adapted for CH₃CCl₃, the model results reduced an earlier estimate for the partial atmospheric lifetime of this trace gas with respect to oceanic uptake by 31%. For some gases, these reductions are even greater when biological removal is included. The results from the study of these and other gases, including some HCFCs, will be presented.

Zhang, J.-Z. Distinction and quantification of carry-over and sample interaction in gas segmented continuous flow analysis. Journal of Automatic Chemistry, 19(6):205-212 (1997).

The formulae for calculation of carry-over and sample interaction are derived for the first time in this study. A scheme proposed by Thiers et al. (two samples of low concentration followed by a high concentration sample and low concentration sample) is verified and recommended for the determination of the carry-over coefficient. The derivation demonstrates that both widely used schemes of a high concentration sample followed by two low concentration samples, and a low concentration sampled followed by two high concentration samples, actually measure the sum of the carry- over coefficient and sample interaction coefficient. A scheme of three low concentration samples followed by a high concentration sample is proposed and verified for determination of the sample interaction coefficient. Experimental results indicate that carry-over is a strong function of cycle time and a weak function of ratio of sample time to wash time. Sample dispersion is found to be a function of sample time. Fitted equations can be used to predict the carry-over, absorbance, and dispersion given sample times, and wash times for an analytical system. Results clearly show the important role of intersample air segmentation in reducing carry-over, sample interaction, and dispersion.

Zhang, J.-Z., and G.A. Berberian. Determination of dissolved silicate in estuarine and coastal waters by gas segmented continuous flow colorimetric analysis. In Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices, Supplement 1. Environmental Protection Agency, EPA 600/R-97072, 366.0-1-366.0-2 (1997).

No abstract.

Zhang, J.-Z., P.B. Ortner, and C.J. Fischer. Determination of nitrite in estuarine and coastal waters by gas segmented continuous flow colorimetric analysis. In Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices, Supplement 1. Environmental Protection Agency, EPA 600/R-97072, 353.4-1-353.4-2 (1997).

No abstract.

Zhang, J.-Z., P.B. Ortner, C.J. Fischer, and L.D. Moore. Determination of ammonia in estuarine and coastal waters by gas segmented continuous flow colorimetric analysis. In Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices, Supplement 1. Environmental Protection Agency, EPA 600/R-97072, 349.0-1-349.0-2 (1997).

No abstract. **1996**

Asher, W.E., and R.H. Wanninkhof. The effect of breaking waves on the analysis of dual-tracer gas exchange measurements. Proceedings, Third International Symposium on Air-Water-Gas Transfer, Heidelberg, Germany, July 24-27, 1995. Aeon Verlag and Studio, 517-528 (1996).

The dual-gaseous tracer technique is a new and reliable method for directly measuring air-sea gas transfer velocities. However, analysis of data from these experiments requires the assumption that the dependence of the transfer velocity on molecular diffusivity is constant. Modeling and laboratory studies indicate that this could be an invalid assumption when gas transfer through bubbles generated by breaking waves is a significant portion of the sea-to-air gas flux. Here, a parameterization of the transfer velocity in terms of wind speed and fractional area whitecap coverage is developed that includes the effects of bubble-mediated exchange processes. It is shown that transfer velocities estimated using this parameterization are consistent with available oceanic gas exchange measurements. The parameterization is then used to investigate the consequences of including whitecap-related transfer processes in the analyses of data derived from dual-tracer experiments. In the case of the tracer pair, sulfur hexafluoride and helium-3, it is shown that assuming a constant diffusivity dependence underestimates transfer velocities of helium-3 by up to 20% at high wind speeds. It is also shown that using the parameterization to normalize the transfer velocity for helium-3 to carbon dioxide results in a 6% decrease in the estimated transfer velocity compared to constant-diffusivity dependence estimates.

Asher, W.E., B.J. Higgins, L.M. Karle, P.J. Farley, C.R. Sherwood, W.W. Gardiner, R.H. Wanninkhof, H. Chen, T.P. Lantry, M. Steckley, E.C. Monahan, Q. Wang, and P.M. Smith. Measurements of gas transfer, whitecap coverage, and brightness temperature in a surf pool: An overview of WABEX-93. Proceedings, Third International Symposium on Air-Water-Gas Transfer, Heidelberg, Germany, July 24-27, 1995. Aeon Verlag and Studio, 205-216 (1996).

Toward a method for estimating air-sea gas transfer velocities, k_L, from remote measurements of fractional area whitecap coverage, W_C, a gas exchange experiment was conducted in an outdoor surf pool during the October 1993 Wave Basin Experiment (WABEX-93). For both spilling and plunging breaking waves, measurements were made of W_C; air-water fluxes of carbon dioxide, helium, nitrous oxide, oxygen, and sulfur hexafluoride; microwave brightness temperature of the water surface, sigma; aqueous-phase turbulence velocities; and bubble size spectra. The data show that k_L, scales as a common, linear relation with W_C for both spilling and plungin breaking waves. The gas transfer data have been used to develop an empirical parameterization for predicting k_L from W_C, Schmidt number, and solubility.

Bishop, J.R., and W.P. Dammann. Cabling and mooring a remotely operated ADCP for real-time data acquisition. Proceedings, Ocean 96 MTS/IEEE, Ft. Lauderdale, Florida, September 23-26, 1996. Marine Technological Society, Vol. 1, 116-119 (1996).

As part of a joint U.S. Army Corps of Engineers, Port of Miami, State of Florida, U.S. EPA, University of Miami (Rosenstiel School), National Oceanic and Atmospheric Administration (NOAA) offshore dredged material disposal program, a real time current monitoring system (RTCMS) was designed by the Ocean Acoustics Division (OAD) of the Atlantic Oceanographic and Meteorological Laboratory (AOML) for deployment offshore of Miami. This system consists of an acoustic Doppler current profiler (ADCP) moored on the ocean floor at a point southwest of the Offshore Dredge Material Disposal Site (ODMDS) and cabled to a nearshore site. The nearshore site chosen was a range marker at the Miami Harbor entrance. From the range marker the data is transmitted via radio modem to the NOAA/AOML/OAD offices on Virginia Key. The high current regime and the requirement for periodic maintenance of the ADCP added unique challenges to the design of the cable and mooring system. Cable selection and routing was performed so as to minimize risk of damage due to recreational activities. For purposes of deployment and serviceability, the cabling and mooring system was divided into three sections. The first section extends from the range marker to a common point in 60 feet of water. The cable was laid and anchored in sandy areas where possible in order to avoid reef impact. The second section connects the common point to the first mooring point at a depth of 400 feet. The final section couples the first mooring point to the ADCP mooring point. The ADCP mooring section consists of a two-point moor with a subsurface center float to suspend the cable above the bottom. The deployment of the system was accomplished in two days on board a 95-foot research vessel equipped with a stern mounted A-frame and deck winches. Divers were utilized to attach the cable to anchors in the shallow water sections, and to inspect the cable after installation.

Black, M.L., R.W. Burpee, and F.D. Marks. Vertical motion characteristics of tropical cyclones determined with airborne Doppler radial velocities. Journal of the Atmospheric Sciences, 53(13):1887-1909 (1996).

Vertical motions in seven Atlantic hurricanes are determined from data recorded by Doppler radar on research aircraft. The database consists of Doppler velocities and reflectivities from vertically pointing radar rays collected along radial flight legs through hurricane centers. The vertical motions are estimated throughout the depth of the troposphere from the Doppler velocities and bulk estimates of particle fallspeeds. Portions of the flight tracks are subjectively divided into eyewall, rainband, stratiform, and "other" regions. Characteristics of the vertical velocity and radar structure are described as a function of altitude for the entire data set and each of the four regions. In all of the regions, more than 70% of the vertical velocities range from -2 to 2 m s^-1. The broadest distribution of vertical motion is in the eyewall region where ~5% of the vertical motions are >5 m s^-1. Averaged over the entire data set, the mean vertical velocity is upward at all altitudes. Mean downward motion occurs only in the lower troposphere of the stratiform region. Significant vertical variations in the mean profiles of vertical velocity and reflectivity are discussed and related to microphysical processes. In the lower and middle troposphere, the characteristics of the Doppler-derived vertical motions are similar to those described in an earlier study using flight-level vertical velocities, even though the horizontal resolution of the Doppler data is ~750 m compared to ~125 m from the in-situ flight-level measurements. The Doppler data are available at higher altitudes than those reached by turboprop aircraft and provide information on vertical as well as horizontal variations. In a vertical plane along the radial flight tracks, Doppler up- and downdrafts are defined at each 300-m altitude interval as vertical velocities whose absolute values continuously exceed 1.5 m s^-1, with at least one speed having an absolute value greater than 3.0 m s^-1. The properties of the Doppler drafts are lognormally distributed. In each of the regions, updrafts outnumber downdrafts by at least a factor of 2 and updrafts are wider and stronger than downdrafts. Updrafts in the eyewall slope radially outward with height and are significantly correlated over larger radial and vertical extents than in the other three regions. If the downwind (tangential) slope with height of updrafts varies little among the regions, updrafts capable of transporting air with relatively large moist static energy from the boundary layer to the upper troposphere are primarily in the eyewall region. Downdrafts affect a smaller vertical and horizontal area than updrafts and have no apparent radial slope. The total upward or downward mass flux is defined as the flux produced by all of the upward or downward Doppler vertical velocities. The maximum upward mass flux in all but the "other" region is near 1-km altitude, an indication that boundary-layer convergence is efficient in producing upward motion. Above the sea surface, the downward mass flux decreases with altitude. At every altitude, the total net mass flux is upward, except for the lower troposphere in the stratiform region where it is downward. Doppler-derived up- and downdrafts are a subset of the vertical velocity field that occupy small fractions of the total area, yet they contribute a substantial fraction to the total mass flux. In the eyewall and rainband regions, for example, the Doppler updrafts cover less than 30% of the area but are responsible for >75% and >50% to the total upward mass flux, respectively. The Doppler downdrafts typically encompass less than 10% of the area yet provide ~50% of the total downward mass flux in the eyewall and ~20% of the total downward flux in the rainband, stratiform, and "other" regions.

Black, M.L., S.H. Houston, R.G. Carter, A.B. Damiano, and R. McNamara. AFRES-NOAA flight-level data comparisons. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.8 (1996).

A coordinated flight between an Air Force Reserve (AFRES) aircraft and both National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft was conducted on 24 October 1995. This mission resulted from a recommendation made at the 49th Interdepartmental Hurricane Conference. The AFRES and NOAA aircraft each recorded, at 1-sec intervals, the standard suite of flight-level meteorological data (winds, temperature, dew point, pressure) and navigational information (e.g., position, true air speed, heading, etc.). The data were collected during clear and light-wind conditions along the Florida west coast, north of Tampa. During portions of the flight, the WP-3D aircraft flew in close formation and executed calibration maneuvers. The NOAA and AFRES aircraft conducted "fly-bys" adjacent to an Air Force Aerostat balloon which was carrying a NOAA calibrated instrument package. The balloon approaches were at altitudes ranging from 1,000 to 15,000 feet and provide the basis for the intercomparisons. Comparisons between the flight-level data collected from the balloon, NOAA, and AFRES aircraft will be presented. Recommendations, if any, will be made to improve the data collection, processing, and strategies for future intercomparison flights. Additionally, the calibration information gained from this flight will be used to investigate the data quality from concurrent flights into tropical cyclones by both the NOAA and AFRES aircraft this past hurricane season. One or more examples of flight-level data collected in hurricane flights will be presented.

Black, P.G., J.R. Proni, J.C. Wilkerson, and C.E. Samsury. Oceanic rainfall detection and classification in tropical and subtropical mesoscale convective systems using underwater acoustic methods. Monthly Weather Review, 125(9):2014-2042 (1996).

Measurements of the underwater sound produced by rain were made at three U.S. coastal sites in a study to determine the feasibility and limitations of the acoustic detection and classification of rainfall over water. In the analysis of the rain sound spectra, concurrent radar reflectivity observations were used to identify convective and stratiform regions of the precipitating clouds overhead. It was found that acoustic classifications of rainfall as to type, based on information in the 4-30 kHz frequency band, were in general agreement with radar-derived classifications. The classification technique is based on use of an acoustic discriminant, D_R, defined as the difference in average spectral levels between the 10-30 kHz and 4-10 kHz bands. A high correlation was found between sound spectrum levels (in dB) in the 4-10 kHz frequency band and radar reflectivity, dBZ, suggesting the possible use of the 4-10 kHz band sound spectral level as a classification tool in the same way that radar reflectivity is used in classifying precipitation. Our results demonstrate the feasibility of the acoustic method for detecting and classifying rainfall at sea.

Black, P.G., M.D. Powell, S.H. Houston, M.L. Black, and M. Hopkins. An air-deployable drifting buoy observing system for monitoring hurricane surface structure in critical air-sea interaction and landfall situations. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.5 (1996).

The 1995 hurricane season illustrated the need for accurate in-situ measurement of air-sea interaction processes and the importance they play in governing intensity estimation, as well as the need for in-situ surface wind observations near the point of hurricane landfall. A long-lasting cold pool in the North Atlantic SSTs, generated by a stationary Hurricane Felix, may have contributed to the weakening of Hurricane Luis, as Luis' cold wake may, in turn, have contributed to the weakening of Hurricane Marilyn. Hurricane Opal's rapid intensification occurred over a warm Loop Current eddy and its rapid weakening was accompanied by SST decreases along the coast ahead of the storm. A nearly-stationary Hurricane Roxanne gradually weakened in the Bay of Campeche in response to strong self-induced SST cooling. Strong air-sea stability offshore from Opal's landfall, together with a single strong eyewall convective cell, produced surface winds that were difficult to estimate from 700 mb reconnaissance data. To address this need, the first operational test of an air-deployed drifting buoy array was carried out during the 1995 season in Hurricanes Luis and Marilyn for the purpose of (1) testing the logistical feasibility of deploying buoy surface sensors in the path of a hurricane, (2) relaying data via satellite in real time to National Hurricane Center (NHC) forecasters and the National Meteorological Center (NMC) data base, and (3) testing their survivability. On 8 September 1995 from 20-21 UTC, three wind speed/direction (WSD) buoys and seven mini-drifting buoys (CLODS) were deployed 300 nmi ahead of Hurricane Luis. The deployment was conducted by the Air Force Reserve 53rd Weather Reconnaissance Squadron from a WC-130 aircraft. One WSD wind sensor failed and three CLODS failed on deployment. Seven buoys measured pressure, air, and sea temperature at hourly intervals, surviving 50 ft seas. The eye crossed the line near 12 UTC, 9 September, passing over one WSD and one CLOD, which reported minimum pressures within 1 mb of that reported by AFRES dropsonde observations. The highest 10-m, sustained wind estimated from the 1-m buoy data was 80 kt with a peak gust of 110 kt. Hurricane forecasters used the data to estimate the radius of gale force and 50 kt winds, which impacted warnings for Bermuda. Information on the extent of surface winds was also passed on to Canadian forecasters concerned about the subsequent landfall in Newfoundland. The data were coded and processed by NMC, appearing on most surface charts. Some coding errors occurred, which are now being remedied. The buoys also observed a 3.5°C drop in SSTs to the right of the storm. The experiment was repeated in Hurricane Marilyn on 18 September 1995 from 1430 to 1530 UTC, with AFRES aircraft deploying three additional WSD buoys and eight CLODs approximately 250 nmi ahead of the storm in a region just south of the Luis buoy locations. A WSD wind vane was damaged on deployment and five of the eight CLODs failed. This still provided NHC forecasters with an unprecedented array of six WSD buoys (four with working anemometers) and seven CLODs for a total of 13 platforms. Of these, three WSD and three CLODs passed through the eye. The lowest measured pressure was about 5 mb higher than reported by NOAA and AFRES aircraft. These data allowed forecasters to discern the surface hurricane, storm, and gale force wind distribution with great precision. It also showed that the cold wake left by Luis a week earlier was strong and covering the eastern semi-circle of Marilyn as it traveled parallel to Luis' track, a factor which may have been responsible for the storm weakening on 19 September. A NOAA WP-3D flight was flown on 19 September to correspond with the time that the storm was over the buoy array. Three additional CLODs equipped with acoustic sensors for wind speed and rain rate detection were deployed along with 35 AXBTs to sample SST and mixed layer depth at fine spatial resolution. These two experiments showed that drifting buoys can be successfully deployed ahead of a hurricane with sufficient accuracy to provide detailed surface wind fields, estimate the surface pressure distribution, and monitor the SST field for possible effects on storm intensity in a real time mode that can enhance forecaster confidence in estimating wind distribution radii. As such, it appears to be a useful tool in critical landfall or strong air-sea interaction situations.

Blackwelder, P., T. Hood, C. Alvarez-Zarikian, T.A. Nelsen, and B. McKee. Benthic foraminifera from the NECOP study area impacted by the Mississippi River plume and seasonal hypoxia. Quaternary International, 31:19-36 (1996).

Benthic foraminifera influenced by the Mississippi River plume and seasonal hypoxia were assessed from Louisiana inner-continental shelf sediment samples. Surface foraminifera assemblages were representative of in-situ populations as established by staining techniques. Community diversity and richness/evenness analyses indicate three regimes: high stress (sediment dominated), intermediate stress (hypoxia dominated), and low stress (low sediment accumulation/high oxygen). Epistominella vitrea and Buliminella morgani are useful tracers of rapid sediment accumulation rate and hypoxia. A bottom-water productivity signal west of the Mississippi River plume is indicated by benthic and planktic foraminifera abundance peaks. Surface benthic foraminifera trends are utilized to interpret changes in historical community structure from hypoxic-area sediments deposited since the turn of the century. The hypoxia-tolerant species Buliminella morgani increases markedly upcore, while hypoxia-intolerant species decrease or disappear. Diversity and dominance trends temporally correspond to a dramatic increase in U.S. fertilizer application. The results of this study have application to paleoenvironmental research spanning longer geologic timescales. The documented relationships between population structure and stressors in river-dominated marine systems may provide a useful analog for recognition of these conditions in the fossil record.

Bufkin, J.M., and U. Rivero. Real-time digital data communication system for a remotely operated ADCP. Proceedings, Ocean 96 MTS/IEEE, Ft. Lauderdale, Florida, September 23-26, 1996. Marine Technological Society, Vol. 1, 72-75 (1996).

An acoustic Doppler current profiler (ADCP) is moored adjacent to the Miami Offshore Dredged Material Disposal Site to monitor in real-time ocean currents during dredge disposal operations. The mooring site is an active shipping channel which would present a low survivability rate for surface radio communications buoys. There are also environmentally sensitive areas which prevent the direct cabling of the ADCP into shore. By combining hardwired cable and radio transmission techniques, a remote telemetry system was designed and installed at a fixed navigational marker that provides system reliability and a stable platform to work from. Most ADCP systems that provide real-time data are cabled back to a recording site which also supplies power to the ADCP down the cable. A self-powered ADCP was utilized since cabling to shore was not a viable option. This presented problems in powering the interface to the data cable and had to be overcome. Powering down the cable was limited since the telemetry unit at the other end of the cable also had to be battery powered. From the ADCP a cable was laid to the closest fixed workable point, which happened to be a navigation marker at the entrance to the Port of Miami. This cable extends approximately three miles, and proper cable drivers had to be located that would deal with this distance. At the navigation marker, a telemetry unit was designed that buffers the received data from the ADCP cable by using a micro controller, and then transmits this data by a UHF radio modem. The data is received and stored by computer at our laboratory approximately five miles away. Power consumption proved to be a major concern, since there are no available power sources at the navigation marker. The ADCP operates from its own internal battery pack, and the telemetry unit was designed to operate from batteries with solar panels to supplement the power. It is able to operate for months unattended. The system was installed in June of 1995, and has since proved to be an extremely reliable system. The design of the telemetry system has proven to be robust, and lends itself to future experiments where data must be transmitted from a remote site.

Burpee, R.W., J.L. Franklin, S.J. Lord, R.E. Tuleya, and S.D. Aberson. The impact of Omega dropwindsondes on operational hurricane track forecast models. Bulletin of the American Meteorological Society, 77(5):925-933 (1996).

Since 1982, the Hurricane Research Division (HRD) has conducted a series of experiments with research aircraft to enhance the number of observations in the environment and the core of hurricanes threatening the United States. During these experiments, the National Oceanic and Atmospheric Administration WP-3D aircraft crews release Omega dropwindsondes (ODWs) at 15-20 min intervals along the flight track to obtain profiles of wind, temperature, and humidity between flight level and the sea surface. Data from the ODWs are transmitted back to the aircraft and then sent via satellite to the Tropical Prediction Center and the National Centers for Environmental Prediction (NCEP), where the observations become part of the operational database. This paper tests the hypothesis that additional observations improve the objective track forecast models that provide operational guidance to the hurricane forecasters. The testing evaluates differences in forecast tracks from models run with and without the ODW data in a research mode at HRD, NCEP, and the Geophysical Fluid Dynamics Laboratory. The middle- and lower-tropospheric ODW data produce statistically significant reductions in 12-60 h mean forecast errors. The error reductions, which range from 16% to 30%, are at least as large as the accumulated improvement in operational forecasts achieved over the last 20-25 years. This breakthrough provides strong experimental evidence that more comprehensive observations in the hurricane environment and core will lead to immediate improvements in operational forecast guidance.

Carsey, T.P., and M.L. Farmer. Nitrogen oxides in the Pacific MBL During ACE-1. 1996 AGU Fall Meeting, San Francisco, CA, December 15-19, 1996. Supplement to EOS, Transactions, American Geophysical Union, 77(46):F76, A12A-16 (1996).

Nitric oxide, nitrogen dioxide, NOy, and PAN (peroxyacetyl nitrate) were measured in the Pacific Ocean boundary layer aboard the R/V Discoverer during the Pacific transit cruise, October 11-November 10, 1995, Seattle to Hobart, Tasmania, and during the ACE-1 cruise, November 15-December 13, 1995, south and east of Tasmania. NO, NO₂, and NOy measurements employed a chemiluminescent NO detector with appropriate conversion; calibration employed standard gases (NO) or calibrated permeation devices (NO₂, NOy). PAN measurements were made with an automated gas chromatograph utilizing a packed column and electron capture detection; calibration was performed using PAN generated by photolytic reaction of acetone with O₂ and NO₂, molybdenum catalyst conversion and chemiluminescent analysis. Mixing ratios of measured nitrogen species will be discussed in relation to meteorological conditions and concentrations of other relevant chemical species.

Carsey, T.P., M.L. Farmer, C.J. Fischer, A. Mendez, V.B. Ross, M. Springer-Young, and M.P. Zetwo. Atmospheric chemistry measurements during Leg 4, 1993 North Atlantic cruise, R/V Malcolm Baldrige. NOAA Data Report, ERL AOML-28(PB96-162581), 137 pp. (1996).

During September 1993, AOML conducted a multi-leg cruise aboard the Malcolm Baldrige in the North Atlantic from Iceland to Miami, Florida. The objective was to evaluate the distribution and transport of tropospheric ozone and ozone precursors in the North Atlantic. The investigation was associated with the North Atlantic Regional Experiment (NARE), a component of the International Global Atmospheric Chemistry (IGAC) project. The cruise track traversed three diverse wind and chemical regimes: pristine polar westerlies, polluted westerlies, and marine southeasterlies. Along this cruise track a large suite of chemical and meteorological data were measured. These included ozone, carbon monoxide in air and surface water, NO, NO₂, Noy, peroxyacetyl nitrate, SO₂, non-methane hydrocarbons (NMHC), and aerosols. The measurements and instrumentation are described in this data report.

Cione, J.J., and S. Raman. Surface cyclone intensity forecasting within the mid-Atlantic Gulf Stream locale using pre-storm low level baroclinic indices. Preprints, AMS Conference on Coastal Oceanic and Atmospheric Prediction, Atlanta, Georgia, January 28-February 2, 1996. American Meteorological Society, Boston (1996).

No abstract.

Cione, J.J., and S. Raman. The impact of storm track on low level mesocyclonic intensification and storm structure within the Gulf Stream locale. Preprints, AMS Conference on Coastal Oceanic and Atmospheric Prediction, Atlanta, Georgia, January 28-February 2, 1996. American Meteorological Society, Boston (1996).

No abstract.

Clark, J.F., P. Schlosser, H.J. Simpson, M. Stute, R.H. Wanninkhof, and D.T. Ho. Relationship between gas transfer velocities and wind speeds in the tidal Hudson River determined by the dual tracer technique. Proceedings, Third International Symposium on Air-Water-Gas Transfer, Heidelberg, Germany, July 24-27, 1995. Aeon Verlag and Studio, 785-799 (1996).

Gas transfer velocities were determined using the dual tracer technique (³He and SF₆) for two 40-60 km reaches of the tidal Hudson River. The experiments were performed near Poughkeepsie, New York in 1993 and near Catskill, New York in 1994. During both experiments wind speeds were measured above the river. The shape of daily axial SF₆ distributions and the evolution of peak concentrations followed patterns predicted by the one-dimensional advection-diffusion equation. Mean gas transfer velocities calculated from the 1994 data using the temporal change in SF₆ inventory (4.6 ± 0.4 cm hr^-1) and the tracer ration (5.3 ± 0.2 cm hr^-1) are in good agreement, suggesting that the dual tracer technique yields reasonable results. The relationships between gas transfer velocity and wind speeds found during these experiments are very similar to those observed previously for lakes, suggesting that wind is the primary source of surface turbulence in these reaches of the tidal Hudson River. The results of the 1993 and 1994 experiments agree very well, indicating that the local geometry of the river is of secondary importance.

Claud, C., K.B. Katsaros, N.M. Mognard, and N.A. Scott. Comparative satellite study of mesoscale disturbances in polar regions. Global Atmosphere and Ocean System, 4(2-4):233-273 (1996).

Mesoscale disturbances in cold air outbreaks (polar lows) occur quite often in high latitude areas of both hemispheres. The lack of conventional meteorological observations over these areas implies heavy reliance on satellite remotely-sensed information. Six lows which formed at different places around the world have been examined in order to derive their dominant features and environments. For this purpose, the combination of a vertical atmospheric sounder (TOVS), a microwave imager (SSM/I) and an altimeter (Geosat) has been used. While most retrieved atmospheric parameters are quite variable from case to case, a number of general statements about polar lows can be made: they all occur in areas of cold and dry air outbreaks; in agreement with the low integrated water vapor content values, the amount of liquid precipitation is very light, and the cloud liquid water content moderate; both SSM/I and Geosat indicate that surface wind speeds in the cloud bands forming the developed systems are of strong to gale force, while the cloud-free center is characterized by low values. Strongest winds and largest wave heights occur on the southwestern flank of the lows in the northern hemisphere and on the north flank in the southern hemisphere.

Dagg, M.J., E.P. Green, B.A. McKee, and P.B. Ortner. Biological removal of fine grain lithogenic particles from a large river plume. Journal of Marine Research, 54:149-160 (1996).

The pelagic tunicate, Oikopleura dioica, feeds by non-selectively filtering particles in the size range of 0.1-10 µm. On the continental shelf of the northern Gulf of Mexico, dominated by the Mississippi River, particulate matter in this size range contains not only microplankton but also numerous lithogenic particles. When O. dioica is abundant it dominates total zooplankton grazing. By ingesting small (<2 µm) lithogenics that effectively do not sink as separate particles, and repackaging them into larger, more rapidly sinking particles, it also significantly alters the fates of these materials and the properties of the surface waters in and around the discharge plume of the Mississippi River.

Dammann, W.P., J.M. Bufkin, U. Rivero, S.J. Stamates, and J.R. Proni. Near real-time observations of offshore current profiles and their application to dredge material disposal activities. Proceedings, Eco-Informa '96: Global Networks for Environmental Information, Lake Buena Vista, FL, November 4-7, 1996. Environmental Research Institute of Michigan, Vol. 11, 563-568 (1996).

An acoustic Doppler current profiler (ADCP) is presently located approximately 7 km east of the Miami Harbor entrance at approximately 130 m depth. This device measures profiles of the current speed and direction in the upper 50 m of the water column directly above the instrument and transmits its data to a computer on shore. These data, sent at 20-minute intervals, are utilized to determine suitability of conditions for disposal of dredge materials. The computer performs a running one-hour average of the current vectors over the 50 m interval and transmits the east- west component to a watchstander hourly via telephone pager. If the westerly component of the current vector exceeds 12 cm per second, disposal operations are suspended. As of the date of this presentation, processed profiles of the data will be available via connection to the world wide web.

Daneshzadeh, Y.-H., J.F. Festa, and R.L. Molinari. Quality control of XBT data collected in the Atlantic Ocean: 1990-1991. NOAA Data Report, ERL AOML-29, 77 pp. (1996).

Delayed mode and real-time XBT data collected in the Atlantic Ocean during 1990 and 1991 were scientifically quality controlled at NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) and the results of the quality control are presented in detail as tables and figures.

DeCosmo, J., K.B. Katsaros, S.D. Smith, R.J. Anderson, W.A. Cost, K. Bumke, and H. Chadwick. Air-sea exchange of water vapor and sensible heat: The Humidity Exchange Over the Sea (HEXOS) results. Journal of Geophysical Research, 101(C5):12,001-12,016 (1996).

Surface layer fluxes of sensible heat and water vapor were measured from a fixed platform in the North Sea during the Humidity Exchange Over the Sea (HEXOS) Main Experiment (HEXMAX). Eddy wind stress and other relevant atmospheric and oceanic parameters were measured simultaneously and are used to interpret the heat and water vapor flux results. One of the main goals of the HEXOS program was to find accurate empirical heat and water vapor flux parameterization formulas for high wind conditions over the sea. It had been postulated that breaking waves and sea spray, which dominate the air-sea interface at high wind speeds, would significantly affect the air-sea heat and water vapor exchange for wind speeds above 15 m/s. Water vapor flux has been measured at wind speeds up to 18 m/s, sufficient to test these predictions, and sensible heat flux was measured at wind speeds up to 23 m/s. Within experimental error, the HEXMAX data do not show significant variation of the flux exchange coefficients with wind speed, indicating that modification of the models is needed.

DeMaria, M., and J. Kaplan. Performance of the SHIPS intensity forecast model during the 1995 Atlantic hurricane season. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.25 (1996).

After the 1994 hurricane season, the statistical hurricane intensity prediction scheme (SHIPS) was modified to include 200 mb temperature as a predictor. This predictor increased the skill of the developmental sample (1989-1994) by 5%-10%. Results from independent cases during the 1995 season showed that this additional variable degrades the SHIPS forecasts. This increase in error appears to be related to modifications in the global model physics that were implemented in early 1995. The revised version of the global model has a temperature bias relative to the earlier version. A method was devised to correct for the temperature bias in the SHIPS forecasts. Results from forecasts with and without the bias correction will be compared.

Dickerson, R.R., P. Kelley, K.P. Rhodes, T.P. Carsey, M.L. Farmer, and P. Crutzen. Measurement of reactive nitrogen compounds over the Indian Ocean. Chemical Engineering News, 74:84 (1996).

No abstract.

Dietrich, D.E., M.J. Bowman, C.A. Lin, and A.M. Mestas-Nunez. Numerical studies of small island wakes in the ocean. Geophysical and Astrophysical Fluid Dynamics, 83:195-231 (1996).

Two and three-dimensional oceanic flows around small islands patterned after Barbados, West Indies (13 deg10 min N latitude: 59 deg 30 min W longitude) were modeled numerically to investigate island wake effects. The two-dimensional simulations closely agreed with laboratory flows, for both attached and shedding wake regimes. As expected, results for a flat bottom confirmed that the Coriolis terms strongly affect pressure but not the flow. For idealized, yet typical incident flow speeds, water column stratification, island topography, and appropriate Coriolis terms, three-dimensional simulations readily produced elongated wake patterns, dominated by surface intensified von Karman-like vortices. Effects of grid resolution, viscosity, bathymetry, and Coriolis forces on wake characteristics were studied. For islands with typical bottom slopes, realistically small horizontal eddy diffusivity has a minor effect compared to bottom drag in generating vorticity. Near-shore bathymetry (viz., the absence or presence of a continental shelf surrounding the island) plays a major role in determining the scale, intensity, and shedding period of vortices. The addition of a 15 km wide continental shelf around the island increased the shedding period by 67%, while reducing the Coriolis force by 50% reduced the shedding period by only 14%. Although observational data is sparse, inferred flow patterns do show von Karman-like structures near Barbados, even if eddies are not located exactly as expected. The numerical computations demonstrate that shedding eddy wakes are easily generated, and lend encouragement to the further search for organized wakes downstream of the island.

Dodge, P.P., S.H. Houston, and C. McAdie. Combined airborne and NEXRAD Doppler radar analyses of the inner core of Hurricane Erin. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.10-A.11 (1996).

An accurate real-time description of the tropical cyclone surface wind field near landfall is important for warning, preparedness, and recovery efforts. Research has helped reduce uncertainties in track and landfall forecasts, but now there is an opportunity to improve the accuracy of the surface wind fields in tropical cyclones, especially near landfall. Scientists at the Hurricane Research Division (HRD) designed the Tropical Cyclone Windfields Near Landfall experiment, part of the Hurricane Field Program, to gather flight-level wind data and make surface wind estimates to improve real-time and post-storm surface wind analyses in tropical storms and hurricanes. One of the objectives of this experiment is to collect airborne Doppler radar to combine with WSR-88D radar data in post-storm three-dimensional wind analyses. In the experiment, a time series of dual-Doppler data sets is collected by flying a single NOAA WP-3D toward or away from a WSR-88D Doppler radar. The aircraft Doppler radar rays are approximately orthogonal to the ground-based Doppler radar rays in that pattern, yielding true dual-Doppler coverage. By 1997, the Atlantic and Gulf coasts will be covered by the network of WSR-88D Doppler radars deployed by the National Weather Service (NWS), Department of Defense, and Federal Aviation Administration. The NWS will equip each radar with a digital recorder to store the base data. The WSR-88D will collect volume scans every 5-6 min. The flight pattern for this experiment is designed to obtain dual-Doppler analyses at intervals of 10-20 min in the inner core. On 1 August 1995, an Aircraft Operations Center WP-3D flew an HRD research mission to record airborne Doppler radar data in Hurricane Erin near the time of landfall on the east coast of Florida. From 2235 UTC to 0204 UTC on 2 August, the aircraft made several penetrations through the eye when the storm was within Doppler range of the Melbourne WSR-88D. The aircraft track was aligned along a radial from the WSR-88D. At the conference we will present preliminary analyses of Erin's wind field derived from airborne and WSR-88D Doppler data collected at 0150 UTC, when the center of circulation was ~170 km from the Melbourne radar.

Drennan, W.M., M.A. Donelan, E.A. Terray, and K.B. Katsaros. Oceanic turbulence dissipation measurements in SWADE. Journal of Physical Oceanography, 26(5):808-815 (1996).

Recent experiments measuring turbulence dissipation rates in the upper ocean can be divided into two types: those supporting an analogy between the upper ocean and lower atmosphere, with dissipation rates following wall layer behavior, and those finding oceanic dissipation rates to be much higher than wall layer predictions. In an attempt to reconcile these two diverse sets of observations, Terray et al. proposed a wave-dependent scaling of the dissipation rate based on the significant wave height and the rate of energy input from the wind to the waves. Their parameterization was derived from observations of strongly forced, fetch-limited waves, although they conjectured that it would apply in typical oceanic conditions as well. This paper reports new measurements of turbulent kinetic energy dissipation made in the North Atlantic Ocean from a SWATH ship during the recent Surface Waves Dynamics Experiment (SWADE). These data support the scaling of Terray et al., verifying its validity when applied to the more fully developed waves typical of the ocean.

Duncombe Rae, C.M., S.L. Garzoli, and A.L. Gordon. The eddy field of the southeast Atlantic Ocean: A statistical census from the Benguela Sources and Transports (BEST) project. Journal of Geophysical Research-Oceans, 101(C5):11,949-11,964 (1996).

Data collected during the Benguela Sources and Transports project were examined to determine some statistical properties of the eddy field observed in the Cape Basin. Seven anticyclonic eddies were encountered during the hydrographic surveys. Two of these were shown to be of Brazil Current origin (this paper and Smythe-Wright et al., 1996). Inverted echo sounder (IES) records of acoustic travel time were scaled to the depth of the thermocline, represented in the Cape Basin by the 10°C isotherm. These records indicate that a minimum of four to six eddies, assumed to be of Agulhas origin, entered the Cape Basin per year during the sampling period. They were associated with depressions in the 10°C isotherm records ranging from 100 to 400 m and of a duration between 30 and 100 days. The thermocline appears to shallow appreciably after the passage of an eddy before relaxing to the local mean. Estimates of the heat and salt contents of the hydrographically surveyed eddies indicated that the mean available heat and salt anomalies of the eddies were 0.55 × 10²⁰ J and 3.5 × 10¹² kg, respectively. Extrapolating the hydrographic data to the eddies detected in the IES record shows the eddy field responsible for the transfer of 2.2 to 3.3 × 10²⁰ J y^-1 (0.007 PW), 14 to 21 × 10¹² kg salt yr^-1, and 2 .6 to 3.8 × 10⁶ m³ s^-1.

Enfield, D.B. Relationships of inter-American rainfall to tropical Atlantic and Pacific SST variability. Geophysical Research Letters, 23(23):3305-3308 (1996).

Area-averaged anomalies of sea surface temperature (SSTA) and rainfall, developed from large-scale data sets, have been used to explore the relative importance of Pacific versus Atlantic SST variability for inter-American (50°S-50°N) climate variability at interannual time scales. SSTA in the tropical Pacific and tropical North Atlantic are comparably related to rainfall north of 15°S, with clear associations distributed between the southeastern United States (US) in the north and northern South America in the south. Although NINO3 explains 25% of the variance of the North Atlantic SSTA index, the rainfall correlations with North Atlantic SSTA are for the most part opposite in sign to those with NINO3. Hence, a significant part of the Atlantic SSTA probably has a direct association with rainfall, rather than being merely an indirect proxy for Pacific ENSO linkages. In contrast to the North Atlantic, South Atlantic SSTA appear to be only related to rainfall in northeast (NE) Brazil. The entire region between Venezuela and NE Brazil appears to be sensitive to both the ITCZ and to antisymmetric configurations of SSTA across the ITCZ, in a manner consistent with the relationships between SST, surface wind and surface wind divergence fields, and with previous studies.

Ffield, A., W.D. Wilson, J.M. Toole, and H.L. Bryden. The impact of eddies on the southwestern Indian Ocean. 1996 AGU Fall Meeting, San Francisco, CA, December 15-19, 1996. Supplement to EOS, Transactions, American Geophysical Union, 77(46):F406, OS21C-09 (1996).

In the Indian Ocean, the Agulhas Current advects warm water southward, balancing slower northward interior flow and input of Indonesian throughflow water. The net transfer of properties through the southwestern Indian Ocean provides the primary link of Indian Ocean water masses to the global ocean. Mesoscale eddies in this region complicate determination of volume transports and associated fluxes of heat and freshwater. While an eddy may contribute nearly zero mass flux across a section when viewed synoptically, over time it can transfer significant heat and freshwater. As part of NOAA/AOML's contribution to the international Indian Ocean WOCE effort, temperature, salinity, and oxygen measurements, along with hull-mounted and lowered ADCP measurements, were obtained along 33°S near the east African coast during March 1995. The characteristics of several energetic eddies revealed in the March 1995 data are presented and compared to other hydrographic observations obtained along the same section. Drifter and altimetry data from the NASA Ocean Altimeter Pathfinder Data Project are used to monitor the spatial and temporal variability of eddies in the southwestern Indian Ocean as well. Together, these data are used to assess the importance of eddy fluxes to the net mass, heat, and freshwater budgets of the Indian Ocean.

Franklin, J.L., S.E. Feuer, J. Kaplan, and S.D. Aberson. Tropical cyclone motion and surrounding flow relationships: Searching for beta gyres in Omega dropwindsonde datasets. Monthly Weather Review, 124(1):64-84 (1996).

In 1982, the National Oceanic and Atmospheric Admininstration's Hurricane Research Division began a series of experiments to collect Omega dropwindsonde (ODW) observations within about 1000 km of the center of tropical cyclones. By 1992, 16 ODW datasets had been collected in ten Atlantic basin hurricanes and tropical storms. Objective wind analyses for each dataset, at ten levels from 100 mb to the surface, have been produced using a consistent set of analysis parameters. The objective analyses, which resolve synoptic-scale features in the storm environment with an accuracy and confidence unattainable from routine operational analyses, have been used to examine relationships between a tropical cyclone's motion and its surrounding synoptic-scale flow. Tropical cyclone motion is found to be consistent with barotropic steering of the vortex by the surrounding flow within 3° latitude (333 km) of the cyclone center. At this radius, the surrounding deep-layer mean flow explains over 90% of the variance in vortex motion. The analyses show vorticity asymmetries that strongly resemble the beta gyres common to barotropic models, although other synoptic features in the environment make isolation of these gyres from the wind fields difficult. A reasonably strong relationship is found between the motion of the vortex (relative to its large scale surrounding flow) and the absolute vorticity gradient of the vortex environment.

Gamache, J.F., and F.D. Marks. Analysis of airborne Doppler observations of the weakening of eastern Pacific Hurricane Olivia on 25 September 1994. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.9 (1996).

The two NOAA WP-3D aircraft observed Hurricane Olivia on 25 September 1994 as its minimum pressure increased by approximately 10 mb in 2.5 hours, and its mean upper-level eyewall winds decreased by more than 10 m s^-1. Winds at all levels became much more asymmetrical. Both aircraft carried vertically scanning Doppler radars in their tails, and a coordinated pattern was flown that provided full coverage of the inner core every 30 minutes. Our analysis extends out to 30 km from storm center. As the aircraft arrived around 2000 UTC, the radar presentation was highly symmetrical, and the first Doppler analysis shows that the tangential wind structure was also highly symmetrical. Three hours later, the reflectivity to the south of the center had weakened, and a highly convective region with reflectivities over 55 dBZ had developed to the north. During the same period, the mean wind shear (difference between 1 km and 9 km levels) in the eyewall increased from approximately 10 m s^-1 to over 20 m s^-1. The storm had already recurved at the beginning of the on-station time, so the rapid changes over the next 3 hours in minimum pressure, upper-level winds, and symmetry may have resulted from a destructive interaction with the larger-scale flow. The three-dimensional structures of reflectivity, tangential wind, and radar reflectivity will be shown at the conference.

Garzoli, S.L. SACC: South Atlantic Climate Change. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida, 27 pp. (1996).

No abstract.

Garzoli, S.L., and A.L. Gordon. Origins and variability of the Benguela Current. Journal of Geophysical Research-Oceans, 101(C1):879-906 (1996).

A subset of the Benguela Sources and Transports (BEST) 1992-1993 data is analyzed to study the magnitude and variability of the large-scale transports in the area. The data consist of inverted echo sounder series and CTD stations. The mean 16-month transport values for the upper 1000 m indicate that of the 13 Sv northward transport within the Benguela Current, 50% is derived from the central Atlantic (which from geometry may be chiefly South Atlantic water), 25% comes from the Indian Ocean (which may be chiefly Agulhas water), and the remaining 25% may be a blend of Agulhas and tropical Atlantic water. A simple schematic of the transport pattern in which a somewhat restricted corridor for Agulhas eddies translation is envisioned. To the west of the eddy corridor flows the South Atlantic source for the Benguela Current; to the east is the Agulhas (Indian Ocean) source. The corridor is breached by South Atlantic and Indian Ocean water as the transient eddy field stirs these water masses.

Garzoli, S.L., A.L. Gordon, V.M. Kamenkovich, D. Pillsbury, and C.M. Duncombe Rae. Variability and sources of the southeastern Atlantic circulation. Journal of Marine Research, 54(6):1039-1071 (1996).

The 1992-1993 Benguela Sources and Transport (BEST) time series provides a quantitative view of Benguela Current transport and the eddy field across 30°S, as well as an estimate of the relation between its barotropic and baroclinic components. This is done by a simultaneous analysis of all the different data sets: inverted echo sounders, pressure sensors, CTD, current meter moorings, and ADCP. The analysis of the time series indicate that the annual mean baroclinic transport of the Benguela Current is approximately 13 Sv. The total transport is 16 Sv. The stationary flow associated with the Benguela Current is mostly confined along the African Continent while a transient flow, composed by large eddies shed from the Agulhas retroflection, composes the western portion of the flow. In the stationary part of the Benguela Current, both barotropic and baroclinic components are equally important while in the transient part, the barotropic is more substantial. Several eddies were observed during the experiment that translates to the west. They start with a speed of 12 km/day and close to the Walvis Ridge it has already diminished to 6-7 km/day. It can be assumed that after crossing the Walvis Ridge, due to their strong barotropic component (they feel the bottom), the speed decreases to that estimate previously obtained in the middle of the basin. The sources of the Benguela Current may include Indian and South Atlantic subtropical thermocline water; the relatively saline, low oxygen tropical Atlantic water and the cooler, fresher subantarctic water. The South Atlantic thermocline and subantarctic inflow is derived from the eastward flowing South Atlantic Current. The Indian Ocean water is injected into the Benguela Current through the Agulhas retroflection eddy and filament processes. A complex stirring effect of contrasting water types is envisioned. The changes in thermocline salinity correlate with transport: in general, when the northward transport is increasing the thermocline salinity also increases. This indicates that the Benguela Current increases in strength by bringing in more subtropical water. As the Agulhas input is most effective in boosting the salinity of the upper thermocline (the South Atlantic Current water being deficient in salinity relative to the Indian Ocean source), we suggest that the spatial variations in transport are tied to Agulhas water influx, presumably within and associated with the eddy field.

Goldenberg, S.B., and L.J. Shapiro. Physical mechanisms for the association of El Niño and west African rainfall with Atlantic major hurricane activity. Journal of Climate, 9(6):1169-1187 (1996).

Physical mechanisms responsible for the contemporaneous association, shown in earlier studies, of North Atlantic basin major hurricane (MH) activity with western Sahelian monsoon rainfall and an equatorial eastern Pacific sea surface temperature index of El Niño are examined, using correlations with 200- and 700-mb level wind data for the period 1968-1992. The use of partial correlations isolates some of the relationships associated with the various parameters. The results support previous suggestions that the upper- and lower-level winds over the region in the basin between ~10°N and 20°N where most MHs begin developing and critical determinants of the MH activity in each hurricane season. In particular, interannual fluctuations in the winds that produce changes in the magnitude of vertical shear are one of the most important factors, with reduced shear being associated with increased activity and stronger shear with decreased activity. The results show that most of these critical wind fluctuations are explained by their relationship to the SST and rainfall fluctuations. Results confirm previous findings that positive (warm) eastern Pacific SST and negative (drought) Sahelian rainfall anomalies are associated with suppressed Atlantic basin tropical cyclone activity through an equatorially confined near-zonal circulation with upper-level westerlies and lower-level easterlies that act to increase the climatological westerly vertical shear in the main development region. SST and rainfall anomalies of the opposite sense are related to MH activity through a zonal circulation with upper-level easterly and lower-level westerly wind anomalies that act to cancel out some of the climatological westerly vertical shear. The results also show that changes in vertical shear to the north of the main development region are unrelated to, or possibly even out of phase with, changes in the development region, providing a possible physical explanation for the observations from recent studies of the out-of-phase relationship of interannual fluctuations in MH activity in the region poleward of ~25°N with fluctuations in activity to the south. The interannual variability of MH activity explained by Sahel rainfall is almost three times that explained by the eastern Pacific SSTs. It is demonstrated that a likely reason for this result is that SST-associated vertical shears are more equatorially confined, so that the changes in shear in the main development region have a stronger association with the rainfall than with the SSTs.

Goldenberg, S.B., L.J. Shapiro, and C.W. Landsea. The hyperactive 1995 Atlantic hurricane season, Part II: Just a "spike" or a harbinger of things to come? Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.35 (1996).

After a relative lull in overall activity during the preceding four years, in 1995 the Atlantic hurricane basin experienced one of the most active seasons on record, with almost every measure of activity over twice the long-term mean. Of particular note was that the season produced five major hurricanes (maximum sustained surface winds >50 m/s) for the first time since 1964. Most of the major hurricanes in the North Atlantic basin form from easterly (African) wave disturbances and are especially sensitive to fluctuations in the tropical climate on the interannual and interdecadal time scales. The fluctuations on these scales that resulted in the "hyperactive" 1995 season and the implications of these fluctuations for the years ahead will be discussed. The chief issue that will be addressed is whether or not the activity of the 1995 season was simply an anomalous "spike" or a harbinger of long-term climate shifts signaling the probability of greater activity in the years to come.

Goni, G.J., S. Kamholz, S.L. Garzoli, and D.B. Olson. Dynamics of the Brazil/Malvinas Confluence based on inverted echo sounders and altimetry. Journal of Geophysical Research-Oceans, 101(C7):16,273-16,289 (1996).

We use data from the GEOSAT altimeter and from ten inverted echo sounder (IES) moorings deployed in the southwest Atlantic Ocean off the Argentine continental shelf to investigate several aspects of the dynamics of the upper layer in the Brazil/Malvinas Confluence region. We use the altimeter data to estimate the sea-height anomalies at each IES location, and the IES data to compute the upper-layer thickness, taken in this work to go to the depth of the 8°C isotherm. We first discuss the sea height and upper-layer thickness variations caused by the passage of the Brazil Current, Malvinas Current, and warm anticyclonic and cold cyclonic eddies. We introduce a two-layer model in which we decompose the sea height into its baroclinic and barotropic contributions. We then propose a method to monitor the thickness of the upper layer and the barotropic and baroclinic transports as a function of the sea-height anomalies and the statistics of the upper-layer thickness and reduced gravity for the region. We compute the reduced gravity values from the slope of a linear fit between the sea-height anomalies and the upper-layer thicknesses. We estimate the reduced gravity values for this region to range from 0.005 to 0.011 m s^-2. We also estimate the mean barotropic sea-height difference using two methods: conservation of mass and conservation of potential vorticity. Finally, we compute the time series for the baroclinic and barotropic transports during the GEOSAT Exact Repeat Mission (ERM) time period. Our results suggest that the mean baroclinic transport in the upper layer decreases from 12 Sv at around 35°S to 7 Sv at 37°S. Our results also indicate that there is a significant barotropic contribution to the upper-layer transport in the Confluence region.

Goni, G.J., S.L. Garzoli, A.J. Mariano, D.B. Olson, and O.B. Brown. Monitoring the upper layer southeastern Atlantic transports and eddy field using altimeter data. 1996 AGU Fall Meeting, San Francisco, CA, December 15-19, 1996. Supplement to EOS, Transactions, American Geophysical Union, 77(46):F16, U11C-08 (1996).

Sea height anomaly data derived from TOPEX/POSEIDON and thermocline depth and dynamic height derived from a set of five inverted echosounders and four moored current meters are used in conjunction in the southeastern Atlantic Ocean to monitor the thermocline depth and transports of the Agulhas/Benguela system. Comparisons between TOPEX/POSEIDON altimeter observations and data from the moored instruments show that the sea surface height anomaly is significantly correlated to the thermocline depth and the sea surface dynamic height. A two-layer approximation with thermocline deviations and a reduced gravity is used to describe the vertical structure of the ocean. The reduced gravity is estimated from the slope of the linear fit of the thermocline depth and sea height anomaly data. The thermocline depth and baroclinic and geostrophic transports are then computed using simple expressions derived from the two-layer model. Analysis of three years of geostrophic transport estimates obtained from TOPEX/POSEIDON data indicate that the Benguela Current may undergo interannual variability up to 20%. However, the primary variability derives from the source waters that form the Benguela Current, i.e., waters from the South Atlantic, Indian Ocean, and tropical Atlantic. The analysis of the depth of the altimeter-derived thermocline field is used to study the formation of rings in the Agulhas retroflection region, to monitor their trajectories, and to estimate their kinetic and available potential energy.

Hacker, P., E. Firing, W.D. Wilson, and R.L. Molinari. Direct observations of the current structure east of the Bahamas. Geophysical Research Letters, 23(10):1127-1130 (1996).

Quasisynoptic absolute velocity sections were obtained in the western North Atlantic to the east of the Bahamas on five cruises from 1992 to 1994, showing complex spatial and temporal variability of the currents throughout the water column. Lowered acoustic Doppler current profilers were used on all cruises; for comparison, an acoustically-tracked free-fall profiler was used on the August 1992 and June 1993 cruises. Where simultaneous profiles from both methods are available, depth-averaged differences are less than 0.01 m s^-1 in the ensemble mean and standard deviation. Though small, the mean difference appears to be statistically non-zero for one of the two Doppler profilers used; no cause has been found. The individual velocity sections show a banded structure of currents in the offshore direction with strong baroclinic and depth-averaged components extending over the full sampling domain. Two sections show a picture of the southward-flowing Deep Western Boundary Current (DWBC) differing from previous observations. During August 1992 and June 1993 the mean DWBC core was located more than 100 km offshore; in observations prior to 1990 it was usually near 50 km offshore. Net southward transport below 800 m integrated from the coast to 400 km offshore varied from 15 to 50 Sv with a mean of about 40 Sv (1 Sv = 1 × 10⁶ m³ s^-1). Our mean is consistent with previous estimates; our sections add new evidence that the transport is highly variable to at least 400 km offshore.

Halliwell, G.R., and D.A. Mayer. Frequency response properties of forced climatic SST anomaly variability in the North Atlantic. Journal of Climate, 9(12):3575-3587 (1996).

Frequency response properties of North Atlantic (5-57°N) sea surface temperature anomaly (T_sa) variability over periods of several months to 20 years are characterized using the Cooperative Ocean Atmosphere Data Set (COADS). Significant direct forcing of T_sa variability by the anomalous wind field (primarily through the resulting anomalous surface turbulent heat flux) is observed in the Western Wind and Trade Wind belts, but not between these belts within the interior of the oceanic subtropical gyre. To analyze the response to this forcing, it is necessary to separate the total anomalous surface turbulent heat flux into a component representing the wind forcing and a component predominantly representing the negative linear feedback (Newtonian relaxation) that is the dominant damping mechanism of large-scale climatic T_sa variability. At frequencies where wind forcing is important, good agreement exists between frequency response properties estimated from data and properties theoretically predicted by a simple linearized slab mixed layer temperature balance. In particular, this balance quantifies the influence of negative feedback damping on the amplitude and phase lag of the response. In the Westerlies, wind forcing is effective over periods from several months to 8 yr, primarily 2-4 yr, and is ineffective at periods of 8-20 yr where forcing by variable oceanic flow has been demonstrated to be important. In the Trades, wind forcing is effective over periods from 8 mo to 13.3 yr, primarily 2-3 yr and 7-13.3 yr. Wind forcing in the Trades is less effective at periods of 3-6 yr where ENSO variability is significant. At frequencies where wind forcing in the Westerlies is significant, forcing and feedback have an equally large influence on T_sa, indicating that the wind-forced response is damped primarily by the negative feedback contained in the anomalous surface turbulent heat flux. In the Trades, feedback by anomalous surface turbulent heat flux is not large enough to balance the wind forcing; other processes must contribute significantly to the damping there. At frequencies where wind forcing is important, T_sa in the Westerlies is not coherent with T_sa in the Trades. The anomalous wind fluctuations driving T_sa in the Westerlies (Trades) are associated with anomalous surface pressure variability in the Icelandic low (subtropical high). Response to a coherent North Atlantic Oscillation (Icelandic Low varying out-of-phase with the subtropical high) is, therefore, not observed. The large T_sa fluctuations observed in the western basin within the Westerly Wind belt propagate to the east and northeast across the Atlantic at a characteristic speed of 6 km day^-1.

Hansen, D.V., and H.F. Bezdek. On the nature of decadal anomalies in North Atlantic sea surface temperature. Journal of Geophysical Research, 101(C4):8749-8758 (1996).

North Atlantic sea surface temperature data from the Comprehensive Ocean-Atmosphere Data Set (COADS) were used to investigate the behavior of temperature anomalies on multiple-year time scales during the period 1948-1992. Monthly anomaly time series for each 2° square from the equator to 70°N were low-pass filtered at four years and normalized by the local standard deviation. Attention is focused on the extreme events, the upper and lower deciles, of the anomaly time series. A 45-year sequence of January maps shows the already familiar phenomena of generally cold conditions prior to 1951, a long warm interval from 1951 through 1967, and again a cold period from 1968 through 1977. The years 1978 through 1982 were largely devoid of persistent strong anomalies, but moderate cold conditions returned during 1983-1986. Warm cnoditions dominated the North Atlantic from 1987 onward. Within these thermal epochs, however, a total of five cold anomaly features and nine warm anomaly features have been identified. These features have individual lifetimes of three to ten years. A typical size is 20° of latitude or longitude, but they range from barely detectable to spanning the width of the basin, the latter especially in lower latitudes. Most of the anomalies move long distances along certain preferred paths. These paths generally follow the routes of the subarctic and subtropical gyres. Anomalies originating off North America along the boundary between the gyres move northeastward toward the Norwegian Sea along the approximate route of the North Atlantic Current. Midlatitude anomalies originating at the eastern boundary tend to spread both northward and southward along the coast. The speed of these movements (1-3 km d^-1) is generally less than the expected speed of the near-surfce ocean circulation. Simple ideas about the effects of beta dynamics and air-sea heat exchanges are briefly considered but do not provide a satisfactory explanation for the movements of the anomalies. The long time scale of these extreme events and the continuity of their movements suggest a useful degree of predictability of sea surface temperature based on persistence and propagation of features.

Hansen, D.V., and P.M. Poulain. Quality control and interpolations of WOCE/TOGA drifter data. Journal of Atmospheric and Oceanic Technology, 13(4):900-909 (1996).

Satellite-tracked drifting buoy data are being collected by numerous investigators and agencies in several countries for the WOCE/TOGA Surface Velocity Program. By the end of the century and thereafter this global data set will provide the definitive climatology and chronology of the surface currents of the world ocean. To expedite completion of research quality data sets for archival and dissemination, a data acquisition activity is being conducted at NOAA/AOML, Miami, Florida. At AOML data from drifting buoys of cooperating operators are quality controlled and optimally interpolated to uniform six-hour interval trajectories for archival at the Marine Environmental Data Service (Canada). This report describes in detail the procedures used in preparing these data for the benefit of second or third party users, or future buoy operators who may wish to process data in a consistent way. Particular attention is given to provide quantitative estimates for uncertainty of interpolation.

Hansen, D.V., and M.S. Swenson. Mixed layer circulation during EqPac and some thermochemical implications for the equatorial cold tongue. Deep Sea Research II, 43(4-6):707-724 (1996).

Surface currents inferred from satellite-tracked drifting buoys were used to develop a chronology of surface currents in the central Pacific for the year encompassing the EqPac field program. Salient features of the chronology are the early months of the program witnessed anomalous eastward current surges near the equator within the moderate El Niño event, followed by a period of anomalously strong westward flow near the equator and eastward flow in the North Equatorial Countercurrent that led, in mid-summer, to an eruption of tropical instability waves that continued until the end of the field program. None of these events was particularly unusual, but they were departures from climatology that influence the interpretation of the biochemical measurements made for EqPac. Results from a semi-quantitative conceptual model indicate that tropical instability waves have more important long-term, as well as short-term, consequences for thermochemical properties of the cold tongue than previously recognized.

Hendee, J.C. Object-oriented analysis of a near real-time marine environmental data acquisition and reporting system. NOAA Technical Memorandum, ERL AOML-90 (PB97-114573), 64 pp. (1996).

The National Oceanic and Atmospheric Administration's Coral Health and Monitoring Program has cooperated with the Florida Institute of Oceanography in developing a near real-time marine environmental monitoring and reporting system. Using the latest in object-oriented analysis techniques, this report describes how data are retrieved from satellite data and archiving facilities, then reformatted for presentation via a remote bulletin board system and facsimile.

Hendee, J.C. Object-oriented design of a near real-time marine environmental data acquisition and reporting system. NOAA Technical Memorandum, ERL AOML-89 (PB97-114581), 29 pp. (1996).

The National Oceanic and Atmospheric Administration's Coral Health and Monitoring Program in Miami, Florida has for the last several years worked cooperatively with the Florida Institute of Oceanography in monitoring meteorological and oceanographic events at selected Coastal-Marine Automated Network sites in the Florida Straits. In a previous report, an object-oriented analysis (OOA) was conducted of the existing system with an eye toward redesigning the system. This report builds on the OOA results from the previous study and utilizes the latest in object-oriented design techniques to design a new system.

Houston, S.H., and M.D. Powell. Real-time surface wind analyses during the 1995 hurricane season. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.29 (1996).

During the 1995 hurricane season, HRD personnel conducted experimental analyses of surface wind distribution in real time and made the analyses available to duty hurricane forecasters and storm surge forecast specialists. More than 80 analyses were conducted. The analyses are based on compositing all available observations from Air Force reconnaissance aircraft, ships, buoys, C-MAN platforms, and surface aviation reports. All data are quality controlled and then processed to conform to a common framework for height (10 m), exposure (marine or open terrain over land), and averaging period (maximum sustained 1 min wind speed). Several hours of observations are usually required to provide sufficient data density and coverage for an analysis, and an analysis domain consists of three or more nested meshes within which the scale of resolvable features can be controlled. The resulting objective analysis is representative of the mean state of the storm during the chosen time period, and a typical 10 hour reconnaissance mission will yield two to three analyses. The analysis product is a streamline and isotach contour plot for a given mesh and is designed to convey the location and strength of the maximum wind, as well as the extent of hurricane force, 50 kt, and/or tropical storm force winds. Analyses conducted in Hurricanes Erin, Felix, Luis, Marilyn, and Opal will be compared to dependent and independent surface wind observations. In some situations there is wide-spread agreement (e.g., Felix, Marilyn, Erin). In other cases (e.g., Luis, Opal), where there is incomplete or questionable surface information or where single level aircraft observations do not adequately convey the level that most influences the surface, there is mixed agreement.

Houston, S.H., W.A. Schaffer, M.D. Powell, and J. Chen. Incorporating HRD surface wind fields into the SLOSH model. Preprints, Conference on Coastal Oceanic and Atmospheric Prediction, Atlanta, GA, January 28-February 2, 1996. American Meteorological Society, Boston, 265-267 (1996).

NOAA's Hurricane Research Division (HRD) has developed new methods to analyze surface winds in tropical cyclones based on all available surface wind observations, including aircraft flight-level observations adjusted to the surface. As part of NOAA's Coastal Ocean Program research on coastal hazards, HRD and the Techniques Development Laboratory (TDL) have evaluated the parametric wind model used as input to the National Weather Service's (NWS) Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model through comparisons with HRD's surface wind analyses in recent hurricanes (Hugo of 1989, Bob of 1991, Andrew of 1992, and Emily of 1993). These comparisons indicated that the SLOSH parametric wind model adequately represented the wind fields in most cases. However, in the case of Emily's closest approach to North Carolina, there were significant underestimates in portions of the SLOSH model wind profile. These reduced winds input to the SLOSH model resulted in an underestimate of storm surge along some sections of the North Carolina coastline. The HRD surface wind fields would likely improve the storm surge calculations for this tropical cyclone if they could be input to the SLOSH model. Techniques are presented here which allow the use of the HRD surface wind fields as input for hindcasting the storm surge in the SLOSH model. Examples are shown for applying these techniques to some recent hurricanes which affected the United States coastline.

Huang, H., R.E. Fergen, J.R. Proni, and J.J. Tsai. Probabilistic analysis of ocean outfall mixing zones. Journal of Environmental Engineering, 122:359-367 (1996).

A methodology for ocean outfall mixing zone analysis is presented. It is based on a combination of four deterministic models for predicting hydrodynamic mixing behaviors of the discharged effluent, a continuous time domain simulation method, and an exceedance probability field concept. The approach provides a framework for evaluating mixing zones in compliance with receiving water criteria that are set in statistical terms. The approach was applied to the Hollywood outfall located off the east coast of south Florida. An exceedance probability field for effluent at a specified relative concentration of 0.021 was created. This field was applicable for determining the exceedance probability-based concentrations of any conservative pollutant at the regulatory mixing zone edge. A comparison of the probabilistic approach with the worst-case approach was made. The use of the worst-case approach was found to be too conservative for the subject outfall.

Huber, M., M. DeMaria, and J. Kaplan. Evaluation of an empirical inland wind decay model for the landfall of Hurricane Opal. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.28-A.29 (1996).

Surface wind observations in the southeast U.S. during the landfall of Hurricane Opal are used to evaluate an empirical inland wind decay model. The model applies a simple two-parameter decay equation to the hurricane wind field at landfall to estimate the maximum sustained surface wind as a storm moves inland. The hurricane wind field at landfall is modeled as a symmetric vortex plus a wave number one asymmetry that is proportional to the storm motion. The model was run using operational information to estimate the landfall storm structure. The model was also run where a post-storm wind analysis prepared by Mark Powell and Sam Houston of the Hurricane Research Division was used to estimate the landfall storm structure. Results from these two runs will be compared with the observed wind field.

Johns, E., W.D. Wilson, and R.L. Molinari. Transport balance of the Intra-Americas Sea: Results from NOAA's Subtropical Atlantic Climate Study. EOS, Transactions, American Geophysical Union, 76(3), OS117 (1996).

No abstract.

Kaplan, J., M. DeMaria, and M. Huber. A preliminary evaluation of forecasts from an empirical inland wind decay model for Hurricane Erin (1995). Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.28 (1996).

In early August of 1995, Hurricane Erin made landfall along both the east coast and panhandle of Florida before eventually becoming extratropical and dissipating near the Virginia/Maryland border. Erin's track across the data-rich Florida peninsula make it a good candidate for evaluating an Empirical Inland Wind Decay Model (IWDM) developed recently at the Hurricane Research Division (HRD) and employed by the National Hurricane Center (NHC) during the 1995 hurricane season for the first time. The IWDM is a simple, two-parameter model developed based upon the assumption that tropical cyclone wind speeds decay exponentially with time after landfall. The decay model has several potential applications including the capability of providing an estimate of the swath of inland wind speeds produced by a landfalling tropical cyclone. This particular model application will be evaluated for landfalling Hurricane Erin by comparing the IWDM predicted wind speeds to the winds at all available inland surface observing stations. Erin's structure and intensity at landfall required to produce the forecast wind swath were determined from information contained in operational NHC hurricane advisories, as well as from detailed near real-time wind analyses produced by Sam Houston and Mark Powell of HRD. The accuracy of the forecast wind swaths produced using both techniques will be discussed.

Landsea, C.W., S.B. Goldenberg, W.M. Gray, and G.D. Bell. The hyperactive 1995 Atlantic hurricane season, Part I: A juxtaposition of favorable conditions. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.34-A.35 (1996).

The 1995 Atlantic hurricane season was a year of near-record hurricane activity: a total of 19 named storms (average is 9.3 for the base period 1950-1990) and 11 hurricanes (average is 5.8) which persisted for a total of 121 named storm days (average is 46.6) and 62 hurricane days (average is 23.9), respectively. There were five intense (or major) hurricanes of Saffir/Simpson category 3, 4, or 5 (average is 2.3 intense hurricanes) with 11.5 intense hurricane days (average is 4.7). The net tropical cyclone activity, based upon the combined values of named storms, hurricanes, intense hurricanes, and their days present, was 229% of the average. This unusually active hurricane season was the result of the juxtaposition of nearly all the physical factors known to enhance seasonal hurricane activity. This convergence of favorable factors has occurred about ten times during the last century. These environmental factors included extremely low vertical wind shear, below-normal sea level pressure and above-normal SST throughout the Caribbean and tropical North Atlantic, as well as a strong west phase of the stratospheric quasi-biennial oscillation. The low vertical wind shear partially resulted from cool phase conditions of the El Niño-Southern Oscillation. Significantly, these anomalies were present in the pre-season environmental fields, as far back as February, and thus preceded the development of any hurricanes. Seasonal hurricane forecasts for 1995 issued at Colorado State University on 30 November 1994, 5 June 1995, and 4 August 1995 were able to anticipate an above-average season, but underforecast the extent of the extreme hurricane activity. The 1996 seasonal forecast will be briefly discussed.

Landsea, C.W., N. Nicholls, W.M. Gray, and L.A. Avila. Downward trends in the frequency of intense Atlantic hurricanes during the past five decades. Geophysical Research Letters, 23:1697-1700 (1996).

There is concern that the enhanced greenhouse effect may be affecting extreme weather events such as tropical cyclones. The North Atlantic basin offers a reliable, long-term record of tropical cyclone activity, though it may not be representative of tropical cyclones throughout the rest of the tropics. The most recent years of 1991 through 1994 have experienced the quietest cyclone activity on record in terms of frequency of tropical storms, hurricanes, and intense hurricanes. This was followed by the 1995 hurricane season, one of the busiest in the past 50 years. Despite 1995's activity, a long-term (five decade) downward trend continues to be evident primarily in the frequency of intense hurricanes. In addition, the mean maximum intensity (i.e., averaged over all cyclones in a season) has decreased, while the maximum intensity attained by the strongest hurricane each year has not shown a significant change.

Lobert, J.M., J.H. Butler, L.S. Geller, S.A. Yvon, S.A. Montzka, R.C. Myers, A.D. Clarke, and J.W. Elkins. BLAST94: Bromine latitudinal air/sea transect 1994 - Report on oceanic measurements of methyl bromide and other compounds. NOAA Technical Memorandum, ERL CMDL-10 (PB96-154471), 45 pp. (1996).

No abstract.

Marks, F.D., and H.A. Friedman. 1996 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 138 pp. (1996).

The basic objective of NOAA's hurricane research field program is the collection of descriptive data that are required to support analytical and theoretical hurricane studies. These studies are designed to improve the understanding of the structure and behavior of hurricanes. The ultimate purpose is to develop improved methods for hurricane prediction. Nine major experiments have been planned, primarily by principal investigators at the Hurricane Research Division (HRD)/Atlantic Oceanographic and Meteorological Laboratory (AOML) of NOAA, for the 1996 Hurricane Field Program. These experiments will be conducted with the NOAA/Aircraft Operations Center (AOC) WP-3D and Gulfstream IV-SP aircraft.

Maul, G.A., M.H. Bushnell, N.J. Bravo, and D.V. Hansen. Observed sea surface height and modeled dynamic height anomaly departures in the tropical Pacific Ocean: 1986-1989. Oceanologica Acta, 20(4):569-584 (1996).

No abstract.

McCartney, M.S., R.G. Curry, and H.F. Bezdek. North Atlantic's transformation pipeline. Oceanus, 39(2):19-23 (1996).

No abstract.

Mielke, P.W., K.J. Berry, C.W. Landsea, and W.M. Gray. Artificial skill and validation in weather forecasting. Weather and Forecasting, 11(2):153-169 (1996).

The results of a simulation study of multiple regression prediction models for meteorological forecasting are reported. The effects of sample size, amount, and severity of nonrepresentative data in the population, inclusion of noninformative predictors, and least (sum of) absolute deviations (LAD) and least (sum of) squared deviations (LSD) regression models are examined on five populations constructed from meteorological data. Artificial skill is shown to be a product of small sample size, LSD regression, and nonrepresentative data. Validation of sample results is examined, and LAD regression is found to be superior to LSD regression when sample size is small and nonrepresentative data are present.

Napp, J.M., L.S. Inzce, P.B. Ortner, D. Siefert, and S. Britt. The plankton of Shelikof Strait as predators, prey, and competitors of larval pollock. Fisheries Oceanography, 5:19-38 (1996).

The vertical distribution of walleye pollock eggs and larvae in Shelikof Strait, Gulf of Alaska, was investigated using data from 36 Multiple Opening-Closing Net and Environmental Sensing System (MOCNESS) tows taken in April and May 1986-1988. Most eggs were found from below 150 m to near bottom, ~300 m, but were progressively shallower later in the season. Eggs in middle stages of development were shallower than younger or older eggs. The vertical distribution of eggs was positively related to observed differences in seawater temperature but showed no relationship to density. Larvae hatch at incubation depth and quickly rise to the upper 50 m of the water column where they remain during larval development. Larger larvae(~7-10 mm standard length) undergo limited diel vertical migration within the upper 50 m. They are deepest during the day, shallowest at dusk, slightly deeper at night, and even deeper at dawn. Their mean depths of occurrence were between 21 and 37 m at all times. At these depths, prey (copepod nauplii) generally were at densities sufficient for larval pollock growth in laboratory studies. Pronounced thermoclines and pycnoclines were present in the part of the water column inhabited by the larvae in late May. Larvae appear to remain below the upper mixed layer during periods of increased turbulence, but at depths during daytime where light was sufficient for feeding, and where prey densities were adequate.

Nelsen, T.A. Chapter 14: Coastal ocean water resources: Linkages with terrestrial freshwater resources, anthropogenic influences, and climate change. In Diachronic Climatic Impacts on Water Resources, A.N. Angelakis and A.S. Issar (eds.). NATO ASI Series, Vol. I36, Springer-Verlag, Berlin Heidelberg, 319-347 (1996).

No abstract.

Nelsen, T.A., M.P. Zetwo, H. Wanless, P. Blackwelder, P. Swart, T. Hood, C. Alvarez-Zarikian, J. Trefry, S. Metz, W.-J. Kang, R. Trocine, L. Tedesco, M. Capps, and M. O'Neal. The sediment record as a monitor of natural and anthropogenic changes in the lower Everglades/Florida Bay ecosystem: A high resolution study. 1996 Florida Bay Science Conference, Miami, Florida, June 1996. Florida Sea Grant/University of Florida Publication, 62-65 (1996).

No abstract.

Nystuen, J.A., J.R. Proni, P.G. Black, and J.C. Wilkerson. A comparison of automatic rain gauges. Journal of Atmospheric and Oceanic Technology, 13(1):62-73 (1996).

Automatic rain gauge systems are required to collect rainfall data at remote locations, especially oceanic sites where logistics prevent regular visits. Rainfall data from six different types of automatic rain gauge systems have been collected for a set of summertime subtropical rain events and for a set of wintertime rain events at Miami, Florida. The rain gauge systems include three types of collection gauges: weighing, capacitance, and tipping bucket; two gauges that inherently measure rainfall rate: optical scintillation and underwater acoustical inversion; and one gauge that detects individual raindrops: the disdrometer. All of these measurement techniques perform well; that is, they produce rainfall estimates that are highly correlated to one another. However, each method has limitations. The collection gauges are affected by flow irregularities between the catchment basin and the measurement chambers. This affects the accuracy of rainfall-rate measurements from these instruments, especially at low rainfall rates. In the case of the capacitance gauge, errors in 1-min rainfall rates can exceed +10 mm h^-1. The rainfall rate gauges showed more scatter than the collection gauges for rainfall rates over 5 mm h^-1, and the scatter was relatively independent of rainfall rate. Changes in drop size distribution within an event could not be used to explain the scatter observed in the optical rain gauge data. The acoustical inversion method can be used to measure the drop size distribution, allowing rainfall classification and estimation of other rain parameters, for example, reflectivity or liquid water content, in addition to rainfall rate. The acoustical inversion method has the advantage of an extremely large catchment area, resulting in very high time resolution. The disdrometer showed a large scatter relative to the other rain gauge systems for low rainfall rates. This is consistent with the small catchment area for the disdrometer system.

Palmer, D.R. Rayleigh scattering from nonspherical particles. Journal of the Acoustical Society of America, 99(4):1901-1912 (1996).

A comprehensive framework is developed for calculating the intensity received by a monostatic sonar system due to backscattering from a cloud of nonspherical particles suspended in the ocean. The cloud can consist of different types of particles having arbitrary shapes, volume distributions, and orientations, as well as an overall mass density that varies spatially within the cloud. In the Rayleigh region it is possible to average over particle orientation exactly. The averaged backscattered intensity depends on particle shape through the eigenvalues of a tensor that can, in principle, be determined by solving a boundary value problem for a harmonic function. Since the solution to this boundary value problem is out of reach practically, bounds are obtained on the backscattered intensity that are independent of particle shape. These bounds form the basis for obtaining estimates of the error that is made by assuming the particles in the cloud scatter sound as if they were spherical. A number of examples and applications are considered, the most important of which is the feasibility of a sonar to image black smoker hydrothermal plumes. The reassuring result that the spherical particle assumption is likely to lead to feasibility criteria that underestimate the performance of a sonar is obtained. The isoperimetric bounds are combined with the principle of maximum entropy, applied to the distribution of particle shapes, to obtain a new expression for the square of the amplitude for backscattering at wave number k₀ from a particle of volume V, specific bulk modulus e and a specific density h: PHI² = (k₀² V/4 pi)² [(e - 1)/e + (h² - 1)/2h]². This amplitude is obtained by averaging over particle orientation and particle shape and is to be compared to the corresponding quantity for a shere PHI_sp² = (k₀² V/4 pi)² [(e - 1)/e + (3 (h - 1))/(2h + 1)]². The use of the new expression is preferred in situations where it is known the particle shapes are quite variable and irregular and where 1.0 < h < 2.5. In all the examples considered it is found the error that results from assuming the particles scatter sound as if they were spherical is small. This is comforting and consistent with one's intuition that in the Rayleigh region the scattered sound should be somewhat insensitive to the shape of the scatterer.

Peng, T.-H., R.H. Wanninkhof, and R. Feely. An evaluation of anthropogenic CO₂. 1996 AGU Fall Meeting, San Francisco, CA, December 15-19, 1996. Supplement to EOS, Transactions, American Geophysical Union, 77(46):F407, OS21D-02 (1996).

The annual increase in total dissolved inorganic carbon (DIC) in seawater caused by the increase in atmospheric CO2 partial pressure is very small (~1 umol/kg/yr). This is a result of the large initial DIC concentration (~2000 umol/kg) in the ocean. However, advancements in DIC measurements in recent years have made it possible to detect the anthropogenic CO₂ signal on decadal time scales. There have been many geochemical survey cruises in the world oceans on which CO₂ system parameters have been measured since the historical GEOSECS survey in 1972-1978. The anthropogenic CO₂ signal in the ocean has been determined by analyzing CO₂ survey data obtained from the NOAA-OACES NATL93 cruise in the North Atlantic, the NOAA-OACES CGC91 cruise in the Northeastern Pacific, and the NOAA-OACES IO95 cruise in the Indian Ocean. After elimination of contribution from respiration of organic matter by using AOU and Redfield ratios, the salinity normalized total DIC concentrations along isopycnal surfaces representing the upper thermocline waters are compared between the new measurements and those observed during GEOSECS. The anthropogenic increase in DIC in the North Atlantic between current cruises and GEOSECS-TTO are apparent, but are not conclusive. In the northeastern Pacific, we can see an increase of 18 umol/kg at sigma_theta = 26.4 between 1974 and 1991. In the Indian Ocean, an increase of 17 umol/kg at sigma_theta = 26.6 between 1978 and 1995 is observed. These increases in DIC become smaller with denser isopycnal surfaces as expected.

Powell, M.D., S.H. Houston, and T.A. Reinhold. Hurricane Andrew's landfall in south Florida. Part I: Standardizing measurements for documentation of surface wind fields. Weather and Forecasting, 11(3):304-328 (1996).

Hurricane Andrew's landfall in south Florida left a swath of destruction, including many failed anemometer recording systems. Extreme destruction led to exaggerated claims of the range of wind speeds that caused such damage. The authors accumulated all available data from surface platforms at heights ranging from 2 to 60 m and reconnaissance aircraft at altitudes near 3 km. Several procedures were used to represent the various types of wind measurements in a common framework for exposure, measurement height, and averaging period. This set of procedures allowed documentation of Andrew's winds in a manner understandable to both meteorologists and wind engineers. The procedures are accurate to ±10% for marine and land observing platforms, and boundary layer model adjustments of flight-level winds to the surface compare within 20% of the nearest surface measurements. Failure to implement the adjustment procedures may lead to errors of 15%-40%. Quality control of the data is discussed, including treatment of peak wind observations and determination of the radius of maximum winds at the surface.

Powell, M.D., and S.H. Houston. Hurricane Andrew's wind field at landfall in south Florida. Part II: Surface wind fields and potential real-time applications. Weather and Forecasting,11(3):329-349 (1996).

All available wind data associated with Hurricane Andrew's passage were analyzed for periods corresponding to landfall south of Miami and emergence from southwest Florida. At landfall in southeast Florida, maximum sustained (1 min) surface wind speeds (V_M1) reached 62 m s^-1 in the northern eyewall over land; by the time Andrew exited the Florida peninsula, the peak value of V_M1 over land decreased to 44 m s^-1. Radar reflectivity observations from Tampa and Melbourne could not support an obvious correlation of convective cell development with coastal convergence during landfall on the southeast coast. On the southwest coast, however, convective cell development in the southern eyewall was supported by a coastal convergence maximum. Comparison of the wind swath with two independent Fujita-scale damage maps indicated that peak swath speeds compared well with speed equivalents in the worst damaged areas but were higher than equivalents in moderately damaged areas. Comparison of the analysis maximum wind swath with an engineering survey of damaged homes suggests that homes exposed to a wide range of wind directions while subjected to high wind speeds suffered the most damage. Potential real-time applications of wind field products include warning dissemination, emergency management, storm surge and wave forecasting, and wind engineering. Development of damage assessment models for disaster mitigation is addressed from the viewpoint of an electrical utility.

Powell, M.D., S.H. Houston, P.P. Dodge, and M.L. Black. Wind fields of Hurricanes Marilyn and Opal at landfall. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.29-A.30 (1996).

Hurricane Marilyn strengthened rapidly while approaching St. Thomas in the U.S. Virgin Islands. A great deal of wind and storm surge-related damage occurred throughout the island. Thanks to the hard work of the San Juan Weather Service Forecast Office, a record of the peak winds in the northern eyewall was recovered from an ASOS station at the airport. These data will be compared to real time analyses of Air Force reconnaissance winds adjusted to the surface. Hurricane Opal underwent rapid changes in intensity as it approached the northwest Florida Gulf coast. After strengthening to a minimum central sea level pressure of 916 mb with a small, well-organized eyewall and outer rainband in the central Gulf of Mexico, Opal interacted with a cold front and mid-lower tropospheric jet and weakened considerably by landfall. The pressure increased to 942 mb, the intense circular inner eyewall maintained convective reflectivity features only in the northern half of the eye, and the eyewall wind maximum was poorly defined and weaker than the outer wind maximum located in an outer rainband well to the east of the center. Opal caused significant storm surge damage, but widespread wind damage was not observed. Preliminary analyses of airborne Doppler radar measurements collected by NOAA research aircraft 4 h before landfall suggest that the interaction with the jet produced a flow through the storm from southwest to northeast. This flow increased with height and caused asymmetries in the surface wind field. The jet had the affect of causing the level of maximum winds to rotate as a function of azimuth. Peak winds were found at the 3 km level on the southeast side of the storm where the jet helped to reinforce the flow. At landfall, 1 km level winds on the east side of the storm may have been less affected by the jet and, therefore, weaker than those at 3 km. In the absence of convective reflectivity features that could transport momentum from 3 km, weaker surface winds would prevail, consistent with relatively minor wind damage. On the west side of the storm at 3 km, the jet had the effect of canceling a portion of the flow leading to a distinct wind minimum. The level of maximum winds on the west side was at 1 km, because the jet was weakest near the surface. Hence, surface wind measurements from C-MAN platforms on the west side of the storm were stronger than Air Force aircraft reconnaissance observations at 3 km. The NOAA WP-3D aircraft data will be combined with WSR-88D data from Eglin Air Force Base to further define the wind field from 1 km and above. If these data support the preliminary analyses, we may need to be more aware of the possible affects that changing synoptic situations may have on the wind field. Data collected from a given level may not provide enough information to gauge what is occurring at the surface; we may need to hasten the transfer of improved surface wind remote sensing systems from research to operations.

Proni, J.R., S.J. Stamates,and J.F. Craynock. Massachusetts Bay water column particulate horizons study. Contract Report DW13940107-01-0, U.S. Environmental Protection Agency, 33 pp. (1996).

No abstract.

Proni, J.R., W.P. Dammann, J.F. Craynock, S.J. Stamates, D. Commons, R. Fergen, H. Huang, R. Ferry, B. Goldenberg, J. Mandrup-Poulson, J. Monson, and R. Williams. Worst case effluent discharge conditions and adaptive processing of effluents for southeast Florida outfalls. Proceedings, 68th Annual Conference, WEFTEC '95, Miami Beach, FL, October 21-25, 1995. Water Environment Federation, 147-158 (1996).

Of substantial interest to entities regulating coastal ocean effluent discharges are so-called "worst case" conditions. In general, "worst case" conditions refer to conditions of poorest dilution as determined by criteria involving ambient current speed distributions. A unique feature of the coastal waters off southeast Florida is the proximity of the Florida Current or Gulf Stream, one of the most powerful oceanic currents on earth with an average daily transport through the Straits of Florida of approximately 32 × 10⁶ m³/sec. An extensive study called the Southeast Florida Outfall Experiment (SEFLOE) was carried out between 1988 and 1994 on the effluent discharges from four major southeast Florida coastal ocean outfalls. All four of these outfalls are located within the western boundary regime of the Florida Current and, therefore, pose unique challenges in determining "worst case" conditions. All four outfall sites are located in water of 30 m depth and are alternately "within" and "external to" the Florida Current. As a consequence of their locations, each of the outfalls is subject to three different ambient current and, hence, dilution regimes. These regimes are (i) site occupied by the Florida Current, (ii) site external to the Florida Current but occupied by a relatively large scale, e.g., kilometers, current eddy, or (iii) site external to the Florida Current but occupied by short-period, e.g., 3-12 hour current variations, possibly being linear and non-linear tides. "Worst case" dilution conditions in the sense of poorest initial and/or subsequent dilution are observed during the occurrence of regime (iii) above. During this regime very small mean currents are observed.

Rogers, R.F., and J.M. Fritsch. A general framework for convective trigger functions. Monthly Weather Review, 124(11):2438-2452 (1996).

A general framework for the trigger function used in convective parameterization routines in mesoscale models is proposed. The framework is based on the diagnosis of the accessibility of potential buoyant energy. Specifically, the trigger function (1) estimates the magnitude of the largest vertical velocity perturbation from a source layer, and (2) calculates the total amount of inhibition between the source layer and the level of free convection. The calculation of perturbation magnitude accounts for such factors as subgrid-scale inhomogeneities, a convective boundary layer, and convergence within the source layer. Specific formulations to quantify these factors are proposed. The trigger is tested in a simulation using the PSU-NCAR mesoscale model MM5. The event chose for simulation is a summertime case exhibiting a variety of environments. The results of the simulation are compared with a simulation using the Fritsch-Chappell (FC) trigger function. It is found that decisions made by the new trigger function are more physically consistent with the local environment than decisions made by the FC trigger.

Rogers, R.F., and J.M. Fritsch. Mesoscale modeling of weakly-forced convection: Sensitivity to surface property specification. Preprints, 11th Conference on Numerical Weather Prediction, Norfolk, VA, August 19-23, 1996. American Meteorological Society, Boston, 386-388 (1996).

It has long been known that properly accounting for the fluxes of heat, moisture, and momentum from the surface is vital in obtaining reliable forecasts at all scales of motion. The importance of accurately representing these processes becomes most readily evident in simulations of convective activity in weakly-forced environments. Traditionally without access to air-surface interaction models, mesoscale models have relied upon specifications of surface parameters (e.g., albedo, moisture availability, roughness length, etc.) at each grid point in order to calculate the surface fluxes and boundary layer evolution. These specifications are based upon categorical decisions in which each grid element is assigned fixed values for each particular surface parameter. The values are considered to be representative of the dominant condition within that grid element. Values vary in discrete steps from one category of surface condition to another. Thus, a given grid element may be, for example, 55% forest and 45% grassland and therefore be assigned a category of "forest." An adjacent element may have the reverse distribution (i.e., 45% forest and 55% grassland) and be assigned a category of "grassland." These specifications are usually time-invariant and, due to the necessity of making categorical assignments, can result in sharp (i.e., step function) artificial gradients of surface parameters across grid points where the actual land surface type transitions vary much more gently. The effects of these time-invariant step functions are investigated in a simulation of convective activity in a weakly-forced environment using the Penn State/NCAR mesoscale model MM5. It is found that significant vertical circulations develop as a result of the artificially sharp gradients in surface parameters and that these circulations are then instrumental in spuriously initiating parameterized convection. The ability of the model to simulate realistic boundary layer evolution and convective initiation is therefore severely compromised in locations where these step-functions occur. A test wherein the step functions are relaxed by smoothing the surface parameter fields is then conducted to determine how removal of the artificially sharp gradients affect the model solution. Results reveal that the boundary layer assumes a more realistic structure and spurious convection is reduced or eliminated over the areas where the step functions were located in the unsmoothed run. The impact of altering these fields on the subsequent simulation is discussed.

Roux, F., and F.D. Marks. Extended velocity track display (EVTD): An improved processing method for Doppler radar observations of tropical cyclones. Journal of Atmospheric and Oceanographic Technology, 13:875-899 (1996).

We present an improved version of the Velocity Track Display (VTD) method, proposed by Lee et al. (1994) to deduce the primary vortex circulation in hurricanes from airborne Doppler radar data obtained during straight-line legs through the storm center. VTD allows the derivation of one projection of the mean horizontal wind, the wave number 0, 1, and 2 components of the tangential wind and one projection of the radial wind, in a series of concentric rings centered on the storm circulation center. The extended VTD (EVTD) algorithm determines additional information through a combination of data collected during successive legs: the Cartesian components of the mean horizontal wind, the wave number 0, 1, and 2 components of the tangential wind, and the wave number 0 and 1 components of the radial wind. Application of EVTD to airborne Doppler data collected on 17 September 1989 in Hurricane Hugo is discussed. Comparisons between the EVTD-derived winds, the flight-level measurements, and winds deduced from "pseudo-dual Doppler" analyses show qualitatively good agreement. These results reveal the asymmetric structure of the storm and show that it was in a deepening stage, with increasing tangential wind, inflow, and upward velocity. Further applications are finally discussed.

Schott, F.A., and R.L. Molinari. The western boundary circulation of the subtropical warmwater sphere. In The Warmwater Sphere of the North Atlantic Ocean, W. Krauss (ed.). Gebrüder Borntraeger, Berlin, Stuttgart, 229-252 (1996).

Herein, we review observational, empirical, and modeling studies of the western boundary region of the North Atlantic's subtropical gyre. Emphasis is placed on recent observational studies that consider both interaction between wind-driven and thermohaline driven currents and characterize the annual and interannual time scales of the regional circulation.

Severinghaus, J.P., W.S. Broecker, T.-H. Peng, and G. Bonani. Transect along 24°N latitude of ¹⁴C in dissolved inorganic carbon in the subtropical North Atlantic Ocean. Radiocarbon, 38(3):407-414 (1996).

The distribution of bomb-produced ¹⁴C in the ocean provides a powerful constraint for circulation models of upper ocean mixing. We report ¹⁴C measurements from an east-west section of the main thermocline at 24°N latitude in the subtropical North Atlantic Ocean in summer 1992, and one profile from the Gulf of Mexico in 1993. Observed gradients reflect the transient invasion of bomb ¹⁴C into the thermocline via mixing along isopycnals from the poleward outcrop, with progressively more sluggish mixing at greater depths. A slight deepening of the profile is observed over the 20-year period since the GEOSECS survey at one location where the comparison is possible.

Sirkes, Z., E. Tziperman, and W.C. Thacker. Combining data and a global primitive equation ocean general circulation model using the adjoint method. In Modern Approaches to Data Assimilation in Ocean Modeling, P. Malanotte-Rizzoli (ed.), Elsevier, Amsterdam, 119-145 (1996).

A primitive equation ocean general circulation model (PE OGCM) in a global configuration similar to that used in coupled ocean-atmosphere models is fitted to climatological data using the adjoint method. The ultimate objective is the use of data assimilation for the improvement of the ocean component of coupled models, and for the calculation of initial conditions for initializing coupled model integrations. We argue that oceanic models that are used for coupled climate studies are an especially appropriate target for data assimilation using the adjoint method. It is demonstrated that a successful assimilating of data into a fully complex PE OGCM critically depends on a very careful choice of the surface boundary condition formulation, on the optimization problem formulation, and on the initial guess for the optimization solution. The use of restoring rather than fixed surface-flux boundary conditions for the temperature seems to result in improved model results. The convergence of the optimization seems very sensitive to the cost formulation in a PE model, and a successful cost formulation is discussed and demonstrated. Finally, the use of simple, sub-optimal assimilation schemes for obtaining an initial guess for the adjoint optimization is advocated and demonstrated.

Springer-Young, M., D.J. Erickson, III, and T.P. Carsey. Carbon monoxide gradients in the marine boundary layer of the North Atlantic Ocean. Journal of Geophysical Research-Atmospheres, 101(D2):4479-4484 (1996).

We present an observational data set that suggests that the ocean source of carbon monoxide (CO) may influence the atmospheric CO concentration in the marine boundary layer (MBL). Atmospheric CO concentration gradient data obtained during the 1992 Atlantic Stratocumulus Transition Experiment (ASTEX) show significantly (range of 2-47 ppbv, average of 15 ppbv) more CO at an altitude of 0.05 to 0.5 m above sea level as compared to 10 m above sea level. The seawater CO concentrations needed to support the fluxes obtained from an atmospheric gradient calculation are much higher than generally reported in the literature. However, studies of CO production by Jones and Amador (1993) and data from Seiler (1978) suggest the possibility that CO production and the resultant flux to the MBL could be 1-2 orders of magnitude higher than currently documented using seawater pumped from depths of 4-10 m below the air-sea interface. We infer that the surface ocean production and sea-air exchange of photochemically produced trace gases such as CO may participate in physical, chemical, and biological processes on vastly different spatial and temporal scales than those inherent to more stable species such as CO₂.

Stamates, S.J., J.F. Craynock, J.R. Proni, V. Fox-Norse, and D.A. Tomey. Acoustic reflector of opportunity distribution as a surrogate for inferring effluent distribution in a survey of Massachusetts Bay. Proceedings, Ocean 96 MTS/IEEE, Ft. Lauderdale, Florida, September 23-26, 1996. Marine Technological Society, Vol. 1, 313-320 (1996).

In 1998, the Massachusetts Water Resources Authority (MWRA) expects to complete the construction of a new oceanic wastewater outfall system which will have the capacity to release as much as 1.2 × 10⁹ (gal) of treated wastewater per day. The design of the system is such that during summer months the effluent plume should be trapped beneath the seasonal thermocline. It is proposed that the spatio-temporal distribution of acoustic reflectors (probably biological) present in the seasonal thermocline is a reasonable surrogate for inferring the spatio-temporal distribution of acoustic reflectors that will result from the release of wastewater effluent. In September 1995, a joint U.S. EPA, MWRA, NOAA survey of Massachusetts Bay was conducted. The primary data sets gathered were acoustic backscatter profiles at 20 kHz and 200 kHz made every 0.5 (sec) with 0.5 (m) vertical resolution. Also, CTD casts and water bottle samples were taken at selected locations. Oceanographic phenomena, such as internal waves and tidal surges in conjunction with topographic features, cause the surrogate scattering layers to be vertically modulated with possible mixing of materials normally trapped within layer boundaries. Analysis of acoustic backscatter measurements provide visualizations of such events and allow for the estimation of the surrogate scattering layer distributions in the vertical and horizontal planes. Quantitative comparison of acoustic backscatter strength with CTD derived density and transmissometry measurements give an indication of the relationship of the surrogate scattering layers to the water density structure at selected sites in the study (and an indication of the reliability of the surrogate). In addition to its role as a surrogate for wastewater, the relationship of the surrogate scattering material layers with respect to the isopycnal surfaces is also considered for the purpose of evaluating the exposure of biota to future wastewater discharge.

Thacker, W.C. Climatic fingerprints, patterns, and indices. Journal of Climate, 9(9):2259-2261 (1996).

The purpose of this note is to point out that Hasselmann's (1993) optimal fingerprints for detecting climatic change follow from the geometrical interpretation of covariance as an inner product.

Thacker, W.C. Metric-based principal components: Data uncertainties. Tellus, 48A:584-592 (1996).

Seeking an index characterizing the best-determined mode of variability leads to a natural generalization of principal-component analysis with an explicit metric characterizing the uncertainties of the data. This formalism, which distinguishes between state-space patterns and patterns of coefficients defining principal components, allows the more accurate data to exert a greater influence on the definition of the indices than they do in conventional principal-component analysis; in all other aspects, the new formalism is the same as the old. Within the context of the simple example of Breterton et al. (1992), metric-based principal-component analysis is shown to be capable of finding correlated patterns of variability in two different data sets.

Thacker, W.C., and R. Lewandowicz. Climatic indices, principal components, and the Gauss-Markov theorem. Journal of Climate, 9(8):1942-1958 (1996).

If indices are to be used as the variables predicted by linear statistical models, it is important to be able to recover as much local information as possible from the values forecast for the indices. Here it is shown that the indices that encapsulate the most information about the local climatic state are determined by a generalized (two-matrix) eigenvalue problem that is equivalent to the usual (one-matrix) eigenvalue problem involving the sample correlation matrix. Thus, the best indices in the sense of providing the most location-specific information are the familiar principal-component indices. Regarding the indices as predictors in linear statistical models similar to those routinely used for estimating meteorological fields from observations reveals the role of the Gauss-Markov theorem in EOF analyses. From this perspective each index can be characterized by two EOF-like maps: the first illustrating the linear combinations of the data used to define the index, and the second displaying the Gauss-Markov weights for the index to predict local variables, both of which are related to the eigenvectors of the sample correlation matrix. Other maps can be used to display information about sampling errors: one to characterize the uncertainty of the weights; another to display the skill with which the index accounts for the training data; and a third to show how well it explains independent data. Such maps are illustrated within the context of 43 years of North Atlantic seasonal sea-surface temperature anomalies. The analysis presented here underlies two additional points. First, any linear combination of the indices would result in an equivalent model yielding exactly the same forecast. Consequently, it may be desirable to use indices that are easier to interpret physically. Second, when indices are regarded as being variables of a linear statistical model, the analysis of sampling error can be formulated in terms of the uncertainty of the Gauss-Markov weights inferred from a limited training set rather than in terms of the sample-to-sample variability of eigenvalues and eigenvectors.

Tsai, J.J., J.R. Proni, H. Huang, and J.F. Craynock. Initial and near-field subsequent dilution at the Key West Outfall. Proceedings, 68th Annual Conference, WEFTEC '95, Miami Beach, FL, October 21-25, 1995. Water Environment Federation, 139-146 (1996).

A one-year field study of discharge from the Key West Outfall was conducted from June 1993 to July 1994. A towed CTD was used to measure salinity about every other month with a fixed current mooring next to the outfall. Salinity deficit was used as a tracer to estimate the minimum surface dilution at the boil and near field subsequent dilution. The measured dilution was rapid within 200 m and reached 100:1 at about 500 m from the boil.

Wang, C., and R.H. Weisberg. Stability of equatorial modes in a simplified coupled ocean-atmosphere model. Journal of Climate, 9(12):3132-3148 (1996).

The stability, periodicity, and horizontal structure of equatorial modes in a coupled ocean-atmosphere model, simplified by the assumption that zonal wind stress anomalies are proportional to sea surface temperature (SST) anomalies lagged by a zonal phase difference, are examined analytically. The gravest coupled Rossby and Kelvin modes coexist with westward and eastward slow modes. Two of these four modes, one propagating westward and the other eastward, are destabilized in each case depending upon the model parameters. For some particular parameter choices, coupled Rossby and Kelvin modes merge with westward and eastward slow modes, respectively. For other parameters, however, they separate and remain distinct from the slow modes. For all of these modes the primary modifications by coupling relative to uncoupled oceanic equatorial waves are a decrease in phase speed and an increase in meridional scale. Among the model parameter effects, those of the zonal phase lag between the wind stress and SST anomalies and the coefficients of thermal and mechanical damping are the most interesting. The frequency of all modes is symmetric about zero phase lag, whereas the growth rate is antisymmetric relative to the uncoupled damping rate. Wind anomalies to the west of SST anomalies favor slow (coupled Rossby and Kelvin) mode growth (decay). Slow (coupled Rossby and Kelvin) mode damping is mainly thermal (mechanical). It may be concluded that coupling affects the structure, propagation, and stability properties of equatorial modes at low frequency. Determining where within the equatorial waveguide and with what efficiency coupling occurs would, therefore, seem to be critical for improved understanding of the ENSO phenomenon.

Wanninkhof, R.H., and M. Knox. Chemical enhancement of CO₂ exchange in natural waters. Limnology and Oceanography, 41(4):689-697 (1996).

Exchange of carbon dioxide (CO₂) under low turbulence conditions and high pH can be enhanced by hydration reactions of CO₂ with hydroxide ions and water molecules in the boundary layer. A series of field experiments was performed on several lakes, including alkaline closed-basin lakes, using enclosures (helmets) to study the enhancement process in nature. In addition, the enhancement of CO₂ exchange was studied in laboratory experiments using freshwater and seawater. The results of the experiments are compared with published theoretical calculations. Within the experimental uncertainties and shortcomings of the chemical enhancement models, reasonable agreement was observed between experimental and theoretical results for seawater. The experiments indicate, in accordance with theory, that chemical enhancement has a minor effect on air-sea gas exchange of CO₂ under average oceanic turbulence conditions. However, for the equatorial CO₂ source regions, with high temperatures and low winds, the calculated CO enhancement amounts to 4% to 8% of the total exchange. The observations on lakes show poorer agreement with models which is attributed to experimental uncertainty and poor characterization of the chemistry of the lake waters. The experiments show that chemical enhancement of CO₂ is ubiquitous for the alkaline close basin lakes with enhancements of up to a factor of three.

Wanninkhof, R.H. W.E. Asher, and E.C. Monahan. The influence of bubbles on air-water-gas exchange: Results from gas transfer experiments during WABEX-93. Proceedings, Third International Symposium on Air-Water-Gas Transfer, Heidelburg, Germany, July 24-27, 1995. Aeon Verlag and Studio, 239-254 (1996).

Bubble-mediated gas transfer velocities were determined in a freshwater surf pool during WABEX-93. Gas transfer of N₂O, He, and SF₆ were measured under eight different mechanically-generated, breaking-wave conditions. Contrary to gas transfer across an air-water interface, where the transfer is solely a function of surface turbulence and the molecular diffusion coefficient of the gas, exchange through bubbles is also a function of the solubility of the gas, bubble size, and bubble penetration depths. The relative rates of gas transfer through bubbles of N₂O, CO₂, He, and SF₆ for the experiment are compared with models developed by Woolf (1995) and Keeling (1992). The model of Woolf shows reasonable agreement with the observed results while that of Keeling overpredicts the exchange of N₂O. The trend suggests that in the surf pool experiments the solubility dependence of the model of Keeling is too strong while that of Woolf is slightly too weak compared to the observations.

Wanninkhof, R.H., S. Doney, T.-H. Peng, R. Feely, and J.L. Bullister. Penetration of anthropogenic CO₂ into the North Atlantic Ocean. EOS, Transactions, American Geophysical Union, 76:128 (1996).

Transient tracers such as ¹⁴C and chlorofluorocarbons offer a powerful constraint on the penetration depth and inventory of anthropogenic CO₂ in the North Atlantic. A qualitative comparison is performed between the transient tracers and anomalies in preformed carbon from a cruise in the North Atlantic along 20/25°W from 5°S to 62°N in 1993 as part of NOAA's Ocean-Atmosphere Carbon Exchange Study (OACES). The analysis is performed in an isopycnal reference frame to distinguish between different water masses. From the apparent oxygen utilization and change in total alkalinity (calculated from pCO₂ and DIC) in CFC-free water, the pre-anthropogenic preformed carbon at each isopycnal is determined. Based on the CFC ages of the water along the isopycnal and fossil fuel CO₂ release histories, the fraction of atmospheric fossil fuel burden taken up with time is determined. These estimates are compared with air-sea fluxes of CO₂ into the ocean at the outcrop regions.

Wanninkhof, R.H., R.A. Feely, H. Chen, C. Cosca, and P.P. Murphy. Surface water fCO₂ in the eastern equatorial Pacific during the 1992-1993 El Niño. Journal of Geophysical Research, 101(C7):16,333-16,343 (1996).

The fugacity of CO₂ in surface water (fCO_2W) was measured in the eastern equatorial Pacific (EEP) during the boreal spring and fall of 1992 and in the spring of 1993. A prolonged El Niño occurred during this period with anomalously warm sea surface temperatures (SST) during the spring of 1992 and 1993. Correspondingly, the fCO_2W values were lower than historical non-El Niño values at the equator. However, the fCO_2W in the spring of 1993 was up to 50 µatm higher than in the spring of 1992, despite similar SSTs. The trend is attributed to the slower response times of factors causing fCO_2W decrease compared to rapid increase of fCO_2W by upwelling cold water with high carbon content and subsequent heating. During the fall of 1992, SSTs south of the equator were 5°C cooler than in the spring, which is indicative of vigorous upwelling of water with high CO₂ content from below the thermocline. Decreases in fCO_2W due to net biological productivity and gas exchange take of the order of months, causing the fCO_2W levels during the spring of 1993 to be elevated compared to the spring of the previous year. Our data and data obtained in 1986 and 1989 along 110°W suggest that fCO_2W maxima in the equatorial Pacific can be either associated with temperature minima or temperature maxima. Despite the multitude of factors which influence fCO_2W, most of the variance can be accounted for with changes in nitrate and SST. A multilinear regression of fCO_2W with SST and nitrate for the 1992 data has a standard error in predicted fCO_2W of 10 µatm. Air-sea fluxes of CO₂ in the EEP were estimated to be 30% higher in the spring of 1993 and 10% higher in the fall of 1992 than in the spring of 1992.

Weisberg, R.H., C. Wang, and D.A. Mayer. An oscillator paradigm for El Niño-Southern Oscillation. 1996 AGU Fall Meeting, San Francisco, CA, December 15-19, 1996. Supplement to EOS, Transactions, American Geophysical Union, 77(46):F40, U32A-03 (1996).

A data-based hypothesis is developed on the mechanism of the El Niño-Southern Oscillation (ENSO). This hypothesis emphasizes the importance of off-equator sea surface temperature (SST) and sea level pressure (SLP) variations in the western Pacific for providing a negative feedback that is necessary for the coupled ocean-atmosphere system to oscillate. The negative feedback derives from equatorial easterly winds over the far western Pacific, driven by off-equator high SLP during the mature phase of El Niño. The off-equator high SLP follows from off-equator low SST that is related to upwelling favorable wind stress curl set up by equatorial west-central Pacific convection. The resulting easterlies over the western equatorial Pacific compete with westerlies over the west-central equatorial Pacific to reverse the sign of the central equatorial Pacific SST anomalies. An analog model embodying these conceptual ideas produces ENSO-like oscillations on interannual time scales. While this oscillator paradigm involves forced oceanic equatorial wave dynamics, it does not require wave reflection at the western boundary.

Willoughby, H.E. Hurricane research from forty thousand feet. Minutes, 50th Interdepartmental Hurricane Conference, Miami, FL, March 26-29, 1996. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A.9 (1996).

NOAA's commissioning of its new Gulfstream IV (G-IV) mid-level jet represents an unprecedented opportunity to answer questions about hurricane motion and intensification. In its initial configuration, the airplane will be able to fly 4,000 nautical miles, attain pressure altitudes near 14 km, and dispense GPS dropsondes. It will carry a C-band nose radar and a workstation to process dropsonde messages for transmission. The G-IV will represent the hurricane research community's first routine access (apart from a few flights by jet aircraft borrowed from NASA) to the upper troposphere since the 1960s. The primary mission of the G-IV will be "synoptic surveillance," dispensing dropwindsondes in the hurricane's surroundings to improve track forecasts. We expect ~20% smaller error based upon experience with turboprop WP-3Ds flying similar missions. With additional instrumentation, primarily microwave/surface wind sensors, the G-IV will ultimately be able to obtain center fixes. These operational missions justify the G-IV's existence, but what can the jet do to improve physical understanding? Because the sounding data will represent nearly the whole tropospheric column, the G-IV can provide a nearly complete picture of the storm's interaction with its surroundings. A simple circumnavigation at 300 to 600 km will support determination of eddy and mean-flow boundary fluxes. The operational synoptic missions will capture the structure of the environmental flow and storm-induced eddies, but radial penetrations at 200 hPa, after the G-IV is certified to fly into hurricanes, may prove to be the best way to evaluate these interactions. From decades of experience with turboprops operating in the lower and mid troposphere, we know a great deal about the convective and vortex-scale structure and dynamics of hurricanes. These observations, combined with conventional synoptic analyses, have led to a consensus that understanding of forcing by upper tropospheric eddies and of advection by vertically-averaged winds are the keys to prediction of intensity and track. The G-IV and the existing WP-3Ds, with their powerful radars and other sensors, are the tools needed to forge this understanding.

Willoughby, H.E., and P.G. Black. Hurricane Andrew in Florida: Dynamics of a disaster. Bulletin of the American Meteorological Society, 77(3):543-549 (1996).

Four meteorological factors aggravated the devastation when Hurricane Andrew struck south Florida: completed replacement of the original eyewall by an outer, concentric eyewall while Andrew was still at sea; storm translation so fast that the eye crossed the populated coastline before the influence of land could weaken it appreciably; extreme wind speed, 82 m s^-1 winds measured by aircraft flying at 2.5 km; and formation of an intense, but nontornadic, convective vortex in the eyewall at the time of landfall. Although Andrew weakened for 12 h during the eyewall replacement, it contained vigorous convection and was reintensifying rapidly as it passed onshore. The Gulf Stream just offshore was warm enough to support a sea level pressure 20-30 hPa lower than the 922 hPa attained, but Andrew hit land before it could reach this potential. The difficult-to-predict mesoscale and vortex-scale phenomena determined the course of events on that windy morning, not a long-term trend toward worse hurricanes.

Willoughby, H.E., and P.G. Black. Correction to Hurricane Andrew in Florida: Dynamics of a disaster (letters to the editor). Bulletin of the American Meteorological Society, 77(5):962 (1996).

No abstract.

Wilson, W.D., E. Firing, J. Kindle, F. Schott, D. Quadfasel, and C. Flagg. Equatorial currents in the western Indian Ocean during 1995. 1996 AGU Fall Meeting, San Francisco, CA, December 15-19, 1996. Supplement to EOS, Transactions, American Geophysical Union, 77(46):F392, OS12A-03 (1996).

Because of the strong, seasonally-varying surface forcing fields, the tropical Indian Ocean has long been recognized by physical oceanographers as an important natural laboratory for studying upper ocean dynamical processes. In 1995, the intensive Indian Ocean WOCE and other coincident field programs (e.g., JGOFS) led to a remarkable concentration of shipboard data collection resources in the region, including the research vessels Knorr, Thomas G. Thompson, Malcolm Baldrige, and Meteor. All were equipped with hull-mounted acoustic Doppler current profilers (ADCPs) and high quality navigation equipment, and nine underway velocity sections were collected in the vicinity of 55°E between 5°N and 5°S during April through December 1995. Additionally, full-depth lowered ADCP (LADCP) velocity measurements are available for many of the sections. This region is especially important to understanding monsoon current dynamics, as it is the link between the equatorial wave guide and the western boundary current (Somali Current) regime. Considerable modeling and observational effort has been spent on this region, trying to determine the relative importance of local and remote wind forcing to the rapid changes observed in the Somali Current. The sections are presented, especially noting their relationship to changes in the equatorial wind field as shown by the FNMOC NOGAPS analysis and their similarities to theoretical and modeled equatorial wave dynamical processes. The April 1995 section, during the monsoon transition period, is dominated by an equatorial undercurrent centered near 100 m, with westward flow below and weak symmetric off-equatorial eastward jets. By late June 1995, some two months after the southwest monsoon onset, there is a westward core at 100 m, with enhanced off-equatorial eastward flows; the changes are consistent with the arrival of equatorial Rossby waves from the interior. Mid-July and early August sections show the effects of the Somali Current low-latitude turnoff jet, which crosses the equator southward near 55°E and returns eastward near 3°S. Sections in late August and early September show the development of the low-latitude effects of the Somali Current, and a final section in January 1996 shows the current field associated with the northeast monsoon.

Yvon, S.A., and J.H. Butler. An improved estimate of the oceanic lifetime of atmospheric CH₃Br. Geophysical Research Letters, 23(1):53-56 (1996.)

Previous estimates of the partial atmospheric lifetime of CH₃Br with respect to degradation in the ocean have not fully accounted for co-variation of sea-surface and boundary layer properties. Here we substantially reduce uncertainty in this calculation by using a coupled, ocean-atmosphere box model and a tightly gridded data set of oceanic and atmospheric properties. The best estimate of the partial atmospheric lifetime of CH₃Br with respect to the ocean is 2.7 y with a possible range, due mainly to the choice of computational procedures for critical terms, of 2.4 to 6.5 y. This range is about one-third of that estimated previously. The total atmospheric lifetime, based upon oceanic, atmospheric, and proposed soil losses with all of their uncertainties, is 0.8 (0.6 to 1.4) y. Only 28% of this total uncertainty is attributable to the uncertainty in oceanic loss.

Yvon, S.A., and E.S. Saltzman. Atmospheric sulfur cycling in the tropical Pacific marine boundary layer (12°S, 135°W): A comparison of field data and model results 2. Sulfur dioxide. Journal of Geophysical Research, 101:6899-6910 (1996).

The atmospheric chemistry of sulfur dioxide over the tropical South Pacific Ocean is investigated using results from field measurements and numerical models. Simultaneous real time measurements of sulfur dioxide and its biogenic precursor dimethylsulfide were made at 12°S, 135°W for a six-day period from March 3-9, 1992. The mean SO₂ and DMS concentrations were 71 ± 56 pptv (1 sigma) and 453 ± 93 pptv (1 sigma) respectively. These measurements are compared to those predicted by a time-dependent photochemical box model of the marine boundary layer. Model estimates of the yield of SO₂ from DMS oxidation range from 27-54%. Even with low yields, DMS is the dominant source of SO₂ in this region. Estimates of vertical entrainment velocities based on the tropospheric ozone budget suggest that vertical entrainment is a minor source of SO₂. The relative rates of various loss mechanisms for SO₂ are: dry deposition to the sea surface (58%), in-cloud oxidation (9%), OH oxidation (5%), an uptake by sea-salt aerosols (28%).

Yvon, S.A., E.S. Saltzman, T.S. Bates, and D.J. Cooper. Atmospheric sulfur cycling in the tropical Pacific marine boundary layer (12°S, 135°W): A comparison of field data and model results 1. Dimethylsulfide. Journal of Geophysical Research, 101:6911-6918 (1996).

Shipboard measurements of atmospheric and seawater DMS were made at 12°S, 135°W for six days during March 1992. The mean seawater DMS concentration during this period was 4.1 ± 0.45 nM (1 sigma, n = 260), and the mean atmospheric DMS mole fraction was 453 ± 93 pmol mol^-1 (1 sigma, n = 843). Consistent atmospheric diel cycles were observed, with a nighttime maximum and a daytime minimum and an amplitude of approximately 85 pmol mol^-1. Photochemical box model calculations were made to test the sensitivity of modeled atmospheric DMS concentrations to the following parameters: (1) sea-to-air flux; (2) boundary layer height; (3) oxidation rate; and (4) vertical entrainment velocities. The observed relationship between mean oceanic and atmospheric DMS levels require the use of and air-sea exchange coefficient which is at the upper limit end of the range of commonly used parameterizations. The amplitude of the diel cycle in atmospheric DMS is significantly larger than that predicted by a photochemical model. This suggests the sea-to-air flux is higher than was previously thought, and the rate of daytime oxidation of DMS is substantially underestimated by current photochemical models of DMS oxidation.

Yvon, S.A., J.M.C. Plane, C.-F. Nien, D.J. Cooper, and E. S. Saltzman. The interaction between the nitrogen and sulfur cycles in the polluted marine boundary layer. Journal of Geophysical Research, 101:1379-1386 (1996.)

Simultaneous measurements are reported of the nitrate radical (NO₃), nitrogen dioxide (NO₂), ozone (O₃), and dimethylsulfide (DMS) in the nighttime marine boundary layer over Biscayne Bay in South Florida. These field observations are analyzed and used to initialize a boundary layer box model which examines the relative importance of the various sinks for NO_x in the marine boundary layer. The results show that the observed lifetime of NO₃ (< 6 min.) is probably controlled both by the loss of nitrogen pentoxide (N₂O₅) to reaction with water vapor and aerosols and by the reaction between NO₃ and DMS. The model is then extended to investigate the loss of nitrogen oxides from an air parcel that remains in the boundary layer with a constant sea-to-air DMS flux for several days. The principal conclusions are (1) that DMS is an important sink for NO₃ at lower NO₂ levels and (2) that the reaction between NO₃ and DMS is an important sink for DMS in the marine boundary layer and could exceed that of the daytime removal by OH.

Yvon, S.A., J.H. Butler, S.A. Montzka, J.M. Lobert, A.D. Clarke, and J.W. Elkins. A comparison of GC/ECD and GC/MS techniques for measuring CH₃. EOS, Transactions, American Geophysical Union, 77(46):F110 (1996).

No abstract. **1995**

Aberson, S.D., S.J. Lord, M. DeMaria, and M.S. Tracton. Short-range ensemble forecasting of hurricane tracks. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 494-496 (1995).

The National Meteorological Center has produced ensemble forecasts once each day using the Medium-Range Forecast (MRF) model since December of 1992. Small perturbations representing the fastest growing modes are added to and subtracted from the initial conditions in order to estimate possible error growth in the model. The mean of each ensemble provides a more reliable forecast than any of the individual forecasts on average, and the ensembles themselves may provide reliable estimates of the range and likelihood of alternative meteorological scenarios. In addition to using the large sample of runs to assess the impact on forecasting, the sample can be used as boundary conditions for other models with more specific goals. The VICBAR hurricane track forecast model will be run for all tropical cyclones in the North Atlantic and North Pacific Oceans for cases between 1 September and 15 September 1994, using the MRF ensembles as boundary conditions. Because the VICBAR model is concerned only with forecasting the location of a tropical cyclone at a particular time, analysis of results is much simpler than for a global model such as the MRF. Results of this study can be used to answer some of the important questions concerning ensemble forecasting, and these can be extended to more general forecast models. These issues include assessing the impact of ensembles on forecast skill, different methods of displaying results of the ensemble, measuring the probability of certain members of the ensemble occurring, and studying whether the atmospheric reality can truly be represented by any of the members of the ensemble.

Atlas, D., P.T. Willis, and F.D. Marks. The effect of convective updrafts and downdrafts on reflectivity-rain rate relations and water budgets. Preprints, 27th Conference on Radar Meteorology, Vail, CO, October 9-13, 1995. American Meteorological Society, Boston, 19-22 (1995).

No abstract.

Bianchi, A., and S.L. Garzoli. Variability and motion of the Brazil-Malvinas Front. Geochimica Acta, 22 (1995).

No abstract.

Bitterman, D.S. Automated XBT launcher for use on ships-of-opportunity. Proceedings, IEEE Oceans '95 Conference, San Diego, CA, October 9-12, 1995. Institute of Electrical and Electronic Engineers (1995).

Currently, the NOAA Volunteer Observing Ship network employs a larger number of merchant vessels to make routine expendable bathythermograph (XBT) and meteorological measurements throughout the world's oceans. While these data have proven to be very useful, there is a need to improve the quality and increase the density of the observations. The XBT profiles are frequently compromised due to the need to launch the probe from less than optimal locations on the ship. Also, the ship's officers can only commit a limited amount of time to this work which severely limits the number of XBT deployments. To improve the XBT measurements, an automated XBT launcher was designed and is currently being tested. It consists of a lightweight, compact launcher mechanism which is linked to a personal computer that performs all control functions and logs data from the deployments. The launcher can be loaded with six probes and can be placed at any location on the ship. The deployments can then be made automatically at predetermined times or geographical positions as determined from a GPS navigation receiver. The system is currently being used for high density XBT surveys on a Mexican registered freighter running between Spain and Mexico.

Bitterman, D.S., and R.C. Millard. Shipboard thermosalinograph intercomparison test results from the NOAA research vessel Malcolm Baldrige. NOAA Technical Memorandum, ERL AOML-82 (PB95-147898), 47 pp. (1995).

An intercomparison test of three commercially available thermosalinographs (TSGs) considered for installation on volunteer observing ships of opportunity was conducted onboard the NOAA Ship Malcolm Baldrige during the period June 2 to September 22, 1993. A Seabird Electronics Company (SBE) Model SBE-21 TSG, a Falmouth Scientific Instruments, Inc. (FSI) TSG, and an Ocean Sensors Instrument, Inc. (OSI) Model OS-200 TSG were evaluated in the test. The three systems were plumbed in series and run continuously for all four months of the cruise. Temperature and conductivity measurements from each TSG were logged to a personal computer (PC). Water samples were drawn every six hours and analyzed for salinity. After removing anomalous sections of data, a drift rate for each instrument was then determined by comparing the thermosalinograph computed salinities to those from the water samples. The OSI thermosalinograph exhibited a salinity drift rate of +0.00738 practical salinity units (psu) per day, the FSI drift rate was +0.001 psu per day, and the SBE drift rate was +0.00063 psu per day. The salinity drift is composed of both conductivity and temperature drifts. The OSI and FSI temperature measurements exhibited systematic temperature errors under various conditions encountered during the test. The SBE TSG needs to improve the flushing of their conductivity cell.

Black, M.L., R.W. Burpee, and F.D. Marks. Two-dimensional spatial structure of hurricane updrafts and downdrafts. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 605-607 (1995).

Vertical motions in seven Atlantic hurricanes are determined from data recorded by Doppler radars on research aircraft. The data base consists of Doppler velocities and reflectivities from vertically pointing radar rays collected along 185 radial flight legs through the hurricane centers. The vertical motions are estimated throughout the depth of the troposphere from the Doppler velocities and bulk estimates of particle fallspeeds. Portions of the flight tracks are subjectively divided into eyewall, rainband, stratiform, and "other" regions. At each altitude, Doppler updrafts and downdrafts are defined to contain vertical motions continuously greater than 1.5 m s^-1 with at least one speed greater than 3.0 m s^-1. Two-dimensional correlation maps centered on the updraft and downdraft maxima at 2.5 and 7.5 km altitude identify the preferred spatial structure of the drafts. The eyewall updrafts correlate significantly over distances of 5-10 km in both the horizontal and vertical, affect much larger areas than updrafts in the other regions, and exhibit a pronounced outward slope of 45 degrees with height. The only other updrafts that appear to slope outward are rainband updrafts at 7.5 km. Downdrafts are significantly correlated over smaller areas than the updrafts and exhibit little or no slope. The eyewall region is the primary location for well-organized updrafts and downdrafts. Comparisons are made of radius-height profiles of reflectivity and vertical velocity in hurricanes that contain widely different eyewall structure. The composite spatial structure of updrafts and downdrafts in the lower and upper troposphere in each of the four regions are presented. The role of the eyewall updrafts to the maintenance of the hurricane's intensity are discussed.

Black, M.L., R.W. Burpee, and F.D. Marks. Vertical motion asymmetries in the hurricane eyewall. Preprints, 27th Conference on Radar Meteorology, Vail, CO, October 9-13, 1995. American Meteorological Society, Boston, 574-576 (1995).

No abstract.

Black, P.G., and L.K. Shay. Observed sea surface temperature variability in tropical cyclones: Implications for structure and intensity change. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 603-604 (1995).

No abstract.

Black, P.G., S.H. Houston, D. Lipscombe, and J. Parrish. AFRES-NOAA intercomparison flight of 13 April 1994. Minutes, 49th Interdepartmental Hurricane Conference, Miami, FL, February 14-17, 1995. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-5 (1995).

An intercomparison flight between an Air Force Reserve (AFRES) aircraft and a National Oceanic and Atmospheric Administration (NOAA) aircraft took place on 13 April 1994. This mission resulted from a recommendation made at the 48th Interdepartmental Hurricane Conference. The AFRES and NOAA aircraft each recorded most flight-level meteorological, as well other data related to the flight (e.g., true air speed, heading, etc.), at 1-sec intervals. In addition to these high-resolution data, the 1-min averages of these data were sent from each aircraft via satellite to the National Hurricane Center in real-time. All of these 1-sec and 1-min data have been compared and there was generally good agreement between the measured variables. The wind data were in very good agreement at the higher wind speeds in the midtroposphere, except in turns where the angle-of-attack measurement is not fully included in the AFRES wind measurement. Methods for improvements in the wind calculations are discussed and additional intercomparison flights during 1995 are recommended.

Black, P.G., J.R. Proni, J.C. Wilkerson, and C.E. Samsury. Classification of convective and stratiform regions in oceanic tropical and subtropical mesoscale convective systems using underwater acoustic methods. Preprints, 27th Conference on Radar Meteorology, Vail, CO, October 9-13, 1995. American Meteorological Society, Boston, 237-239 (1995).

No abstract.

Black, P.G., R. McIntosh, C. Swift, J. Carswell, K. St. Germain, I. Popstefanija, and M. Goodberlet. Ocean surface wind, stress, and rain rate measurements in tropical cyclones from concurrent airborne microwave scatterometer and radiometer observations. Preprints, 27th Conference on Radar Meteorology, Vail, CO, October 9-13, 1995. American Meteorological Society, Boston, 623-625 (1995).

No abstract.

Black, R.A., and J. Hallett. The relationship between the evolution of the ice phase hydrometeors with altitude and the establishment of strong electric fields in Hurricane Claudette. Preprints, Conference on Cloud Physics, Dallas, TX, January 1995. American Meteorological Society, Boston (1995).

No abstract.

Black, R.A., H.B. Bluestein, and M.L. Black. Unusually strong vertical motions in a Caribbean hurricane. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 260-262 (1995).

No abstract.

Broecker, W.S., S. Sutherland, W. Smethie, T.-H. Peng, and G. Ostlund. Oceanic radiocarbon: Separation of the natural and bomb components. Global Biogeochemical Cycles, 9(2):263-288 (1995).

An improved method has been developed for the separation of the natural and bomb components of the radiocarbon in the ocean. The improvement involves the use of a very strong correlation between natural radiocarbon and dissolved silica. This method is applied to radiocarbon measurements made on samples collected during the Geochemical Ocean Sections Study (GEOSECS), Transient Tracers in the Ocean (TTO) and South Atlantic Ventilation Experiment (SAVE) expeditions. On the basis of this new separation we provide not only an estimate of the global inventory of bomb ¹⁴C inventory and penetrations along thermocline isopycnals in the North Atlantic Ocean but also between the times of the GEOSECS (1972-1973) and TTO (1980-1982) surveys and in the South Atlantic Ocean between the times of the GEOSECS (1973) and SAVE (1987-1989) surveys. In addition, we show that the bomb tritium to bomb C ratio (expressed in the tritium units [TU] 81 units/100%) for waters entering the thermocline of the northern hemisphere is about nine times higher than for those entering the southern hemisphere thermocline. This contrast offers long-term potential as an indicator of inter-hemispheric transport of upper ocean waters.

Butler, J.H., J.M. Lobert, S.A. Yvon, and L.S. Geller. The distribution and cycling of halogenated trace gases between the atmosphere and ocean. In The Expedition ANTARKTIS XII of RV Polarstern in 1994/1995 Reports of Legs ANT XII/1 and 2, G. Kattner and K. Fütterer (eds.), Ber. Polarforsch., 168:27-39 (1995).

No abstract.

Cantillo, A.Y., L. Pikula, J. Beattie, E. Collins, K. Hale, and T. Schmidt. Natural and anthropogenic events impacting Florida Bay, 1910-1994 time line. NOAA Technical Memorandum, NOS ORCA-90, 510 pp. (1995).

Florida Bay is a coastal lagoon, on average less than 3 m deep, approximately 1,000 square miles in area, located between the south Florida mainland and the Florida Keys. In recent years, adverse environmental changes have been noted in the Bay. Currently, a multi-agency multi-year effort is underway to restore the ecosystem of south Florida, including that of Florida Bay. To assist in determining the Bay's former condition and to catalogue changes, events that may have affected or have occurred in the Bay are described, listed, and graphically displayed in a common time scale. The time coverage begins in 1910 with construction activities along the Florida Keys, and in what later became the Everglades National Park. Included are global scale atmospheric, geological, and astronomical phenomena such as El Niño events, volcanic eruptions, and solar activity that may affect local weather. On local scales, documented are: dieoffs of species such as seagrasses, sponges, and fishes; environmental occurrences of algal blooms, coral reef degradation, fishery catch changes, and soil subsidence; and human activities such as population increases and construction. Awareness of the environmental importance of the Bay is documented in legislation affecting environmental regulations nationwide and in the Bay area; and environmental programs and studies performed currently and in the past by federal, state, municipal, academic, and civic organizations.

Carleton, A.M., L.A. McMurdie, K.B. Katsaros, H. Zhao, N.M. Mognard, and C. Claud. Satellite-derived features and associated atmospheric environments of Southern Ocean mesocyclone events. Global Atmosphere and Ocean System, 3(2-3):208-248 (1995).

Mesoscale cyclones in cold air outbreaks are generated frequently over the southern oceans poleward of about 50°S. Polar orbiting satellites sensing in visible and IR wavelengths supply cloud information from which processes important in mesocyclone development have been inferred. However, direct retrieval of the integrated cloud liquid water (ICLW) and water vapor (IWV) contents, precipitation occurrence, and surface wind speeds associated with mesocyclones, is possible using microwave radiometry. We present three mesocyclone cases, analyzed using data from the DMSP (Defense Meteorological Satellite Program) SSM/I (Special Sensor Microwave/Imager), supplemented with data from the Geosat radar altimeter and the TOVS (TIROS-N Operational Vertical Sounder). The mesocylones possess different IR cloud signatures, but have common features in the microwave: low to moderate ICLW, low IWV, light rain, and strong to gale-force surface winds. Mesocyclones appear predominantly baroclinic (TOVS); however, the role of sea-air interactions cannot be ruled out. These case investigations confirm the value of multiple satellite systems for mesoscale studies in remote ocean areas.

Carsey, T.P., M.L. Farmer, C.J. Fischer, A. Mendez, A.A. Pszenny, V.B. Ross, P.-Y. Whung, M. Springer-Young, and M.P. Zetwo. Atmospheric chemistry measurements from the 1992 ASTEX/MAGE cruise. NOAA Data Report, ERL AOML-26 (PB95-179552) 90 pp. (1995).

No abstract.

Chen, H., R.H. Wanninkhof, R. Feely, and D. Greeley. Measurements of fugacity of carbon dioxide in seawater: An evaluation of a method based on infrared analysis. NOAA Technical Memorandum, ERL AOML-85 (PB95-271029), 54 pp. (1995).

An analysis system is described to measure the fugacity of CO₂ (fCO₂)¹ in 500 mL of seawater (discrete samples) by infrared analysis. The unit has been used on oceanographic research cruises sponsored by the Ocean-Atmosphere Carbon Exchange Study (OACES) of NOAA since 1991 for a total of approximately 10,000 measurements. The precision of the analyses based on replicate samples during routine analysis is 0.2%. Precision is primarily limited by sample storage, and the difference between headspace gas and water CO₂ concentrations prior to equilibration. The precision and accuracy of the instrument is estimated in several different ways. A preliminary side by side test of two different discrete fCO₂ systems using an infrared (IR) analyzer and a gas chromatograph (GC) shows a variability of 0.8% without significant bias. For surface waters the discrete measurements are compared with measurements from a continuous flowing underway system which was deployed on all cruises. Select comparisons with fCO₂ calculated from spectrophotometric pH and DIC (Total Dissolved Inorganic Carbon) measurements are performed. These comparisons are limited by uncertainty in the magnitude and the temperature dependence of the carbon and borate dissociation constants. Indirect comparisons are made with pCO₂ measurements of Drs. Takahashi and Chipman of LDEO in the South Atlantic and equatorial Pacific (EqPac). Although the measurements were performed months (for the EqPac study in 1992) to years (for the South Atlantic study in 1989 and 1991) apart, some inferences can be made by normalizing the fCO₂ values and by performing the comparison in property space. The comparison indicates that the precision of our system is comparable to that of the LDEO system. The surface values obtained from the LDEO system during EqPac are 1.5 to 3% lower. There is inconclusive evidence that some of the subsurface LDEO pCO₂ values are lower as well. However, the comparison of subsurface values for the North Atlantic Deep Water in the South Atlantic study shows good agreement. Because of the current uncertainty in dissociation constants, there is no a priori way to determine which value is correct.

Cione, J.J., and S. Raman. A numerical investigation of surface-induced mesocyclogenesis near the Gulf Stream. Tellus, 47A:815-833 (1995).

No abstract.

Cione, J.J., S. Raman, L.J. Pietrafesa, X. Li, R.A. Neuherz, and K. Keeter. Operational utilization of the Atlantic Surface Cyclone Intensification Index (ASCII). Proceedings, American Meteorological Society Regional Training Symposium for Operational Forecasters in the Carolinas and Virginia, Raleigh, North Carolina, November 6-8 1995. American Meteorological Society, Boston (1995).

No abstract.

Clark, J.F., P. Schlosser, R.H. Wanninkhof, H.J. Simpson, W.S.F. Schuster, and D.T. HO. Gas transfer velocities for SF₆ and ³He in a small pond at low wind speeds. Geophysical Research Letters, 22(2):93-96 (1995).

Gas transfer velocities for two gases, SF₆ (sulfur hexafluoride) and ³He, were determined in a small pond by injecting a mixture of these gases into the water and monitoring the decline of their concentrations over the next eight days. For wind speeds between 1.5-2.5 m s^-1, no variations of gas transfer velocity with wind speed could be resolved with our data. Gas transfer velocities at wind speeds greater than 3 m s^-1 were substantially larger and consistent with other lake tracer experiments. From the ratio of gas transfer velocities for SF₆ and ³He, we calculated the Schmidt number exponent to be 0.57 ± 0.07.

Claud, C., K.B. Katsaros, N.M. Mognard, and N.A. Scott. Synergetic satellite study of a rapidly deepening cyclone over the Norwegian Sea: 13-16 February 1989. Global Atmosphere and Ocean System, 3(1):1-34 (1995).

In oceanic regions, conventional meteorological observations are often insufficient for following the progression of atmospheric depressions, which generally leads to poor prediction in terms of strength and location. Since observations from polar-orbiting satellites probe nearly every region of the earth about twice a day, they can be used to track the propagation and evolution of weather systems and potentially improve the forecasts. The synoptic and mesoscale aspects of a rapidly intensifying cyclone, which persisted over the northern Atlantic Ocean and the Norwegian Sea for four days in February 1989, are presented. A combination of three instruments was used: the TIROS-N Operational Vertical Sounder (TOVS; 19 infrared, 1 visible and 4 microwave channels), the Special Sensor Microwave/Imager (SSM/I; a passive microwave radiometer with 7 channels), and an active radar altimeter (Geosat). The combination of TOVS and SSM/I provides a rough estimation of the air-sea fluxes, which are of the same order of magnitude as for rapidly intensifying storms found previously over other maritime areas. This case study confirms the value of using a combination of satellite instruments for studying weather systems in data-sparse maritime areas.

Crane, M.L., R.H. Smith, M.H. Bushnell, W.D. Wilson, and S. Tosini. NSWC moored ADCP data, 1994 (Straits of Florida, 26°04.00'N, 80°03.50'W). CD-ROM, NODC-59, National Oceanographic Data Center, Washington, D.C. (1995).

This database contains acoustic Doppler current profiler (ADCP) data collected during 1994 on the eastern shelf of Florida. The data were collected at 10-minute intervals by a bottom mounted 300-kHz ADCP unit (from RD Instruments, San Diego, CA), and is offshore Ft. Lauderdale, Florida, at a depth of 140 m. This instrument is positioned at approximately 26°04.0'N by 80°03.5'W. The unit is supported by the United States Naval Surface Warfare Center (NSWC), which receives binary data directly from the ADCP by way of a submerged cable. Following negotiations in 1993, a cooperative effort was established between the National Oceanic and Atmospheric Administration (NOAA) and the Naval Surface Warfare Center to forward the binary ADCP data collected by NSWC to the NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) in Miami, Florida. Since April 1994, AOML has been receiving the binary data from NSWC.

Dagg, M.J., and P.B. Ortner. Zooplankton grazing and the fate of phytoplankton in the northern Gulf of Mexico. Proceedings, 1994 Synthesis Workshop, Baton Rouge, LA, April 26-28, 1994. Louisiana Sea Grant Program, 21-27 (1995).

The copepod community consumes a significant fraction of the phytoplankton production that is stimulated by riverine nutrient inputs in the northern Gulf of Mexico. In addition, there is strong evidence that Appendicularians are important consumers of small particles (including pico-phytoplankton). The primary fate of phytoplankton production in this river-dominated shelf is to be grazed by zooplankton.

Dammann, W.P., and J.R. Proni. Fort Pierce, Florida dredge material discharge study. Contract Report RM-CW-94-0033, U.S. Army Corps of Engineers, 6 pp. (1995).

No abstract.

Darling, R.W.R., S.H. Houston, and H.E. Willoughby. Parametric models of hurricane surface winds for storm surge calculations. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 454-456 (1995).

No abstract.

Dodge, P.P., F.D. Marks, J.F. Gamache, J.S. Griffin, and N.F. Griffin. EVTD radar analyses of the inner core of Hurricane Olivia (1994). Preprints, 27th Conference on Radar Meteorology, Vail, CO, October 9-13, 1995. American Meteorological Society, Boston, 299-301 (1995).

No abstract.

Dodge, P.P., F.D. Marks, J.F. Gamache, J.S. Griffin, Jr., and N.F. Griffin. The evolution of the inner core of Hurricane Olivia (1994) from EVTD Doppler radar analyses. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 463-465 (1995).

On 24 and 25 September 1994, the Hurricane Research Division (HRD) and the Aircraft Operations Center (AOC) of NOAA conducted experiments in eastern Pacific Hurricane Olivia, 1400-1500 km southwest of Puerto Vallarta. Each day two aircraft flew simultaneously through the center at altitudes of 3 and 4.3 km, recording radar data for dual-Doppler estimates of the wind field. The experiment required a strong hurricane, and Olivia certainly met that requirement. On 24 September the minimum sea-level pressure (MSLP) dropped from 954 mb to 948 mb in 3.5 h and the maximum flight level winds increased from 50 m s^-1 to 61 m s^-1 on the last pass through the center. The next day Olivia had deepened further to 926 mb, and maximum flight level winds were 65-70 m s^-1 on almost every pass. The radius of maximum winds contracted from 20 km to 12 km during the two days of the experiment. Each aircraft collected Doppler data in 15 passes through the storm on the 24th and the 25th. Eventually the Doppler data from both aircraft will be analyzed with dual-Doppler algorithms to yield a time series of three-dimensional wind fields, but in this paper we use the Extended Velocity Track Display (EVTD) technique to estimate the evolution of the mesoscale features of the windfield. EVTD provides a coarser estimate than the full dual-Doppler solution, but the computation is much faster. Indeed, data from one aircraft can be used to estimate the windfield in real-time; EVTDs computed on the upper aircraft during Olivia show that the azimuthally averaged tangential winds increased on the first day from 50-55 m s^-1 to over 60 m s^-1 on the last pass. EVTD analyses on the second day show that the winds remained 60-65 m s^-1 throughout the flight. HRD plans to send such analyses from reconnaissance aircraft to the National Hurricane Center during the 1995 hurricane season. In the single-aircraft EVTDs, data from successive passes are combined and filtered to give a time series of three-dimensional wind estimates. Orthogonal legs with simultaneous radar data from both aircraft permit us to construct "true EVTD" analyses that are closer to true dual-Doppler wind analyses than the single-aircraft EVTDs. We will use the Olivia data to compare these two types of EVTD analysis.

Dupuis, H., A. Weill, K.B. Katsaros, and P.K. Taylor. Turbulent heat fluxes by profile and inertial dissipation methods: Analysis of the atmospheric surface layer from shipboard measurements during the SOFIA/ASTEX and SEMAPHORE experiments. Ocean-Atmosphere Interactions, 1065-1074 (1995).

Heat flux estimates obtained using the inertial dissipation method, and the profile method applied to radiosonde soundings, are assessed with emphasis on the parameterization of the roughness lengths for temperature and specific humidity. Results from the inertial dissipation method show a decrease of the temperature and humidity roughness lengths for increasing neutral wind speed, in agreement with previous studies. The sensible heat flux estimates were obtained using the temperature estimated from the speed of sound determined by a sonic anemometer. This method seems very attractive for estimating heat fluxes over the ocean. However, allowance must be made in the inertial dissipation method for non-neutral stratification. The SOFIA/ASTEX and SEMAPHORE results show that, in unstable stratification, a term due to the transport terms in the turbulent kinetic energy budget, has to be included in order to determine the friction velocity with better accuracy. Using the profile method with radiosonde data, the roughness length values showed large scatter. A reliable estimate of the temperature roughness length could not be obtained. The humidity roughness length values were compatible with those found using the inertial dissipation method.

Enfield, D.B., and J.E.Harris. A comparative study of tropical Pacific sea surface height variability: Tide gauges vs. the NMC data-assimilating OGCM, 1982-1992. Journal of Geophysical Research, 110:8661-8675 (1995).

To help assess the effectiveness of the model-based analysis and prediction procedures at the National Meteorological Center (NMC), we compare the seasonal and nonseasonal components of sea level from 44 tide gauges in the tropical Pacific with those of the dynamic heights output by two 11-year model reanalyses (1982-1992), at the same locations, which differ mainly in their wind forcing. Both reanalyses assimilate ocean thermal data and incorporate most of the procedures used by NMC in producing operational ocean analyses and experimental coupled model climate forecasts. The reanalyses reproduce the broad patterns of annual amplitude and phase, and of seasonal and nonseasonal variance, except for severe underestimates along the eastern boundary, especially north of the equator. The annual cycles and interannual departures of zonal flow indices estimated from selected island pairs near the dateline show good correspondence for the North Equatorial Countercurrent (NECC) and somewhat flawed and noisy comparisons for the North Equatorial Current (NEC) and South Equatorial Current (SEC). The reanalyses also reproduce the large scale time and space patterns of nonseasonal variability in the first three empirical orthogonal functions (EOFs), which together explain about 65% of the anomalous variability and characterize the El Niño/Southern Oscillation cycle. The first two EOF modes describe the westward migration of three ENSO episodes and the third mode appears to capture differences between episodes. However, the reanalysis based on the anomalous winds generated by the NMC medium range forecast model shows significant discrepancies in the large scale spatial and temporal variability. These discrepancies disappear in the reanalysis based on departures of the FSU analyzed wind fields. Hence, the wind forcing critically affects the reanalysis in spite of the assimilation of ocean thermal data. Future improvements in the atmospheric model to produce a more realistic evolution of the wind field can therefore lead to significantly better model integrations, in the analysis and initialization mode (with data assimilation) as well as in the coupled model forecast mode.

Esenkov, O.E. Unstable convective modes in a two-layer system. In Rotating Convection. Summer study program in Geophysical Fluid Dynamics, WHOI/MIT, 147-163 (1995).

No abstract.

Feely, R.A., R.H. Wanninkhof, C. Cosca, H. Chen, M. Steckley, and P. Murphy. Distributions of fCO₂ in the eastern equatorial Pacific during and after the 1992-1993 El Niño: Global fluxes of carbon and its related substances in the coastal sea-ocean-atmosphere system. Proceedings, IGBP Symposium, Sapporo, Japan, November 1994. Hokkaido University, 360-367 (1995).

As part of the U.S. JGOFS Equatorial Pacific Process Study, measurements of fCO₂ were determined for the atmosphere and in the surface waters of the central and eastern equatorial Pacific during the spring and autumn of 1992 and 1993, and the spring of 1994 after the 1992-1993 ENSO event. Surface water fCO₂ data indicate significant differences between the springtime El Niño conditions and the autumn post-El Niño conditions. The autumn fugacity (DELTA fCO₂) maxima were approximately 15-55 µatm higher than in the spring. The lower surface DELTA fCO₂ values in the spring data set were the result of: (1) advection of CO₂-depleted water from the west at the equator near 170°W; and (2) reduced upwelling and lower DELTA fCO₂ distributions as consequence of lighter zonal winds in the eastern Pacific from 140°W to 110°W. In the spring of 1993 elevated sea surface temperatures were observed in spring of 1992. In spring 1994 sea surface temperatures were near the climatological mean and fCO₂ levels were 70-90 µatm higher than the 1992 levels. These results clearly indicate that the largest sustained fCO₂ variations in the eastern equatorial Pacific occur during ENSO events.

Feely, R.A., R.H. Wanninkhof, C.E. Cosca, P.P. Murphy, M.F. Lamb, and M.D. Steckley. CO₂ distributions in the equatorial Pacific during the 1991-1992 ENSO event. Deep-Sea Research II, 42(2-3):365-386 (1995).

As part of the U.S. JGOFS Equatorial Pacific Process Study, measurements of CO₂ species concentrations were made in the atmosphere and in the surface waters of the central and eastern equatorial Pacific during the boreal spring and autumn of 1992. Surface water fCO₂ data indicate significant differences between the springtime El Niño conditions and the autumn post-El Niño conditions. The autumn fugacity (DELTA fCO₂) maxima were approximately 15-55 µatm higher than in the spring. The lower surface DELTA fCO₂ values in the spring data set were the result of: (i) advection of CO₂-depleted water from the west at the equator near 170°W; and (ii) reduced upwelling and lower DELTA fCO₂ distributions as a consequence of lighter zonal winds in the eastern Pacific from 140°W to 110°W. Assuming the springtime data are representative of the El Niño conditions and the autumn data are representative of the post-El Niño conditions, it is estimated that the net annual CO₂ flux during the 1991-1992 ENSO period is 0.3 Gt C. Over 60% of this flux occurred during the four-month period in the autumn when DELTA fCO₂ values were close to normal. The net annual reduction of the ocean-atmosphere CO₂ flux during the 1991-1992 El Niño is estimated to be on the order of 0.5-0.7 Gt C.

Feuer, S.E., and J. Kaplan. Tropical cyclone intensity change and environmental kinematic structure in Omega dropwindsonde data sets. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 362-364 (1995).

Since 1982, the Hurricane Research Division (HRD) of the NOAA/Atlantic Oceanographic and Meteorological Laboratory has conducted airborne experiments to collect environmental data from Atlantic basin tropical cyclones. These synoptic-flow experiments (SFEs) are performed aboard one or two NOAA WP-3D aircraft, from which Omega dropwindsondes (ODWs) are released within 1000 km of the storm center over a 9-10 h period. As the ODWs descend, kinematic and thermodynamic soundings are obtained from flight level (400-500 mb) down to the surface. Through 1992, HRD has acquired 16 SFE data sets. Three-dimensional wind analyses have been produced using the HRD nested objective analysis algorithm. For each SFE case, post-processed ODW winds, along with rawinsonde, NOAA, and USAF reconnaissance aircraft, surface ship, commercial aircraft, and GOES satellite observations, were analyzed with a two-dimensional, cubic spline-based routine at 10 mandatory levels. Consistent filtering parameters were applied to all of the data sets. Raw observations were thoroughly scrutinized; erroneous ones were subjectively removed. Cross-sections of the analyzed wind fields were subsequently examined, and adjustments were made to ensure vertical continuity between the analysis levels. The resultant wind fields accurately depict the environment surrounding the tropical cyclones beyond 300 km from the storm center. We have successfully composited the analyzed wind fields to examine the mean kinematic, synoptic-scale structure of the tropical cyclones in our data set. Composites of various diagnostic quantities have been made for the full set of SFE cases, as well as stratified subgroupings. These composited fields are being used to compare the mean large-scale structure of storms with different intensification rates. Results will be presented at the conference.

Ffield, A., R.L. Molinari, W.D. Wilson, and R.H.Wanninkhof. Repeat hydrography along WHP lines 15°W, 17°N, and 11°W. International WOCE Newsletter, 20:23-24 (1995).

No abstract.

Finley, S.V., P.J. Fitzpatrick, J.A. Knaff, and C.W. Landsea. A systematic bias in the Aviation model's forecast of the Atlantic TUTT: Implications for tropical cyclone forecasting. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 238-240 (1995).

No abstract.

Fitzpatrick, P.J., J.A. Knaff, C.W. Landsea, and S.V. Finley. A systematic bias in the Aviation model's forecast of the Atlantic tropical upper tropospheric trough: Implications for tropical cyclone forecasting. Weather and Forecasting, 10(2):433-446 (1995).

This study uncovers what appears to be a systematic bias in the National Meteorological Center's Aviation (AVN) model at 200 mb over the Caribbean Sea. In general, the 48 h forecast in the vicinity of the Tropical Upper Tropospheric Trough (TUTT) underpredicts the magnitude of the westerly 200-mb winds on the order of 5-10 m s^-1. This unrealistic weakening of the TUTT and associated cold lows by the AVN model results in erroneous values of the vertical (850-200 mb) wind shear. These systematic errors are in the same order of magnitude as the minimum shear threshold for tropical cyclone genesis and development. Thus, 48-h tropical cyclone formation and intensity forecasts based upon the AVN model are often incorrect in the vicinity of the TUTT. Knowing the correct future upper wind regime is also crucial for track forecasting of more intense tropical cyclones, especially in cases of recurvature. It is shown that simple persistence or climatology of the 200-mb winds south of a TUTT axis is superior to the AVN model's 48-h forecast. Until this bias in the AVN is successfully removed, the tropical cyclone forecaster for the Atlantic basin should be aware of this systematic error and make subjective changes in his/her forecasts. For 200-mb west winds greater than or equal to 10 m s^-1, forecasts based on persistence are best, while for west winds less than 10 m s^-1, half climatology and half persistence is the preferable predictor. If the TUTT is weak such that 200-mb easterly winds occur, climatology tends to be the best predictor as it nudges the forecast back to a normal westerly wind regime.

Gamache, J.F. Preliminary three-dimensional analyses of dual-platform airborne Doppler observations of intense convection in eastern Pacific Hurricane Olivia (1994). Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 254-256 (1995).

On 24 and 25 September 1994, coordinated two-aircraft airborne Doppler missions were flown into eastern Pacific Hurricane Olivia. The storm was located approximately 1500 km west-southwest of Puerto Vallarta, Mexico, the base of operations. The purpose of the experiment was to study the evolution of a tropical cyclone's reflectivity structure and three-dimensional wind field. On the first day the hurricane had a fairly slowly changing precipitation structure, dropping central pressure, and increasing winds. The precipitation structure on the second day evolved from symmetric to asymmetric, the winds appeared to be fairly constant, and the central pressure was increasing. The environmental shear appeared to change from easterly during the first day to southwesterly during the second day. During the 3.5 hours on station of 24 September, the extrapolated minimum surface pressure dropped from 954 mb in the first pass to 948 mb on the last pass. Real-time EVTD (Extended Velocity Track Display) analyses showed the mean tangential wind maximum increasing from 50-55 m s^-1 on the first pass to over 60 m s^-1 on the last pass, and the radius of maximum winds contracting from 20 km to 16 km. This is the most rapid deepening of a tropical cyclone observed during a coordinated airborne Doppler mission. When the aircraft re-entered the storm the next day the radius of maximum winds had decreased to 12 km, the extrapolated minimum surface pressure was 926 mb, and EVTD revealed the azimuthally-averaged tangential winds to be between 60-65 m s^-1. These wind speeds were maintained while the aircraft were on station; however, the extrapolated minimum surface pressure dropped to 925 mb on the second pass, but increased to 935 mb by the eighth and final pass, about 3.5 hours later. It is possible that some of this increased pressure is associated with the strong asymmetric convection occurring near the end of the mission that might have produced a wind and pressure field that were temporarily out of balance. During several penetrations on the 24th and 25th, there were elevated reflectivity maxima that are indicative of large graupel and vertical winds probably in excess of 10 m s^-1. The three-dimensional wind fields observed during each of the hurricane penetrations will eventually be analyzed; however, during the conference the wind fields associated with the strong convective events and elevated reflectivity maxima will be emphasized.

Gamache, J.F., F.D. Marks, and F. Roux. Comparison of three airborne Doppler sampling techniques with airborne in-situ wind observations in Hurricane Gustav (1990). Journal of Atmospheric and Oceanic Technology, 12(1):171-181 (1995).

Three different airborne Doppler radar sampling strategies were tested in Hurricane Gustav (1990) on 29 August 1990. The two new strategies were the fore-aft scanning technique (FAST) and airborne dual-platform Doppler sampling. FAST employs radar scans in cones pointing alternately fore and aft of the vertical plane that is perpendicular to the flight track. The airborne dual-platform sampling uses two Doppler radars, each aboard a separate aircraft. The Doppler radars scan strictly in the vertical plane normal to the flight track. The aircraft fly simultaneously along different, preferably perpendicular, tracks. The third strategy tested in Hurricane Gustav was single-platform sampling, which uses one Doppler radar on one aircraft that flies two consecutive, usually orthogonal, flight tracks. The antenna scans in the plane normal to the flight track. The third technique had been used previously in hurricanes and other disturbed weather. The rms differences between the aircraft in-situ winds and the Doppler winds derived near the aircraft by single-platform sampling, dual-platform sampling, and FAST are found to be 7.8, 5.1, and 2.5 m sec^-1, respectively. These results suggest that in hurricanes dual-platform, flat-plane sampling and FAST both enable substantial improvements in the accuracy and temporal resolution of airborne Doppler wind fields over those obtained from single-platform, flat-plane scanning. The FAST results should be applicable to dual-beam sampling, which began in 1991. The actual rms errors of Doppler winds from the flight tracks, at levels well above flight level, and in highly sheared environments may be significantly higher than the above differences.

Garzoli, S.L., A. Gordon, and C. Duncombe Rae. Benguela Current sources and transports. U.S. WOCE Report, 17-19 (1995).

No abstract.

German, C., B.A. Barreiro, N.C. Higgs, T.A. Nelsen, E.M. Ludford, and M.R. Palmer. Seawater-metasomatism in hydrothermal sediments (Escanaba Trough, northeast Pacific). Chemical Geology, 119:175-190 (1995).

Hydrothermal sediments from the NESCA vent-field, Escanaba Trough, are enriched in a number of typical "vent-fluid" metals for which fluid data for the same, sediment-hosted, site exhibit anomalous depletion. These results are consistent with cooling of rising fluids and precipitation of various metal sulfide, sulfate, and oxide phases in-situ with the sediment column, prior to expulsion of the fluids from the seabed. Significant enrichments of Mg and U, elements which are quantitatively removed from high-temperature vent fluids, are also observed in the Escanaba Trough sediments, however. Enrichments of these elements cannot derive from simple conductive cooling of the rising vent-fluids but, instead, are believed to result from extensive seawater-metasomatism as relatively fresh unreacted seawater is heated from below by hot sediments and/or percolating vent-fluids in the upper levels of the circulation system. Calculated seawater/sediment interaction ratios range from -5:1 to 2500:1 of seawater per gram of sediment. Pb, Sr, and Nd isotope distributions for the Escanaba sediments are consistent with combined sediment-fluid and seawater-sediment interactions. Pb isotope ratios for hydrothermal and background sediments coincide with local sulfide deposits but are much more radiogenic than local MORB. This indicates not only that complete isotopic re-equilibration must occur between the hot, rising fluids and the host sediments but, in addition, that sediment composition appears to dominate the Pb isotopic composition of these fluids. Sr and Nd isotope ratios in the hydrothermally altered sediments, which are distinct from background ratios, coincide closely with modern seawater values, providing confirmatory evidence that extensive interactions must also have occurred between these hydrothermal sediments and relatively fresh, unreacted seawater.

Goldenberg, S.B., and L.J. Shapiro. A new look at the relationship between El Niño, west African rainfall, and North Atlantic tropical cyclone activity. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 585-587 (1995).

In previous studies, El Niño events have been shown to be associated with decreased tropical cyclone activity in the Atlantic basin. Studies have also established a strong association between increased (decreased) rainfall over west Africa (specifically the west Sahel) and increased (decreased) Atlantic basin activity. The primary physical mechanism for both of these associations appears to be an equatorially-confined Walker-cell-type circulation which acts to modify the vertical shear over the main tropical cyclone development region; reduced (increased) shear contributing to increased (decreased) Atlantic basin tropical cyclone activity. Recent studies have identified two types of El Niño events and different phases of atmospheric coupling likely controlling the teleconnection between the equatorial east Pacific sea-surface temperature (SST) anomalies and west African monsoonal rainfall amounts. The probably non-homogeneous physical mechanisms for the teleconnections would suggest a stratification of the years to better resolve the different physical mechanisms responsible for the associations between El Niño events, west African rainfall fluctuations, and variability in Atlantic basin tropical cyclone activity. The grouping of all of the years of data together for previous studies possibly gives an overly-simplistic picture of the relationships. This study will present results of the application of various stratification methodologies to the present problem. El Niño-associated equatorial eastern Pacific SST anomalies are typically largest in the spring, out of phase with the summer Atlantic hurricane season. Other investigators have found a delayed atmospheric response to eastern Pacific SST anomalies. Results will also be presented that include a closer examination of lag (predictive) relationships between eastern Pacific SSTs and both the circulation anomalies and tropical cyclone activity. Particular attention will be given to those features, such as vertical shear, that impact the character of the hurricane season.

Goni, G.J., G. Podesta, O.B. Brown, and J. Brown. Mesoscale ocean variability signal recovered from altimeter data in the southwest Atlantic Ocean: A comparison of orbit error correction in three GEOSAT data sets. Bolm Inst. Oceanogr., S. Paulo, 43(2):101-110 (1995).

Orbit error is one of the largest sources of uncertainty in studies of ocean dynamics using satellite altimeters. The sensitivity of GEOSAT mesoscale ocean variability estimates to altimeter orbit precision in the southwest Atlantic is analyzed using three GEOSAT data sets derived from different orbit estimation methods: (a) the original GDR data set, which has the lowest orbit precision; (b) the GEM-T2 set, constructed from a much more precise orbital model; and (c) the Sirkes-Wunsch data set, derived from additional spectral analysis of the GEM-T2 data set. Differences among the data sets are investigated for two tracks in dynamically dissimilar regimes of the southwestern Atlantic Ocean, by comparing (a) distinctive features of the average power density spectra of the sea height residuals, and (b) space-time diagrams of sea height residuals. The variability estimates produced by the three data sets are extremely similar in both regimes after removal of the time-dependent component of the orbit error using a quadratic fit. Our results indicate that altimeter orbit precision with appropriate processing plays only a minor role in studies of mesoscale ocean variability.

Hansen, D.V., and H.F. Bezdek. Testing winds against other variables from COADS. Proceedings, International COADS Winds Workshop, Kiel, Germany, May 31-June 2, 1994. U.S. Department of Commerce, 85-90 (1995).

No abstract.

Hendee, J.C. Ocean Profiler: Software for the at-sea merging of oceanographic data. NOAA Technical Memorandum, ERL AOML-86 (PB96-128186), 13 pp. (1995).

Ocean Profiler is a computer program (software) that was constructed to meet the needs of oceanographers working at sea to build a master database of parameters as the data are generated. This report represents the technical manual for the operation of the software. Descriptions are provided for the loading, importing, and exporting of data files. Editing of data, adding of stations and fields to the database, deleting and cleaning up of data records, and replacing of certain values with others are features supported by the software. A Remote Bulletin Board System and an FTP site for downloading, a World-Wide Web location, and an e-mail address are provided for additional support for the software.

Hendee, J.C. Operations manual for PELAGOS: An expert system for quality control and feature recognition of oceanographic data from the open ocean. NOAA Technical Memorandum, ERL AOML-87 (PB96-131255), 63 pp. (1995).

An expert system was developed to aid oceanographers and data managers in the quality control and feature recognition of oceanographic data from the open ocean. Oceanographic data collected from the open ocean are screened for proper ranges against data collected from the same area during former cruises. Calculations are also performed on the data as a cross-check of certain parameters against others. The system developed runs on the PC, the Macintosh, and a UNIX workstation. The system is easily configurable to report only oceanographic parameters of interest. Data are read from, and output to, ASCII files. Source code is provided, and a list of avenues for further development is presented.

Houston, S.H., and M.D. Powell. Real-time surface wind analyses in support of marine warnings in tropical cyclones. Preprints, Second International Workshop on Wind and Earthquake Engineering for Offshore Coastal Facilities, Berkeley, CA, January 17-19, 1995. University of California at Berkeley, 323-328 (1995).

Real-time analyses of tropical cyclone wind observations are generated by the Hurricane Research Division (HRD) on an experimental basis. This paper describes analyses that apply to nearshore and offshore commercial activities affected by tropical cyclones. These products can help determine the extent of tropical storm and hurricane force winds for marine warnings. They can also be used as input to storm surge and wave models, as well as for estimating peak wind gusts associated with tropical cyclones.

Houston, S.H., W.A. Schaffer, M.D. Powell, and J. Chen. Comparisons of SLOSH parametric and HRD analyzed surface wind fields in recent hurricanes. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 619-621 (1995).

In recent years, the Hurricane Research Division (HRD) has developed new techniques to analyze the surface wind fields in tropical cyclones based on all available surface wind observations, including aircraft flight-level observations adjusted to the surface. As part of NOAA's Coastal Ocean Program research on coastal hazards, the Techniques Development Laboratory (TDL) and HRD are evaluating wind fields used as input to the National Weather Service's (NWS) Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model through comparisons with HRD's surface wind field analyses. The SLOSH model-computed water levels are used primarily by government and emergency management officials to plan for the evacuation of populations from coastal areas prone to flooding from storm surge produced by tropical cyclones. The model was developed for real-time forecasting of hurricane storm surges on continental shelves, across inland water bodies, and along coastlines. The values used to initiate the SLOSH model are each tropical cyclone's position, size, and intensity. Using these input parameters, a wind field is computed by SLOSH, which is used as the primary forcing mechanism for the oceanographic processes. Previously, the SLOSH model has been tested for hurricane landfalls along the U.S. coastlines and has been found to have an accuracy of ±20% when the hurricane is adequately described. Hurricane wind field cases examined in this study include Hugo (1989) at landfall in South Carolina, Bob (1991) at landfall in New England, Andrew (1992) at landfall in south Florida and Louisiana, as well as the closest approach of Bob (1991) and Emily (1993) to the North Carolina Outer Banks.

Huang, H., J.R. Proni, and J.J. Tsai. Comment on "Probabilistic approach to initial dilution of ocean outfalls," by H. Huang, J.R. Proni, and J.J. Tsai. Water Environment Research, 67:880-881 (1995).

No abstract.

Johns, E. Sources of the Florida Current: Results from NOAA's Subtropical Atlantic Climate Study. Proceedings, Chapman Conference on the Circulation of the Intra-Americas Sea, La Parguera, Puerto Rico, January 22-26, 1995. IOC Workshop Report No. 111, Intergovernmental Oceanographic Commission, AIII.5 (1995).

The Florida Current is a major component of the Atlantic's thermohaline circulation, which is believed to play a significant role in controlling the global climate. To quantify the net heat flux of the Florida Current, recirculating flow, which would not lead to a net heat flux, must be distinguished from cross-equatorial flow which carries significant interhemispheric exchanges of mass, heat, and salt. Previous studies using historical data have indicated that some 45% of the transport of the Florida Current, primarily in the <24°C and 7-12°C temperature ranges, originates in the southern hemisphere (Schmitz and Richardson, Deep- Sea Res., vol. 38, suppl., 1991). However, the available historical data are somewhat limited in space and time. Herein, we examine the transport and water masses of the Florida Current and surrounding inflows to the Caribbean Sea using more recent data, in an effort to further refine and quantify our understanding of its source waters. Using shipboard hydrographic and direct velocity data collected as part of NOAA's Subtropical Atlantic Climate Study between 1984 and 1991, we have examined the volume transport and water mass properties of the Florida Current, the northern passages into the Caribbean Sea (Windward, Mona, and Anegada), and across the Caribbean Sea along 63°30'W. The transport analysis suggests that the circulation into the Caribbean Sea is different than reported in earlier studies, with a greater proportion of the flow entering through the northern passages (Windward, Mona, and Anegada) and a smaller amount through the more southern passages of the Lesser Antilles. Distributions of salinity, oxygen, and silica indicate that the conclusions of earlier studies about the sources of the Florida Current are generally correct. However, there are indications in our more recent data that the freshest waters of the Florida Current in the 17-24°C range do not enter the Caribbean through any of the passages but rather are formed in the Gulf of Mexico by mixing and freshwater input. In addition, the silica distributions suggest that the main thermocline waters of the Florida Current, which in the earlier studies were considered to be primarily of northern origin, may also include a significant component from the south.

Jones, R.W., M. DeMaria, and C.R. Hagelberg. A comparison of data assimilation techniques in barotropic track forecasts of west Pacific typhoons. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 141-142 (1995).

Recently, Bennett et al. (1993) reported results of data assimilation with a generalized inverse method that was applied to 10 cases for track forecasting of Pacific typhoons using a nondivergent barotropic model. DeMaria and Jones (1993) reported similar experiments in the Atlantic basin using the method of model fitting or "adjoint method." In contrast with DeMaria and Jones, who found many cases where the results of assimilation were not as good as the control forecasts with no assimilation, Bennett et al. found reduced track forecast errors for all 10 cases. Results will be presented for typhoon track forecasts using the data of Bennett et al. together with the model fitting strategy of DeMaria and Jones. The generalized inverse method results will be compared with the adjoint method results.

Kaplan, J. An examination of the role of large-scale forcing on the rapid intensification of Hurricane Emily (1987). Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 332-334 (1995).

Hurricane Emily (1987) intensified rapidly to hurricane strength just prior to crossing the island of Bermuda around 1200 UTC on 25 September. This period of rapid intensification was not anticipated by numerical guidance or operational forecasters. Consequently, insight into the physical processes that facilitated Emily's intensification are of interest both to the research and operational communities. During the 24 h period leading up to Emily's rapid intensification, the Hurricane Research Division (HRD) of the Atlantic Oceanographic and Meteorological Laboratory (AOML) conducted two synoptic-flow experiments (SFEs) within Emily's (1987) large-scale environment. SFEs have been conducted by the HRD for the past 13 years and are designed to collect wind and thermodynamic data within approximately a 1000 km radius of tropical cyclones by deploying Omega dropwindsondes from research aircraft flying near 400 mb. The data collected during these SFEs have been combined with other available conventional (e.g., rawinsonde, satellite, and ship) data sources and analyzed using the HRD nested analysis scheme. The analyses have been performed at the mandatory levels over a 2000 km × 2000 km domain centered on Emily. These analyses are being used to investigate the change in storm structure prior to the rapid intensification of Emily. The possible role that an upper-level trough to the northwest of Emily may have played in Emily's rapid intensification are also being investigated, since previous studies have suggested that interactions between upper-level troughs and tropical cyclones appear to be positively correlated with intensification provided that other environmental factors (e.g., vertical wind shear and sea-surface temperature) remain favorable. The interaction between Emily and the upper-level trough is being examined by evaluating the forcing terms in the secondary circulation equation (e.g., fluxes of momentum, heat, and moisture) to determine if the changes in these quantities are consistent with the structural changes and intensification observed in Emily. Results from these investigations will be presented at the conference.

Kaplan, J., and M. DeMaria. A simple empirical model for predicting the decay of tropical cyclone winds after landfall. Journal of Applied Meteorology, 34(11):2499-2512 (1995).

An empirical model for predicting the maximum wind of landfalling tropical cyclones is developed. The model is based upon the observation that the wind speed decay rate after landfall is proportional to the wind speed. Observations also indicate that the wind speed decays to a small, but nonzero, background wind speed. With these assumptions, the wind speed is determined from a simple two-parameter exponential decay model, which is a function of the wind speed at landfall and the time since landfall. A correction can also be added that accounts for differences between storms that move inland slowly and storms that move inland rapidly. The model parameters are determined from the National Hurricane Center best track intensities of all U.S. landfalling tropical cyclones south of 37°N for the period 1967-1993. Three storms that made landfall in Florida prior to 1967 were also included in the sample. Results show that the two parameter model explains 91% of the variance of the best track intensity changes. When the correction that accounts for variations in the distance inland is added, the model explains 93% of the variance. This model can be used for operational forecasting of the maximum winds of landfalling tropical cyclones. It can also be used to estimate the maximum inland penetration of hurricane force winds (or any wind speed threshold) for a given initial storm intensity. The maximum winds at an inland point will occur for a storm that moves inland perpendicular to the coastline. Under this assumption, the maximum wind at a fixed point becomes a function of the wind speed at landfall and the translational speed of motion. For planning purposes, maps of the maximum inland wind speed can be prepared for various initial storm intensities and speeds of motion. The model can also be applied to the entire wind field of an individual storm to provide a two-dimensional field of the maximum wind during a given storm. Examples of each of these applications are presented.

Katsaros, K.B., and W.T. Liu. Microwave radiometers for studies of the ocean and the marine atmosphere. In Oceanographic Applications of Remote Sensing, M. Ikeda and F.W. Dobson (eds.). CRC Press, Boca Raton, 257-269 (1995).

Measurements of oceanographic and marine meteorological parameters by microwave instruments on satellites started in the 1960s on several Russian satellites. In this chapter we discuss microwave radiometers only, leaving out discussion of sounders and active microwave sensors (radars). The list of microwave radiometers on satellites is quite long. We give a short recapitulation of the experience gained with the early microwave radiometers in space, and then concentrate on the characteristics of the current operational system, the Special Sensor Microwave/Imager (SMM/I), on satellites in the Defense Meteorological Satellite Program (DMSP). Some characteristics of the atmosphere with respect to microwave radiation and emission characteristics of the sea surface are recalled. The instrument, its sampling characteristics, and a few applications are then discussed, followed by a selected bibliography containing review articles that pursue the subject in greater depth.

Keeling, R.F., and T.-H. Peng. Transport of heat, CO₂, and 0₂ by the Atlantic's thermohaline circulation. Philosophical Transactions of the Royal Society of London B, 348:133-142 (1995).

We estimate transport of heat, CO₂, and O₂ by the Atlantic's thermohaline circulation using an approach based on differences in the chemical and physical characteristics of North Atlantic Deep Water (NADW), Antarctic Intermediate Water (AAIW), and the northward return flow across the equator. The characteristics of the return-flow waters are constrained by imposing conservation of phosphate in the North Atlantic as a whole. Based on a total equatorial return flow of 13 × 10⁶ m³ s^-1, we find that the Atlantic north of the equator is a source of 7.7 ± 1.4 × 10¹⁴ W to the atmosphere, a sink of 0.51 ± 0.21 × 10¹⁴ mol of O₂, and preindustrially was a sink of 0.33 ± 0.15 × 10¹⁴ mol of CO². Uptake of O₂ and CO₂ by the North Atlantic is driven mainly by thermal, as opposed to biological, processes.

Klein, B., R.L. Molinari, T.J. Muller, and G. Seidler. A transatlantic section at 14.5°N: Meridional volume and heat fluxes. Journal of Marine Research, 53:929-957 (1995).

Two high-resolution hydrographic sections occupied during February and March 1989 in the western and eastern basins of the North Atlantic at 14.5°N are combined to study the water mass structure and meridional mass and heat transports. Absolute velocities were determined using these data and an earlier section at 8°N in a linear inverse analysis. Mass balance for several layers representing the main water masses in the region and a zero net divergence for the sum of geostrophic and Ekman transport between the two sections are assumed. Using the annual mean of Ekman transports (13.6 Sv, 14.5°N), (15.2 Sv, 8°N) based on the climatology by Isemer and Hasse (1985), the annual average fluxes for the sections at 8°N and 14.5°N have been calculated. For the annual mean the strength of the meridional overturning cell at 14.5°N amounts to 15.9 Sv with an associated heat transport of 1.22 PW. A similar value can be obtained at 8°N where the annual mean heat transport reaches 1.18 PW and the overturning cell measures 15 Sv. The total northward heat transport is strongly dominated by the wind-driven Ekman heat transport. In-situ values of heat transport using the actual wind-driven transports for the respective months yield even higher estimates. Heat transport at 14.5°N rises to 1.37 × 0.42 PW (February) and the maximum is now at the 8°N section, 1.69 × 0.52 PW (May). Comparisons of our results with another tropical section at 11°N occupied concurrently demonstrate the large variabiltiy in heat transport related to changes in the wind field. Due to extremely weak winds in the eastern Atlantic and a resulting low Ekman transport, the in-situ value of heat transport through this section ranged between 0.30 × 0.18 PW and 0.59 × 0.18 PW depending on the value chosen for the Ekman transport. The lower of the two heat transport estimates results from calculations with the acutal observed winds and the other using a monthly climatological mean. That even the computations with the climatological monthly mean give such a low heat transport points to additional changes in the baroclinic structures between 11°N and 14.5°N.

Lamb, M.F., T.P. Lantry, J.C. Hendee, K.E. McTaggart, P.P. Murphy, R.A. Feely, R.H. Wanninkhof, F.J. Millero, R.H. Byrne, E.T. Peltzer, and D. Frazel. Chemical and hydrographic measurements from the equatorial Pacific during boreal autumn 1992. NOAA Data Report ERL PMEL-56 (PB95-274809), 173 pp. (1995).

In the boreal autumn of 1992, NOAA's Climate and Global Change Program sponsored a major cooperative effort with the U.S. JGOFS Program in the central and eastern equatorial Pacific to investigate the unique role of equatorial processes on CO₂ cycling during and following the 1991-1992 ENSO event. Data were collected meridionally along four transects, generally between 10°N and 10°S. The first leg (Leg 3) included the 140°W and 125°W transects; the second leg (Leg 4) sampled along 110°W, and the third leg (Leg 5) included stations along 95°W and three short transects extending westward from the Peru coast. Chemical parameters sampled included fCO₂, DIC, TAlk, pH, TOC, and nutrients. Ancillary measurements of salinity, temperature, and dissolved oxygen (DO) were also taken. Descriptions of sampling methods and data summaries are given in this report.

Landsea, C.W. SHIFOR94: Atlantic basin tropical cyclone intensity forecasting. Australian Physical Oceanography and Australian Meteorological and Oceanography Society Joint Conference, Lorne, Australia, February 20-22, 1995. APOC/AMOS, 69 (1995).

Intensity forecasting of tropical cyclones has always been extremely difficult, with most basins showing little to no skill even at 24 h predictions. Any additional objective aid that can provide skillful guidance for the forecaster would be useful. SHIFOR94 is a climatology-persistence based empirical forecasting technique that is to be used for the Atlantic basin. It is fundamentally different than Jarvinen, Neumann, and Pike's SHIFOR (Statistical Hurricane Intensity FORecasting) in that, in addition to the usual predictors of current intensity, location, motion, and Julian date, use is made of climatological vertical shear, sea surface temperatures, and sub-surface sea temperatures. CLIPER, the climatology-persistence statistical track model, is run to provide future positions and appropriate climatological values of the above parameters. Results have been found that suggest decreases in 24 h intensity forecasts by 10 to 20% over the use of simple climatology and persistence (i.e., SHIFOR). These improvements correspond to 0.5 to 1.0 m s^-1 decrease in errors that average near 6 m s^-1 with SHIFOR. Note that "official" forecasts issued by the U.S. National Hurricane Center at the 24 h mark average only slightly better with errors of 5.5 m s^-1. Investigations are also undertaken to determine whether the use of seasonal predictors utilized for hurricane activity (e.g., ENSO, QBO, etc.) can provide any improvement in the day-to-day intensity forecasting by their inclusion in this model. Lastly, plans of extending this model to 72 h (and possibly 120 h) and its possible application toward Australian basin tropical cyclone forecasting are discussed.

Landsea, C.W. SHIFOR94: Atlantic tropical cyclone intensity forecasting. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 365-367 (1995).

No abstract.

Lantry, T.P., M.F. Lamb, J.C. Hendee, R.H. Wanninkhof, R.A. Feely, F.J. Millero, R. Byrne, E.T. Peltzer, W.D. Wilson, and G.A. Berberian. Chemical and hydrographic measurements from the equatorial Pacific during boreal spring 1992. NOAA Data Report, ERL AOML-27 (PB95-227773), 133 pp. (1995).

From February 24 to May 19, 1992, the National Oceanic and Atmospheric Administration's (NOAA) Climate and Global Change Program sponsored a major cooperative effort with the U.S. Joint Global Ocean Flux Study (U.S. JGOFS) to study the role of equatorial processes on CO₂ cycling in the central and eastern equatorial Pacific during the 1991-1992 El Niño Southern Oscillation (ENSO) event. The NOAA Ship Malcolm Baldrige performed four transequatorial sections in the region and this report presents hydrographic and chemical data from that cruise, including tables of the following data from each station: hydrography from each CTD cast at the bottle trip depths, dissolved oxygen, fCO₂, DIC, pH, TAlk, nutrients, and TOC. Descriptions of the sampling techniques and analytical methods used in the collection and processing of these data are also presented.

MacIntyre, S., R.H. Wanninkhof, and J.P. Chanton. Chapter 3: Trace gas exchange across the air-water interface in fresh water and coastal marine environments. In Biogenic Trace Gases: Measuring Emissions from Soil and Water, P.A. Matson and R.C. Harriss (eds.). Blackwell Science, Cambridge, 52-97 (1995).

No abstract.

Marks, F.D., and H.A. Friedman. 1995 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 138 pp. (1995).

No abstract.

Mayer, D.A., J.F. Festa, R.L. Molinari, and D.W. Behringer. Model and observed upper layer temperature structure of the gyres of the Atlantic Ocean. Proceedings, ACCP Principal Investigators Meeting, Miami, Florida, May 2-4, 1995. University Corporation for Atmospheric Research, 205 pp. (1995).

No abstract.

McAdie, C.J., P.P. Dodge, and S.H. Houston. Mesoscale features of Tropical Storm Beryl (15-16 August 1994) as detected by the WSR-88D. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 320-322 (1995).

The spatial resolution of the WSR-88D, in conjunction with the Doppler velocities it provides, makes it possible to examine the mesoscale features contained within the parent circulation of the tropical cyclone. Tropical Storm Beryl, which made landfall on 16 August 1994, near Panama City, Florida, was observed by the WSR-88D at Eglin AFB. Among the few tropical cyclones observed by this new radar to date, this was the first for which digital data was recorded, although not until near the time of landfall. Among the mesoscale features observed is a well-defined mesocyclone. The velocity couplet is found on the upwind extremity of a rainband, and is associated with a Bounded Weak Echo Region. The mesocylone occurs offshore, about 1 h prior to landfall. This is believed to the first time the WSR-88D has detected a mesocyclone within a parent tropical cyclone circulation. As earlier work suggests (Parrish et al., 1982), the passage of an intense rainband seems to correlate with the time maximum gusts are recorded at surface observing sites. An effort is made in the present case to relate the Doppler velocities aloft with winds reported by both C-MAN and the conventional reporting network.

Millero, F.J., W. Yao, K. Lee, J.-Z. Zhang, and D.M. Campbell. The carbonate system near the Galapagos Islands. University of Miami Technical Report, RSMAS-95-001, 104 pp. (1995).

During the IRONEX cruise and theh PlumEX experiments around the Galapagos Islands, measurements were made on the components of the carbonate system. The carbonate parameters pH, TA (total alkalinity), TCO₂ (total carbon dioxide), and fCO₂ (fucacity of CO₂) were determined. The pH measurements (± 0.002) were made using spectrophotometric techniques, the TA (± 2 µmol kg^-1) measurements were made by potentiometric titrations, the TCO₂ (± 2 µmol kg^-1) were determined by coulometry and the fCO₂ in the surface waters (± 2 µatm) was determined using an infrared detector. A significant decrease of the surface TCO₂ (7 µmol kg^-1) and fCO₂ (11 µatm) in the Fe patch was detected within 48 hours of the iron release. This decrease, however, did not continue. A good correlation was found between TCO₂, pH, and fCO₂ with temperature in the surface waters around the Galapagos Islands. The effect of high primary production on the CO₂ system in the downstream plume is overshadowed by the upwelling waters with high CO₂.

Millero, F.J., J.-Z. Zhang, K. Lee, J. Aicher, S. Mane, S. Olivella, D.O. Medina, and P.A. Steinberg. Ph and total alkalinity measurements in the North Atlantic. University of Miami Technical Report, RSMAS-95-004, 81 pp. (1995).

This report gives the results of our pH (spectrophotometry and potentiometry), total alkalinity (TA), and total inorganic carbon dioxide (TCO₂) measurements made in the North Atlantic during the Joint Global Ocean Flux Study (JGOFS) sponsored by the National Oceanic and Atmospheric Administration (NOAA). Measurements of TA on 91 samples of Certified Reference Materials (CRMs) with the three cells at sea indicate that the systems have a reproducibility of ± 3 µmol/kg in TA. The resulting pH, TA, and TCO₂ are thought to be precise to ± 0.002 (spectrophotometry) and ± 0.01 (potentiometry) in pH, ± 3 µmol kg^-1 in TCO₂, and ± 3 µmol kg^-1 in TA. Our titration results will be combined with NOAA measurements of TCO₂ (coulometry) and fCO₂ to characterize the CO₂ system in the North Atlantic.

Mognard, N.M., and K.B. Katsaros. Statistical comparison of the special sensor microwave imager/and the Geosat altimeter wind speed measurements over the ocean. Global Atmosphere Ocean System, 2(4):291-299 (1995).

Wind speed data from quasi-simultaneous measurements obtained by the Special Sensor Microwave/Imager (SSM/I) and the Geosat altimeter acquired over the world ocean are compared. Under good atmospheric conditions, the standard deviation of wind speed differences are only 1.2 m/s, but can reach 1.7 m/s. To assess the cause of the larger differences, integrated cloud water content and the presence of precipitation are computed using SSM/I multifrequency algorithms, and significant wave heights are measured along the altimeter tracks. The atmospheric and sea state measurements derived from the two satellite sensors show that differences between the two wind speed estimates are mostly caused by the interference of the atmosphere with the ocean surface emission and reflection in the microwave frequencies used. Significant wave height has no discernible effect on the satellite wind speed estimates.

Mognard, N.M., and K.B. Katsaros. Weather patterns over the ocean observed with the special sensor microwave/imager and the Geosat altimeter. Global Atmosphere Ocean System, 2(4):301-323 (1995).

A combination of quasi-simultaneous measurements of atmospheric and sea state parameters by the Special Sensor Microwave/Imager (SSM/I) and the Geosat altimeter are analyzed in diverse weather patterns such as anticyclones, atmospheric fronts, and in a hurricane. Estimates of integrated water vapor and integrated cloud liquid water content, an index for the scattering by large ice particles, the presence of precipitation, and the ocean surface wind speed are derived using SSM/I multifrequency algorithms. Significant wave height and ocean surface wind speed are calculated along the altimeter tracks. Variations in the atmospheric and sea state measurements derived from the two satellite sensors are analyzed. In regions of precipitation, where there are no SSM/I wind estimates, the altimeter sea state estimates give the location and measurement of the wind speed gradients as well as measurements of significant wave height variations. The synergetic use of microwave passive and active satellite sensors yields new and complementary insights into the structure of the lower atmosphere across different weather conditions.

Nelsen, T.A., P. Blackwelder, T. Hood, C. Zarikian, J.H. Trefry, S. Metz, B. Eadie, and B. McKee. Retrospective analysis of NECOP area sediments: Biogenic, inorganic and organic indicators of anthrogenic influences since the turn of the century. Proceedings, 1994 Synthesis Workshop, Baton Rouge, LA, April 26-28, 1994. Louisiana Sea Grant Program, 90-101 (1995).

Surface and cored sediments from the NECOP study area were analyzed for physical (coarse-grain texture, composition), biological (foraminifera), and chemical (organic and inorganic) properties. Results of analyses for surface samples indicated spatial patterns of benthic foraminifera dictated by sediment accumulation rate and regions of seasonal hypoxia. The latter also correlated well with the distribution of surface authigenic glauconite. Temporal variability, determined from core samples, indicated transitions in benthic foraminifera community structure with upcore increases in hypoxia tolerant assemblages. Transitions in glauconite abundance, organic carbon, and other chemical parameters strongly correlated temporally with increases in fertilizer application in the United States.

Niiler, P.P., A.S. Sybrandy, K. Bi, P.M. Poulain, and D.S. Bitterman. Measurements of the water-following capability of holey-sock and TRISTAR drifters. Deep-Sea Research I, 42(11/12):1951-1964 (1995).

Since 1985, a number of measurements have been made in deep water to determine the water-following characteristics of mixed layer drifters with both holey-sock and TRISTAR drogues at 15 m depth. The measurements were done by attaching two neutrally buoyant vector measuring current meters (VMCMs) to the top and the bottom of the drogues and deploying the drifters in different wind and upper ocean shear conditions for periods of 2-4 h. The average velocity of the VMCM records was taken to be a quantitative measure of the slip of the drogue through the water, observed to be 0.5-3.5 cm s^-1. The most important hydrodynamic design parameter which influenced the slip of the drogue was the ratio of the drag area of the drogue to the sum of the drag areas of the tether and surface floats: the drag area ratio R. The most important environmental parameters which affected the slip were the wind and the measured velocity difference across the vertical extent of the drogue. A model of the vector slip as a function of R, vector wind and velocity difference across the drogue was developed and a least squares fit accounts for 85% of the variance of the slip measurements. These measurements indicated that to reduce the wind produced slip below 1 cm s^-1 in 10 m s^-1 wind speed, R > 40. Conversely, if the daily average wind is known to 5 m s^-1 accuracy, the displacement of the R = 40 drifter can be corrected to an accuracy of 0.5 km day^-1.

Ooyama, K.V. A thermodynamic foundation for modeling the moist atmosphere. Part II: Tests of microphysics in the formation of squall lines. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 219-221 (1995).

It was proposed (Ooyama, 1990) that the separation of dynamics and thermodynamics by their primary roles would simplify the design of numerical models of the moist atmosphere. The dynamics is to predict temporal changes in the spatial distribution of conservative properties, such as mass, momentum and energy, while the thermodynamics is to diagnose the state of each chemical component of the matter in the atmosphere. In particular, the pressure that affects the motion of the matter is treated strictly as a thermodynamic state variable. The theory originally covered only reversible thermodynamic processes. It is now extended to include Kessler type microphysics of precipitation. A numerical model of the moist atmosphere in a vertical two-dimensional plane has been developed to test the extended theory. The model is nonhydrostatic, and comprises six prognostic variables: two velocity components, and four density variables for the dry air, the total water substance, the total entropy (air and water), and the precipitating water. The spatial numerics is spectral by the SAFER method, and the time-integration is by the semi-implicit method. To control side-lobe oscillations due to Gibbs' phenomena at the cloud boundaries, nonlinear diffusion is employed with variable coefficients which are derived from the deformation of a high-passed motion field. The model has been tested in numerical experiments for the simulation of long-lived squall lines, following the theoretical guide by Rotunno et al. (1988), and the results generally agree with their theory. The basic state in the experiments is a typical tropical atmosphere with enhanced relative humidity, and with a constant wind (U) everywhere except in a bottom layer of about 2 km in height. Within the bottom layer, the wind decreases gradually toward zero at the ground. A warm bubble initiates an initial convective cell, and its rain-loaded, evaporatively-cooled downdraft generates a pool of cold air that spreads in a thin layer above the ground. New cells and more downdrafts are generated in succession near the leading (down-shear) edge of the cold pool, perpetuating the dynamic system of a squall line. Although new cells may rise on either side of downdrafts, there is a favored side which depends on U. If U is faster than the spreading speed of the cold pool, new cells rise more often behind the downdraft of an earlier cell than in front, so that the squall line as a system travels slower than U. If the reverse is true, the favored side is switched and the squall line travels faster than U. The paper will also discuss other problems of general interest, which have been noted in the test.

Ortner, P.B., and M.J. Dagg. Nutrient-enhanced coastal ocean productivity in the Gulf of Mexico. EOS, Transactions, American Geophysical Union, 76(10):97, 109 (1995).

No abstract.

Ortner, P.B., T.N. Lee, P.J. Milne, R.G. Zika, M.E. Clarke, G.P. Podesta, P.K. Swart, P.A. Tester, L.P. Atkinson, and W.R. Johnson. Mississippi River flood waters that reached the Gulf Stream. Journal of Geophysical Research, 100(C7):13,595-13,601 (1995).

Distributions of physical, biological, and chemical parameters in Florida Keys coastal waters seaward of the reef track were surveyed on September 9-13, 1993, as part of a coordinated multi-disciplinary study of surface transport processes. A band of low-salinity water was observed along the shoreward side of the Florida Current over the downstream extent of the survey from Miami to Key West. Biological and chemical indicators within the band, together with its large volume, satellite imagery, and a surface drifter trajectory suggested the recent Mississippi River flood as the source.

Palmer, D.R. Acoustic imaging of underwater plumes. Acoustical Imaging, 21:241-255 (1995).

We review the research that has been done to acoustically image naturally occurring underwater plumes. Since our interest is in the use of acoustical techniques to study fluxes of material and heat across the ocean-seafloor interface, the review is limited to studies of those plumes that result from vents located on the seafloor. The review was undertaken to gain perspectives that might help in our efforts to image black-smoker hydrothermal plumes in the deep ocean. Specifically, we wanted to identify common themes in hardware development, experimental design, and data analysis and interpretation. After describing the general structure of an underwater plume and discussing the advantages of sonar imaging, we survey the individual experimental efforts. These include observations of offshore and deep-ocean hydrocarbon plumes, buoyant plumes from a submarine spring, and buoyant and neutrally-buoyant hydrothermal plumes. We then make some general statements about the characteristics of imaging sonars and their platforms, sonar calibration, scattering mechanisms, and the potential for Doppler measurements. Finally, we discuss the importance of in-situ observations. We argue that acoustical imaging can complement but cannot replace in situ measurements. In fact, it is not extreme to adopt the point of view that the primary purpose of acoustical imaging of underwater plumes is to support the collection of in-situ data.

Palmer, D.R., L. Krige, G. Brundrit, and K. Metzger. ATOC-FACT arrival-time differences. Journal of the Acoustical Society of America, 97:3265 (1995).

No abstract.

Peng, T.-H. Chapter 14: Future climate surprises. In Future Climates of the World: A Modeling Perspective, A. Henderson-Sellers (ed.). Elsevier Science, Amsterdam, 517-535 (1995).

No abstract

Peng, T.-H., and W.S. Broecker. Estimate of interhemispheric ocean carbon transport based on CO₂ and nutrient distribution. In Ecological Time Series, T.M. Powell and J.H. Steele (eds.). Chapman and Hall, New York, 28-47 (1995).

No abstract.

Powell, M.D., S.H. Houston, and I. Ares. Real-time damage assessment in hurricanes. Minutes, 49th Interdepartmental Hurricane Conference, Miami, FL, February 14-17, 1995. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-23 (1995).

The ultimate cost of a disaster is related to the amount of time taken for a community to recover; a faster, more organized recovery will help to mitigate the losses associated with a tropical cyclone. Real-time information on the actual areas impacted by a hurricane's eyewall and strongest winds should help minimize confusion and assist recovery management at the earliest stages of a disaster. The ability of Geographic Information Systems to link meteorological field information to damage statistics from infrastructure databases makes damage assessment modeling a possibility. In a project co-sponsored by Florida Power and Light Corporation, several meteorological products are being evaluated for use in estimating structural damage severity. Geo-referenced statistics on the damaged facilities in 16 subareas affected by Hurricane Andrew in south Florida were available for categories of uniform structures. Damage to these facilities was correlated with quantities derived from meteorological fields believed to be associated with damage. The goal of this work is to construct a model that can estimate facility damage in real time as the storm is in progress. Comparisons of damage in these areas to poststorm surveys completed by several groups suggest that significant damage in the Florida City-Homestead area may have been related to the range of wind directions experienced during the storm. Hence, wind steadiness is an important predictor in the prototype damage assessment model. Other predictors are discussed and the potential cost effectiveness of this modeling approach is examined. Beyond the electrical utility industry, other segments of the infrastructure could benefit from a similar approach. With models available for all segments of the infrastructure, a preliminary indication of the impact of the disaster would be possible while the storm is in progress or immediately afterward instead of waiting days for visual assessments to be completed. Scenarios for the impact of hurricanes on a community could also be created by applying the damage model to a historical or model-simulated wind field and a given radar reflectivity structure.

Powell, M.D., S.H. Houston, and I. Ares. Real-time damage assessment in hurricanes. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 500-502 (1995).

The ultimate cost of a disaster is related to the amount of time taken for a community to recover; a faster, more organized recovery will help to mitigate the losses associated with a tropical cyclone. Real-time information on the actual areas impacted by a hurricane's eyewall and strongest winds should help minimize confusion and assist recovery management at the earliest stages of a disaster. The ability of Geographic Information Systems to link meteorological field information to damage statistics from infrastructure databases makes damage assessment modeling a possibility. In a project co-sponsored by Florida Power and Light Corporation, several meteorological products are being evaluated for use in estimating structural damage severity. Geo-referenced statistics on the damaged facilities in 16 subareas affected by Hurricane Andrew in south Florida were available for categories of uniform structures. Damage to these facilities was correlated with quantities derived from meteorological fields believed to be associated with damage. The goal of this work is to construct a model that can estimate facility damage in real time as the storm is in progress. Comparisons of damage in these areas to poststorm surveys completed by several groups suggests that significant damage in the Florida City-Homestead area may have been related to the range of wind directions experienced during the storm. Hence, wind steadiness is an important predictor in the prototype damage assessment model. Other predictors are discussed and the potential cost effectiveness of this modeling approach is examined. Beyond the electrical utility industry, other segments of the infrastructure could benefit from a similar approach. With models available for all segments of the infrastructure, a preliminary indication of the impact of the disaster would be possible while the storm is in progress or immediately afterward instead of waiting days for visual assessments to be completed. Scenarios for the impact of hurricanes on a community could also be created by applying the damage model to a historical or model-simulated wind field and a given radar reflectivity structure.

Proni, J.R., J.J. Tsai, and J.F. Craynock. Acoustic profiling of disposed dredge material in the 6-mile MUD dumpsite, New York. Contract Report 68-C8-0105, U.S. Environmental Protection Agency, 17 pp. (1995).

No abstract.

Prospero, J.M., and P.B. Ortner, Co-covenors. Report: South Florida Coastal Ocean Ecosystem Workshop, Miami, FL, February 27-28, 1995. Cooperative Institute for Marine and Atmospheric Research, 164 pp. (1995).

The South Florida Coastal Ocean Ecosystem (SoFCOE) encompasses Florida Bay, the coral reefs of the Florida Keys, and the ocean margins of the unique Everglades ecosystem. All these regions are interconnected; they are also closely linked to, and affected by, the waters of the Straits of Florida, the Gulf of Mexico, and the Caribbean Sea through the effects of various current systems. Over the past few decades, the SoFCOE has undergone great changes due to altered freshwater flow through South Forida, sharply increased human population in South Florida, including the Florida Keys, and intensified sports and commercial fishing. These changes have resulted in extensive degradation in many locations. Continued rapid growth in the region could greatly exacerbate these stresses. Major efforts have been initiated to protect and restore these environments and, as a result, the SoFCOE is emerging as a key study area for improving methods and principles of management and protection of regional coastal resources that are of national interest.

Pujals, G., C. Bakker, M.D. Powell, and S.H. Houston. Demonstration of object-oriented software for real-time acquisition and presentation of meteorological fields in hurricanes. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 303-305 (1995).

NOAA scientists at the Hurricane Research Division (HRD) in Miami have been developing a real-time surface wind analysis system. The purpose is to provide forecasters with diagnostic information regarding the extent of hurricane force and tropical storm force winds at various radii. This information can then be used in marine advisories and for determining hurricane and tropical storm warnings for tropical cyclones making landfall. The system consists of utilities, tasks, and applications that acquire, process, examine, and analyze meteorological data. First, Unix-based scripts are used to bring in the most recent data automatically from marine and land-based surface observations, aircraft flight level data, and gridded fields. These data are then processed to a common framework and examined with HRD's Quality Control software package. We then incorporate the storm track to choose time intervals and mesh sizes for storm-relative analysis, as well as the weighting factors and additional analysis parameters for each mesh. Once all the desired parameters are set, a run file is created based on these parameters. The file, in turn, runs the analysis. The output parameters are then displayed graphically. An electronic poster will present the steps involved in bringing in data automatically. Examples of these steps will be shown for Hurricane Andrew's landfall on south Florida. Wind data from surface observations received in real time and after the fact are shown in the Quality Control application. Comparisons between the surface observation and the aircraft measured winds from flight level, as well as after adjustments to the surface, are also shown. The graphical interface for choosing meshes and filter wavelengths is shown, and finally, surface wind analyses are presented.

Samsury, C.E., M.L. Black, and R.E. Orville. The relationship of cloud-to-ground lightning with radar reflectivity and vertical velocity in Hurricanes Bob (1991) and Emily (1993). Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 257-259 (1995).

In-situ flight-level and radar data from the NOAA WP-3D aircraft, digitized data from NWS radars, and cloud-to-ground (CG) lightning data from the National Lightning Detection Network are analyzed for a study of the electrification of Hurricanes Bob (1991) and Emily (1993). The data were collected over 12-18 h as both storms passed just east of Cape Hatteras, North Carolina. Hurricanes Bob and Emily had maximum sustained winds of 100 kts but differed greatly in reflectivity structure and lightning characteristics. In Emily, the highest reflectivities were near the eyewall with much lower reflectivity outside the eyewall. Emily had very few CG lightning flashes, averaging less than 10 h^-1. In addition, 30% of the flashes detected were positive, a larger percentage than in any storm noted in the literature. In contrast to Emily, Bob contained convectively-active rainbands that had several hundred mostly negative flashes. Most of the flashes were located near regions of highest reflectivity, similar to results of other studies. Results from this and previous research suggest that CG lightning in hurricanes, regardless of polarity, occurs almost exclusively in regions of high reflectivity. In addition, the existence of convective rainbands or lack thereof critically impacts the amount of CG lightning associated with hurricanes. An impetus for this study was to increase knowledge of hurricane CG lightning characteristics, such as multiplicity (strokes/flash) and polarity. Most importantly, in addition to determining the location of CG lightning relative to the storm center as done with other hurricanes, this research expands on the limited previous work. In this study, the relationship between vertical velocity, radar reflectivity, and CG lightning is investigated. Flight-level and Doppler-derived vertical velocities, and horizontal and vertical radar reflectivity data from airborne and land-based radars are used to analyze the microphysical environment associated with the CG lightning in hurricanes. These data are also used to study the correlation between lightning and hurricane intensification.

Schmid, C., H. Schäfer, G. Podestá, and W. Zenk. The Vitória eddy and its relation to the Brazil Current. Journal of Physical Oceanography, 25(11):2532-2546 (1995).

In late austral summer 1991, a cyclonic thermocline eddy was detected in the subtropical western South Atlantic off the Brazilian shelf near the city of Vitória. This Vitória eddy was tracked for 55 days by surface drifters drogued at 100 m depth. The drifters had been deployed in the western boundary current regime by FS Meteor as part of a basin-wide surface current study. The analysis of a combined CTD/XBT section across the Vitória eddy, together with drifter data and satellite images of the thermal surface structure, revealed the unexpected complexity of the region. The eddy interacted not only with the local topography and the Brazil Current, located further offshore, but also with an extended upwelling regime north of Cabo Frio. The hydrographic and kinematic properties and anomalies of the Vitoria eddy are analyzed and compared with similar vortices described elsewhere in the literature.

Serafy, J.E., S. Lutz, T.R. Capo, P.B. Ortner, and P. Lutz. Anchor tags affect swimming performance and growth of juvenile red drum (Sciaenops ocellatus). Marine Behavior and Physiology (UK), 27(3):1-7 (1995).

Swimming efficiency and growth of anchor-tagged red drum (Sciaenops ocellatus) juveniles were compared with untagged controls. The O₂ consumption of fish swimming at different speeds was measured in a Blaska-type respirometer. Daily growth rates of tagged and untagged red drum were compared over 42 days of feeding fixed rations of live mosquitofish (Gambusia affinis) to siblings held individually in 380 L tanks. At swimming speeds of <1.0 body lengths per second (bl s^-1), no differences in O₂ consumption were found. However, at speeds of 1.5-2.5 bl s^-1, tagged red drum O₂ consumption was significantly greater (by 36-39%) than that of untagged fish (anova, P <0.05), indicating a substantially impaired swimming efficiency. Daily growth rates of tagged an untagged fish also differed significantly (P < 0.02). Tagged fish grew at a mean rate of 0.95 mm d^-1, and 1.45 g d^-1, while untagged fish (controls) grew at 1.14 mm d^-1 and 1.62 g d^-1. Results suggest that internal anchor tags, which weighed less than 1% of fish body weight, represented a hydrodynamic drag burden that reduced swimming performance and growth. These effects may decrease growth and/or survival in the wild and thus bias estimates of biological parameters in stock assessment and enhancement studies.

Thacker, W.C. Statistical modeling for numerical modelers. GKSS-Forschungszentrum, 7-80 (1995).

This report contains the material that formed the basis for a series of lectures presented at the GKSS Research Center during the summer of 1994. The audience consisted primarily of meteorologists and oceanographers who were familiar with numerical modeling typical of numerical weather prediction, and the intent of the lectures was to provide an overview of ideas and techniques of statistical modeling within the context of predicting the seasonal-to-interannual climate. Because of the large numbers of variables needed to characterize climatic fields and the opposing requirement that statistical models have a relatively small number of predictors, emphasis is placed on the use of indices constructed as linear combinations of field variables as predictors.

Tsai, J.J., H. Huang, and J.R. Proni. Acoustic observations of bottom surge from dredged material discharge in the open ocean. Chemistry and Ecology, 10:71-85 (1995).

Bottom surges generated from dredged material discharges in the open ocean have been observed using high frequency acoustic concentration profilers in several field studies during the past five years. The locations, water depths, bottom slopes, oceanographic conditions, and the dredged material composition differed from study to study. Observed surges at three dredged material disposal sites may develop more than one surge peak for a single discharge. For water depths of the order of 10 m, surge height of the leading peak was estimated to be about one quarter of the water depth. For water of greater depth, of the order of 100 m, surge height reached 70 m, about 70% of the water depth. Surge height is established instantaneously when dredged material hits the bottom, and remains relatively constant as the surge advances horizontally. Total surge length reached 150 m for water depths of 10 m when measured from the impact point to the leading edge. For water depths of more than 100 m, the surge length reached more than 100 m. Length of the leading surge peak was as large as 45 m at this water depth. Dimensional analysis was applied to relate the surge height of the leading surge peak to discharge parameters and oceanographic conditions. Results showed that the ratio of surge height to water depth was proportional to 1/10 power of the ratio of discharge volume to the third power of water depth.

Wanninkhof, R.H., R.A. Feely, D.K. Atwood, G.A. Berberian, W.D. Wilson, P.P. Murphy, and M.F. Lamb. Seasonal and lateral variations in carbon chemistry of surface water in the eastern equatorial Pacific during 1992. Deep-Sea Research II, 42(2-3):387-409 (1995).

During the (boreal) spring and fall of 1992, the NOAA Ocean-Atmosphere Carbon Exchange Study did an intensive survey of upper water column (<1000 m) chemistry in the eastern equatorial Pacific from 110°W to 170°W. The spring-time conditions were influenced by an El Niño that had disappeared before the fall cruises. This contributed to a large seasonal contrast in surface temperature, carbon, nutrient concentrations, and thermocline depth. Nitrate, total inorganic carbon, and fugacity of CO₂ values were significantly lower in the spring, while sea surface temperatures south of the equator were higher. The seasonal change in surface water chemistry at the equator is due to changes in upwelling of nutrient and carbon-enriched water. Oxygen and CO₂ anomalies at the surface point to approximately a three-fold increase in upwelling of thermocline water in the fall compared to the spring. The large-scale spatial variations in the surface chemistry patterns remained unchanged between spring and fall. There was a westward decrease in surface-water carbon and nitrate concentrations and a strong north to south asymmetry with higher carbon and nitrate values south of the equator. This pattern is attributed to input of carbon and nutrients with the South Equatorial Current from the east. Using velocities obtained from surface drifter tracks, along with reasonable gas exchange estimates and a "Redfield analysis" to account for export biological production, this westward decrease in carbon and nutrients can be quantitatively accounted for in the region from 0° to 3°S and 110°W to 140°W in the spring. In the fall the calculated concentration decrease is greater than observed, which is attributed to input from local equatorial upwelling along the pathway of water transit.

Willis, P.T., and J. Hallett. The cloud microphysical and electrical characteristics of a stratiform melting layer. Preprints, Conference on Cloud Physics, Dallas, TX, January 15-20, 1995. American Meteorological Society, Boston, 240-245 (1995).

This paper examines the microphysical characteristics and the structure of the electric field in a region of stratiform precipitation. The data were obtained in an aircraft advecting spiral descent, during which it attempted to stay with the trajectory of the dominant particles as they fell and melted (-5°C to 10°C) in a stratiform precipitation region in Hurricane Jimena (eastern Pacific, 24 September 1991). The evolution of the hydrometeors through the melting layer from PMS image data is presented. Hydrometeor size distributions, and example particle images, are shown for levels above the melting layer and for layers through the melting layer. The temperature profile through the melting layer displays an expected nearly isothermal layer 250 m deep near 0°C, and a second near-isothermal layer at 3°C. The measured 5 cm and 3 cm radar reflectivity factor profiles through the melting layer are presented. The vertical profiles of the measured electric field, the vertical component and one horizontal component, are presented. Field strengths of approximately 25 kv m^-1 are found just above the melting layer. Changes in the structure of the electric field are compared to the microphysical characteristics through the melting layer. The melting layer characteristics are compared to the mid-latitude profiles shown in other studies.

Willis, P.T., R.A. Black, F.D. Marks, and D. Baumgardner. Airborne rain drop size distributions in TOGA-COARE. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 431-433 (1995).

Details of rain drop size distributions are important in understanding precipitation formation processes in tropical cloud systems, and in the quantitative interpretation of radar data, as well as other remote sensing data. Describing the evolution of raindrop spectra and fitting observed distributions with suitable analytical functions is a cloud physics problem of considerable practical importance. This is particularly true for tropical clouds and cloud systems. Parameterizations of drop size distributions have wide application in modeling and remote sensing applications. For this study a large sample of TOGA COARE airborne imaging drop spectrometer data from the NCAR Electra aircraft was reduced into approximately 15,000 six second (~0.7 km spatial scale) drop size distributions. Mean drop size distributions have been computed for these drop size distributions sorted into rainfall rate categories. Functional fits to these mean drop size distributions are computed (Willis, 1984; Willis and Tattelman, 1989). Exponential and gamma distribution function fits to these mean drop size distributions are explored using several fitting methods. These data are further sorted into subsets by elevation, and by whether the precipitation is stratiform or convective. Mean drop size distributions for these subsets are also computed for categories of rainfall rate. Radar reflectivity-rainfall rate relationships (Z-R), overall and for a convective/stratiform sorting, are derived from the drop size distribution data set. These Z-R relations are compared to other relations commonly used for convection and other clouds.

Willoughby, H.E. Eye thermodynamics. Preprints, 21st Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 24-28, 1995. American Meteorological Society, Boston, 357-358 (1995).

Central sea-level pressures of the most intense tropical cyclones are approximately 10% lower than ambient. An adiabatic descent of 3 km in the eye is enough to produce the vertically-integrated 30°C warming necessary for the low hydrostatic pressure. In balanced models, convective entrainment of air from the eye into the eyewall causes the subsidence. Balanced models also predict, and observations confirm, that the eye contracts during intensification. Eye soundings show warm and dry air aloft, separated by an inversion from cloudy air below that follows a moist adiabat almost to the surface. I hypothesize that the air above the inversion has remained in the eye since it was enclosed when the eyewall formed. Loss of mass through entrainment into the eyewall is balanced by shrinking of the eye's volume with little detrainment aloft from the eyewall into the eye. The air sinks as mass below it is drawn outward from the bottom of the eye. Dew point depressions at the inversion are 10-30°C rather than the approximately 100°C that would occur if the air originated at the tropopause. The moist air below the inversion derives primarily from frictional inflow under the eyewall and secondarily from descent induced by evaporation of condensate mixed across the inside edge of the eyewall. The moist air's residence time in the eye is much shorter than that of the dry air above the inversion. The depth of the inversion is determined by the balance between frictional inflow and loss through entrainment into the eyewall. The convective bubbles in the eyewall are buoyant with respect to the air around the eye, but not with respect to the eye itself. Collectively, they act as a "heat pump" that does work on the eye by forcing thermally indirect descent. When the convection is intense, net entrainment lowers the inversion, warming and drying the eye. When the convection weakens, net frictional inflow raises the inversion, cooling the eye and filling it with clouds. This interpretation suggests that convection intensifies tropical cyclones through induced adiabatic warming of the eye sounding, not through vertical mixing that acts to adjust the eyewall sounding toward thermodynamic equilibrium with the sea.

Willoughby, H.E. Normal-mode initialization of barotropic vortex motion models. Journal of the Atmospheric Sciences, 52(24):4501-4514 (1995).

An important limitation of numerical hurricane track forecasts is the difficulty in coaxing the vortex to assume the correct initial motion. Results from a semispectral, barotropic, linear model suggest a remedy. When the model is initialized from axisymmetry and rest in a quiescent environment on a northern hemisphere beta plane, the vortex moves toward the northwest. The asymmetric streamfunction field is a dipole such that flow between the cyclonic and anticyclonic gyres advects the vortex. This asymmetry appears to reflect a free oscillation because the asymmetric structure, and the induced motion, persists for a long time in the absence of forcing. When the beta effect is turned off, the motion continues on an f plane, and the dipole can be rotated and scaled to produce any desired initial motion. In the normal-mode interpretation, a vortex with cyclonic circulation throughout accelerates poleward rapidly because the beta effect forces a neutral mode at zero frequency. A vortex with angular momentum reduced to zero by encirclement of the cyclonic core with an annulus of anticyclonic flow experiences weaker forcing of a mode at the most anticyclonic orbital frequency of the axisymmetric circulation. Although the latter mode has a weak barotropic instability, acceleration along the curving track is slow, so that this vortex is promising for track forecasting. By careful choice of vortex position and the normal-mode asymmetry's amplitude and orientation at some time before the beginning of the forecast calculation, it is possible to "preinitialize" the vortex to pass through a target initial position at the initial time with an arbitrarily chosen initial velocity. In completely cyclonic vortices that have asymptotic decay of the swirling flow with radius, radial wave energy propagation damps the mode at zero frequency. Experimentation with a variety of axisymmetric vortex structures suggest that, with this single qualification, existence of the previously described modes is a general property of barotropic vortices scaled to resemble hurricanes.

Willoughby, H.E. Normal-mode initialization of barotropic vortex-motion models. Minutes, 49th Interdepartmental Hurricane Conference, Miami, FL, February 14-17, 1995. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-19 (1995).

A serious limitation of both barotropic and baroclinic hurricane track forecast models is the difficulty in coaxing the vortex to assume the correct initial motion. Results from a semispectral, shallow-water barotropic, vortex-following, linear model suggest a way around this difficulty. When this model is initialized from axisymmetry and rest in a quiescent environment on a northern-hemisphere beta plane, the vortex moves toward the northwest because wavenumber-one normal modes with nearly zero frequency are excited. The modal streamfunction fields are dipoles such that flow between their cyclonic and anticyclonic gyres moves the vortex by advection. Because the modes are free oscillations, their asymmetric structures and the motions they induce can persist for long times even in the absence of forcing. If the beta effect is turned off, the motion continues on an f plane. The modal streamfunctions can be rotated and scaled to produce any desired initial motion. A vortex with cyclonic circulation throughout accelerates poleward too rapidly because the beta effect forces a neutral mode at zero frequency. A vortex with angular momentum reduced to zero by encirclement of the cyclonic core with an annulus of anticyclonic circulation experiences weaker forcing of a mode whose frequency is the most anticyclonic orbital frequency of the symmetric circulation. Although this mode has a weak barotropic instability, acceleration along the curving track is slower so that the latter vortex is more promising for track forecasting. By careful choice of vortex position and the normal-mode's amplitude and orientation at some time before the beginning of the forecast calculation, it is possible to "preinitialize" the vortex to pass through a target initial position at the initial time with an arbitrarily chosen initial velocity. If the preinitialization begins early enough, start-up transients die away by the initial time and acceleration away from the desired target velocity is slow.

Wilson, W.D., W.E. Johns, and M.D. Hendry. Measurements of current structure and transport in the Windward Islands Passages: 1991-1993. Proceedings, Chapman Conference on the Circulation of the Intra-Americas Sea, La Parguera, Puerto Rico, January 22-26, 1995. IOC Workshop Report No. 111, Intergovernmental Oceanographic Commission, AIII.5-AIII.6 (1995).

The Windward Islands Passages Monitoring Program has been designed to obtain inexpensive regular measurements of transport and water mass characteristics in the major southern passages to the Caribbean towards the goal of understanding the interhemispheric exchange of upper ocean waters in the western tropical Atlantic. Many present theories of North Atlantic circulation have the southward cross-equatorial Deep Western Boundary Current flow compensated by a northward transport of upper ocean South Atlantic water. This scenario is supported by the work of Schmitz and Richardson (1991, hereafter SR91), which contains a reanalysis of hydrographic and current measurements made in the southern passages in March and April of 1970 (Stalcup and Metcalf, 1972). Their analysis indicated that of 19 × 10⁶ m³/s (1 × 10⁶ m³/s = 1 Sv) entering the Caribbean through the three southernmost passages, 13 Sv were of South Atlantic origin. To better resolve the mean flow and the percentage of waters of South Atlantic origin, a Barbados Coast Guard vessel, the HMBS Trident, which makes regular patrols through the islands, has been equipped to collect standard hydrographic measurements (CTD and water samples) and velocity profiles using a lowered ADCP. Since the program's inception in December 1991, a total of ten cruises have been made, with repeat section occupations in Grenada, St. Vincent, St. Lucia, and Dominica Passages. Whenever possible, geostrophic velocity estimates have been referenced with upper layer measured currents to estimate full passage transports. The structure of the observed velocity and transport fields is similar to that described by SR91; however, mean transports are significantly smaller. Total westward transport through the three southernmost passages ranges from approximately 3 to 17 Sv with a mean value of 10 Sv, with no clear annual cycle apparent as yet in the data. Time series of current profiles collected in July 1994 in the Grenada and St. Vincent passages have been analyzed and used to predict and remove the barotropic tidal component from the transport data in these two passages, which account for 85% of the transport. The transports and their vertical structure are also consistent with recent results from a high-resolution numerical model of the North Atlantic which includes forcing by a simulated thermohaline circulation at the northern and southern boundaries (Johns et al., 1995). Salinity and dissolved oxygen measurements are presently being analyzed to determine water mass origins. Without the benefit of this analysis, exact estimates of the transport of South Atlantic water are impossible, but the low mean total transport numbers strongly suggest that significantly less than 13 Sv of upper ocean South Atlantic transport is occurring at the western boundary south of 15°N.

Wilson, W.D., W.E. Johns, J.A. Routt, and M.D. Hendry. Windward Islands Passages Monitoring Program: Physical oceanographic data collected on cruises WI-04, HMBS Trident, 7-13 December 1992, WI-05, HMBS Trident, 7-12 February 1993, and WI-06, HMBS Trident, 24-28 March 1993. NOAA Technical Memorandum, ERL AOML-84 (PB95-208674), 116 pp. (1995).

No abstract.

Yvon, S.A., and J.H. Butler. Global mean wind speed from COADS: Implications for the calculation of gas transfer velocities. EOS, Transactions, American Geophysical Union, 76(46):F107 (1995).

No abstract.

Yvon, S.A., and J.H. Butler. Uncertainties in the effect of the ocean on the atmospheric lifetime of methyl bromide. EOS, Transactions, American Geophysical Union, 76(17):S162 (1995).

No abstract.

Yvon, S.A., J.H. Butler, J.M. Lobert, and L.S. Geller. Depth profiles of methyl bromide and CFC-12 in the Atlantic Ocean. EOS, Transactions, American Geophysical Union, 76(17):S168 (1995).

No abstract. **1994**

Aberson, S.D. The accuracy of tropical cyclone prediction. Minutes, 48th Interdepartmental Hurricane Conference, Miami, FL, February 15-18, 1994. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A54-A56 (1994).

No abstract.

Aberson, S.D., and M. DeMaria. Verification of a nested barotropic hurricane track forecast model (VICBAR). Monthly Weather Review, 122(12):2804-2815 (1994).

A nested analysis and barotropic hurricane track forecast model (VICBAR) was run for tropical cyclone cases in the North Atlantic basin during the 1989-1993 hurricane seasons. VICBAR is compared to the other operational hurricane track forecast models and is shown to perform as well as each of these. VICBAR forecasts are stratified by initial date, intensity, and location to assess the variability of model performance. VICBAR produces the best forecasts for hurricane cases, for cases initiated earliest in the hurricane season, for cases moving the most slowly northward, and for those moving westward. The forecasts with the largest errors are examined to illustrate the limitations of the model and to determine whether these cases can be identified operationally.

Atlas, D., and P.G. Black. The evolution of convective storms from their footprints on the sea as viewed by synthetic aperture radar from space. Bulletin of the American Meteorological Society, 75(7):1183-1190 (1994).

SEASAT synthetic aperture radar (SAR) echoes from the sea have previously been shown to be the result of rain and winds produced by convective storms; rain damps the surface waves and causes echo-free holes, while the diverging winds associated with the downdraft generate waves and associated echoes surrounding the holes. Gust fronts are also evident. Such a snapshot from 8 July 1978 has been examined in conjunction with ground-based radar. This leads to the conclusion that the SAR storm footprints resulted from storm processes that occurred up to an hour or more prior to the snapshot. A sequence of events is discerned from the SAR imagery in which new cell growth is triggered in between the converging outflows of two pre-existing cells. In turn, the new cell generates a mini-squall line along its expanding gust front. While such phenomena are well known over land, the spaceborne SAR now allows important inferences to be made about the nature and frequency of convective storms over the oceans. The storm effects on the sea have significant implications for spaceborne wind scatterometry and rainfall measurements. Some of the findings herein remain speculative because of the great distance to the Miami weather radar--the only source of corroborative data.

Baringer, M.O., and R.A. Fine. Deep circulation in the western subtropical North Atlantic from Trident. Proceedings, Principal Investigators Meeting, Princeton, New Jersey, May 9-11, 1994. Atlantic Climate Change Program, 135-137 (1994).

No abstract.

Baringer, M.O., and R.A. Fine. Deep circulation in the western subtropical North Atlantic from Trident. EOS, Transactions, American Geophysical Union, 75(44):396 (1994).

The new Trident data set provides nutrients and transient tracers to describe and quantify the recirculations of the coldest waters in the subtropical North Atlantic. As part of the ACCP Trident cruise during August 3-31, 1992, approximate zonal sections from the western boundary to the Mid-Atlantic Ridge (MAR) were obtained along nominal latitudes of 22.5°N and 26.5°N which included hydrography, nutrients, CFCs, tritium/helium, and spot velocity measurements using LADCP and Pegasus profilers. These data confirm the net northward flow of 5 Sv of AABW with its associated high silica, low CFC, low salinity signature of southern source waters. Waters colder than 1.5°C with the low potential vorticity signature of Antarctic Bottom Water (AABW) enters the subtropical North Atlantic along our 22.5°N section with 9 Sv of southern waters below 1.8°C flowing northward between the western flank of the Mid-Atlantic Ridge and about 60°W. This northward flowing bottom water branches to the north of 22.5°N and recirculates to the east and west of Bermuda around the Hatteras and Solm Abyssal Plains in approximately equal parts. Northeast of Bermuda it mixes with North Atlantic Deep Water (NADW) as hypothesized by McCartney (1994; Schmitz and McCartney, 1993) and again returns southward across the 26.5°N section near Bermuda as a slightly warmer (1.7-1.8°C) water mass. This is confirmed by the near linear mixing relationship found in this recirculating water between the low F11, high Si AABW and the high F11, low Si NADW. This modified AABW/NADW then flows northward again to the west of Bermuda around the Hatteras Abyssal Plain, upwells and finally joins the southward flowing Deep Western Boundary Current (DWBC) at the Blake Bahama Outer Ridge. Along the western boundary the southward flow is associated with recirculation of this low potential vorticity (PV) water that has upwelled and joined the DWBC. This water is identified as a slightly warmer (1.9°C) low PV transport mode. Below 1.9°C, the CFC/silica concentrations are inversely correlated (Smethie, 1993). Transport estimates show a net northward flow of 5 Sv AABW consistent with the tracer patterns, which provide considerable detail about the circulation. The transport estimates indicate that there is intense recirculation of the deep flows at Abaco (order of 35 Sv) and other locations. The intense recirculations generate no net export of MNADW. Although the circulation patterns are substantially different in detail across these two latitudes, the net transports are remarkably similar, confirming the continuous nature of the DWBC and the large scale of these abyssal recirculations. CFCs and silica confirm the modified nature of the low PV water flowing around Bermuda, additionally they suggest a secondary mixing history of AABW that is observed in the DWBC. AABW appears to have mixed with older NADW around Bermuda but within the DWBC itself the mixing history suggests the more direct connection between high CFC "younger" DWBC water and AABW (also suggested by Smethie, 1993).

Bitterman, D.S., and W.D. Wilson. A compact CTD system with programmable controller for obtaining in-situ water samples. Proceedings, IEEE Oceans '93 Conference, Victoria, British Columbia, October 18-22, 1993. Institute of Electrical and Electronic Engineers, Volume I, 144-148 (1994).

No abstract.

Black, P.G., and S.H. Houston. Comparison of NOAA and Air Force wind measurements in Hurricane Emily near Cape Hatteras. Minutes, 48th Interdepartmental Hurricane Conference, Miami, FL, February 15-18, 1994. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A33-A41 (1994).

No abstract.

Black, R.A., H.B. Bluestein, and M.L. Black. Unusually strong vertical motions in a Caribbean hurricane. Monthly Weather Review, 122(12):2722-2739 (1994).

Unusually strong updrafts and downdrafts in the eyewall of Hurricane Emily (1987) during its rapidly deepening phase are documented by both in-situ aircraft measurements and a vertically pointing Doppler radar. Updrafts and downdrafts as strong as 24 and 19 m s^-1, respectively, were found. Mean updrafts and downdrafts were approximately twice as strong as those found in other hurricanes. Updrafts had approximately the same width as downdrafts. The most vigorous updrafts were located in the front quadrants of the storm, and most of the strongest downdrafts were found in the rear quadrants. The downdrafts could not be explained in terms of evaporative or melting cooling or precipitation drag. Evidence is presented that moist symmetric instability initiated by precipitation loading may have been responsible for the strong downdrafts.

Broecker, W.S., and T.-H. Peng. Stratospheric contribution to the global bomb radiocarbon inventory: Model versus observation. Global Biogeochemical Cycles,, 8:377-384 (1994).

An attempt is made, through modeling, to account for the decline in the ¹⁴C/C ratio in atmospheric CO₂ after its bomb-test-induced peak in 1963. The model suggests that as of 1964 about one-third of the bomb ¹⁴C remained in the stratosphere and that it was released to the troposphere with an e-folding time of about seven years. By contrast, measurements carried out in the stratosphere suggest that at that time the excess was closer to one quarter of the total and that the e-folding time for its decline was 3 ± 1 years. The anomaly between model and observation cannot be attributed solely to an inadequacy in the representation of the terrestrial biosphere. Rather, it must reflect either an inadequacy in the ocean model or in the measured stratospheric inventories.

Brundit, G., L. Krige, D.R. Palmer, A. Forbes, and K. Metzger. Acoustic thermometry of ocean climate: Feasibilty, Ascension-Cape Town. Proceedings, Second European Conference on Underwater Acoustics, Copenhagen, Denmark, July 4-8, 1994. Commission of the European Communities Federation of Acoustic Societies of Europe, Brussels, Luxembourg, Volume 2, 1019-1024 (1994).

No abstract.

Burpee, R.W., S.D. Aberson, P.G. Black, M. DeMaria, J.L. Franklin, J.S. Griffin, S.H. Houston, J. Kaplan, S.J. Lord, F.D. Marks, M.D. Powell, and H.E. Willoughby. Real-time guidance provided by NOAA's Hurricane Research Division to forecasters during Emily of 1993. Bulletin of the American Meteorological Society, 75(10):1765-1783 (1994).

The Hurricane Research Division (HRD) is NOAA's primary component for research on tropical cyclones. In accomplishing research goals, many staff members have developed analysis procedures and forecast models that not only help improve the understanding of hurricane structure, motion, and intensity change, but also provide operational support for forecasters at the National Hurricane Center (NHC). During the 1993 hurricane season, HRD demonstrated three important real-time capabilities for the first time. These achievements included the successful transmission of a series of color radar reflectivity images from the NOAA research aircraft to NHC, the operational availability of objective mesoscale streamline and isotach analyses of a hurricane surface wind field, and the transition of the experimental dropwindsonde program on the periphery of hurricanes to a technology capable of supporting operational requirements. Examples of these and other real-time capabilities are presented for Hurricane Emily.

Carsey, T.P., M.L. Farmer V.B. Ross, M. Springer-Young, and M.P. Zetwo. Trace gas aerosol species in the boundary layer of the North Atlantic during September 1993. EOS, Transactions, American Geophysical Union, 74:95 (1994).

No abstract.

Cione, J.J., and S. Raman. A three-dimensional numerical investigation of surface-induced coastal cyclogenesis near the Gulf Stream. Proceedings, Life Cycles of Extratropical Cyclones International Symposium, Bergen, Norway, June 27-July 1, 1994. Vol III, 52-55 (1994).

No abstract.

Cione, J.J., and S. Raman. Two-dimensional numerical simulations of Gulf Stream-enhanced offshore cold advection. Preprints, 6th Conference on Mesoscale Processes, Portland, Oregon, July 18-22 1994. American Meteorological Society, Boston, 270-273 (1994).

No abstract.

Clark, J.F., R.H. Wanninkhof, P. Schlosser, and H.J. Simpson. Gas exchange rates in the tidal Hudson River using a dual tracer technique. Tellus, 46B:274-285 (1994).

Gas exchange rates have been determined in the tidal Huson River by injecting two inert gases, ³He and sulfur hexafluoride (SF₆), and monitoring their decline with time. Their distributions along the main axis of the river were approximately Gaussian and maximum concentrations of excess ³He and SF₆ observed during each transect decreased from about 6500 × 10^-16 cm³ STP g^-1 and 250 ppt (part per trillion by volume), respectively, to values close to atmospheric equilibrium concentration were observed. After three days of mixing, tracer concentrations in bottom samples were 0-19% greater than in surface samples. Gas transfer velocities were calculated from the temporal change in the depth-averged excess ³He/SF₆ ratio from stations having maximum tracer concentrations. They ranged from 1.5 to 9.0 cm h^-1 and correlated well with mean wind speed.

Commons, D.N., J.R. Proni, and R. Fergen. Coastal oceanographic characteristics and their impact on marine biotoxicity studies during the SEFLOE II. Fourth Environmental Toxicology and Risk Assessment Symposium, Montreal, Quebec, Canada, April 11, 1994. American Society for Testing and Materials, 73-91 (1994).

A study, called the Southeast Florida Outfall Experiment II (SEFLOE II), was conducted from February 1991 through August 1992 at four open ocean outfalls to determine their effluent dispersion characteristics in the coastal ocean. The objectives of SEFLOE II were to assess the effect of the Florida Current and its associated spin-off eddies upon initial dilution and farfield dilution of the surfacing wastewater plumes in order to facilitate evaluation of mixing zone parameters, comparison of laboratory bioassay results to actual field bioassay results, evaluation of indicator bacteria die-off and dilution characteristics, and analysis of nutrient reductions as a function of distance and time. This paper deals with the impact of coastal oceanographic characteristics upon the biotoxicity aspect of the study. During the SEFLOE II study, a total of 1,727 acute bioassays (1,424 static acute screening bioassays and 303 static acute definitive bioassays) and 109 short-term chronic bioassays were analyzed. Plant whole effluent toxicity (WET) bioassays at different dilutions and time intervals were directly compared to bioassays analyzed on samples taken from the outfall dispersion plumes. These ocean bioassay results were then evaluated with contemporaneous current direction and speed data to determine initial and farfield dilutions and calculate actual Eulerian and Lagrangian exposure times. In all ocean bioassay tests no potential acute toxicity was demonstrated. SEFLOE II is a major investigation of the impact of a major ocean current on outfall plume behavior. The bioassay comparison indicated that standard bioassay methodology does not adequately take into consideration the substantial differences in dilution ratios and typical exposure times between laboratory analyses and actual environmental field conditions. The results of the study appear to indicate that a new look needs to be taken at bioassay methodology, especially for ocean outfalls based upon the initial and farfield mixing conditions.

Refer all requests for SEFLOE II report to:
Hazen and Sawyer, PC
4000 Hollywood Boulevard
Hollywood, FL 33021
(305) 987-0066 (Voice)
(305) 987-2947 (Fax)

Commons, D.N., J.R. Proni, H. Huang, W.P. Dammann, B.M. Goldenberg, J.G. Monson, and R.E. Fergen. Real world toxicity testing of an open ocean discharger. 66th Annual Conference and Exposition, Surface Water Quality and Ecology, Anaheim, CA, October 3-7, 1993. Water Environment Federation, Volume VII, 15-26 (1994).

A study, called the Southeast Florida Outfall Experiment II (SEFLOE II), was conducted from February 1991 through August 1992 at four open ocean outfalls. The objective of the study was to assess the effect of the Florida Current and coastal oceanographic characteristics upon the surfacing effluent plumes. During the study, the results from laboratory bioassays on plant effluent samples were compared with results from bioassays on contemporaneous ocean dispersion plume samples. Acute bioassay species used were the mysid Mysidopsis bahia and the estuarine fish Menidia beryllina. The mysid Mysidopsis bahia, and the estuarine fish Menidia beryllina, the sea urchin Arbacia punctulata, and the macroalga Champia parvula were the species used in short-term chronic bioassays during the SEFLOE II study. The results of these comparisons indicate a disparity between exposure times and dilutions in laboratory bioassays, and those exposure times and dilutions were actually demonstrated in the receiving waters.

Daneshzadeh, Y.-H., J.F. Festa, and S.M. Minton. Procedures used at AOML to quality control real time XBT data collected in the Atlantic Ocean. NOAA Technical Memorandum, ERL AOML-78 (PB94-173283), 50 pp. (1994).

Quality control (QC) procedures developed and implemented at AOML for the examination of real time XBT data are presented. The steps required to QC XBT data are outlined in a "cookbook" format. The methods employed are primarily subjective, as many of the stages involve interactive input from the user.

DeMaria, M., and S.D. Aberson. Development of a nested spectral hurricane model. In Research Activities in Atmospheric and Oceanic Modelling, G.J. Boer (ed.). CAS/JSC Working Group on Numerical Experimentation, Report No. 19, WMO/TD-No. 592, 5.36 (1994).

No abstract.

DeMaria, M., and J. Kaplan. A statistical hurricane intensity prediction scheme (SHIPS) for the Atlantic basin. Weather and Forecasting, 9(2):209-220 (1994).

A statistical model for predicting intensity changes of Atlantic tropical cyclones at 12, 24, 36, 48, and 72 h is described. The model was developed using a standard multiple regression technique with climatological, persistence, and synoptic predictors. The model developmental sample includes all of the named Atlantic tropical cyclones from 1989 to 1992, with a few additional cases from 1982 to 1988. The sample includes only the times when storms were over the ocean. The four primary predictors are (1) the difference between the current storm intensity and an estimate of the maximum possible intensity determined from the sea surface temperature, (2) the vertical shear of the horizontal wind, (3) persistence, and (4) the flux convergence of eddy angular momentum evaluated at 200 mb. The sea surface temperature and vertical shear variables are averaged along the track of the storm during the forecast period. The sea surface temperatures along the storm track are determined from monthly climatological analyses linearly interpolated to the position and date of the storm. The vertical shear values along the track of the storm are estimated using the synoptic analysis at the beginning of the forecast period. All other predictors are evaluated at the beginning of the forecast period. The model is tested using a jackknife procedure where the regression coefficients for a particular tropical cyclone are determined with all of the forecasts for that storm removed from that sample. Operational estimates of the storm track and initial storm intensity are used in place of best track information in the jackknife procedure. Results show that the average intensity errors are 10%-15% smaller than the errors from a model that uses only climatology and persistence (SHIFOR), and the error differences at 24, 36, and 48 h are statistically significant at the 99% level.

DeMaria, M., and J. Kaplan. Sea surface temperature and the maximum intensity of Atlantic tropical cyclones. Journal of Climate, 7(9):1324-1334 (1994).

An empirical relationship between climatological sea surface temperature (SST) and the maximum intensity of tropical cyclones in the North Atlantic basin is developed from a 31-year sample (1962-1992). This relationship is compared with the theoretical results described by Emanuel. The theoretical results are in agreement with the observations over a wide range of SST, provided that the tropopause temperature is assumed to be a function of SST. Each storm is examined to determine how close the observed intensity comes to the maximum possible intensity (MPI). Results show that only about 20% of Atlantic tropical cyclones reach 80% or more of their MPI at the time when they are the most intense. On average, storms reach about 55% of their MPI. Storms that are farther west and farther north tend to reach a larger fraction of their MPI. Storms are also more likely to reach a larger fraction of their MPI in August-November than in June-July. There is considerable interannual variability in the yearly average of the ratio of the observed maximum intensity to the MPI.

DeMaria, M., C.A. Mattocks, and M.D. Powell. Report, First South Florida Atmospheric Modeling Workshop, Miami, FL, November 29, 1994. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, 17 pp. + figs. (1994).

The first South Florida Atmospheric Modeling Workshop was held at the Atlantic Oceanographic and Meteorological Laboratory (AOML) on Tuesday, November 29, 1994. Attendance was about 30 people involved in various aspects of geophysical modeling. The primary purpose of the workshop was to facilitate the exchange of information between various groups involved in atmospheric, oceanographic, and hydrological modeling of the south Florida area. Much of this work is related to the NOAA-sponsored Florida Bay research program. Formal talks were given in the morning and early afternoon, followed by a lively discussion session. A synopsis of each talk and the discussion are included below.

Donoso, M.C., J.E. Harris, and D.B. Enfield. Upper ocean thermal structure of the eastern tropical Pacific. NOAA Technical Report, ERL 450-AOML 36 (PB95-171781), 226 pp. (1994).

A rigorous quality control (QC) procedure developed to assure the research quality of upper ocean thermal data, mainly from expendable bathythermographs, is described in detail. The QC scheme takes into account recommendations from different data centers and is carried out completely by oceanographers. The region of interest corresponds to the tropical Pacific from 30ºN to 30ºS and from the dateline to the west coast of the Americas. For a 15 year period (1979-1993) 212,891 stations from five data sources (National Oceanographic Data Center, Joint Environmental Data Analysis Center, southeast Pacific, Navy declassified, and Tropical Ocean and Global Atmosphere Subsurface Data Center) were originally processed, of which 113,589 profiles were kept after rejecting duplicates and submitting the data to the scientific QC process. The accepted temperature-depth profiles were binned into boxes of 2 latitude by 5 longitude. The climatology and bimonthly thermal fields (sea surface temperature, temperature at 50 m, temperature at 100 m, temperature of the 0-400 m layer, 20ºC isotherm depth, and 15ºC isotherm depth) are mapped.

Drennan, W.M., M.A. Donelan, N. Madsen, K.B. Katsaros, E.A. Terray, and C.N. Flagg. Directional wave spectra from a SWATH ship at sea. Journal of Atmospheric and Oceanic Technology, 11(4):1109-1116 (1994 ).

During the Surface Wave Dynamics Experiment (SWADE), the SWATH ship Frederick G. Creed was equipped with an array of wave staffs for the estimation of wave directional spectra. This paper reports on the first such estimates taken from a ship at sea. An algorithm for removing the effects of the ship motion, including those resulting from the Doppler shifting of observed frequencies, is presented along with some results from the SWADE experiment. A comparison with directional wave spectra taken from a nearby buoy shows the fidelity of the method.

Enfield, D.B., and D.A. Mayer. Inter-American rainfall response to tropical Atlantic and Pacific SST variability. EOS, Transactions, American Geophysical Union, 1994 Fall Meeting, paper #031E-5 (1994).

No abstract.

Esenkov, O.E. Simulation of coastal currents in a two-layer ocean with a particle-in-cell method. Masters Thesis, Darmouth College, 88 pp. (1994).

No abstract.

Feely, R.A., R.H. Wanninkhof, C.E. Cosca, M.J. McPhaden, R.H. Byrne, F.J. Millero, F.P. Chavez, T. Clayton, D.M. Campbell, and P.P. Murphy. The effect of tropical instability waves on CO₂ species distributions along the equator in the eastern equatorial Pacific during the 1992 ENSO event. Geophysical Research Letters, 21(4):277-280 (1994).

Tropical instability waves have been shown to have a major impact on the variability of temperature and nutrients along the equatorial wave guide. In order to assess the impact of these features on carbon species distributions during an ENSO event, sea surface temperature, salinity, sigma-t, nitrate, CO₂ fugacity, total inorganic carbon, total alkalinity, and pH along the equator were measured from 130°W to 100°W during 8-15 May 1992. Concurrent moored measurements of surface currents and temperature were also made at 0°, 110°W. Results indicate that tropical instability waves, with periods of 15-20 days and zonal wavelengths of 700-800 km, controlled the observed spatial variability of the CO₂ species, nitrate, and hydrographic parameters at the equator.

Forde, E.B., J.C. Hendee, and R.H. Wanninkhof. Hydrographic, carbon dioxide, nutrient, and productivity measurements from the South Atlantic during July and August of 1991. NOAA Data Report, ERL AOML-24 (PB94-180668), 96 pp. (1994).

From July 11 to September 2, 1991, the National Oceanic and Atmospheric Administration's (NOAA) Carbon Dioxide (CO₂) and Radiatively Important Trace Species (RITS) programs participated in an oceanographic research cruise conducted aboard the NOAA ship Malcolm Baldrige. This report presents the research from that cruise that was conducted for the CO₂ program, which has recently been renamed the Ocean-Atmosphere Carbon Exchange Study (OACES). During leg 1 of this cruise (Fortaleza, Brazil to Montevideo, Uruguay), 33 CTD hydrographic casts and 17 Go-Flo™ hydrographic (productivity) casts were conducted. Samples were also collected while underway on leg 1, for the determination of the fugacity of CO₂ (fCO₂) of the air and surface water. Leg 2 (Montevideo, Uruguay to Fortaleza, Brazil) collected 21 days of underway fCO₂ measurements, conducted five CTD hydrographic casts, and nine Go-Flo™ hydrographic (productivity) casts. This report contains tables of the following data: hydrography from each CTD cast at the bottle trip depths (including salinity, oxygen and nutrients), discrete carbon parameters, underway carbon parameter values, and data from productivity casts. Descriptions of the sampling techniques and analytical methods used in the collection and processing of these data are also presented in this report.

Franklin, J.L., S.J. Lord, S.D. Aberson, and M. DeMaria. The impact of ODW data on track forecasts of Hurricane Emily. Minutes, 48th Interdepartmental Hurricane Conference, Miami, FL, February 15-18, 1994. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A57-A67 (1994).

The NOAA/Hurricane Research Division conducted two synoptic-flow experiments in Hurricane Emily on 30 and 31 August 1993, as Emily was approaching the U.S. eastern seaboard. On the 30th, two P-3 aircraft released 44 ODWs in the storm environment, concentrating on the area north of the hurricane, to measure the location and structure of a high pressure ridge responsible for Emily's westward motion. Data from 36 ODWs were encoded and successfully transmitted to NMC and NHC. At the request of NHC, a second mission was conducted on the 31st. While all of the ODW messages were successfully transmitted to NHC and NMC in real time, software problems at NMC prevented roughly one-third of the ODWs from reaching the objective track forecast models for the 0000 UTC 30 August forecast cycle. Afterwards, the software problems were fixed and NMC reran the Global Spectral Model (AVN), once using the full ODW data set, and again using none of the ODW data, to assess the ODWs' true value. By accurately specifying the strength and structure of the high-pressure ridge north of the hurricane, the ODWs improved the forecast with a more accurate initial direction and a recurvature that closely paralleled the actual path of Emily. Forecast errors in the global model were reduced by up to 66%. The ODW impact was also evaluated using VICBAR, HRD's barotropic track model. The impact of the Emily ODWs on VICBAR was small, about 10%. This is because VICBAR uses a large bogus vortex that overwhelms the impact of any data within several hundred kilometers of the center. Results for the 31st are not yet available; however, the data were used subjectively by the hurricane forecasters. On this day the ODWs showed that Emily was about to pass the longitude of the mid-tropospheric high center. With this knowledge, forecasters were able to confidently predict that Emily would recurve without affecting the northeastern states.

Garzoli, S.L., and C. Giulivi. What forces the variability of the southwestern Atlantic boundary currents? Deep-Sea Research, 41(10):1527-1550 (1994).

A marked variability in the location of the front originating at the confluence of the Brazil and Malvinas Currents has been observed from both surface and subsurface observations. Modeling experiments using climatological winds predict a seasonal variability on the latitude of separation of the Brazil Current from the coast. During the Confluence program (November 1988-February 1990) and from data collected with an array of inverted echo sounders, the location of the confluence front and its variability was established. In this paper, the observed oceanic variability is analyzed simultaneously with the wind product from the European Center for Medium Weather Forecast (ECMWF) obtained for the period of the observations. The ECMWF data is validated against in-situ indirect wind magnitude observations obtained from a sub-array of the Confluence deployments. The large-scale anomalies are explored through the comparison with the climatological wind fields obtained from Hellerman and Rosenstein (1983), Journal of Physical Oceanography, 13:1093-1104. From the analysis it is concluded that the main source of variability of the Confluence front is the local wind forcing. There is a variability in the location of the front due to the seasonal cycle of the winds in the South Atlantic. In addition to this seasonal variability, the latitude of separation of the Brazil Current from the coast presents a marked interannual variability that is forced from anomalous wind patterns south of the Confluence. There is no apparent correlation between wind-forced pulses in the Antarctic Circumpolar Current and the observed anomalous northward penetration of the Malvinas Current.

Garzoli, S.L., A.L. Gordon, and D. Pillsbury. Initial results from the BEST cruises. WOCE Notes, 6(1):10-11, 15 (1994).

No abstract.

Gould, W.J., Y. Desaubies, B.M. Howe, D.R. Palmer, F. Schott, and C. Wunsch. Acoustic thermometry in the Atlantic: A report to SCOR WG 96. Scientific Committee on Oceanic Research, International Council of Scientific Unions, 18 pp. (1994).

No abstract.

Gould, W.J., Y. Desaubies, B.M. Howe, D.R. Palmer, F. Schott, and C. Wunsch. Acoustic thermometry in the Atlantic. Proceedings, Second European Conference on Underwater Acoustics, Copenhagen, Denmark, July 4-8 1994. Commission of the European Communities Federation of Acoustic Societies of Europe, Brussels, Luxenbourg, Volume 2, 105-107 (1994).

No abstract.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Predicting Atlantic basin seasonal tropical cyclone activity by 1 June. Weather and Forecasting, 9(1):103-115 (1994).

This is the third in a series of papers describing the potential for the seasonal forecasting of Atlantic basin tropical cyclone activity. Earlier papers by the authors describe seasonal prediction from 1 December of the previous year and from 1 August of the current year; this work demonstrates the degree of predictability by 1 June, the "official" beginning of the hurricane season. Through three groupings consisting of 13 separate predictors, hindcasts are made that explain 51%-72% of the variability as measured by cross-validated agreement coefficients for eight measures of seasonal tropical cyclone activity. The three groupings of predictors include (1) an extrapolation of quasi-biennial oscillation of 50- and 30-mb zonal winds and the vertical shear between the 50- and 30-mb zonal winds (three predictors); (2) west African rainfall, sea level pressure, and temperature data (four predictors); and (3) Caribbean basin and El Niño-Southern Oscillation information including Caribbean 200-mb zonal winds and sea level pressures, equatorial eastern Pacific sea surface temperatures and Southern Oscillation index values, and their changes in time (six predictors). The cross validation is carried out using least sum of absolute deviations regression that provides an efficient procedure for the maximum agreement measure criterion. Corrected intense hurricane data for the 1950s and 1960s have been incorporated into the forecasts. Comparisons of these 1 June forecast results with forecasts results from 1 December of the year previous and 1 August of the current year are also given.

Hacker, P., E. Firing, W.D. Wilson, R.L. Molinari, and M.H. Bushnell. Direct current velocity measurements during the Trident cruise in the subtropical western North Atlantic, August 1992. Proceedings, Principal Investigators Meeting, Princeton, New Jersey, May 9-11, 1994. Atlantic Climate Change Program, 162-165 (1994).

No abstract.

Hendee, J.C. Data management for the Nutrient Enhanced Coastal Ocean Productivity program. Estuaries, 17(4):900-903 (1994).

The Nutrient Enhanced Coastal Ocean Productivity (NECOP) Data Management Program (NDMP) is designed to ensure tracking of samples and archival of all NECOP data in uniform formats, thus allowing ready access to data by NECOP investigators and the scientific community at large. The NDMP may broadly be described as possessing several functions: oceanographic sample tracking, data review and formatting, data dissemination, formation and supply of data products, and data transmittal to the National Oceanographic Data Center (NODC). Figure 1 gives an outline of data flow through the data manager, and is described below.

Hendee, J.C. Object-oriented database management system and their application to oceanography. Earth System Monitor, 4(4):6-9 (1994).

No abstract.

Houston, S.H., and M.D. Powell. Observed and modeled wind and water-level response from Tropical Storm Marco (1990). Weather and Forecasting, 9(3):427-439 (1994).

The Hurricane Research Division (HRD) analyzes surface wind fields in tropical storms and hurricanes using surface wind observations and aircraft flight-level wind measurements in the vicinity of the storms. The analyzed surface wind fields for Tropical Storm Marco (1990) were compared with the wind fields used for input in the National Weather Service's Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The HRD wind fields were also used to determine the wind speeds and directions corresponding tothe storm surge at tide gauges along Florida's west coast. The observed storm surge at the gauges was compared with the storm surge computed by the SLOSH model. Time series of the SLOSH model winds were compared with the time series based on the analyzed wind field at each tide gauge, because in most cases there were no wind observations available at these gauges. The comparisons of the analyzed and modeled winds and the observed and modeled storm surge show that the SLOSH model reasonably represented the extreme storm tide effects on two basins with relatively complicated coastlines. However, SLOSH overestimated surface winds in areas of offshore flow, resulting in predictions of excessive negative surge. It is suggested that real-time storm surge model calculations, based on input from real-time surface wind analyses, have potential for the support of emergency management response and infrastructure recovery efforts during and immediately following landfall.

Houston, S.H., and M.D. Powell. Surface wind fields in hurricanes during the 1993 season. Minutes, 48th Interdepartmental Hurricane Conference, Miami, FL, February 15-18, 1994. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A42-A43 (1994).

Surface wind fields were analyzed by NOAA's Hurricane Research Division (HRD) both in real-time and after the fact for the 1993 Atlantic hurricane season. The real-time wind fields were provided to forecasters at the National Hurricane Center (NHC) for Hurricanes Emily and Gert as each storm approached the coast. In the case of Emily, the storm remained offshore, but passed within 37 km of Cape Hatteras, North Carolina during 31 August to 1 September. For Gert, real-time surface wind analyses included several hours prior to and during the landfall of the storm south of Tampico, Mexico on 20 September. In addition to the Hurricane Emily real-time surface wind field analyses, post-storm analyses of the storm's circulation have been done. These latest Emily wind fields include additional surface observations which were not available in real-time.

Huang, H., J.R. Proni, and J.J. Tsai. Probabilistic approach to initial dilution of ocean outfalls. Water Environment Research, 6:787-793 (1994).

This paper presents a probabilistic approach to develop initial dilution criteria or standards for ocean outfall design and environmental impact assessment of effluent discharges. In contrast to a currently used "worst case" approach, in which a particular combination of parameters affecting initial dilution is specified and an associated initial dilution is calculated using a deterministic dilution model, the probabilistic approach provides a framework for combining data for the parameters which are often available in the form of time series or described in statistics; the result of the probabilistic approach is a description of initial dilution as a function of cumulative or exceedance probability, from which the exposure risk level to marine environment can be estimated and criteria or standards can be defined. The proposed methodology basically consists of implementing a probabilistic method with a deterministic initial dilution model. The probabilistic method could be time domain simulation, Monte Carlo simulation, or first-order uncertainty analysis; while the deterministic initial dilution model could be a mathematical model, a physical model, or an empirical equation. A case study is presented of the Miami-Central Outfall on the east coast of south Florida to compare the probabilistic approach with the "worst case" approach. In this case study, time domain simulation using actual data sets was employed to generate a time series of initial dilutions (dilutions were calculated using a semi-empirical equation). Some statistics of initial dilution were then obtained from the simulated dilution time series. It is found that for this case study the "worst case" dilution is 17.3 (minimum surface or near-surface dilution) and the associated cumulative probability of 5.4%.

Jones, R.W., and M. DeMaria. Data assimilation for tropical cyclone prediction models. In Research Activities in Atmospheric and Oceanic Modelling, G.J. Boer (ed.). CAS/JSC Working Group on Numerical Experimentation, Report No. 19, WMO/TD-No. 592, 1.33 (1994).

No abstract.

Johnson, G.C., T.B. Sanford, and M.O. Baringer. Stress on the Mediterranean Outflow Plume: Part 1. Velocity and water property measurements. Journal of Physical Oceanography, 24:2072-2083 (1994).

In September 1988, six sections were occupied across the Mediterranean outflow plume in the Gulf of Cadiz, within 100 km of the Strait of Gibraltar. Vertical profiles of temperature and salinity were collected at CTD stations. Velocity and temperature profiles were collected with XCPs at a subset of these stations. At the channel base, the plume undergoes geostrophic adjustment and turns northwest to flow along the continental slope. There it decelerates and spreads gradually down the slope as friction slows the current and allows it to cross isobaths. Within the plume, downstream velocity and density increase rapidly in the interfacial layer with depth to the velocity maximum, or nose, -150 m above the bottom. Below the nose, in the bottom layer, downstream velocity decreases rapidly toward the bottom but the stratification is weak. Ekman-like veering occurs in the interfacial layer. Local bottom stresses on the plume are estimated by fitting the near-bottom velocity profiles to a log-layer model. These stresses are compared with bulk estimates of total stresses from momentum budget residuals (Baringer, 1993) and of interfacial stresses from combining the mean vertical shear with bulk turbulent dissipation estimates. The downstream pattern of the sum of the local bottom stresses and the bulk interfacial stresses agrees well in magnitude and distribution with that of the bulk total stresses. The largest stresses reach a mean of 5 Pa where the plume is flowing rapidly westward down a channel after exiting the strait, thinning and accelerating. These stresses are an order of magnitude larger than mean wind-stress values over the ocean gyres and exceed most bottom stress estimates in other regions.

Kaplan, J., and M. DeMaria. Preliminary results from a simple model for predicting tropical cyclone winds over land. Minutes, 48th Interdepartmental Hurricane Conference, Miami, FL, February 15-18, 1994. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A110-A112 (1994).

No abstract.

Katsaros, K.B. ERS-I studies at the Department of Oceanography from Space. Proceedings, Oceans '94 Conference, Brest, France, September 13-16, 1994. Institute of Electrical and Electronics Engineers, New York, vol. 1, I.94-I.98 (1994).

The Department of Oceanography from Space at Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER) was established in 1991 just before the launch of the first European Research Satellite ERS-I. It encompasses a research team (The Laboratory of Oceanography from Space) and a French Processing and Archiving Facility, the French PAF, for the ERS data also known as Centre ERS d'Archivage et de Traitement - CERSAT). The work of the two research groups of the Laboratory of Oceanography from Space, dealing with Atmosphere-Ocean Interaction and Sea Ice, is described and the objectives of our future endeavors are presented. The CERSAT and its organization are presented in a poster paper at this conference.

Katsaros, K.B., J. DeCosmo, R.J. Lind, R.J. Anderson, S.D. Smith, R. Kraan, W. Oost, K. Uhlig, P.G. Mestayer, S.E. Larsen, M.H. Smith, and G. DeLeeuw. Measurements of humidity and temperature in the marine environment during the HEXOS main experiment. Journal of Atmospheric and Oceanic Technology, 11(4):964-981 (1994).

Accurate measurement of fluctuations in temperature and humidity are needed for determination of the surface evaporation rate and the air-sea sensible heat flux using either the eddy correlation or inertial dissipation method for flux calculations. These measurements are difficult to make over the ocean, and are subject to large errors when sensors are exposed to marine air containing spray droplets. All currently available commercial measurement devices for atmospheric humidity require frequent maintenance. Included in the objectives of the Humidity Exchange over the Sea program were testing and comparison of sensors used for measuring both the fluctuating and mean humidity in the marine atmosphere at high wind speeds and development of techniques for the protection of these sensors against contamination by oceanic aerosols. These sensors and droplet removal techniques are described and comparisons between measurements from several different systems are discussed in this paper.

Kendall, A.W., L.S. Incze, and P.B. Ortner. Vertical distribution of eggs and larvae of walleye pollock (Theragra chalcogramma) in Shelikof Strait, Gulf of Alaska. Fisheries Bulletin, 92:540-554 (1994).

The vertical distribution of walleye pollock eggs and larvae in Shelikof Strait, Gulf of Alaska, was investigated using data from 36 Multiple Opening-Closing Net and Environmental Sensing System (MOCNESS) tows taken in April and May, 1986-1988. Most eggs were found from below 150 m to near bottom at depths of 300 m, but were progressively shallower later in the season. Eggs in middle stages of development were shallower than younger or older eggs. The vertical distribution of eggs was positively related to observed differences in seawater temperature but showed no relationship to density. Larvae hatch at incubation depth and quickly rise to the upper 50 m of the water column where they remain during larval development. Larger larvae ( 7-10 mm standard length [SL]) undergo limited diel vertical migration within the upper 50 m. They are deepest during the day, shallowest at dusk, slightly deeper at night, and even deeper at dawn. Their mean depths of occurrence were between 21 and 37 m at all times. At these depths, prey (copepod nauplii) generally were at densities sufficient for larval pollock growth in laboratory studies. Pronounced thermoclines and pycnoclines were present in the part of the water column inhabited by the larvae in late May. Larvae appear to remain below the upper mixed layer during periods of increased turbulence, but at depths during daytime where light was sufficient for feeding, and where prey densities were adequate.

Kenyon, T.N., and M.C. Pazos. Data from drifting buoys deployed in the equatorial Pacific between April 1, 1987 and June 30, 1988. NOAA Technical Report, ERL AOML-25 (PB94-219177), 174 pp. (1994).

No abstract.

Landsea, C.W., W.M. Gray, P.W. Mielke, and K.J. Berry. Forecasting seasonal Sahelian rainfall by 1 December of the previous year. Proceedings, International Conference on Monsoon Variability and Prediction, Trieste, Italy, WMO/TD No. 619. World Meteorological Organization, 496-503 (1994).

No abstract.

Landsea, C.W., W.M. Gray, P.W. Mielke, and K.J. Berry. Seasonal forecasting of Atlantic hurricane activity. Weather, 49:273-284 (1994).

No abstract.

Lawler, A.J., R.E. Fergen, A. Fairey, and J.F. Craynock. Comparison of acoustical and dye monitoring techniques for in-harbor mixing of Charleston's Plum Island Wastewater Treatment Plant effluent. Proceedings, Conference on Challenges and Opportunities in the Marine Environment, Washington, D.C., September 7-9, 1994. Marine Technology Society, 740-747 (1994).

The City of Charleston Plum Island Wastewater Treatment Plant (WWTP) discharges effluent through a multiport diffuser, designed for rapid initial dilution, into the Charleston Harbor. The original permit conditions for the Plum Island WWTP were based on initial dilution values determined by the EPA "initial dilution" model UPLUME. However, the City conducted a field study to determine actual instream waste concentration. A conventional dye study was performed by injecting a known amount of dye into the effluent and measuring the concentration of dye in the harbor. The second technology used was an innovative technique using acoustical backscatter data corrected to eliminate the background signal generated within the water column that is not related to the wastewater plume. Field data was used to determine an average initial dilution and farfield dilution during worst case (minimum mixing) conditions. Correlation of the two techniques provided validation of the acoustical methodology as an accurate measurement system for the determination of the dilution of the wastewater with distance from the outfall. In addition, the acoustic measurement gives continuous values, not just that of a given sampling point, and allows the entire plume configuration to be depicted pictorially. This allows the characterization of the microstructure in the rising plume and farfield plume that is not available with other techniques.

Lawler, A.J., R.E. Fergen, A. Fairey, and J.F. Craynock. Comparison of acoustical and dye monitoring techniques for in-harbor mixing of Charleston's Plum Island Wastewater Treatment Plant effluent. 66th Annual Conference and Exposition, Surface Water Quality and Ecology, Anaheim, CA, October 3-7, 1993. Water Environment Federation, Volume VII, 235-245 (1994).

Lee, W.-C., P.P. Dodge, F.D. Marks, and P.H. Hildebrand. Mapping of airborne Doppler radar data. Journal of Atmospheric and Oceanic Technology, 11(2):572-578 (1994).

Two sets of equations are derived to (1) map airborne Doppler radar data from an aircraft-relative coordinate system to an earth-relative coordinate system, and (2) remove the platform motion from the observed Doppler velocities. These equations can be applied to data collected by the National Oceanic and Atmospheric Administration WP-3D system, the National Center for Atmospheric research ELDORA system, and other airborne radar systems.

Lee, W.-C., F.D. Marks, and R.E. Carbone. Velocity track display: A technique to extract real-time tropical cyclone circulations using a single airborne Doppler radar. Journal of Atmospheric and Oceanic Technology, 11(2):337-356 (1994).

The concept and formulation of a real-time Doppler radar wind field analysis technique, velocity track display (VTD), is presented. The VTD algorithm is a harmonic analysis method similar to the velocity-azimuth display technique for ground-based radars; however, it is designed to deduce the primary circulation properties of atmospheric vortices such as tropical cyclones. When an aircraft equipped with a Doppler radar scanning in a track-orthogonal plane penetrates a cyclonic circulation, VTD decomposes Doppler velocities on cylindrical rings into tangential, radial, and the mean cross-track component of the wind velocity. Obtaining estimates of the vortex circulation requires data from only one aircraft flight leg instead of two in the pseudo-dual Doppler radar method. As a test, the VTD technique was applied to two orthogonal legs ("figure 4" pattern) in Hurricane Gloria (1985). The entire computation was completed about 15 min after the end of each flight leg with little or no human interaction. The reconstructed hurricane vortex structure (the mean tangential wind, mean radial wind, and the total tangential wind) is consistent with those documented in the literature by elaborate techniques that demand extensively interactive decisions and intensive computations. The output consists of about 4,000 Fourier coefficients, which can be transmitted from an aircraft to a forecast center via geosynchronous satellite link in real-time for further analysis and as initialization for tropical cyclone models. A version of VTD was run successfully on board a NOAA WP-3D during the 1991 hurricane season.

Lighthill, J., G. Holland, W. Gray, C.W. Landsea, G. Craig, J. Evans, Y. Kurihara, and C. Guard. Global climate change and tropical cyclones. Bulletin of the American Meteorological Society, 75(11):2147-2157 (1994).

This paper offers an overview of the authors' studies during a specialized international symposium (Mexico, 22 November-1 December 1993) where they aimed at making an objective assessment of whether climate changes, consequent on an expected doubling of atmospheric CO₂ in the next six or seven decades, are likely to increase significantly the frequency or intensity of tropical cyclones (TCs). Out of three methodologies available for addressing the question they employ two, discarding the third for reasons set out in the appendix. In the first methodology, the authors enumerate reasons why, in tropical oceans, the increase in sea surface temperature (SST) suggested by climate change models might be expected to affect either (i) TC frequency, because a well-established set of six conditions for TC formation include a condition that SST should exceed 26°C, or (ii) TC intensity, because this is indicated by thermodynamic analysis to depend critically on the temperature at which energy transfer to air near the sea surface takes place. Careful study of both suggestions indicates that the expected effects of increased SST would be largely self-limiting, (i) because the other five conditions strictly control how far the band of latitudes for TC formation can be further widened, and (ii) because intense winds at the sea surface may receive their energy input at a temperature significantly depressed by evaporation of spray, and possibly through sea surface cooling. In the second methodology, the authors study available historical records that have very large year-to-year variability in TC statistics. They find practically no consistent statistical relationships with temperature anomalies; also, a thorough analysis of how the El Niño-Southern Oscillation cycle influences the frequency and distribution of TCs shows any direct effects of local SST changes to be negligible. The authors conclude that, even though the possibility of some minor indirect effects of global warming on TC frequency and intensity cannot be excluded, they must effectively be "swamped" by large natural variability.

Maddox, R.A., and H.F. Bezdek. Surface wind-pressure gradient relationships in central Florida. Monthly Weather Review, 122(11):2596-2602 (1994).

An extended series of surface observations is used to compare observed surface winds with winds computed using the geostrophic relationship. These computations are done for both steady and unsteady wind regimes. Large differences are found in the comparisons of observed to computed winds. The differences exhibit pronounced seasonal and diurnal variability that appear to reflect both boundary layer stability and small-scale wind and pressure fields--for example, those attending land--sea breezes and thunderstorms. The results of this study may be useful to those engaged in studying global data sets and to modelers, who are continually challenged to improve the treatment of parameterization of turbulent processes. However, it is not obvious that any simple parameterization can be applied to obtain an accurate estimate of the surface wind in central Florida, given only the large-scale pressure gradient or a model-predicted wind above the surface as input. The use of the pressure field to estimate surface winds is an uncertain exercise at best.

Marks, F.D., and H.A. Friedman. 1994 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 138 pp. (1994).

No abstract.

Martin, J.H., K.H. Coale, K.S. Johnson, S.E. Fitzwater, R.M. Gordon, S.J. Tanner, C.N. Hunter, V.A. Elrod, J.L. Nowicki, T.L. Coley, R.T. Barber, S. Lindley, A.J. Watson, K. Van Scoy, C.S. Law, M.I. Liddicoat, R. Ling, T. Stanton, J. Stockel, C. Collins, A. Anderson, R. Bidigare, M. Ondrusek, M. Latasa, F.J. Millero, K. Lee, W. Yao, J.-Z. Zhang, G. Friederich, C. Sakamoto, F. Chavez, K. Buck, Z. Kolber, R. Greene, P. Falkowski, S.W. Chisholm, F. Hoge, R. Swift, J. Yungel, S. Turner, P. Nightingale, A. Hatton, P. Liss, and N.W. Tindale. Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean. Nature, 371:123-129 (1994).

The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km² in the open equatorial Pacific Ocean with iron. This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production. Similar increases were found in a chlorophyll-rich plume downstream of the Galapagos Islands, which was naturally enriched in iron. These findings indicate that iron limitation can control rates of phytoplanton productivity and biomass in the ocean.

Mayer, D.A., and R.H. Weisberg. On the observational basis for ENSO modeling using COADS. EOS, Transactions, American Geophysical Union, 75(44):360 (1994).

With 30 years of data from COADS, anomalies of SST, zonal and meridional wind stress (tau_x, tau_y) and sea level pressure (P_b) fields are examined over a global domain from 20°S-20°N. Important regions of covariability among the data have been identified and are discussed in the context of eastern and western Pacific variability. Maximum correlation, cross-correlation and EOF analyses are equivalent in capturing simple statistical relationships between a zonal pressure gradient index and the rest of the data (SST, tau_x, and tau_y). Greatest variability resides in the central and eastern Pacific for SST and in the west-central Pacific for tau_x and tau_y. The latter is characterized by a large meridional asymmetry with most of the variability north of the equator. Both tau_x and tau_y have much smaller correlation scales than those for SST, i.e., regional scales are degraded owing to large wavenumber bandwidths. This variability is represented by reference time series from the maximum correlation analysis and canonical time series from the first EOF modes. All of these time sequences are statistically indistinguishable but are specific to significantly different correlation regions with different spatial scales. Data in regions identified by EOF modes above the first are not simply related to data elsewhere and in many cases appear to be chaotic. Important regions are not always associated with maximum variability. An important example is the disproportionate influence that minimum variability of SST has on P_b over the warm pool in the far western Pacific and reflects the distinctly different background states characterized by incipient instability in the west and relative stability in the east. A model that considers only simple thermodynamics and a hydrostatic atmosphere shows that only 1 Wm^-2 of condensation heating in the lower troposphere is required to change the surface pressure by 1 mb/mo. This is consistent with observed excitation rates for P_b during ENSO episodes. Linear regression analyses between anomalies of SST and P_b in the eastern and western Pacific suggest that the coupling coefficient may be larger in the west by a factor of two despite the SST anomalies being large in the east by a factor of five.

McCartney, M.S., and M.O. Baringer. The Subantarctic Mode Water--Antarctic Intermediate Water connection in the South Pacific Ocean. EOS, Transactions, American Geophysical Union, 75(3):204 (1994).

No abstract.

Mestas-Nunez, A.M., D.B. Chelton, M.H. Freilich, and J.G. Richman. An evaluation of ECMWF-based climatological wind stress fields. Journal of Physical Oceanography, 24(7):1532-1549 (1994).

A new mean monthly wind stress climatology based on seven years (1980-1986) of operational weather analyses by the European Centre for Medium-Range Weather Forecasts (ECMWF) has been derived by Trenberth et al. This climatology (referred to here as the TLO climatology) potentially represents a significant improvement over climatologies derived only from conventional wind observations. An attempt is made here to quantify the absolute accuracy of the TLO climatology by comparison with global wind stress fields constructed from vector winds measured by the SEASAT-A Satellite Scatterometer (SASS) during 1978. From a simulated SASS data set, it is shown that the magnitudes of the SASS stresses must be increased by about 7% to account for a systematic error that can be attributed to the scatterometer spatial- and temporal-sampling characteristics. After applying this correction, differences between the TLO climatology and SASS winds in the tropics are most likely related to known limitations of the ECMWF analyses. At latitudes south of 50°S, interannual variability and uncertainties in the operational weather analyses are o large that it is not possible to evaluate the TLO climatology on the basis of comparisons with SASS data. Outside of these equatorial and high southern latitude bands, the TLO stresses are shown to be systematically stronger than SASS by almost 50%. It is found that this difference can be entirely accounted for if the 1980-1986 ECMWF 1000-mb analyses are not interpreted as 10-m winds, as they were in constructing the TLO climatology. This conclusion is supported by an independent comparison of the synoptic ECMWF wind speed estimates with coincident buoy observations.

Millero, F.J., J.-Z. Zhang, E. Peltola, M. Roche, S. Olivella, M. De Alessi, and B. Vargas. Total alkalinity measurements in the South Pacific. University of Miami Technical Report, RSMAS-94-003, 207 pp. (1994).

In spring 1994, we participated in one CO₂ cruise in the South Pacific during the Joint Global Ocean Flux Study (JGOFS) sponsored by the National Oceanic and Atmospheric Administration (NOAA). This report gives the results of our pH, total alkalinity (TA), and total inorganic carbon dioxide (TCO₂) measurements made in the South Pacific during the cruise. The results were obtained by a potentiometric titration of seawater samples with HCl. Measurements on 116 samples of Certified Reference Material with the three cells at sea indicate that the systems have a reproducibility of ± 3.3 µmol kg^-1 in TA. The resulting pH, TA, and TCO₂ are thought to be precise to ± 0.01 in pH, ± 3 µmol/kg in TA, and ± 3 µmol/kg in TCO₂. Our titration results will be combined with the NOAA measurements of TCO₂ and fCO₂ to characterize the CO₂ system in this region.

Millero, F.J., J.-Z. Zhang, D.M. Campbell, W. Yao, K. Lee, M. Helmer, S. Mane, S. Olivella, S. Cass, D.G. Purkerson, J. Aicher, P.A. Steinberg, and D. Medina. Total alkalinity measurements in the eastern equatorial Pacific. University of Miami Technical Report, RSMAS-94-005, 229 pp. (1994).

In 1992, we made measurements on the carbonate system on two cruises (spring and fall) in the eastern equatorial Pacific during the Joint Global Ocean Flux Study (JGOFS) sponsored by the National Oceanic and Atmospheric Administration (NOAA). This report gives the results of our pH, total alkalinity (TA), and total inorganic carbon dioxide (TCO₂) measurements made during the spring and fall cruises. The results were obtained by a potentiometric titration of seawater with HCl acid. Measurements on the Certified Reference Materials during the cruise with the three cells indicate that the systems have a reproducibility of ± 2-4 µmol kg^-1 in TA. The titration values of TCO₂ determined on the Certified Reference Materials and the samples collected at sea were about 20 ± 6 µmol kg^-1 (spring) and 17 ± 6 µmol kg^-1 (fall) too high. This offset in TCO₂ is independent of depth and is due to the non-Nernstian Behavior of the electrodes. The measured values of pH, TA, and TCO₂ are thought to be precise too ± 0.01 in pH, ± 3 µmol kg^-1 in TA, and ± 5 µmol kg^-1 in TCO₂. These results will be combined with NOAA's AOML and PMEL groups to characterize the CO₂ system in this region.

Molinari, R.L., and E. Johns. Upper layer temperature structure of the western tropical Atlantic. EOS, Transactions, American Geophysical Union, 75(3):224 (1994).

No abstract.

Molinari, R.L., and E. Johns. Upper layer temperature structure of the western tropical Atlantic. Journal of Geophysical Research, 99:18,225-18,233 (1994).

Mean monthly topographies of the 20°C and 10°C isothermal surfaces are used to describe the vertical displacements of the upper and lower thermocline in the western tropical Atlantic. The isotherm topographies are generated from expendable bathythermograph data collected between 1966 and 1993. The topographies confirm, and extend closer to the coast, earlier findings that demonstrate large spatial and temporal variability in the region. For example, the ridge and trough systems observed previously in the interior are shown, and their extension to the western boundary is described. In particular, it is shown that the ridge associated with the North Equatorial Countercurrent (NECC) extends from the interior northwestward along the western boundary, reaching farther north along the boundary in the upper thermocline than in the lower thermocline. South of the equator the northwestern corner of the countercurrent trough is apparent on the lower surface but not on the upper. The annual and semiannual harmonics of the vertical isotherm displacements account on the average for about 60% of the total variance on both surfaces. The horizontal structure of the first harmonic amplitude is similar for both surfaces, showing maximum amplitude along the axis of the NECC ridge. Minimum amplitudes are observed to the north along the axis of the NECC ridge. Minimum amplitudes are observed to the north along the axis of the countercurrent trough. These distributions are similar to the pattern of the first harmonic amplitude of the wind stress curl, supporting earlier studies of curl forcing of near-surface current features.

Molinari, R.L., and W.D. Wilson. Absolute velocity properties of the Deep Western Boundary Current at 26.5°N. EOS, Transactions, American Geophysical Union, 75(44):396 (1994).

The Deep Western Boundary Current (DWBC) is an important component of meridional oceanic heat flux in the subtropical North Atlantic. Direct velocity observations obtained from sensors deployed from research vessels have been collected in the DWBC from 1985 to 1994. Both Pegasus, a free-fall acoustically tracked unit, and a lowered acoustic Doppler current profiler (LADCP) were used. Intercomparisons of total water column velocity profiles obtained during an August 1992 cruise show differences between the two sensors of only 0.1 m s^-1 in depth-averaged velocity components and 0.02-0.04 m s^-1 in shear observations. A section was repeatedly occupied east of Abaco Island, the Bahamas, at 26.5°N. Prior to 1992, on average, the DWBC was characterized by a mid-depth (1500 to 2500 m) meridional speed core of about 0.2 m s^-1. During the majority of these cruises, the DWBC core was typically some 50 km offshore, with some excursions to about 100 km offshore. During 1992, the mid-depth DWBC core was located some 150 km offshore. This core remained some 100-150 km offshore during June and September 1993 cruises. During April and July 1994, the core was found at its historical position 50 km offshore. Considerable variability is observed in total transport below 800 m within 400 km of the boundary. On all but the June 1994 cruise, transport was approximately 40 Sv. During June 1994, transport was only 10 Sv. Significant changes in vertical shear structure also are observed. When the DWBC core is located onshore, a level of no motion is typically located at 800 m. When offshore, the meridional velocity component can be unidirectional from top to bottom, complicating the task of computing geostrophic velocities from only density observations.

Molinari, R.L., D. Battisti, K. Bryan, and J. Walsh. Atlantic Climate Change Program. Bulletin of the American Meteorological Society, 75(7):1191-1199 (1994).

The Atlantic Climate Change Program (ACCP) is a component of NOAA's Climate and Global Change Program. ACCP is directed at determining the role of the thermohaline circulation of the Atlantic Ocean on global atmospheric climate. Efforts and progress in four ACCP elements are described. Advances include: (1) descriptions of decadal and longer term variability in the coupled ocean-atmosphere-ice system of the North Atlantic; (2) development of tools needed to perform long-term model runs of coupled simulations of North Atlantic air-sea interaction; (3) definition of mean and time-dependent characteristics of the thermohaline circulation; and (4) development of monitoring strategies for various elements of the thermohaline circulation.

Nelsen, T.A., P. Blackwelder, T. Hood, B. McKee, N. Romer, C. Alvarez-Zarikian, and S. Metz. Timed-based correlation of biogenic, lithogenic, and authigenic sediment components with anthropogenic inputs in the Gulf of Mexico NECOP study area. Estuaries, 17(4):873-885 (1994).

Hypotheses related to variability in seasonal hypoxic conditions, coastal nutrient enhancement, and offshelf transport of carbon on the Louisiana continental shelf were tested by characterization of biogenic, lithogenic, and authigenic components from two shelf and one Mississippi Canyon sediment cores. The authigenic-phase glauconite occurs above detection limits only in the core from the hypoxic area. A major increase in glauconite concentration was coincident with the onset (~1940) of the increased use of commercial fertilizers in the United States. In the same hypoxic-area core, benthic foraminifera species diversity decreases upcore from approximately the turn of the century to the present in a manner concurrent with glauconite and fertilizer increases. A subset of opportunistic benthic foraminifera species, known to become more prominent in stressed environments (i.e., hypoxic), increased upcore from ~52% of the total population at core bottom to ~90% at core top. These benthic foraminifera population and diversity changes were not apparent in a "control" core outside the area of documented hypoxia. Seaward of the shelf, in the Mississippi Canyon, coincident increases in sediment accumulation rate, percentages of coarse fraction and of organic carbon at core top indicate increased offshelf transport of carbon and other components. Quartz percentages indicate that episodic down-canyon transport has been active to core bottom (prior to the mid 1800s).

Nystuen, J.A., J.R. Proni, C.A. Lauter, Jr., J.M. Bufkin, U. Rivero, M. Boland, and J.C. Wilkerson. APL disdrometer evaluation. NOAA Technical Memorandum, ERL AOML-83 (PB95-181681), 48 pp. (1994).

The Ocean Acoustics Division at the Atlantic Oceanographic and Meteorological Laboratory has evaluated a new disdrometer design developed by the Applied Physics Laboratory of John Hopkins University. Modified electronics have been added to the data processing circuitry to reduce temperature sensitivity and increase the dynamic range of the instrument. Calibration was performed using water drops from 0.6-5.5 mm diameter impacting the sensor head at terminal velocity. Field comparison to a Joss-Waldvogel disdrometer shows equal performance characteristics at low rainfall rates and slightly better performance for rainfall rates above 100 mm/hr. Engineering circuit design details and physical design of the calibration apparatus are described.

Oost, W.A., C.W. Fairall, J.B. Edson, S.D. Smith, R.J. Anderson, J.A.M. Wills, K.B. Katsaros, and J. DeCosmo. Flow distortion calculations and their application to HEXMAX. Journal of Atmospheric and Oceanic Technology, 11:357-365 (1994).

No abstract.

Ooyama, K.V. Another way of modeling the tropical cyclone. Proceedings, International Meeting on Numerical Prediction of Tropical Cyclones, Tokyo, Japan, January 17-21, 1994. Japan Meteorological Agency, Tokyo, 233-237 (1994).

No abstract.

Ooyama, K.V. Hurricane track and intensity predictions at HRD. Proceedings, International Meeting on Numerical Prediction of Tropical Cyclones, Tokyo, Japan, January 17-21, 1994. Japan Meteorological Agency, Tokyo, 85-89 (1994).

No abstract.

Palmer, D.R. Application of isoperimetric inequalities to the problem of acoustic scattering from irregularly shaped objects. Journal of the Acoustical Society of America, 95:3020-3021 (1994).

It is of general interest to determine the extent that acoustic remote sensing can estimate physical properties of particulates suspended in the ocean. One question that can be asked is how well the concentration of particulates can be determined from measurements of the backscattered acoustic intensity. When it applies, Rayleigh scattering theory provides the relationship between the concentration and the intensity. The assumption is always made in application of the theory that the individual scatterers can be regarded as spheres. While this assumption is intuitively reasonable, it is desirable to have error estimates. In this work, bounds are derived for the error that can occur in mass-concentration estimates due to the spherical-scatterer assumption. These bounds are obtained using the theory of isoperimetric inequalities and are rigourous; depending only on the validity of Rayleigh scattering theory. The formalism is applied to the problem of estimating the concentration of particulates in black smoker hydrothermal plumes.

Palmer, D.R. ATOC-FACT arrival-time differences. ATOC Occasional Notes, No. 17, 5 pp. (1994).

No abstract.

Petty, G.W., and K.B. Katsaros. The response of the SSM/I to the marine environment. Part 2: A parameterization of the effect of the sea surface slope distribution on emission and reflection. Journal of Atmospheric and Oceanic Technology, 11(3):617-628 (1994).

Based on a geometric optics model and the assumption of an isotropic Gaussian surface slope distribution, the component of ocean surface microwave emissivity variation due to large-scale surface roughness is parameterized for the frequencies and approximate viewing angle of the Special Sensor Microwave/Imager. Independent geophysical variables in the parameterization are the effective (microwave frequency dependent) slope variance and the sea surface temperature. Using the same physical model, the change in the effective zenith angle of reflected sky radiation arising from large-scale roughness is also parameterized. Independent geophysical variables in this parameterization are the effective slope variance and the atmospheric optical depth at the frequency in question. Both of the above model-based parameterizations are intended for use in conjunction with empirical parameterizations relating effective slope variance and foam coverage to near-surface wind speed. These empirical parameterizations are the subject of a separate paper.

Powell, M.D. The consensus standard for surface wind characterization: Origin and implications for hurricane research and forecasting. Minutes, 48th Interdepartmental Hurricane Conference, Miami, FL, February 15-18, 1994. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A22-A32 (1994).

No abstract.

Price, J.F., and M.O. Baringer. Overflows and deep water production by marginal seas. Progress in Oceanography 33:161-200 (1994).

Outflows of dense water from marginal seas provide a continuous renewal of the deep open ocean. Much of this water comes from one of four major outflows (Mediterranean Sea, Weddell Sea, and two from the Norwegian-Greenland Sea) that each have a characteristic property signature. Here we examine some of the processes that set these properties by reviewing historical data and by an analysis of numerical simulations. Our simulation model makes several of the streadtube approximations of Smith (1975), but goes on to include a Froude number-dependent parameterization of entrainment, a parameterization of broadening due to bottom drag, and it can accept real bottom topography and oceanic temperature and salinity profiles. This model is able to simulate some of the main features of each of the outflows, including the source to product water conversion process. The numerical simulation of the Mediterranean outflow is initialized at the west end of the Strait of Gibraltar (T=13.4°C and S=37.8 ppt) and allowed to flow freely into the Gulf of Cadiz. Within the first 50 km the outflow descends to about 600 m depth and accelerates to a maximum speed of about 1.2 m/s. This raises the Froude number above 1, and causes very strong entrainment of fresher, overlying North Atlantic Central Water. Entrainment more than doubles the volume transport and reduces the temperature and salinity to 12.4°C and 36.5 ppt, which reduces the density by about 1 kg/m³. Entrainment stops where the Coriolis force turns the outflow parallel to the local topography. The Mediterranean outflow continues on to Cape St. Vincent as a nearly geostrophic current that slowly descends the continental slope until becoming neutrally buoyant at a depth of about 1000 m, roughly consistent with the observed outflow. The other three outflows show a somewhat similar pattern in that strong entrainment generally occurs over short segments of the path where the bottom topography is relatively steep, typically just beyond the shelf-slope break. These outflows lose much less of their density anomaly (about 0.03 kg/m³ in the Weddell Sea case, about 0.1 kg/m³ in the Denmark Strait case, and about 0.2 kg/m³ in the Faeroe Bank Channel case) and continue to the bottom in their respective basins. They lose much less of their initial density primarily because there is less density contrast between these outflows and the overlying oceanic water; they reach the bottom primarily because the oceanic water column in polar and subpolar seas is very weakly stratified. This and other results indicate that the properties of the oceanic water column are of great importance in determining the product water of a marginal sea outflow.

Proni, J.R., H. Huang, and W.P. Dammann. Initial dilution of southeast Florida ocean outfalls. Journal of Hydraulic Engineering, 120:1409-1425 (1994).

Initial dilutions of four ocean outfalls (the Miami-Central, Miami-North, Hollywood, and Broward outfalls) on the east coast of south Florida were determined from dye and salinity studies. In the dye studies, continuous injections of the red dye Rhodamine-WT into effluent were conducted; dye concentrations were measured using a deck-mounted fluorometer with a ship-towed sampler and from grab water samples. In the salinity studies, temperature and conductivity were measured using a towed conductivity-temperature-depth device (CTD); salinity deficit was taken as a tracer to determine initial dilution. Results show that initial dilutions determined from both methods are consistent. Data for initial dilution and for environmental and effluent parameters are interpreted using the dimensional analysis method. A comparison is made between the present data and data from previous studies. Data for Hollywood and Broward outfalls (single-port discharges) are consistent with previous data. Data for Miami-Central and Miami-North outfalls (multiport diffuser discharges) are not consistent with data for single-port discharges. A value of C₁ = 0.15 for the asymptotic solution for the buoyancy-dominated nearfield is suggested.

Pszenny, A.A., T.P. Carsey, P.-Y. Whung, M.P. Zetwo, M.L. Farmer, and C.J. Fischer. Measurements of various chemical concentrations in the marine boundary layer during the 1992 ASTEX/MAGE experiment. EOS, Transactions, American Geophysical Union, 75:89 (1994).

No abstract.

Quilfen, Y., K.B. Katsaros, and B. Chapron. Remote sensing of extreme events with satellite microwave sensors. Proceedings, Oceans '94 Conference, Brest, France, September 13-16, 1994. Institute of Electrical and Electronics Engineers, New York, I-64-I-69 (1994).

Unprecedented views of surface wind and wave fields in tropical cyclones (TC) are now provided respectively by the C-band (5.3 GHz) scatterometer and Synthetic Aperture Radar (SAR) on the European Remote Sensing Satellite-1 (ERS-1). Indeed, their signals at C-band are able to penetrate the thick convective clouds of these storms, observing the wind fields and directional wave spectra with good accuracy. Patterns of sea-state and surface wind are described and compared with the forecasting model of the European Centre for Range Medium Weather Forecasts. It shows that this kind of strong mesoscale event is often missed by the model, mainly due to the lack of input data and because TC physics are not well understood. The use of microwave data allow greater confidence and greater temporal and spatial coverage for monitoring TCs over the open ocean. The combination of observations of different parameters by several sensors is necessary for two reasons: (1) in order to improve the understanding of feedback mechanism between the surface wind and heat fluxes that govern the development and behavior of TC's; (2) in order to know how the different parameters interact to modify the radar measurements (e.g., influence of sea-state and atmospheric water content on scatterometer wind measurements, knowledge of the wind vector to resolve ambiguities in the wave directional spectrum as measured by the SAR). Improvements of the actual scatterometer system are discussed in order to define the best system for tropical cyclone monitoring in the future.

Quilfen, Y., K.B. Katsaros, and B. Chapron. Surface wind fields structures in tropical hurricanes surveyed by ERS-1 scatterance meters and relationships with waves and atmospheric precipitations. Proceedings, New Frontiers in Oceanic Remote Sensing, Paris, France, December 17, 1993. Institut Oceanographique, Monaco, 13-22 (1994).

Signals emitted by satellite microwave radars are not affected by the various precipitations, with special consideration at the rain. This is specially true for the "Active Microwave Instrument" aboard the satellite ERS-1 that emit signals in the C band (5.3 GHz). The functions of this instrument are both as a scatterance meter of the wind and as a synthetic aperture radar. It allows wind and waves imagery in the ocean surface, even in regions where hurricanes and precipitations are very important. A Special Sensor Microwave/Imager aboard a U.S. Department of Defense satellite gives a survey of rainfall intensity, and gives also a description of convective structures that may be related to the divergence field of surface winds.

Rogers, R.F., J.M. Fritsch, and J.S. Kain. A new trigger function for mesoscale convective systems. Preprints, 10th Conference on Numerical Weather Prediction, Portland, OR, July 18-22, 1994. American Meteorological Society, Boston, 105-107 (1994).

No abstract.

Saltzman, E.S., S.A. Yvon, D.J. Cooper, T.S. Bates, and A.M. Thompson. Atmospheric dimethylsulfide cycling at a tropical South Pacific station (12°S, 135°W): A comparison of field data and model results. EOS, Transactions, American Geophysical Union, 75(16):82 (1994).

No abstract.

Schott, F., J. Reppin, E. Johns, and W.D. Wilson. Cross-equatorial warm water transfer in the western tropical Atlantic. EOS, Transactions, American Geophysical Union, 75(3):224 (1994).

No abstract.

Thacker, W.C., and R. Lewandowicz. Dynamics of information and uncertainty. Tellus, 46A:651-670 (1994).

The question of what information might be inferred from a set of data is posed in terms of the uncertainties of model variables determined by a least-squares fit. When a dynamical model is fitted to asynoptic data, the uncertainty can be characterized by a region in the model's phase space surrounding the point associated with the best fit. Changes in the shape and orientation of this region as it evolves indicate how information is redistributed dynamically among the model variables, much as kinetic and potential energy might be redistributed. These ideas are illustrated within the context of single and double oscillator systems. Information about the state of a shallow-water model is shown to depend sensitively on the sampling interval of fictitious altimetric data.

Thacker, W.C., and R. Raghunath. The rigid lid's contribution to the ill-conditioning of oceanic inverse problems. Journal of Geophysical Research, 99(C5):10,131-10,141 (1994).

Fitting oceanographic general circulation models to data is a difficult computational undertaking. This paper addresses difficulties stemming from the rigid lid approximation. Adjusting the barotropic stream function to achieve the fit, in effect, requires the solution of a hidden elliptical equation, the resolution-dependent difficulty of the elliptical problem manifest in the optimization problem. Adjusting the independent (subsurface) baroclinic velocity variables also contributes to the ill-conditioning of the least squares computation, but Lagrange multipliers can be used to adjust all baroclinic velocity variables (surface and subsurface) symmetrically. Similarly, Lagrange multipliers can be used to adjust the total velocity variables, thereby circumventing the use of barotropic stream function and baroclinic velocities; determining the multipliers at each optimization iteration requires the solution of an elliptical partial differential equation, the solution of which can be thought of as a preconditioning transformation.

Trefry, J.H., S. Metz, T.A. Nelsen, R.P. Trocine, and B.J. Eadie. Transport of particulate organic carbon by the Mississippi River and its fate in the Gulf of Mexico. Estuaries, 17(4):839-849 (1994).

This study was designed to determine the amount of particulate organic carbon (POC) introduced to the Gulf of Mexico by the Mississippi River and assess the influence of POC inputs on the development of hypoxia and burial of organic carbon on the Louisiana continental shelf. Samples of suspended sediment and supporting hydrographic data were collected from the river and >50 sites on the adjacent shelf. Suspended particles collected in the river averaged 1.8 ± 0.3% organic carbon. Because of this uniformity, POC values (in µmol l^-1) correlated well with concentrations of total suspended matter. Net transport of total organic carbon by the Mississippi-Atchafalaya River system averaged 0.48 × 10¹² moles y^-1 with 66% of the total organic carbon carried as POC. Concentrations of POC decreased from as high as 600 µmol l^-1 in the river to <0.8 µmol l^-1 in offshore waters. In contrast, the organic carbon fraction of the suspended matter increased from <2% of the total mass in the river to >35% along the shelf at >10 km from the river mouth. River flow was a dominant factor in controlling particle and POC distributions; however, time-series datashowed that tides and weather fronts can influence particle movement and POC concentrations. Values for apparent oxygen utilization (AOU) increased from -60 µmol l^-1 to >200 µmol l^-1 along the shelf on approach to the region of chronic hypoxia. Short-term increases in AOU were related to transport of more particle-rich waters. Sediments buried on the shelf contained less organic carbon than incoming river particles. Organic carbon and delta ¹³C values for shelf sediments indicated that large amounts of both terrigenous and marine organic carbon are being decomposed in shelf waters and sediments to fuel observed hypoxia.

Vaughan, S.L., and R.L. Molinari. Water mass variability in the Deep Western Boundary Current: A comparison of results based on differencing along isobars and isopycnals. EOS, Transactions, American Geophysical Union, 75(44):396 (1994).

Changes in hydrographic properties between synoptic sections separated in time can be estimated by differencing along either isobaric or isopycnal surfaces. A time series of hydrographic data is available from 10 years of repeat occupations of a section transversing the Deep Western Boundary Current (DWBC) at 26.5°N. The series illustrates the potential problems associated with using difference sections computed along isobaric surfaces to assess changes in large scale water mass characteristics. The magnitudes of differences along isobaric surfaces were considerably greater than those calculated along isopycnal surfaces between the same years. For June 1993 minus March 1987, for example, maximum potential temperature (theta) and salinity (S) differences were .25°C and .02 in the isobaric sections and .07°C and .01 in the isopycnal sections. Most of the differences in the isobaric sections were apparently due to vertical motion of the isopycnals and not to actual changes in water mass characteristics. A method developed by Bindoff and McDougall (JPO, 24, 1994) for distinguishing differences due to changes in processes at the water mass source region (warming or freshening) from vertical movement of the isopycnals ("heave") was applied to several pairs of sections from the Abaco time series. Terms representing changes in theta and S along both isobars and isopycnals were calculated for the three cores of the DWBC, as defined by freon concentrations, and plotted against one another. The high freon upper (3.2-5.0°C) and deep (1.8-2.4°C) cores consist mainly of recently ventilated high latitude water while the middle low freon core (2.4-3.2°C) consists mainly of recirculated interior Atlantic water. In the upper and middle layers, initial results were inconclusive, but in the deep layer, in several pairs of sections, the dominance of the "heave" process was evident along with some suggestion of changes in the source regions.

Wakimoto, R.M., and P.G. Black. Damage survey of Hurricane Andrew and its relationship to the eyewall. Bulletin of the American Meteorological Society, 75(2):189-200 (1994).

A damage map documenting Hurricane Andrew's destructive landfall over southern Florida is presented. Vectors that represent the direction of winds causing damage to trees and structures are shown along with an F-scale rating in order to assess the strength of the near-surface winds. It is hypothesized that increased surface roughness once the hurricane made landfall may have contributed to a surface wind enhancement resulting in the strongest winds ever estimated (F3) for a landfall hurricane. This intense damage occurred primarily during the "second" period of strong winds associated with the east side of the eyewall. For the first time, a well-defined circulation in the damage pattern by the second wind was documented. A superposition of radar data from Miami and Key West on top of the damage map provides the first detailed examination of the relationship between the eyewall and the surface flow field as estimated from the damage vectors.

Wang, C., and R.H. Weisberg. Equatorially trapped waves of a coupled ocean-atmosphere system. Journal of Physical Oceanography, 24(9):1978-1998 (1994).

Equatorially trapped waves of a simplified coupled ocean-atmosphere system are described by applying the formalism for conventional equatorially trapped waves with the assumption that the zonal wind stress and sea surface temperature perturbations are proportional. In this system, inertial-gravity and Rossby-gravity waves are unaffected by coupling whereas Rossby and Kelvin waves are affected, and in the low-frequency limit, these Rossby and Kelvin waves transform to slow westward and eastward propagating wave modes, respectively. The primary modifications by air-sea coupling are a decrease in phase speed and an increase in meridional scale. The properties of these coupled waves are useful in discussing several features, observed and modeled, relative to the evolution of the El Niño-Southern Oscillation.

Wang, C., and R.H. Weisberg. On the "slow mode" mechanism in ENSO-related coupled ocean-atmosphere models. Journal of Climate, 7(11):1657-1667 (1994).

A linear perturbation, coupled ocean-atmosphere model is revisited for further insights into El Niño-Southern Oscillation phenomenon. The model oscillates as a slow, eastward propagating mode interpreted as a divergence mode, whose energetics are controlled by the ocean. Growth requires that the work performed by the wind stress minus the work required to effect the ocean divergence exceeds the loss terms. The intrinsic scale of the atmosphere relative to the basin width is important. For sustainable oscillations, the ocean basin must be large enough so that oppositely directed divergence can develop on opposite sides of the basin. The global aspect of the atmospheric pressure field suggests that continental heating may provide either a direct source affecting adjacent oceans, or a connection between oceans. The important model parameters are the coupling and warming coefficients and the ocean Kelvin wave speed. The importance of the Kelvin wave speed derives from its specification of the background buoyancy state for the ocean. Upon further simplification, an analytical solution gives simialr parameter dependence as found numerically and shows that growth requires both large zonal wavelength and a zonal phase lag between the anomalies of wind stress and SST.

Watson, A.J., C.S. Law, K.A. Van Scoy, F.J. Millero, W. Yao, G.E. Friederich, M.I. Liddicoat, R.H. Wanninkhof, R.T. Barber, and K.H. Coale. Minimal effect of iron fertilization on sea-surface carbon dioxide concentrations. Nature, 371:143-145 (1994).

No abstract.

Williams, R.G., and J.R. Proni. Acoustic remote sensing of wastewater outflow. Seventh International Symposium on Acoustic Remote Sensing and Associated Technologies of the Atmosphere and Oceans, Boulder, CO, October 4, 1994. Boundary-Layer Meteorology, Proceedings Volume, I-43-I-49 (1994).

The Ocean Acoustics Division of NOAA's Atlantic Oceanographic and Meteorological Laboratory has been monitoring water currents in the vicinity of a Miami municipal wastewater outfall three miles offshore Virginia Key, Florida. An array of Aanderaa impeller-and-vane current meters has been used to monitor current patterns for over one year to determine pathways for the transport of the effluent plume extending outward from the diffuser. NOAA's National Ocean Service deployed a bottom-mounted 1200 kHz RD Instruments' acoustic Doppler current profiler (ADCP) adjacent to the diffuser, at 20 m depth. Mean profiles of current velocity and relative acoustic backscatter were obtained at a vertical resolution of 1 meter, using 15-minute averages of 256 individual pings. Temporal patterns of discharge were obtained from the ADCP; spatial patterns were obtained by towing a 200 kHz acoustic echo sounder over the diffuser. The correlation matrix computed from these data provides useful information for delineating the plume in time and space. Additional bottom-mounted ADCPs and acoustic tracklines would allow mapping of the plume from the diffuser site to any nearby site of concern, thereby permitting assessment of any possible environmental impact. This technology can be readily applied to other sites in the U.S. and abroad.

Willis, P.T., J. Hallett, R.A. Black, and W. Hendricks. An aircraft study of rapid precipitation development and electrification in a growing convective cloud. Atmospheric Research, 33:1-24 (1994).

The rapid initial precipitation growth and initial electrification of a convective cloud, growing as a new cell on the upshear side of a cloud system in Florida, is traced from radar data and aircraft penetrations at the -7°C to -10°C level. This study combines radar, microphysical, and electrical measurements so that an examination of the interactions between the cloud dynamics, microphysics, and electrification is possible. The first pass (-7°C) was characterized by a strong 23 m/s updraft, all liquid cloud water, no precipitation, and no significant electrification. In the 300 s between the two penetrations, precipitation developed very rapidly from <15 dBZ to >45 dBZ, and the vertical component of the electric field increased from below the measurement threshold to -25 kv/m. The second penetration, which started at -7°C and ended at -10°C, was still exclusively updraft, but with lesser peak velocities and a more complex structure; i.e., no downdraft, but with relative minima in the updraft. The microphysics of the second pass displayed a segment of exclusively cloud liquid water (no precipitation size hydrometeors), a small segment of all liquid precipitation size hydrometeors, a small region of mixed hydrometeors and an extensive region of graupel hyrdometeors, ranging in size from 100 µm to several mm. High cloud liquid water coexisted with the liquid and graupel by hydrometeors in the strong updrafts. The electrification was observed to occur exclusively in the segments of the cloud pass where graupel were observed. Within this graupel region, where the graupel often coexisted with supercooled cloud liquid water, a significant electric field occurred only at relative minima in the updraft. These relative velocity minima were also minima in the cloud liquid water content. The observed updraft velocities in these relative minima were close to balance velocities for the observed larger graupel hydrometeors. The strongest updrafts, where the formation and the riming growth of graupel was the greatest (maxima in cloud liquid water content), were not the locations of significant electrification at this flight level.

Willoughby, H.E. Nonlinear motion of a shallow water barotropic vortex. Journal of Atmospheric Science, 51(24):3722-3744 (1994).

Nonlinear motions of a shallow water barotropic vortex on a beta plane differ substantially from the analogous linear motions. The nonlinear model described here, in which wavenumber 1-3 asymmetries interact with each other and the mean vortex, predicts that an initially completely cyclonic vortex will accelerate toward the north-northwest, reaching a speed of 2.5 m s^-1 at 48 h. During the rest of the 240-h calculation, the speed varies by <0.5 m s^-1 as the direction turns from north-northwest to northwest. The vortex accelerations are in phase with temporal changes of vortex-relative angular momentum (L_R). The turning back of track coincides with a transition of the wavenumber 1 asymmetry from a single dipole to double dipole. The latter structure appears to be another orthogonal solution of the second-order radial structure equation for a neutral linear normal mode. The corresponding linear model, in which forces only wavenumber 1, shows only the single dipole structure and straight north-northwest accelerating motion that reaches a speed of 9 m s^-1 at 240 h. The slower motion in the nonlinear model stems from wave-induced changes in the axisymmetric vortex and vacillation between the orthogonal and modal structures. A nonlinear calculation with zero initial L_R on a beta plane follows a curving path dictated by a barotropically unstable linear mode for the first 144 h. Subsequently, the double dipole structure for that mode appears as the track turns toward the northwest and the speed accelerates from 1 to 2 m s^-1. A spatially uniform geostrophic environment on an f plane causes vortex motion by advection and by propagation. The potential vorticity (PV) gradient due to the current acts as much as beta does. Although the PV gradient is typically 0.1 of that due to beta, the induced propagation toward high potential vorticity is 1/2-1/4 of that on a beta plane because superposition of the vortex on a geopotential gradient amplifies the PV gradient's effect. In a quiescent environment on an f plane, initial asymmetries that project onto the normal modes induce long-lasting motion that retains about half its speed to 240 h. If the initial speed is <2 m s^-1, vacillation between orthogonal modal structures may cause dramatic turns and accelerations of the vortex track.

Willoughby, H.E. Nonlinear shallow-water vortex motion. In Research Activities in Atmospheric and Oceanic Modelling, G.J. Boer (ed.). CAS/JSC Working Group on Numerical Experimentation Report No. 19, WMO/TD-No. 592, 5.37 (1994).

No abstract.

Willoughby, H.E. The Twentieth Conference on Hurricanes and Tropical Meteorology. Bulletin of the American Meteorological Society 75(4):601-611 (1994).

No abstract.

Wilson, W.D. Deep ocean current profiling with a lowered broadband acoustic Doppler current profiler. Proceedings, Oceans '94 Conference, Brest, France, October 1994. Institute of Electrical and Electronics Engineers, New York, 660-665 (1994).

An RD Instruments 150 kHz broadband acoustic Doppler current profiler (ADCP) has been mounted on a CTD frame and used to measure current velocity shear below the instrument during casts as deep as 5500 m. By using processing techniques similar to those described by Firing and Gordon for (1) a 300 kHz narrowband ADCP and Fischer and Visbeck and (2) a 150 kHz narrowband ADCP, as well as some more recently developed algorithms, the raw profiles are merged with CTD data, corrected, edited, integrated, and averaged to produce unreferenced profiles of current velocity. Using GPS navigation data and the measured velocities, the profiles are referenced to produce absolute velocity profiles for both the upcasts and downcasts. This paper describes data collection and processing procedures, instrument settings, and modifications made to the standard self-contained instrument to accommodate an external, rechargeable battery pack. The absolute velocity profiles obtained compare favorably with simultaneous Pegasus measurements. During five such comparisons made on a cruise in the equatorial Atlantic Ocean in June 1993, depth-averaged eastward and northward velocity components agreed to an average of 0.3 cm s^-1 with an rms difference of 0.7 cm s^-1; absolute velocity comparisons between the instruments compare favorably. The lowered ADCP (LADCP) provides full water column absolute velocity profiles, coincident with CTD measurements, with the accuracy of a Pegasus profiler. It has the advantage of not requiring any extra shiptime and being independent of auxiliary bottom-mounted hardware. For use in this application, the RD Instruments high-powered 150 kHz broadband ADCP used seems to have advantages over both the 150 and 300 kHz narrowband instruments.

Wilson, W.D., E. Johns, and R.L. Molinari. Upper ocean circulation in the tropical North Atlantic Ocean in August 1989. EOS, Transactions, American Geophysical Union, 75(3):224 (1994).

No abstract.

Wilson, W.D., E. Johns, and R.L. Molinari. Upper layer circulation in the western tropical North Atlantic Ocean during August 1989. Journal of Geophysical Research, 99(C11):22,513-22,523 (1994).

Shipboard acoustic Doppler current profiler (ADCP) current velocity and CTD temperature, salinity, and dissolved oxygen measurements are used to map the flow field above the sigma_theta = 26.8 isopycnal (approximately the upper 300 m of the water column) in the North Brazil Current (NBC) retroflection region (0° to 14°N, 60° to 40°W) during August of 1989. The water column is divided into a near surface, upper thermocline layer (above sigma_theta = 24.5), and a main to sub-thermocline layer (sigma_theta = 24.5 to sigma_theta = 26.8). In the upper layer, the eastward flowing North Equatorial Countercurrent (NECC) is composed of 16 × 10⁶ m³/s of NBC transport that has retroflected from the coast between 6°N and 8°N, and 8 × 10⁶ m³/s of North Equatorial Current (NEC) transport returning eastward. An anticyclonic eddy with a 10 × 10⁶ m³/s transport lies northwest of the NBC retroflection. No throughflow is observed along the boundary, and only a small portion of the observed NEC transport (1.5 × 10⁶ m³/s) enters the Caribbean Sea. In the lower layer, the NBC transports 8 × 10⁶ m³/s into the subthermocline North Equatorial Undercurrent (NEUC). In addition, 15 × 10⁶ m³/s joins the NEUC from the north. At 44°W the subsurface core of the NEUC lies south of the near-surface core of the NECC. Nearly half of the NEUC transport is made up of a mixed water type with salinity-oxygen (S-O₂) characteristics intermediate to the characteristics of the original component transports. There is no evidence of continuous NBC flow into the Caribbean Sea in the lower level. The closed eddy to the north of the retroflection, however, contains water masses with South Atlantic S-O₂ properties.

Wilson, W.D., W.E. Johns, and M.D. Hendry. Measurements of current structure and transport in the Windward Islands Passages: 1991-1993. Proceedings, Principal Investigators Meeting, Princeton, New Jersey, May 9-11, 1994. Atlantic Climate Change Program, 168-172 (1994).

No abstract.

Wilson, W.D., W.E. Johns, M.D. Hendry, and J.A. Routt. Windward Island Passages Monitoring Program: Physical oceanographic data collected on cruise WI-91-01, HMBS Trident, 15-21 December 1991. NOAA Technical Memorandum, ERL AOML-76 (PB94-129079), 62 pp. (1994).

No abstract.

Wilson, W.D., W.E. Johns, J.A. Routt, and M.D. Hendry. Windward Island Passages Monitoring Program: Physical oceanographic data collected on cruises WI-02, HMBS Trident, 6-10 May 1992 and WI-03, HMBS Trident, 19-23 September 1992. NOAA Technical Memorandum ERL, AOML-79 (PB94-194131), 107 pp. (1994).

No abstract.

Yvon, S.A., E.S. Saltzman, and D.J. Cooper. The budget of sulfur dioxide in the tropical South Pacific marine boundary layer (12°S, 135°W). EOS, Transactions, American Geophysical Union, 75(16):82 (1994).

No abstract.

Zhang, J.-Z., and F.J. Millero. Investigation of metal sulfide complexes in seawater using cathodic stripping square wave voltammetry. Analytica Chimica Acta, 284:497-504 (1994).

Cathodic stripping square wave voltammetry has been used to detect H₂S in seawater over a wide range of concentrations (nM to mM). The addition of metal ions to the solutions was found to depress the signal. This depression was attributed to the formation of metal sulfide complexes [MHS⁺, M(HS)₂]. Stability constants for the formation of sulfide complexes with Cd²⁺, Cu²⁺, Cu⁺, Pb²⁺, Zn²⁺, Co²⁺, Fe²⁺, Mn²⁺, Ni²⁺, and Hg²⁺ have been estimated in sea water at pH 8.0 and 25°C using this method. The stability constants of cadmium sulfide complexes (log beta_CdHS = 6.3 and log beta_Cd(HS)2 = 12.7) were found to be in reasonable agreement with previous measurements. The values of log beta_CuHS = 7.0 and log beta_Cu(HS)2 = 13.0; log beta_PbHS = 7.1 and log beta_Pb(HS)2 = 13.5; log beta_ZnHS = 6.0 and log beta_Zn(HS)2 = 13.7; log beta_FeHS = log beta_Co(HS) = log beta_NiHS = 5.3 and log beta_Mn(HS) = 6.7 were also obtained. Correction for the formation of strong chloro complexes for Hg²⁺ and Cu⁺ in seawater gave measured values close to the literature values. The results have been used to determine the speciation of HS^- in surface seawater and of a number of metal ions in various anoxic basins.

Zhang, J.-Z., and F.J. Millero. Kinetics of oxidation of hydrogen sulfide in natural waters. In Environmental Geochemistry of Sulfide Oxidation, C.N. Alpers and D.W. Blowes (eds.). ACS Symposium Series 550, American Chemical Society, Washington, D.C., 393-409 (1994).

Recently we have studied the oxidation of H₂S with O₂ in natural waters as a function of pH (4 to 10), temperature (278.15 to 338.15 K), and salinity (0 to 36). The major products formed from the oxidation of H₂S were SO₃^2-, S₂O₃^2-, and SO₄^2-. A kinetic model was developed to predict the distribution of the reactants and products over a wide range of conditions. Dissolved and particulate metals have a significant effect on the rates of oxidation and the product formation. Field measurements made in the Black Sea, Framvaren Fjord, Chesapeake Bay, and Cariaco Trench are in reasonable agreement with the values predicted from laboratory studies at the same concentration of Fe²⁺. **1993**

Aberson, S.D., M. DeMaria, and R.E. Kohler. A four year (1989-1992) sample of a nested barotropic hurricane track forecast model (VICBAR). Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 292-295 (1993).

No abstract.

Bergamasco, A., P. Malanotte-Rizzoli, W.C. Thacker, and R.B. Long. The seasonal steady circulation of the eastern Mediterranean determined with the adjoint method. Deep-Sea Research, 40(6):1269-1298 (1993).

In this paper we use a rather unconventional approach to determine the steady seasonal circulation of the eastern Mediterranean. Traditional calculations rely either on prognostic models spun-up with different forcing functions or on inverse methods having rather simple dynamics. In the present applications one of the most sophisticated inverse techniques, the adjoint method of control theory, is used to find the model state that is optimally consistent with the model dynamics, with a prescribed climatology and is steady in time. The model used is the GFDL primitive equation model in its fully time-dependent non-linear version forced by seasonal wind-stress fields that are kept steady for each calculation. The prescribed climatology consists of the seasonal hydrographies of the temperature and salinity fields. Steadiness upon the seasonal time scale is required as a term in the cost function of the adjoint that penalizes the tendencies of the prognostic variables. This use of the adjoint method reconstructs the steady seasonal wind-driven circulation in an ocean with a prescribed baroclinic structure. As such, it is equivalent to a prognostic spin-up calculation with steady winds and the robust diagnostic applied, i.e., adding a term that relaxes the temperature and salinity fields to the seasonal climatologies with a time constant of three months. To assess the "success" of these calculations, the success of the inversion must be quantified. The examination of the final data misfits and steady state residuals shows that steady state has indeed been reached. The steady-state residuals are always much smaller than the data misfits and both of them are always small, well below the one standard deviation value for each field. Thus, we can assess that a meaningful solution had indeed been attained. To assess further if these solutions are reasonable, we have carried out for comparison robust diagnostic calculations with a time constant of three months. The circulations thus obtained are extremely similar to the adjoint solutions in reproducing the overall patterns as well as the individual sub-basin scale gyres and interconnecting currents and meandering jets. The circulations obtained with the two approaches are also equally strong. However, both the adjoint and the robust diagnostic results produce an overall barotropic transport that is one order of magnitude bigger than that observed. They also both show anomalously strong vortex structures in regions of sharp topographic breaks connecting the deep interior to the shelves, for which no observational evidence is available. These unrealistic features can be explained by taking into account that with the short time scale of three months used in both approaches biased solutions may be obtained. These biases are due to inconsistencies between the rough topography used and the smooth climatologies, that lead to a misrepresentation of the important JEBAR effect. This explanation is supported by a further robust diagnostic calculation in which the time constant is increased in the deep layers that gives a circulation intensity much more realistic.

Bitterman, D.S., and D.V. Hansen. Evaluation of sea surface temperature measurements from drifting buoys. Journal of Atmospheric and Oceanic Technology, 10(1):89-96 (1993).

Three drift-buoy designs have been deployed since 1988 in substantial numbers in the tropical Pacific Ocean by United States participants as part of the Tropical Ocean Global Atmosphere (TOGA) Pan Pacific Surface Current Study. These include the Low Cost Tropical Drifter designed and built at the Atlantic Oceanographic and Meteorological Laboratory, the Low Cost Drifter (LCD) designed and built by the Massachusetts Institute of Technology Draper Laboratories, and the Ministar Drifter designed and built at the Scripps Institution of Oceanography and built by Technocean Inc., San Diego, California, which has subsequently become known as the World Ocean Climate Experiment standard drifter. This report contains an evaluation of the performance of the sea surface temperature measurement system carried by these buoy designs. Based on comparisons of the monthly mean SST derived from the available XBT and CTD casts and on intercomparisons among each of the buoy types, all three designs appear to include a warm bias in the surface temperatures they report. The LCD showed a larger mean bias and diurnal variation from solar heating than the other two buoy types. This difference is probably due to the location chosen for its sensor, resulting in poor thermal contact with the surrounding water.

Black, M.L. Comparisons of tropical cyclone intensity with eyewall vertical velocities. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 520-523 (1993).

No abstract.

Black, M.L., and P.P. Dodge. Time-lapse radar images of Hurricanes Hugo (1989) and Andrew (1992). Preprints, 26th International Conference on Radar Meteorology, Norman, OK, May 24-28, 1993. American Meteorological Society, Boston, 97-99 (1993).

No abstract.

Black, P.G., and A.V. Litinetski. Mesoscale fields in Hurricane Gilbert according to data measurements by airborne meteorological laboratories. Meteorology and Hydrology (in Russian), 2:27-37 (1993).

No abstract.

Black, R.A., J. Hallett, and C.P.R. Saunders. Aircraft studies of precipitation and electrification in hurricanes. Preprints, Conference on Atmospheric Electricity, St. Louis, MO, October 4-8, 1993. American Meteorological Society, Boston, J20-J25 (1993).

No abstract.

Black, R.A., P.T. Willis, and J. Hallett. The development of ice particles and the establishment of electric fields in a maritime tropical cumulus cloud. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 81-84 (1993).

No abstract.

Bliven, L.F., J.-P. Giovanangeli, R.H. Wanninkhof, and B. Chapron. A laboratory study of friction-velocity estimates from scatterometry: Low and high regimes. International Journal of Remote Sensing, 14(9):1775-1785 (1993).

Measurements from scatterometers pointing at wind-waves in three large wave-tanks are examined to study fetch effects and the correlation with wind friction-velocity u_*. Time-series measurements were made at 13, 35, and 95 m with a Ka-band scatterometer aimed upwind at 30° incidence angle and vertical polarization. Average normalized radar cross-section sigma-o values from all fetches follow a common trend for sigma-o as a function of u_*, so the fetch dependence is negligible. An empirical power-law model yields a high correlation between sigma-o and u_*, but because systematic anomalies arise, we re-examine a turbulence approach that delineates low and high regimes with a transition at u_* of approximately 25 cm s^-1. Using this criteria, the data are well represented by a two-section power-law relationship between sigma-o and u_*.

Broecker, W.S., and T.-H. Peng. Evaluation of the ¹³C constraint on the uptake of fossil fuel CO₂ by the ocean. Global Biogeochemical Cycles, 7(3):619-626 (1993).

The proposal by Quay et al. (1992) that the time histories of ¹³C in atmospheric CO₂ and oceanic SIGMA CO₂ provide a constraint on the magnitude of uptake of fossil fuel CO₂ by the ocean is examined. Our analysis suggests that, while the potential is there, the data base is too inaccurate to permit a distinction to be made among the carbon budgets currently on the table. Examples are given to demonstrate that the twenty or so percent uncertainties in the size of the effective exchange reservoir and in the magnitudes of the temporal changes in the ¹³C/¹²C ratio in atmospheric CO₂ and ocean SIGMA CO₂ are just too large to permit a reliable estimate of oceanic uptake of fossil fuel CO₂. We conclude that tracer-verified ocean general circulation models offer much better estimates than that based on the ¹³C budget.

Broecker, W.S., and T.-H. Peng. Greenhouse Puzzles. Eldigio Press, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, 251 pp. (1993).

No abstract.

Broecker, W.S., and T.-H. Peng. Interhemispheric transport of carbon through the ocean. In The Global Carbon Cycle, M. Heimann (ed.). Springer-Verlag, Berlin, 551-570 (1993).

No abstract.

Broecker, W.S., and T.-H. Peng. What caused the glacial to interglacial CO₂ change? In The Global Carbon Cycle, M. Heimann (ed.). Springer-Verlag, Berlin, 95-115 (1993).

Scenarios put forward to explain the 80 µatm glacial to interglacial change in atmospheric CO₂ content are evaluated. The conclusion is that no single mechanism is adequate. Rather, contributions from temperature, sea ice, biological pumping, nutrient deepening, and CaCO₃ cycling must be called upon. The observation that the ¹³C/¹²C ratio for Antarctic foraminifera was 0.9 ± 1^o/_oo lower during glacial than during interglacial time constitutes a huge fly in the ointment for all scenarios proposed to date.

Broecker, W.S., Y. Lao, M. Klas, E. Clark, G. Bonani, S. Ivy, and T.-H. Peng. A search for an Early Holocene CaCO₃ preservation event. Paleoceanography, 8(3):333-339 (1993).

No abstract.

Broecker, W.S., G. Ostlund, S. Sutherland, T.-H. Peng, T. Takahashi, and W. Smethie. Radiocarbon Atlas, Volume I: Thermocline of the Atlantic Ocean. Lamont-Doherty Earth Observatory, Palisades, New York (1993).

No abstract.

Broecker, W.S., G. Ostlund, S. Sutherland, T.-H. Peng, T. Takahashi, and W. Smethie. Radiocarbon Atlas, Volume II: Thermoclines of the Pacific and Indian Oceans. Lamont-Doherty Earth Observatory, Palisades, New York (1993).

No abstract.

Brundrit, G., L. Krige, D.R. Palmer, J. Penrose, A. Forbes, and K. Metzger. Acoustic thermometry of ocean climate: Feasibility, Ascension-Cape Town. Second International Meetingon Global Acoustic Monitoring of the Ocean, Brest, France, June 20-22, 1993. Institut Francais de Recherche Pour l'Exploitation de la Mer (IFREMER), 8-10 (1993).

No abstract.

Cione, J.J., S. Raman, and L.J. Pietrafesa. The effect of Gulf Stream-induced baroclinicity on U.S. east coast winter cyclones. Monthly Weather Review, 121:421-430 (1993).

No abstract.

Claud, C., N.M. Mognard, K.B. Katsaros, A. Chedin, and N.A. Scott. Satellite observations of a polar low over the Norwegian Sea by Special Sensor Microwave Imager, Geosat, and TIROS-N Operational Vertical Sounder. Journal of Geophysical Research, 98(C8):14,487-14,501 (1993).

Many polar lows are generated at the boundary between sea ice and the ocean, in regions of large temperature gradients, where in situ observations are rare or nonexistent. Since satellite observations are frequent in high-latitude regions, they can be used to detect polar lows and track their propagation and evolution. The Special Sensor Microwave/Imager (SSM/I) providing estimates of surface wind speed, integrated cloud liquid water content, water vapor content, and precipitation size ice-scattering signal over the ocean; the Geosat radar altimeter measuring surface wind speed and significant wave height; and the TIROS-N Operational Vertical Sounder (TOVS) allowing the determination of temperature and humidity profiles in the atmosphere have been used in synergy for a specific case which occurred in the Norwegian Sea on January, 23-24 1988. All three instruments show sharp atmospheric gradients associated with the propagation of this low across the ocean, which permit the detection of the polar low at a very early stage and tracking it during its development, propagation, and decay. The wind speed gradients are measured with good qualitative agreement between the altimeter and SSM/I. TOVS retrieved fields prior to the formation of the low confirm the presence of an upper level trough, while during the mature phase baroclinicity can be observed in the 1000-500 hPa geopotential thicknesses. Comparisons between satellite-retrieved products and analyses of the operational Norwegian limited area model (150- and 50- km mesh) highlight the importance of satellites for the monitoring of such mesoscale phenomena.

Clayton, T., P. Murphy, M.F. Lamb, F.J. Millero, R.H. Byrne, R.H. Wanninkhof, and R.A. Feely. The internal consistency of CO₂ measurements in the equatorial Pacific. Marine Chemistry, 44(2-4):269-280 (1993).

During a recent NOAA JGOFS equatorial Pacific cruise, all four analytical parameters of the carbonate system were measured: pH, total alkalinity (TA), total carbon dioxide (TCO₂), and the fugacity of carbon dioxide (fCO₂). The measurements made during leg 2 on surface waters have been used to examine the internal consistency of the carbon dioxide system in these waters. The internal consistency of the measurements was examined by using various inputs of the measured parameters (pH-TA, pH-TCO₂, pH-fCO₂, fCO₂-TCO₂, and TA-TCO₂) to calculate the components of the CO₂ system. The results indicate that the measurements have an internal consistency of ±0.003-0.006 in pH, ±5-7 µmol kg^-1 in TCO₂, and ±6-9 µAtm in fCO₂ if reliable constants are used for the dissociation of carbonic acid in seawater. These results indicate that our present understanding of the thermodynamics of the carbonate system in seawater is close to the present accuracy in measuring the various parameters of the system (±0.0002 in pH, ±4 µmol kg^-1 in TA, ±2 µmol kg^-1 in TCO₂, and ±2 µAtm in fCO₂).

Commons, D.N., J.R. Proni, H. Huang, W.P. Dammann, B.M. Goldenberg, J.G. Monsoon, and R.E. Fergen. Real world toxicity testing of an open ocean discharger. Proceedings, 66th Annual Conference and Expedition, Anaheim, CA, October 3-7, 1993. Water Environment Federation, 26 pp. (1993).

A study, called the Southeast Florida Outfall Experiment II (SEFLOE II), was conducted from February 1991 through August 1992 at four open ocean outfalls. The objective of the study was to assess the effect of the Florida Current and coastal oceanographic characteristics upon the surfacing effluent plumes. During the study, the results from laboratory bioassays on plant effluent samples were compared with results from bioassays on contemporaneous ocean dispersion plume samples. Acute bioassay species used were the mysid Mysidopsis bahia and the estuarine fish Menidia beryllina. The sea urchin Arbacia punctulata and the macroalga Champia parvula were the species used in short-term chronic bioassays during the SEFLOE II study. The results of this comparison indicate a disparity between exposure times and dilutions in laboratory bioassays, and those exposure times and dilutions actually demonstrated in the receiving waters.

DeMaria, M., and R.W. Jones. Optimization of a hurricane track forecast model with the adjoint model equations. Monthly Weather Review, 121(6):1730-1745 (1993).

The method of model fitting, or "adjoint method," is tested in a barotropic hurricane track forecast model. The model vorticity field at the beginning of an assimilation period is adjusted to minimize a cost function that is defined as the squared difference between the model vorticity and the vorticity from a sequence of analyses separated by 12 h. After the cost function is minimized, the model vortex closely follows the observed storm track during the assimilation period, indicating that information about the past track of the storm is being included in the model solution. Track forecasts using the assimilation procedure are compared with control forecasts where the model is initialized with a single analysis at the end of the assimilation period. Results from a series of 18 forecasts for Hurricane Hugo (1989) show that within a 12-h assimilation period the average track forecast errors are smaller than those of the control forecasts out to about 48 h. The forecast errors using a 24-h assimilation period are larger than the errors with a 12-h assimilation period. The method described by Derber in which a forcing term that minimizes the cost function is added to the vorticity equation is applied to extend the length of the assimilation period. The forcing function has very localized extrema in the vicinity of the vortex because the scale of the vortex is comparable with the distance that the vortex moves during the assimilation period. This localized forcing interferes with the subsequent motion of the storm during the forecast period. The magnitude of the localized forcing is reduced if the vorticity at the beginning of the assimilation period is first adjusted, and then the forcing term is added to further reduce the cost function. When the combined procedure is used, the average track errors are smaller than the errors in the control simulations out to 72 h. Forecasts from four additional storms from the 1989 Atlantic hurricane season are also presented. In two of these cases, the assimilation degrades the control forecasts. The degradation appears to be related to errors in the operational estimates of the storm positions and to poor first-guess fields used in the analyses.

DeMaria, M., and J. Kaplan. Verification of a statistical hurricane intensity prediction model. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 303-304 (1993).

No abstract.

DeMaria, M., J.J. Baik, and J. Kaplan. Upper-level eddy angular momentum fluxes and tropical cyclone intensity change. Journal of the Atmospheric Sciences, 50(8):1133-1147 (1993).

The eddy flux convergence of relative angular momentum (EFC) at 200 mb was calculated for the named tropical cyclones during the 1989-1991 Atlantic hurricane seasons (371 synoptic times). A period of enhanced EFC within 1500 km of the storm center occurred about every five days due to the interaction with upper-level troughs in the midlatitude westerlies or upper-level, cold lows in low latitudes. Twenty-six of the 32 storms had at least one period of enhanced EFC. In about one-third of the cases, the storm intensified just after the period of enhanced EFC. In most of the cases in which the storm did not intensify, the vertical shear increased, the storm moved over cold water, or the storm became extratropical just after the period of enhanced EFC. A statistically-significant relationship (at the 95% level) was found between the EFC within 600 km of the storm center and the intensity change during the next 48 h. However, this relationship could only be determined using a multiple regression technique that also accounted for the effects of vertical shear and sea surface temperature variations. The EFC was also examined for the ten storms from the 1989-1991 sample that had the largest intensification rates. Six of the ten periods of rapid intensification were associated with enhanced EFC. In the remaining four cases the storms were intensifying rapidly in a low-shear environment without any obvious interaction with upper-level troughs.

Dodge, P.P., M.L. Black, P.A. Leighton, B.A. Christoe, F.D. Marks, and R.W. Burpee. Time-lapse radar images of Hurricane Andrew's landfalls. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 163-166 (1993).

No abstract.

Dodge, P.P., and R.W. Burpee. Characteristics of rainbands, radar echoes, and lightning near the North Carolina coast during GALE. Monthly Weather Review, 121(7):1936-1955 (1993).

Characteristics of mesoscale rainbands and echoes in radar reflectivity data recorded during the field phase of the Genesis of Atlantic Lows Experiment (GALE) are presented. The primary sources of data were radar microfilm and manually-digitized radar (MDR) reports from the operational National Weather Service (NWS) radars at Cape Hatteras (HAT) and Wilmington (ILM), North Carolina. The data set also included cloud-to-ground lightning flashes that were recorded by the network operated by the State University of New York at Albany. The analyses included rainbands of at least 90-km length with lifetimes of at least 2 h. Nearly all of the rainbands were within 400 km of synoptic-scale or coastal fronts. Warm-sector rainbands predominated. Rainbands were classified by the location of their initial detection relative to the land, coastal shelf, and Gulf Stream. Rainbands were initially identified more frequently over the Gulf Stream and less often over the coastal shelf than the corresponding fractional areas monitored by the radars. Statistical tests determined significant differences in the sample means of the MDR and lightning data between the Gulf Stream and land regions that were largely a consequence of many more hours with MDR and lightning over the Gulf Stream. Composites relative to the beginning and ending of the rainband cases indicated that differences between the Gulf Stream and land were small shortly after the initial detection of rainbands and large just before the detection of rainbands. The largest Gulf Stream-land disparities occurred, on the average, during low-level cold and dry advection at HAT. Trunk and Bosart reported a convective echo maximum over the Gulf Stream near HAT and discussed physical processes that can account for the convective maximum. Analysis of one idealized distribution of convection, however, supports the likely role of sampling limitations of the NWS radar network in determining the location of the convective echo maximum near HAT.

Fine, R.A., E. Johns, and R.L. Molinari. Deep Western Boundary Current structure in the region of the Blake-Bahama outer ridge. Proceedings, Principal Investigators Meeting of the Atlantic Climate Change Program, Miami, FL, March 9-11, 1992. NOAA Climate and Global Change Program, Special Report No. 7, 137-142 (1993).

No abstract.

Franklin, J.L., S.J. Lord, S.E. Feuer, and F.D. Marks. Multi-scale objective kinematic analyses and the motion of Hurricane Gloria (1985). Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 537-540 (1993).

No abstract.

Franklin, J.L., S.J. Lord, S.E. Feuer, and F.D. Marks. The kinematic structure of Hurricane Gloria (1985) determined from nested analyses of dropwindsonde and Doppler radar data. Monthly Weather Review, 121(9):2433-2451 (1993).

A set of three-dimensional, filtered, multiple-nested objective analyses has been completed for the wind field of Hurricane Gloria for 0000 UTC 25 September 1985. At this time Gloria was one of the most intense hurricanes ever observed in the Atlantic basin, with a minimum sea level pressure of 919 mb. The nested analyses, based on observations from airborne Doppler radar and Omega dropwindsondes, simultaneously describe eyewall and synoptic-scale features, and are the most comprehensive analyses of a single hurricane constructed to date. The analyses have been used to document the multiscale kinematic structure of Gloria and to investigate the relationship between the kinematic fields and the motion of the vortex. The analyses indicate that the vortex was unusually barotropic. The radius of maximum wind (RMW) was nearly vertical below 500 mb, with a slight inward slope with heights between 750 and 550 mb. The strongest azimuthal mean tangential winds were found well above the boundary layer, near 550 mb, where the RMW was smallest. We speculate that this unusual structure was associated with a concentric eye cycle. A persistent asymmetry in the distribution of eyewall convection was associated with the vertical shear of the environmental flow. The vortex moved approximately 2.5 m s^-1 faster than the deep layer mean flow averaged at 667 km radius from the center. Barotropic models have predicted a relationship between the relative motion of the vortex and the gradients of absolute vorticity in the cyclone's environment; however, the predicted relationship was not found in Gloria. The vortex also did not move with the mean flow in the immediate vicinity of the center; the motion of the hurricane was most consistent with the 300-850 mb layer mean flow well outside the eyewall, at a radius of 65 km. The analyses suggest that the environmental flow near the center had been distorted by eyewall convection, with the scale of the distortion determined by the local Rossby radius of deformation.

Friedman, H.A. 1993 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 121 pp. (1993).

No abstract.

Gamache, J.F. The angular momentum of the hurricane inner core as observed by airborne Doppler radar. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 533-536 (1993).

No abstract.

Gamache, J.F. The effect of global positioning satellites upon the accuracy of dual-aircraft Doppler observations. Preprints, 26th International Conference on Radar Meteorology, Norman, OK, May 24-28, 1993. American Meteorological Society, Boston, 402-403 (1993).

No abstract.

Gamache, J.F., R.A. Houze, Jr., and F.D. Marks. Dual-aircraft investigation of the inner core of Hurricane Norbert. Part III: Water budget. Journal of the Atmospheric Sciences, 50(19):3221-3243 (1993).

The hydrometeor water budget of Hurricane Norbert on 24 September 1984 is computed using two microphysical retrieval techniques. Three-dimensional distributions of condensation, evaporation, precipitation, and advection of cloud and precipitation are computed, and a bulk water budget is computed as the volume integral of these distributions. The role of the microphysical retrievals is to provide the three-dimensional distribution of cloud water content, since it cannot be determined with the equipment available. Both retrieval methods use the steady-state continuity equation for water. The first method determines precipitation formation mechanisms from the radar-reflectivity and Doppler wind fields. The cloud water content is determined, through microphysical modeling, to be the amount necessary to explain the rate of precipitation formation. The second method (that of Hauser et al.) solves the water continuity equations as a boundary value problem, while also employing microphysical modeling. This method is applied in three dimensions for the first time. Asymmetries in the water budget of Hurricane Norbert were important, apparently accounting for nearly half of the net condensation. The most condensation and heaviest precipitation was to the left of the storm track, while the strongest evaporation was to the rear of the storm. Many of the downdrafts were unsaturated because they were downwind of the precipitation maximum where little water was available for evaporation. Since evaporation in the downdrafts was significantly less than the condensation in their counterpart updrafts, net condensation (bulk condensation-bulk evaporation) was significantly greater than would be implied by the net upward mass flux. Much of the vapor required to account for the greater bulk condensation appears to have come from enhanced sea surface evaporation under the dry downdraft air to the right of the storm track. The net outflow of condensate from the storm inner core was quite small, although there were appreciable outward and inward horizontal fluxes at certain locations. A maximum of ice outflow to the left of the storm track in front of the storm corresponded well to the ice particle trajectories that Houze et al. suggested were feeding the stratiform precipitation found farther outward from the storm center.

Garzoli, S.L. Geostrophic velocity and transport variability in the Brazil-Malvinas Confluence. Deep-Sea Research, 40(7):1379-1403 (1993).

This paper presents the results from a study of the dynamics of the Brazil-Malvinas Confluence in the southwestern Atlantic based on data collected with an array of inverted echo sounders. Dynamic height series were obtained at 10 different sites for a period of 15 months. The data are analyzed in terms of dynamic height, geostrophic velocities, and transports. The large variability previously inferred from satellite observations is observed in the dynamic height field of the surface, relative to 100 m, and is attributed to changes in the latitude of separation, the meandering of the Confluence front towards the east, and eddy generation. The eddy circulation observed is both cyclonic and anticyclonic. These eddies are observed both between the southward edge of the Brazil Current and the northward edge of the Malvinas Current and superimposed to the main flows. The diameter of the eddies is two to three times the Rossby radius of deformation. The highest observed values of the geostrophic velocities (102 cm/s at 36.5°S and -61 to -62 cm/s at 37.6°S) are associated with the large shear in frontal situations. The northward penetration of the Malvinas Current occurs during 1988 and 1990 during the southern hemisphere winter. This is in agreement with results from a previous deployment, satellite observations, and model results. The Brazil Current transport is at 35.2°S and 36.5°S, -24 Sv towards the south and -20 Sv between 37.7°S and 38°S (reference 1000 m). The transport of the Brazil Current return at 35.2°S is of the same value as the southward flow: 24 Sv. For the Malvinas Current, the estimates indicate a northward transport of 5 Sv at 37.7°S (reference 1000 m). These values are considered as a lower limit. The array captured only about half the flow due to the location of the deployments, and only the baroclinic component. The transport should be at least doubled to compensate the value obtained for the Malvinas return flow at the same latitudes, -24 Sv.

Goldenberg, S.B., and L.J. Shapiro. Relationships between tropical climate and interannual variability of North Atlantic tropical cyclones. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 102-105 (1993).

No abstract.

Gray, W.M., and C.W. Landsea. Examples of the large modification in U.S. east coast hurricane spawned destruction by prior occurring west African rainfall conditions. ICSU/WMO International Symposium on Tropical Cyclone Disasters, October 12-16, 1992, Beijing, China. J. Lighthill, Z. Zhemin, G. Holland, and K. Emanuel (eds.), Peking University Press, 182-189 (1993).

This paper discusses the surprisingly strong prediction (by 1 August) relationship which exists between west African rainfall and U.S. hurricane spawned destruction along the U.S. east coast and peninsula Florida for the period 1950-1991. Ninety-eight percent of such damage occurs after this data. Over four-fifths of east coast hurricane-spawned damage occurs during the highest third rainfall years. The last quarter century western Sahel drought has caused a large reduction in U.S. east coast hurricane damage.

Gray, W.M., and C.W. Landsea. West African rainfall and Atlantic basin intense hurricane activity as proxy signals for Atlantic conveyor belt circulation strength. Preprints, 4th Symposium on Global Change, Anaheim, CA. American Meteorological Society, Boston (1993).

No abstract.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Predicting Atlantic basin seasonal tropical cyclone activity by 1 August. Weather and Forecasting, 8(1):73-86 (1993).

More than 90% of all seasonal Atlantic tropical cyclone activity occurs after 1 August. A strong predictive potential exists that allows seasonal forecasts of Atlantic basin tropical cyclone activity to be issued by 1 August, prior to the start of the active portion of the hurricane season. Predictors include June-July meteorological information of the stratospheric quasi-biennial oscillation (QBO), west African rainfall, the El Niño-Southern Oscillation (ENSO), as well as sea level pressure anomalies (SLPA), and the upper-tropospheric zonal-wind anomalies (ZWA) in the Caribbean basin. Use of a combination of these global and regional predictors provides a basis for making cross-validated (jackknifed) 1 August hindcasts of subsequent Atlantic seasonal tropical cyclone activity that show substantial skill over climatology. This relationship is demonstrated in 41 years of hindcasts of the 1950-1990 seasons. It is possible to independently explain more than 60% of the year-to year variability associated with intense (category 3-4-5) hurricane activity. This is significant because over 70% of all United States tropical cyclone damage comes from intense hurricanes, and over 98% of intense hurricane activity occurs after 1 August. Empirical evidence suggests that least sum of absolute deviations (LAD) regression yields substantially more improved cross-validated results than an analogous procedure based on ordinary least sum of squared deviations (OLS) regression. This improvement surprisingly occurs even with the squared Pearson product-moment correlation coefficient for which one might anticipate OLS regression to yield better cross-validated results than LAD regression.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Summary of author's seasonal Atlantic basin tropical cyclone activity predictions by 1 June and comparison with other forecast times of 1 December and 1 August. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 240-243 (1993).

No abstract.

Hallett, J., W. Hendricks, R.A. Black, C.P.R. Saunders, and I. Brooks. Aircraft observations of precipitation development and hydrometeor charge in Florida cumuli. Proceedings, Conference on Atmospheric Electricity, St. Louis, MO, October 4-8, 1993. American Meteorological Society, Boston, 785-790 (1993).

No abstract.

Houston, S.H., and M.D. Powell. Surface wind fields during Hurricane Bob's (1991) landfall in New England. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 139-142 (1993).

No abstract.

Houston, S.H., F.D. Marks, and P.G. Black. A ship passes through Hurricane Andrew's eye. Mariners Weather Log, 37(1):64-69 (1993).

No abstract.

Jensen, R.E., S.H. Houston, C.L. Vincent, and M.D. Powell. Evaluation of a third generation wave model for the U.S. Atlantic coast. Ocean Wave Measurement and Analysis, Proceedings, Second International Symposium, New Orleans, LA, July 25-28, 1993. American Society of Civil Engineers, New York, 433-447 (1993).

No abstract.

Johns, E., and A.M. Wilburn. Hydrographic observations in the western tropical and subtropical North Atlantic Ocean: Atlantic Climate Change Program (ACCP) and Western Tropical Atlantic Experiment (WESTRAX) during 1990. NOAA Data Report, ERL AOML-22 (PB93-184760), 102 pp. (1993).

No abstract.

Johns, E., and A.M. Wilburn. Hydrographic observations in the western tropical and subtropical North Atlantic Ocean: Atlantic Climate Change Program (ACCP) and Western Tropical Atlantic Experiment (WESTRAX) during 1991. NOAA Data Report, ERL AOML-23 (PB93-184778), 82 pp. (1993).

No abstract.

Jones, R.W., and M. DeMaria. Further results of variational data assimilation with a barotropic hurricane track forecast model. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 333-336 (1993).

No abstract.

Kaplan, J., and W.M. Frank. The large-scale inflow-layer structure of Hurricane Frederic (1979). Monthly Weather Review, 121(1):3-20 (1993).

Aircraft rawinsonde, satellite, ship, and buoy data collected over a 40-h period were composited to analyze the inflow-layer structure of Hurricane Frederic (1979) within a radius of 10° latitude of the storm center. To improve the quality of the composite analyses, the low-level, cloud-motion winds (CMW's) employed in this study were assigned a level of best fit (LBF). A LBF was assigned to each CMW by determining the level at which the closest agreement existed between CMW and ground-truth wind data (e.g., rawinsonde, aircraft, ship, and buoy). The CMW's were then adjusted vertically to uniform analysis levels, combined with ground-truth wind data, and objectively analyzed. These objectively analyzed wind fields were used to obtain kinematically-derived fields of vorticity, divergence, and vertical velocity. An angular-momentum budget was also computed to obtain estimates of surface drag coefficients. The low-level CMW's in this study were found to have LBF's ranging from 300 to 4000 m. It was shown that judicious use of this knowledge leads to substantial improvements in the estimates of the radial flow, but relatively insignificant improvement in the estimates of the rotational component of the wind. These results suggest that the common practice of assigning all low-level CMW's in a tropical cyclone environment to a constant level of 900-950 mb (approximately 500-1000 m) is probably appropriate for computations that depend primarily upon the rotational wind component. These findings, however, also indicate that failure to account for variations in LBF's of low-level CMW's could result in substantial errors in calculations that are sensitive to the radial wind. The kinematic analyses showed that the asymmetric wind structure observed previously in studies of Frederic's inner core extends out to at least 10° latitude radius. Frederic was characterized by strong northeast-southwest radial flow through the storm and a pronounced northwest-southeast asymmetry of the tangential wind field at each analysis level. Analysis of Frederic's surface 560 m angular-momentum budget showed that the mean value of the surface drag coefficient beyond 2° radius was approximately 1.8 × 10^-3.

Katsaros, K.B., M.A. Donelan, and W.M. Drennan. Flux measurements from a SWATH ship in SWADE. Journal of Marine Systems, 4(2-3):117-132 (1993).

The Surface Wave Dynamics Experiment (SWADE) took place east of the U.S. coast in the winter of 1990-1991. A major objective of the research program is to refine our understanding of the relationship between fluxes to the sea surface and the sea state as determined from directional wave spectra. Simultaneous measurements of turbulent fluxes of mass, momentum and energy between sea and air, with the directional wave spectra, were required to meet this objective. In this article we describe the process of obtaining turbulent flux measurements from a small water-plane-area twin hull (SWATH) ship.

Lamb, M.F., R.A. Feely, L.D. Moore, and D.K. Atwood. Total CO₂ and nitrate measurements in the southwest Pacific during austral autumn (1990). NOAA DR ERL PMEL-42 (PB93-188415), 68 pp. (1993).

During austral autumn of 1990, total CO₂ and nitrate measurements were made in the South Pacific as part of the Climate and Global Change (C&GC) program. Data were collected during two legs. Sampling for Leg 1 began along 170°W from 15°S to 60°S, then angled northwest toward New Zealand across the Western Boundary Current. Leg 2 included a reoccupation of some stations between 30°S and 15°S on 170°W, and measurements from 15°S to 5°N along 170°W. Ancillary measurements of salinity were also taken. Descriptions of sampling and methods and data summaries are given in this report.

Landsea, C.W. A climatology of intense (or major) Atlantic hurricanes. Monthly Weather Review, 121(6):1703-1713 (1993).

The variability of intense (or major) hurricanes in the Atlantic basin is investigated on both intraseasonal and interannual time scales. Differences are highlighted in characteristics between intense hurricanes and the weaker minor hurricanes and tropical storms. Intense hurricanes show a much more peaked annual cycle than do weaker tropical cyclones. Ninety-five percent of all intense hurricane activity occurrs during August to October. In addition, over 80% of all intense hurricanes originate from African easterly waves, a much higher proportion than is observed for weaker cyclones. Of all classes of Atlantic basin tropical cyclones, the intense hurricanes display the greatest year-to-year variability. The incidence of intense hurricanes also has decreased during the last two decades. A small portion of this decreased activity appears to be due to an overestimation of hurricane intensity during the period spanning the 1940s through the 1960s. After adjusting for this bias, however, a substantial downward trend in intense hurricane activity during recent years is still apparent. Given that intense hurricanes are responsible for more than 70% of all destruction caused by tropical cyclones in the United States, an understanding is needed of the physical mechanisms for these observed variations of intense hurricane activity.

Landsea, C.W., W.M. Gray, P.W. Mielke, and K.J. Berry. Forecasting seasonal Sahelian rainfall by 1 December of the previous year. Proceedings, 18th Annual Climate Diagnostics Workshop, Boulder, CO. NOAA, 394-397 (1993).

No abstract.

Landsea, C.W., W.M. Gray, P.W. Mielke, and K.J. Berry. Predictability of seasonal Sahelian rainfall by 1 December of the previous year and 1 June of the current year. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 473-476 (1993).

No abstract.

Lee, T.N., W. Johns, R. Zantopp, and E. Johns. Moored measurement of the thermohaline circulation and meridional heat flux in the western subtropical Atlantic at 26.5°N. Proceedings, Principal Investigators Meeting of the Atlantic Climate Change Program, Miami, FL, March 9-11, 1992. NOAA Climate and Global Change Program, Special Report No. 7, 143-153 (1993).

No abstract.

Marks, F.D., D. Atlas, and P.T. Willis. Probability-matched reflectivity-rainfall relations for a hurricane from aircraft observations. Applied Meteorology, 32(6):1134-1141 (1993).

The probability-matching method (PMM) was used to determine the relation between the distribution of equivalent reflectivity Z_e measured by an airborne C-band radar and that for concurrently measured rain rate R by a disdrometer on the same aircraft in the eyewall and outer bands of Hurricane Anita in 1977. When the PMM is applied to the disdrometer population of Z's and R's, one finds that the Z-R relations differ significantly from those obtained by linear regression of their logarithms. Such regression relations are deceptive. When PMM is applied to the set of Z_e's and R's, we get a family of Z_e-R relations as a function of range which differ significantly from the traditional disdrometer-based Z-R relation for hurricanes by Jorgensen and Willis (JW). These new relations are approximate power laws with slope (exponent) which decrease with increasing range. At ranges less than 35 km the reflectivity in the eyewall exceeds that in the outer bands and is consistent with the expectation from the disdrometer-based relations. At greater ranges the converse is true due to beamwidth averaging over a broader beam and different vertical profiles of reflectivity in the eyewall and outer bands. We also devise a method to obtain an "effective zero range" Z_e-R relation. This differs from the JW relation by -8.2 dBZ and reflects an error in the radar calibration. This approach is a novel way to calibrate an airborne meteorological radar. The methods may be used with any type of rainstorm and provide a means of using airborne radar and disdrometer systems for air-truthing rainfall measurements from space.

Mayer, D.A., and R.H. Weisberg. A description of COADS surface meteorological fields and the implied Sverdrup transports for the Atlantic Ocean from 30°S to 60°N. Journal of Physical Oceanography, 23:2201-2221 (1993).

Using COADS data spanning 1947-1988, we describe the regional nature of the Atlantic Ocean wind-driven circulation between 30°S-60°N, and its annual and interannual variability. The Sverdrup stream function defines the circulation gyres. Our focus is on three central gyres: the northern hemisphere anticyclonic subtropical gyre, the cyclonic tropical gyre just north of the equator, and the clockwise equatorial gyre straddling the equator. This stream function, computed with constant drag coefficient and air density, compares favorably with that from other climatologies. In the Straits of Florida, differences between the annual cycle in Sverdrup transport and observations may be due to regional winds farther north. In the tropical gyre, the Sverdrup circulation argues against a continuous western boundary current transporting water from the equatorial region into the Caribbean in boreal winter. Instead, the interior Sverdrup circulation implies a southeastward flowing boundary current, bringing to question the mechanisms for the known inter-hemisphere and inter-gyre exchanges of heat and mass. A conceptual model is proposed involving two stages. First, the western boundary current closing the clockwise equatorial gyre is instrumental in storing heat and mass between the North Equatorial Countercurrent ridge and the North Equatorial Current trough in boreal summer. Transport farther north, across the tropical gyre and into the subtropical gyre, in boreal winter is then accomplished by Ekman transport, as the seasonal change in wind stress torque deepens the thermocline, thus allowing for vortex stretching and northward Sverdrup transport over the region of warmest waters. Once in the subtropical gyre, the Ekman transport continues to be northward despite the fact that the Sverdrup transport reverses to be s outhward. Annual and interannual variability is addressed by examining the spectrum of curl and its regional distribution. Outside the tropics and the Sargasso Sea, interannual exceeds annual variability by at least a factor of 1.5. A pentadal analysis in the subtropical gyre indicates that wind stress curl was not a major factor in the density structure differences reported between 1955-1959 and 1970-1974, and, hence, these require other explanations.

McCreary, J.P., P.K. Kundu, and R.L. Molinari. A numerical investigation of dynamics, thermodynamics, and mixed-layer processes in the Indian Ocean. Progress in Oceanography, 31:181-244 (1993).

A 2½-layer thermodynamic numerical model is used to study the dynamics, thermodynamics, and mixed-layer physics of the Indian Ocean circulation. A surface mixed layer of temperature T_m is imbedded in the upper layer of the model, and entrainment and detrainment in the mixed layer are determined by wind stirring and surface cooling. There is also detrainment w_d through the base of the upper layer that models subduction. Monthly climatological data, including air temperature T_a and specific humidity q_a, are used to force the model, and model sea surface temperature (SST), T_m, is used to determine the sensible and latent heat fluxes. With a few notable exceptions, our main run solution compares well with observed current and SST data; this is particularly true for T_m, which typically differs from observed SST by less than 0.5-1.0°C. Our analyses focus on three topics: the relative importance of remote versus local forcing, the thermodynamic processes that determine the model SST field, and the development of meridional circulation cells. There are a number of examples of remotely forced circulations in our main run. During the spring a northeastward countercurrent flows against the prevailing winds along the Somali coast north of 4°N, and from October through February a southwestward Somali Undercurrent is present from the tip of Somalia to 3°N; both of these flows result in part from forcing during the previous Southwest Monsoon. From March through May there is another southwestward Somali Undercurrent south of 7°N, generated primarily by the propagation of a Rossby wave from the west coast of India. The currents along the west coast of India are either strongly influenced or dominated by remote forcing from the Bay of Bengal throughout the year. A northeastward flow is well established along the east coast of India in March, long before the onset of the Southwest Monsoon; it is remotely forced either by upwelling favorable, alongshore winds elsewhere within the Bay of Bengal or by negative wind curl in the western Bay. Finally, the Agulhas Current is strengthened considerably in a solution that includes throughflow from the Pacific Ocean. To investigate the relative importance of thermodynamic processes, we carried out a series of test calculations with various terms dropped from the T_m equation. There is little effect of T_m when the sensible heat flux is set to zero, or when the solar radiation field is replaced by a spatially smoothed version. When temperature advection is deleted, T_m is most strongly affected near western boundaries since isotherms are no longer shifted there by the swift currents; the annual-mean, surface-heat-flux field Q is also changed, with Q becoming more positive (negative) to compensate for the absence of warm (cold) currents. Without entrainment cooling, T_m never cools during the summer in the intense upwelling regions in the northern ocean, and the annual-mean heat gain through the ocean surface (the area integral of Q over the basin) reverses to become a net heat loss. In individual tests without entrainment cooling, with T_a=T_m, and with q_a set to 80% of its saturated value q_s, model SST warms near the northern and southern boundaries during their respective winters by about 1°C, indicating that several processes contribute to wintertime cooling. The T_m field degrades considerably in a single test run with both T_a=T_m and q_a=0.8 q_s, so that one or the other of these external forcing fields is required to be able to simulate SST accurately. The annual-mean circulation has two meridional circulation cells. In the Tropical Cell, water subducts in the southern ocean, flows equatorward in the lower layer of the western-boundary current, and is entrained back into the upper layer in the open-ocean upwelling regions in the southern ocean. In the Cross-Equatorial Cell, the subducted water crosses the equator near the western boundary, where it is entrained in the regions of intense coastal upwelling in the northern ocean. The strength of the cells is directly related to the assumed magnitude of the subduction rate w_d, but their structure is not sensitive to the particular parameterization of w_d used.

McLeish, W.L., J.R. Proni, S.J. Stamates, W.P. Dammann, and J.F. Craynock. Nearshore current measurements for the SEFLOE II project, 1991-1992. NOAA Technical Memorandum, ERL AOML-75 (PB93-227676), 106 pp. (1993).

A compilation of current measurements in 25-m water depth off southeast Florida is presented.

Millero, F.J., J.-Z. Zhang, K. Lee, and D.M. Campbell. Titration alkalinity of seawater. Marine Chemistry, 44:153-165 (1993).

The titration system is described that was used to measure the total alkalinity of seawater (TA) during the Joint Global Ocean Flux Study (JGOFS) sponsored by the National Oceanic and Atmospheric Administration (NOAA) in the equatorial Pacific. It consists of a piston titrator, a pH meter, and a glass thermostated cell. Since the new pH meters and titrators have RS232 interfaces, the system can be easily connected to a personal computer. The computer programs used to carry out the titration and to determine TA, pH_sw (pH on the seawater scale), and TCO₂ from the full titration curve are described. A typical titration takes 20 min and consists of 25 points. Six separate titration cells were calibrated to be used on three systems at sea. The reliability of the electrodes was examined by titrations of 0.7 m NaCl with HCl at a pH near 3 and using seawater buffers at a pH near 8. Although most electrodes did not have Nernstian behavior over the entire pH range, all gave precise values of TA for a given solution. The individual cells were calibrated using standard Na₂CO₃ and seawater standards prepared in our laboratory and Certified Reference Material (CRM) provided by Dickson. The cells gave reliable values of TA, but the values of pH_sw were low (0.02) and values of TCO₂ were high (20 µmol kg^-1) due to the non-Nernstian behavior of the electrodes at a pH near 8.0. If the slope determined from the buffers is used, the titrations yield reliable values of TA, TCO₂, and pH_sw. Measurements on Dickson standards with the three cells at sea indicate that the systems have a reproducibility of ± 2-4 µmol kg^-1 (fall) and 20 ± 6 µmol kg^-1 (spring) too high. This offset in TCO₂ is independent of depth and is due to the non-Nernstian behavior of the electrodes. The offset is not due to unknown protolytes.

Millero, F.J., J.-Z. Zhang, S. Fiol, S. Sotolongo, R.N. Roy, K. Lee, and S. Mane. The use of buffers to measure the pH of seawater. Marine Chemistry, 44:143-152 (1993).

The pH of seawater can be measured in the field using potentiometric and spectrophotometric methods. The use of pH standards or buffers is an important aspect of the calibration of both methods in a laboratory on a common concentration scale. The buffers can also be used to monitor the performance of pH meter and spectrophotometer during a cruise. A procedure is described for the determination of the pH of seawater, where the proton concentration is expressed as moles kg-H₂O^-1 using seawater buffers. The buffers are prepared in synthetic seawater in the laboratory by the methods outlined by Bates and coworkers. We have prepared four buffers (Bis, Tris, Morpholine, and 2-Amino-pyridine) that cover a pH range from 6.8 to 8.8. The EMF values of the buffers were measured with a H₂, Pt/AgCl, Ag electrode system after their preparation and bottling for use at sea. The measured EMF values were found to be in good agreement (± 0.05 mV) with the original measurements of Bates and coworkers from 0 to 45°C. The measured pH of these buffers are in good agreement (± 0.001 pH units) with the values calculated from the equations of Dickson on the total pH scale based on Bates et al. Studies are underway to access the long-term stability of these buffers. We have also used these buffers to calibrate systems used to make potentiometric and spectrophotometric measurements of pH on seawater relative to the H₂, Pt/Ag, AgCl electrode from 5 to 45°C.

Molinari, R.L., E. Johns, R. Raghunath, W.E. Johns, and R.J. Zantopp. The Deep Western Boundary Current from 29°N to the equator. Proceedings, Principal Investigators Meeting of the Atlantic Climate Change Program, Miami, FL, March 9-11, 1992. NOAA Climate and Global Change Program, Special Report No. 7, 155-156 (1993).

No abstract.

Murray, J.W., M.W. Leinen, R.A. Feely, J.R. Toggweiler, and R.H. Wanninkhof. Equatorial Pacific: A process study in the central equatorial Pacific. Oceanography, 5(3):134-143 (1993).

No abstract.

Napp, J.M., P.B. Ortner, D.V. Holliday, and R.E. Pieper. Biomass spectra Gulf Stream epizooplankton communities. Deep-Sea Research, 40(3):445-459 (1993).

Zooplankton biovolume data from a multi-frequency acoustic profiling system were used to construct biovolume-size spectra for the Gulf Stream and the southern California Bight. These spectra were linear through most, but not all, of the size range sampled (0.025-4.00 mm, ESR). Analysis of covariance was sometimes a useful tool to distinguish among spectra taken at different times and places. Difference spectra offered an alternative method of visualizing disparities between spectra. We compared our acoustically-derived spectra from the Gulf Stream with those obtained from other oceans with different samplers and those obtained in the same waters with a different sampler. The results indicate that differences attributable to sampler bias within the same system presently make it difficult, if not impossible, to interpret comparison from different samplers in different ecosystems.

Palmer, D.R. Tropical Atlantic network design considerations. Proceedings, Second International Meeting on Global Acoustic Monitoring of the Ocean, Brest, France, June 20-22, 1993. Institut Francais de Recherche Pour l'Exploitation de la Mer (IFREMER), 32-34 (1993).

No abstract.

Palmer, D.R., T.M. George, J.J. Wilson, L.D. Weiner, J.A. Paisley, R. Mathiesen, R.R. Pleshek, and R.R. Mabe. Reception at Ascension Island, South Atlantic, of the transmissions from the Heard Island Feasibility Test. NOAA Technical Memorandum, ERL AOML-73 (PB93-176261), 29 pp. (1993).

The objective of the Heard Island Feasibility Test was to ensonify the global ocean with a single source to determine the feasibility of acoustically measuring the extent of ocean warming. Underwater acoustic signals were transmitted from a ship in the southern Indian Ocean and monitored at listening stations throughout the world. At Ascension Island, about 9,200 km from the source ship, all transmissions from the Heard Island Feasibility Test were recorded on at least eight hydrophones and, for many transmissions, on 11 hydrophones. The depths of most of these hydrophones are near the depth of the sound channel axis but some are considerably deeper. All are bottom mounted. Signal-to-noise ratios were found to be surprisingly high. Averaged over the CW transmissions and in a 1 Hz band, signal-to-noise ratios for the axial hydrophones south of the island range from about 19 to 30 db, adjusted to a source level of 220 db (referenced to 1 µPa at 1 m). The average signal-to-noise ratio for a hydrophone at a depth approximately 0.8 km below the axis is about 16 db, suggesting acoustic energy was not restricted to a narrow interval in depth centered about the sound channel axis. The travel time of the earliest arrival was found to be about 1 h, 44 min, 17 s. A late, reverberative signal was observed for at least 22 min after termination of the direct signal. An unexpected combination of phase stability and amplitude variability was observed in the received signals. Continuing analysis of the Ascension data set is likely to provide considerable information about the characteristics of acoustic signals that have propagated global distances.

Peng, T.-H. Possible reduction of atmospheric CO₂ by iron fertilization in the Antaractic Ocean. In A Global Warming Forum: Scientific, Economic, and Legal Overview, R.A. Geyer (ed.). CRC Press, Boca Raton, 263-285 (1993).

No abstract.

Peng, T.-H., and T. Takahashi. Ocean uptake of carbon dioxide. In Heat Transfer in Turbulent Flows, R.A. Amano, R.H. Pletcher, S.A. Sherif, R.G. Watts, and A.N. Anand (eds.). American Society of Mechanical Engineers, 117-134 (1993).

Factors controlling the capacity of the ocean for taking up anthropogenic CO₂ include carbon chemistry, distribution of alkalinity, pCO₂ and total concentration of dissolved CO₂, sea-air pCO₂ difference, gas exchange rate across the sea-air interface, biological carbon pump, ocean water circulation and mixing, and dissolution of carbonate in deep sea sediments. A general review of these processes is given and models of ocean-atmosphere system based on our understanding of these regulating processes are used to estimate the magnitude of CO₂ uptake by the ocean. We conclude that the ocean can absorb up to 35% of the fossil fuel emission. Direct measurements show that 55% of CO₂ from fossil fuel burning remains in the atmosphere. The remaining 10% is not accounted for by atmospheric increases and ocean uptake. In addition, it is estimated that an amount equivalent to 30% of recent annual fossil fuel emissions is released into the atmosphere as a result of deforestation and farming. To balance global carbon budget, a sizable carbon sink besides the ocean is needed. Storage of carbon in terrestrial biosphere as a result of CO₂ fertilization is a potential candidate for such missing carbon sinks.

Peng, T.-H., E. Maier-Reimer, and W.S. Broecker. Distribution of ³²Si in the world ocean: Model compared to observation. Global Biogeochemical Cycles, 7(2):463-474 (1993).

Calculations of the ³²Si/SiO₂ ratio obtained in ocean models are compared with measurements of this ratio made as part of the GEOSECS program (Somayajulu et al., 1987, 1991). A major difference is found; while the models predict threefold to fivefold higher ratios in the deep Atlantic Ocean than in the deep Pacific and Indian Oceans, no such difference is seen in the measurements. This points to a flaw in the measurements. Our modeling results suggest that the most interesting application for this 120-year half-life cosmogenic isotope is as a monitor of upwelling. However, considering the expense and difficulty associated with ³²Si measurements, such studies may prove impractical.

Powell, M.D. Wind forecasting for yacht racing at the 1991 Pan American Games. Bulletin of the American Meteorological Society, 74(1):5-16 (1993).

The U.S. Sailing Team competed successfully at the 1991 Pan American Games despite having no previous experience with the sailing conditions off Havana, Cuba. One of the key factors in the team's success was meteorological support in the form of wind climate analysis; application of sea breeze forecasting typical of the south Florida area, modified by tropical weather systems; and effective preregatta briefing.

Powell, M.D. Wind measurement and archival under the automated surface observing system (ASOS): User concerns and opportunity for improvement. Bulletin of the American Meteorological Society, 74(4):615-623 (1993).

The National Weather Service, as a part of its modernization effort, is implementing the Automated Surface Observing System (ASOS). Much discussion has occurred about various aspects of ASOS versus the current system of manual and automated observations. Based upon a study of the ASOS specifications and an informal survey of potential ASOS wind data users, defects of the wind sampling and archival strategy chosen for ASOS are discussed in terms of their impact on various user groups. Limitations include: (1) hourly observation average periods that do not conform to international recommendations for wind reporting made by the World Meteorological Organization; (2) no regular archival of high-resolution data--potentially valuable research data are destroyed if not identified within a 12-h period; and (3) no emergency power for operation in severe weather conditions. An alternative sampling and archiving strategy is recommended that benefits a wider cross section of users, without detracting from aviation and forecast service requirements, at a cost of less than 1% of the original ASOS portion of the National Weather Service's modernization budget.

Powell, M.D., and S.H. Houston. Analysis of surface wind fields in Hurricane Andrew. Preprints, 7th National Conference on Wind Engineering, UCLA, CA, June 27-30, 1993. Wind Engineering Research Council, College Station, 523-532 (1993).

No abstract.

Powell, M.D., and S.H. Houston. Surface wind field analyses in Hurricane Andrew. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 58-61 (1993).

No abstract.

Powell, M.D., S.H. Houston, and T.A. Reinhold. Standardizing wind measurements for documentation of surface wind fields in Hurricane Andrew. Proceedings, Conference on Hurricanes of 1992, Miami, FL, December 1-3, 1993. American Society of Civil Engineers, New York, Volume VI, 1-13 (1993).

No abstract.

Price, J.F., M.O. Baringer, R.G. Lueck, G.C. Johnson, I. Ambar, G. Parilla, A. Cantos, M.A. Kennelly, and T.B. Sanford. The Mediterranean Outflow. Science, 259:1277-1282 (1993).

No abstract.

Proni, J.R., J.F. Craynock, and J.J. Tsai. Miami Harbor Dredge Material Disposal Project: Total suspended solids measurements. Contract Report W81EWF-2-C228, U.S. Army Corps of Engineers, Jacksonville, FL, 72 pp. (1993).

No abstract.

Pszenny, A.A.P., C.J. Fischer, A. Mendez, and M.P. Zetwo. Direct comparison of cellulose and quartz fiber filters for sampling submicrometer aerosols in the marine boundary layer. Atmospheric Environment, 27A:281-284 (1993).

Lodge (1986) and Harrison et al. (1987) called attention to the possibility that Whatman 41 filter material (hereafter W41) may not retain particles with 100% efficiency under all conditions. Subsequently, several groups have presented evidence confirming that W41 has imperfect collection efficiency but that for most applications the losses are tolerably small (Harrison, 1987; Lowenthal and Rahn, 1987; Watts et al., 1987). This is not always the case, however (Kitto and Anderson, 1988). W41 has been used often for "final" filters in cascade impactors when mass-size distributions of inorganic species in marine boundary layer (MBL) aerosols are to be determined (e.g., McDonald et al., 1982; Savoie and Prospero, 1982; Duce et al., 1983; Keene et al., 1990; Pszenny, 1992). Because the upstream impaction stages remove virtually all aerosols larger than about 0.5 µm diameter and, therefore, the majority of total MBL aerosol mass, and because MBL fine-particle mass concentrations are usually relatively low, it bears checking whether collection inefficiency artifacts may be important under these conditions. To our knowledge such a check has not been reported previously. In this short contribution we report the results of a direct comparison of W41 with Pallflex Tissuquartz 2500 QAT-UP quartz fiber (hereafter QTZ) used as final filters in high-volume cascade impactors sampling open-ocean surface air.

Rogers, R.F., and R.E. Davis. The effect of coastline curvature on the weakening of Atlantic tropical cylcones. International Journal of Climatology, 13, 287-299 (1993).

This study attempts to determine the relationship between the curvature of the coastline and the filling (increase in central pressure) of hurricanes and tropical storms by comparing both the rate of filling and the total filling for storms striking convex, concave, and linear coastlines. The USA and Mexican coastline was approximated by a subjective smoothing procedure, and the coastal curvature corresponding to each landfalling Atlantic tropical cyclone from 1900 to 1979 was measured and grouped into one of the three curvature categories. Storm-filling rates and total amounts of filling were determined before and after landfall by computing the change in wind speed for various Saffir-Simpson hurricane intensity categories. The averages of these variables within each strength and curvature grouping were compared in order to determine if they were statistically different. Storms were also compared in order to determine if stronger storms fill a greater total amount than weaker storms, regardless of the coastline's curvature. Concave coasts were found to be associated with storms filling both more rapidly and by a greater amount than convex coasts for weak hurricanes and strong tropical storms, and they were associated with storms that filled by a greater amount for hurricanes of moderate strength. This most likely results from the lower water-to-land ratios associated with storms striking concave coasts and the reduction in latent and sensible heat fluxes from the surface. Also, stronger storms were found to fill more rapidly and by a greater total amount than weaker storms, and storms striking the East Coast generally filled more rapidly and by a greater total amount than storms striking the Gulf Coast or Florida.

Rona, P.A., and D.R. Palmer. Acoustic imaging beneath the sea. In Physics News in 1992, P.F. Schewe and B.P. Stein (eds.). American Institute of Physics, New York, 1-2 (1993).

No abstract.

Rona, P.A., and D.R. Palmer. Imaging plumes beneath the sea. Journal of the Acoustical Society of America, 93(1):569-570 (1993).

No abstract.

Saltzman, E.S., S.A. Yvon, and P.A. Matrai. Low level atmospheric sulfur dioxide measurements using HPLC/fluorescence. Journal of Atmospheric Chemistry, 17:73-90 (1993).

An automated technique for measuring SO₂ in ambient air has been developed. Air is passed through a gas/liquid exchange coil with an aqueous absorber solution containing 10 µM formaldehyde and 0.84 mM Na₂EDTA. The SO₂ rapidly equilibrates with bisulfite (HSO₃^-) and sulfite (SO₃^-2) in the aqueous solution. The aqueous S(IV) is subsequently reacted with o-phthaldehyde in the presence of excess ethanolamine to form a fluorescent isoindole in a continuous flow stream. This derivative is then separated using reversed phase HPLC and detected via fluorescence with excitation and emission wavelengths at 330 and 380 nm, respectively. The lower limit of detection is 7 pptv (S/N=3), with a measurement period of eight minutes per sample. The instrument response is linear over several orders of magnitude.

Shapiro, L.J., and S.B. Goldenberg. Intraseasonal oscillations over the Atlantic. Journal of Climate, 6(4):677-699 (1993).

Winds at low (near-surface) and 200-mb levels from National Hurricane Center objective analyses are used to elucidate the dynamics of the tropical and subtropical intraseasonal oscillations for the North Atlantic/northeast Pacific regions, including over the continents, for the years 1980-1989. The intraseasonal oscillations are broken into three bands, with long (50-85 day), intermediate (30-55 day), and short (13-29 day) periods. Winter and summer seasons are analyzed separately. A complex empirical orthogonal function technique is used to derive the dominant modes of intraseasonal variability over the region, including their propagation characteristics. Statistically-distinct modes of variability are found only during the winter and only for the long-period and short-period bands. The dominant mode of coupled 200-mb, low-level, long-period variability during winter has a dipole structure. It has a substantial equivalent barotropic component in the subtropics, as well as a baroclinic structure consistent with quasigeostrophic midlatitude systems. Negative outgoing longwave radiation anomalies tend to be in phase with a low-level convergence/upper-level divergence couplet, which lies approximately one-quarter wavelength to the east of the cyclonic vorticity centers. The long-period oscillations during 1981-1988 are dominated by three events, with periods between about 60 and 70 days. There is a negative correlation, explaining about 50% of the variance, between the magnitude of the mode and an index of El Niño based on sea surface temperatures in the eastern equatorial Pacific. The dominant modes of short-period variability during winter appear as zonally-oriented wave trains similar to those found by previous investigators of global-scale fluctuations. Rotation of the modes of 200-mb variability effectively separates them into their propagating and standing components. Approximately one-half of the variance in the meridional wind near teleconnection centers of action is found in the eastward propagating component. The dominant mode of coupled 200-mb/low-level variability propagates to the east, and has a vertical structure similar to that in the long-period band. It has a predominant period near 18 days.

Siegenthaler, U., and T.-H. Peng. Summary of workshop on radiocarbon distributions as a constraint for global carbon cycle modeling. In The Global Carbon Cycle, M. Heimann (ed.). Springer-Verlag, Berlin, 570-574 (1993).

No abstract.

Snyder, R.L., W.C. Thacker, K. Hasselmann, S. Hasselmann, and G. Barzel. Implementation of an efficient scheme for calculating nonlinear transfer from wave-wave interactions. Journal of Geophysical Research, 98(C8):14,507-14,525 (1993).

Nonlinear transfer from wave-wave interactions is an important term in the action-balance equation governing the evolution of the surface-gravity-wave field. Computation of this term, however, has hitherto been so consuming of computer resources that its full representation has not been feasible in nonparametric two-dimensional computer models of this equation. This paper describes the implementation of a hybrid computational scheme, incorporating a simplification first proposed by Thacker into the EXACT-NL Boltzmann integration scheme of Hasselmann and Hasselmann. This hybrid scheme retains EXACT-NL's symmetry, precision, and two-stage structure, but, by transferring a spectrum-independent preintegration from the second stage to the first, dramatically accelerates the resulting second-stage computation, enabling a relatively efficient and precise determination of nonlinear transfer in two-dimensional wave models. Physically, this preintegration collects together in single hybrid interactions, multiple interactions belonging to identical spectral-band quadruplets. Thus, all possible interactions are represented, and these interactions are represented in a uniquely efficient manner consistent with the spectral representation. We compute the coefficients in the resulting second-stage hybrid sum by essentially sorting and pre-summing the coefficients generated by a piecewise-constant first-stage EXACT-NL computation, using a variant of EXACT-NL that replaces the gather-scatter operations with a simpler bin-assignment procedure and employs a somewhat simpler set of integration variables. By exploiting the natural scaling of the integrand and partially pre-summing prior to sorting, we are able to further improve the efficiency of this computation for the deep-water case and to refine its integration-grid resolution almost to convergence. In wave-model computations of nonlinear transfer, vectorization on the spatial grid points of the model and selective truncation of the hybrid sum potentially reduce the working computation time for a single model time step to well under one Cray Y-MP single-processor CPU second per hundred grid points, while preserving a remarkably faithful representation of the full transfer.

Thompson, A.M., J.E. Johnson, A.L. Torres, A.C. Kelly, E. Atlas, J. Greenberg, N.M. Donahue, S.A. Yvon, E.S. Saltzman, B.G. Heikes, B.W. Mosher, A.A. Shashkov, and V.I. Yegorov. Ozone observations and a model of marine boundary layer photochemistry during SAGA-3. Journal of Geophysical Research, 98:16,955-16,968 (1993).

A major purpose of the third joint Soviet-American Gases abd Aerosols (SAGA 3) oceanographic cruise was to examine remote tropical marine O₃ and photochemical cycles in detail. On leg 1, which took place between Hilo, Hawaii, and Pago-Pago, American Samoa, in February and March 1990, shipboard measurements were made
of O₃, CO, CH₄, nonmethane hydrocarbons (NMHC), NO, dimethyl sulfide (DMS), H₂S, H₂O₂, organic peroxides, and total column O₃. Postcruise analysis was performed for alkyl nitrates and a second set of nonmethane hydrocarbons. A latitudinal gradient in O₃ was observed on SAGA 3, with O₃ north of the intertropical convergence zone (ITCZ) at 15-20 parts per billion by volume (ppbv) and less than 12 ppbv south of the ITCZ but never =3 ppbv as observed on some previous equatorial Pacific cruises (Piotrowicz et al., 1986; Johnson et al., 1990). Total column O₃ (230-250 Dobson units (DU)) measured from the Akademik Korolev was within 8% of the corresponding total ozone mapping spectrometer (TOMS) satellite observations and confirmed the equatorial Pacific as a low O₃ region. In terms of number and constituents measured, SAGA 3 may be the most photochemically complete at-sea experiment to date. A one-dimensional photochemical model gives a self-consistent picture of O₃-NO-CO-hydrocarbon interactions taking place during SAGA 3. At typical equatorial conditions, mean O₃ is 10 ppbv with a 10-15% diurnal variation and maximum near sunrise. Measurements of O₃, CO, CH, NMHC,
and H₂O constrain model calculated OH to 9 × 10⁵ cm^-3 for 10 ppbv O₃ at the equator. For DMS (300-400 parts per trillion by volume (pptv)) this OH abundance requires a sea-to-air flux of 6-8 × 10⁹ cm^-2 s^-1, which is within the uncertainty range of the flux deduced from SAGA 3 measurements of DMS in seawater (Bates et al., this issue). The concentrations of alkyl nitrates on SAGA 3 (5-15 pptv total alkyl nitrates) were up to 6 times higher than expected from currently accepted kinetics, suggesting a largely continental source for these species. However, maxima in isopropyl nitrate and bromoform near the equator (Atlat et al., this issue) as well as for nitric oxide (Torres and Thompson, this issue) may signify photochemical and biological sources of these species.

Tsai, J.J., J.R. Proni, W.P. Dammann, and J.R. Craynock. Acoustic detection of particulates from dredged material discharges in the oceanic dredged material disposal site for the Calcasieu Bar Channel, Gulf of Mexico, August 19-29, 1991. Contract Report DWI-35-54001, U.S. Environmental Protection Agency, Narragansett, RI, 32 pp. (1993).

A study of the behavior of dredged material discharged in the Calcasieu Ocean Dredged Material Disposal Site using acoustical remote sensing techniques in combination with other measurement systems has provided substantial information on the dispersion and general behavior of such discharges. Information was obtained on discharged material plume structure, particulate transport, and water column residual. Features observed during the study include increasing plume width during the convective descent, possible bottom surges, and persistent near-bottom nepheloid layers. Residual water column dredged material concentrations were observed for times in excess of one hour and twenty minutes after discharge. Residual water column concentrations appear to diminish slowly and may persist for long periods of time. Determination of the general movement of water column residual material is made possible through use of the acoustic technique.

Velden, C., S. Nieman, S.D. Aberson, and J.L. Franklin. Tracking motions from satellite water vapor imagery: Quantitative applications to hurricane track forecasting. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 193-196 (1993).

No abstract.

Wakimoto, R.M., and P.G. Black. Damage survey of Hurricane Andrew and its relationship to the radar-detected eyewall. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 54-57 (1993).

No abstract.

Wanninkhof, R.H., and K. Thoning. Measurement of fugacity of CO₂ in surface water using continuous and discrete sampling methods. Marine Chemistry, 44(2-4):189-204 (1993).

Instrumentation and methodology is described which is used for measurement of the fugacity (or partial pressure) of carbon dioxide (fCO₂ or pCO₂) in surface seawater. Two separate instruments were developed for the measurements. One is an underway system which measures the mixing ratio of CO₂, XCO₂, in a headspace in equilibrium with surface seawater continuously pumped into a 24 l-equilibrium chamber. The other is a discrete system in which 460 ml aliquots of water are equilibrated with a 120 ml headspace. Both systems use a non-dispersive infrared analyzer as detector. In the underway instrument the average XCO₂ in the headspace of an equilibration chamber is measured at near in-situ temperature over 20 min each hour. At a cruising speed of 13 knots this translates into a space averaged fCO₂ value over 8 km. The underway system is ideally suited for mapping of the surface water fugacity over large geographic regions. Samples from the discrete instrument are analyzed at 20°C. The primary function of the system is for measurement of CO₂ and other (carbon) parameters sub-sampled from the same aliquot. To calculate the fCO₂ in water for in-situ conditions from the mixing ratio in the headspace of the flask of the discrete system, small carbon mass balance and, sometimes significant, temperature corrections have to be applied. Comparison of 100 surface values obtained in the South Atlantic using the underway and discrete systems shows that the average difference of pCO₂ values for the two systems ranges from -4.3 µatm to -8.6 µatm, depending on the temperature correction, with a standard deviation of 4 µatm. The differences show scatter of up the 15 µatm which we attribute to a mismatch between the point samples for the discrete system and the integrated samples for the underway system.

Wanninkhof, R.H., W.E. Asher, R. Weppernig, H. Chen, P. Schlosser, C. Langdon, and R. Sambrotto. Gas transfer experiment on Georges Bank using two volatile deliberate tracers. Journal of Geophysical Research, 98(C11):20,237-20,248 (1993).

A gas exchange experiment was performed on Georges Bank using the deliberate tracers sulfur hexafluoride (SF₆) and helium 3 (³He). The concentrations of the tracers were measured in the water column over a period of 10 days. During this time the patch grew from an 8-km-long injection streak to an area of about 500 km². The gas transfer velocity was determined from the change in the ratio of the tracers over time scaled to the ratio of their Schmidt numbers. A near-linear relationship between gas exchange and wind speed was observed based on four experimental points covering a wind speed range from 3 to 11 m/s. The results fall in the upper part of the range of gas transfer-wind speed relationships developed to date. Wind speeds during the experiment obtained from anemometers on the ship, on a free floating drifter, and on a fixed mooring showed significant differences. With the ability to measure gas transfer velocities over the ocean on time scales of several days, accurate wind speed/stress measurements are imperative to obtain a robust relationship between gas transfer and wind speed.

Willis, P.T., J. Hallett, W. Hendricks, and R.A. Black. Hydrometeor development and structure of a convective cell. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, 74-77 (1993).

No abstract.

Willoughby, H.E. Mature structure and evolution. In Global Perspectives on Tropical Cyclones (chapter 2 in preliminary edition), E.L. Elsberry (ed.). World Meteorological Organization, Geneva, 62 pp. (1993).

No abstract.

Willoughby, H.E. Nonlinear shallow-water vortex motion. Preprints, 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, TX, May 10-14, 1993. American Meteorological Society, Boston, J38-J40 (1993).

No abstract.

Yvon, S.A., and E.S. Saltzman. A time-dependent photochemical box model for atmospheric chemistry (PBMAC). RSMAS Technical Report 93-008, University of Miami, Miami, Florida, 78 pp. (1993).

No abstract.

Yvon, S.A., E.S. Saltzman, D.J. Cooper, and V. Koropalov. Atmospheric hydrogen sulfide over the equatorial Pacific (SAGA-3). Journal of Geophysical Research, 98:16,979-16,983 (1993).

Atmospheric H₂S concentrations were measured over the equatorial Pacific on Leg 1 of the SAGA-3 cruise during February and March of 1990. Five north-south transects were made across the equator between Hawaii and American Samoa. The concentrations ranged from below the detection limit of 0.4 ± 0.5 (1 sigma) to 14.4 ppt with an average value of 3.6 ± 2.3 ppt (1 sigma, n=72). The highest concentrations were found on the easternmost two transects just south of the equator. The average concentration of 3.6 ppt observed on this cruise is the lowest reported value for background atmospheric H₂S over the tropical oceans. A lack of correlation between ²²²Rn and H₂S rules out a significant continental source. Model calculations indicate that the oceanic source of H₂S in this region is in the range of 9 to 21 × 10^-8 moles m^-3 day^-1. From this flux, the concentration of free sulfide (H₂S + S⁼) in the surface mixed layer of the ocean is estimated to be in the range of 32 to 67 pmol liter^-1. In the atmosphere, the oxidation of H₂S produces SO₂ at a rate of 2.1 to 4.4 × 10^-11 moles m^-3 day^-1 which is only a small fraction of that estimated from the oxidation of DMS in this region. A diurnal cycle was not observed in the H₂S data recorded during this cruise.

Zhang, J.-Z., and F.J. Millero. The chemistry of the anoxic waters in the Cariaco Trench. Deep-Sea Research, 40(5):1023-1041 (1993).

The Cariaco Trench has been widely used as a natural laboratory for the study of anaerobic processes since the deep waters were found to be anoxic in 1954. In the summer of 1990 on a cruise of the R.V. Thomas Washington, we had the opportunity to measure a number of chemical parameters (salinity, H₂S, O₂, pH, TCO₂, NH₄⁺, PO₄^3-, SiO₂, SO₃^2-, and S₂O₃^2-) in the eastern and western basins of the Cariaco Trench. The oxic-anoxic interface was located at 330 m in both basins. The concentrations of H₂S, NH₄⁺, PO₄^3-, and SiO₂ in the deep waters of the Cariaco Trench have increased with time. The linear extrapolations of H₂S and NH₄⁺ with time indicate that the trench was oxic around 1915. This turnover may be related to earthquakes that occurred in 1900 and 1929. The ratio of C/N/P/S in the anoxic waters was found to be close to 106:16:1:53, the ratio predicted from the oxidation of phytoplankton by sulfate. Micromolar concentrations of SO₃^2- and S₂O₃^2- were found below the interface in the intermediate waters. These intermediates appear to be due to the oxidation of H₂S by the sinking of oxygenated surface waters. The rates of oxidation of H₂S with oxygen also were measured in the Cariaco Trench waters at 25°C. Measurements were made on surface waters, deep waters, and mixtures of deep and surface waters. Oxidation rates were found to be 10 times faster in the deep waters than for surface seawater with added H₂S due to Fe²⁺ in the deep waters. The intermediates SO₃^2- and S₂O₃^2- formed during the oxidation of H₂S were also determined. A simple kinetic model was used to fit the results.

Zhang, J.-Z., and F.J. Millero. The products from the oxidation of H₂S in seawater. Geochimica et Cosmochimica Acta, 57:1705-1718 (1993).

The oxidation of sulfide in seawater is an overall second-order reaction, first-order with respect to both sulfide and oxygen. The major products formed from the oxidation of H₂S with O₂ have been measured in water and seawater as a function of pH (4-10), temperature (10-45°C), and salinity (0-36). The major products formed from the oxidation of H₂S were SO₃^2-, S₂O₃^2-, and SO₄^2-. The pH dependence of the product distribution has been attributed to the effect of pH on the rate of the individual reaction steps. A kinetic model was developed to account for the distribution of the reactants and products. The model is based on the following overall reactions:

H₂S + O₂ (k₁) --> Products (SO₃),

H₂SO₃ + O₂ (k₂ --> Products (SO₄), and

H₂S + H₂SO₃ + O₂ k₃ --> Products (S₂O₃).

Rate constants were determined for the oxidation of HS^- and formation of SO₃^2- (k₁), for the oxidation of SO₃^2- and production of SO₄^2- (k₂) and for the formation of S₂O₃^2- from HS^- and SO₃^2- (k₃). These values of k₁, k₂, and k₃ as a function of pH, temperature, and salinity can predict the concentrations of the measured reactants and products within experimental error. The effect of metals (Fe³⁺, Fe²⁺, Mn²⁺, Cu²⁺, and Pb²⁺) and oxides (alpha-FeOOH and MnO₂) on the product distribution has also been examined. The field measurements from the Framvaren Fjord (Norway) and Cariaco Trench (Venezuela) are in reasonable agreement with the laboratory results at the same concentration of Fe²⁺ as in the anoxic basins.

**1992**

Aberson, S.D., and M. DeMaria. VICBAR: 1991 verification and plans for 1992. Minutes, 46th Annual Interdepartmental Hurricane Conference, Homestead Air Force Base, FL, January 14-17, 1992. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-20 (1992).

No abstract.

Asher, W.E., P.J. Farley, R.H.Wanninkhof, E.C. Monahan, and T.S. Bates. Laboratory and field measurements concerning the correlation of fractional area foam coveraging with air/sea gas transport. In Precipitation Scavenging and Atmosphere-Surface Exchange, Vol. 2, The Semonin Volume: Atmosphere Surface Exchange Processes, S.E. Schwartz and W.G.N. Slinn (eds.). Hemisphere, Washington, D.C., 815-828 (1992).

Laboratory results have demonstrated that bubble plumes are a very efficient air/water gas transport mechanism. Because breaking waves generate bubble plumes, it may be possible to correlate air/sea gas transport velocities with whitecap coverage. This correlation may then allow transport velocities to be predicted from measurements of apparent microwave brightness temperature through the increase in sea surface microwave emissivity associated with breaking waves. In order to develop this remote-sensing based method for predicting air/sea gas fluxes, the whitecap simulation tank at Battelle/Marine Sciences Laboratory was used to measure transport velocities for oxygen, helium, sulfur hexafluoride, and dimethyl sulfide. This allowed the gas exchange process to be studied as a function of fractional area bubble plume coverage, molecular diffusivity (or Schmidt number), and water temperature. Using these results, an empirical model has been developed that permits prediction of the transport velocity in the Whitecap Simulation Tank from bubble plume coverage and Schmidt number. The implications of these results to the analysis of in situ dual-tracer air/sea gas transport data are also discussed.

Atwood, D.K., J.C. Hendee, and A. Mendez. An assessment of global warming stress on Caribbean coral reef ecosystems. Bulletin of Marine Science, 51(1):118-130 (1992).

There is evidence that stress on coral reef ecosystems in the Caribbean region is increasing. Recently, numerous authors have stated that major stress results from "abnormally high" seasonal sea surface temperatures (SST) and have implicated global warming as a cause, stating that recent episodes of coral bleaching result therefrom. However, an analysis of available SST data sets shows no discernible warming trend that could cause an increase in coral bleaching. Given the lack of long-term records synoptic with observations of coral ecosystem health, there is insufficient evidence available to label temperatures observed in coincidence with recent regional bleaching events as "abnormally" high.

Black, M.L., and H.E. Willoughby. The concentric eyewall cycle of Hurricane Gilbert. Monthly Weather Review, 120(6):947-957 (1992).

Hurricane Gilbert of 1988 formed an outer eyewall as it intensified rapidly toward a record minimum pressure of 888 hPa in the western Caribbean. The outer eyewall strengthened and contracted, while the inner eyewall showed some signs of weakening before landfall on the Yucatan Peninsula. Remarkably, both eyewalls survived passage over land, but the storm was much weaker when it entered the Gulf of Mexico. Although the primary cause of weakening was passage over land, the effect of the contracting outer eyewall may have contributed. Later, the outer eyewall completely replaced the inner eyewall. Subsequently, it contracted steadily but slowly as Gilbert maintained nearly constant intensity over the cooler waters of the Gulf before final landfall on the mainland of Mexico.

Black, P.G., and A.V. Litinetski. Flight-level and surface wind observations in Hurricane Gilbert from AN-12 "Cyclone" and WP-3D "Orion" aircraft. Proceedings, 5th International Symposium on Tropical Meteorology, Obninsk, Russia, May 27-31, 1992. USSR State Committee on Hydrometeorology, 20-31 (1992).

No abstract.

Black, P.G., S. Carson, R. McIntosh, K. St. Germain, C.C. Swift, and J. Wilkerson. The NOAA WP-3D capability for surface wind measurement using UMASS dual active/passive remote sensing and its application to present and future hurricane reconnaissance. Minutes, 46th Annual Interdepartmental Hurricane Conference, Homestead Air Force Base, FL, January 14-17, 1992. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-30 (1992).

No abstract.

Broecker, W.S., and T.-H. Peng. Interhemispheric transport of carbon dioxide by ocean circulation. Nature, 356:587-589 (1992).

Although anthropogenic emissions of carbon dioxide have today created a greater atmospheric CO₂ concentration in the Northern than in the Southern Hemisphere, a comparison of interhemispheric CO₂ profiles from 1980 and 1962 led Keeling and Heimann to conclude that, before the Industrial Revolution, natural CO₂ sources and sinks acted to set up a reverse (south to north) gradient which drove about one gigatonne of carbon each year through the atmosphere from the Southern to the Northern Hemisphere. At steady state, this flux must have been balanced by a counter flow of carbon from north to south through the ocean. Here we present a means to estimate this natural flux by a separation of oceanic carbon anomalies into those created by biogenic processes and those created by CO₂ exchange between the ocean and atmosphere. We find that before the Industrial Revolution, deep water formed in the northern Atlantic Ocean carried about 0.6 gigatonnes of carbon annually to the Southern Hemisphere, providing support for Keeling and Heimann's proposal. The existence of this oceanic carbon pump also raises questions about the need for a large terrestrial carbon sink in the Northern Hemisphere, as postulated by Tans et al. to balance the present global carbon budget.

Burpee, R.W., and P.P. Dodge. Analyses of visible satellite imagery of the south Florida sea breeze circulation. Preprints, 5th Conference on Mesoscale Processes, Atlanta, GA, January 5-10, 1992. American Meteorological Society, Boston, 77-80 (1992).

No abstract.

Burpee, R.W., J.S. Griffin, F.D. Marks, and J.L. Franklin. Real-time airborne analysis of aircraft data supporting operational hurricane forecasting. Minutes, 46th Annual Interdepartmental Hurricane Conference, Homestead Air Force Base, FL, January 14-17, 1992. NOAA Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-29 (1992).

No abstract.

Carsey, T.P., and M.L. Farmer. Active nitrogen gases in the North Atlantic boundary layer during ASTEX. EOS, Transactions, American Geophysical Union, 73:84 (1992).

No abstract.

Cione, J.J., L.J. Pietrafesa, S. Raman, and J. Churchill. The influence of Gulf Stream position on offshore storm intensification. Proceedings, American Geophysical Union Conference, New Orleans, Louisiana, January 27-31, (1992).

No abstract.

Claud, C., K.B. Katsaros, G.W. Petty, A. Chedin, and N.A. Scott. A cold air outbreak over the Norwegian Sea observed with the TIROS-N operational vertical sounder (TOVS) and the special sensor microwave/imager (SSM/I). Tellus, 44A(2):100-118 (1992).

Until recently, the scarcity of meteorological observations over polar areas has limited studies of high-latitude weather systems, but now data from polar orbiting satellites offer a new opportunity to observe and describe these systems. TOVS data have been used successfully for delineating synoptic and sub-synoptic systems, since they provide the vertical temperature structure of the atmosphere; SSM/I observations have proved valuable for analyzing storms through water vapor and rain determinations. These positive results prompted us to analyze simultaneous TOVS and SSM/I observations obtained during a cold air outbreak over the Norwegian Sea. After a description of the instruments and the retrieval schemes, the mutually supporting information from these two independent instruments is discussed. Implications for the monitoring of polar lows are presented.

Craynock, J.F., W. McLeish, and J.R. Proni. Acoustical characterization of an effluent plume in the Charleston Harbor estuarine system. Contract Report 91-0036866, Commissioners of Public Works of the City of Charleston, South Carolina, 22 pp. (1992).

A study of the effluent discharge from the City of Charleston Plum Island plant into the Ashley River/Charleston Harbor was carried out on January 14-15, 1992. Advanced acoustical methods, dye injection methods, and other advanced technologies were used in the study. The plumes originating from the risers of the outfall discharge line were observed to rise to the river surface while merging, such inter-plume merging beginning at about 2-3 m below the river surface. The plume dilution was about 17 to 1, i.e., plume dye concentration was about one-seventeenth the whole effluent dye concentration in the plant. Dye concentration measurements, made in the direction of current flow during a flood tide, indicated an effective dilution of about 50 to 1 at a distance of approximately 200 m from the discharge riser locations. Further up the river about 2-3 km from the discharge, at the Bascule Bridge and in the Wappoo Creek area, no dye was detected and acoustical reflectivity data indicated an absence of effluent material. Acoustical measurements were made in a direction downriver of the discharge point, where dyed plume material had not yet reached, and opposite to the direction of the ongoing flood tide. Effective dilutions ranging from 40 to 1 to 150 to 1 were observed in this region southeast of the discharge. The detection of two extraneous plumes, possibly natural springs, were made in the downriver portion of the study.

Dagg, M.J., and P.B. Ortner. Mesozooplankton grazing and the fate of carbon in the northern Gulf of Mexico. Proceedings, NECOP Workshop on Nutrient Enhanced Coastal Ocean Productivity, Chauvin, Louisiana, October 2-3, 1991. Texas A&M University Press, College Station, 117-121 (1992).

Grazing of the mesozooplankton community (organisms >200 µm) on phytoplankton was measured in two regions of the continental shelf west of the Mississippi River delta. Grazing by individual organisms was measured experimentally and scaled to the community by application of abundance and distribution data collected on several temporal and spatial scales by various methods. One of the principal fates of phytoplankton production stimulated by nutrient enrichment from the Mississippi River is to be grazed by the mesozooplankton community.

Dammann, W.P., and J.R. Proni. Chapter 6: Sediment plume measurements within acoustic concentration profiler. In Report 1: Dredged Material Plume Survey Data Report, N.C. Kraus (ed.). U.S. Army Corp of Engineers, Technical Report DRP-91-3, 311-345 (1992).

No abstract.

Davis, R.E., and R.F. Rogers. A synoptic climatology of severe storms in Virginia. The Professional Geographer, 44, 319-332 (1992).

A synoptic climatology is developed for Virginia using 21 years of late spring and summer surface and upper air observations. The climatology is produced by applying a combination of principal components analysis and cluster analysis such that each day is classified into one of a distinct number of synoptic situations. Days on which at least one severe storm occurred in Virginia are merged with the synoptic climatology. A majority of severe storms are associated with one synoptic situation distinguished by moderate instability and a high moisture content.

DeMaria, M., S.D. Aberson, K.V. Ooyama, and S.J. Lord. A nested spectral model for hurricane track forecasting. Monthly Weather Review, 120(8):1628-1643 (1992).

A numerical method for including a wide range of horizontal scales of motion is tested in a barotropic hurricane track forecast model. The numerical method uses cubic B-spline representations of variables on nested domains. The spline representation is used for the objective analysis of observations and the solution of the prediction equations (shallow-water equations on a Mercator projection). This analysis and forecasting system is referred to as VICBAR. The VICBAR model was tested in near real-time during the 1989 and 1990 Atlantic hurricane seasons. For the 1989 season, VICBAR had skill comparable with, or greater than, that of the operational track forecast models. For the 1990 season, VICBAR had skill comparable with that of the operational track forecast models, except at 72 h when QLM (a three-dimensional mesoscale model) had greater skill than VICBAR. During both 1989 and 1990, VICBAR had considerably more skill for forecasts of hurricanes than for forecasts of tropical storms. For the 1990 season, VICBAR was generalized to include time-dependent boundary conditions from a global forecast model. These boundary conditions improve the VICBAR forecasts, especially for the longer range forecasts (60-72 h). The skill of the VICBAR is sensitive to the choice of the background field used in the objective analysis and the fields used to apply the boundary conditions. The use of background fields and boundary condition fields from a 12 h old global model forecast significantly reduced the VICBAR skill relative to the use of fields from the current global forecast.

Eadie, B.J., J.A. Robbins, P. Blackwelder, S. Metz, J.H. Trefry, B. McKee, and T.A. Nelsen. A retrospective analysis of nutrient enhanced coastal ocean productivity in sediments from the Louisiana continental shelf. Proceedings, NECOP Workshop on Nutrient Enhanced Coastal Ocean Productivity, Chauvin, LA, October 2-3, 1991. Texas A&M University Press, College Station, 7-14 (1992).

Sediments have been collected and analyzed to obtain evidence in support of the argument that anthropogenic nutrient loading has led to changes in coastal water quality and increased productivity. Cores representing approximately 100 years of input show unmistakable signs of increased accumulation of organic carbon beginning early in the 1900's. Organic tracers show that virtually all of this increase appears to be of marine origin. At two sites within the plume/hypoxia region, preliminary estimates are that 50% to 70% more organic carbon is presently accumulating than at the turn of the century. These preliminary interpretations provide strong support for the central themes of the NECOP program. Analysis and interpretation of further supporting information is continuing.

Enfield, D.B. Historical and prehistorical overview of El Niño/Southern Oscillation. In El Niño: Historical and Paleoclimatic Aspects of the Southern Oscillation, H.F. Diaz and V. Markgraf (eds.). Cambridge University Press, Cambridge, 95-117 (1992).

This paper presents a thumbnail sketch of what El Niño/Southern Oscillation (ENSO) is, how it may have existed (or not) in previous epochs, and its relation to paleoclimatic studies. El Niño is a recurrent aperiodic, interannual (2-5 years) warming of the tropical Pacific Ocean, with an associated atmospheric counterpart, the Southern Oscillation. The two synchronous phenomena appear to occur as the result of an unstable interaction between ocean and atmosphere and vacillate between two contrasting states. They are of very large spatial scale and involve remote interannual climatic perturbations beyond the equatorial Pacific region of intense interaction. These "teleconnections" are one of the primary ways in which El Niño-like fluctuations during historical and prehistorical epochs have been preserved in surrogate records by biospheric and geological processes. Analyses of historical, proxy, and geological information suggest that: (1) ENSO has existed intermittently, as today, over at least the last 5,000 years; and (2) its statistics are probably nonstationary during that period, although apparently not in relation to variations of the background climate, such as the Little Ice Age. Evidence as to the existence of ENSO prior to 5,000 BP is mainly geological and as yet equivocal. Strategies for paleoclimatic research in this area are discussed in regard to several possible scenarios.

Festa, J.F., and R.L. Molinari. An evaluation of the WOCE volunteer observing ship-XBT network in the Atlantic. Journal of Atmospheric and Oceanic Technology, 9:305-317 (1992).

A volunteer observing ship (VOS)-expendable bathythermograph (XBT) network has been proposed for the Atlantic Ocean to satisfy World Ocean Circulation Experiment (WOCE) objectives in the upper water column. These objectives include measuring changes in upper-layer temperature. An evaluation of the proposed WOCE XBT network to resolve variability in sea surface temperature (SST), temperature distribution at 150 m (T150), and average temperature of the upper 400 m (T400L) between 25°S and 35°N is performed. A sampling design study based on an optimum interpolation (OI) of the historical XBT data set is used to construct uncertainty distributions for various XBT networks. The OI technique requires statistical representations of the variability (in the form of structure functions) of the three variables that are derived from the historical database. The structure functions and various sampling grids are used to construct uncertainty maps. Two seasons are used in the analysis of SST. In both seasons, uncertainties in mapped SST values for the proposed WOCE grid range from 0.3°C to 0.4°C in regions of adequate data coverage. Errors are larger along the boundary. Uncertainties in the T150 fields are larger (0.5°-0.7°) because of the smaller scales of spatial variability at depth. Errors in T400L range from 0.3°C to 0.4°C. The effects of alternative observing strategies on the error maps are shown. Finally, error maps derived from the XBT network as it exists today (i.e., incomplete) are given. The maps indicate that monthly resolution is not available from the incomplete network.

Fine, R.A., E. Johns, and R.L. Molinari. Deep Western Boundary Current structure in the region of the Blake Bahama Outer Ridge. EOS, Transactions, American Geophysical Union, 72(51):32 (1992).

No abstract.

Friedman, H.A., and C.A. Arnhols. 1992 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 116 pp. (1992).

No abstract.

Froelich, P.N., V. Blanc, R.A. Mortlock, S.N. Chillrud, W. Dunstan, A. Udomkit, and T.-H. Peng. River fluxes of dissolved silica to the ocean were higher during glacials: Ge/Si in diatoms, rivers, and oceans. Paleoceanography, 7(6):739-767 (1992).

Two centric marine diatom species, Thalassiosira oceanica and Thalassiosira antarctica, were grown in batch cultures to determine the incorporation of germanium (Ge) and silicon (Si) into siliceous shells (opal). The results were modeled as Ge/Si "isotope" fractionation. During exponential growth, diatoms take up and incorporate Ge/Si from solution without major discrimination against Ge. During stationary phase growth near silica limitation, the Antarctic species (T. antarctica) discriminates slightly against Ge but integrated (Ge/Si)_opal produced over the latter portion of the growth cycle is indistinguishable from the initial solution ratio. These results confirm experiments using radioactive ⁶⁸Ge that showed absence of fractionation during diatom silica uptake (Azam and Volcani, 1981), in contrast to two-box ocean models that invoke 50% Ge discrimination by diatoms to explain the observed "excess" surface ocean germanium concentration (Murnane and Stallard, 1988; Froelich et al., 1989) and late Pleistocene ocean sediment (Ge/Si)_opal records (Mortlock et al.,1991). Runs of a 10- box ocean Ge and Si model (PANDORA) with 50% discrimination reproduce the excess surface ocean Ge but introduces curvature into the deep ocean Ge versus Si relationship that is not observed in the oceans. Thus, 50% fractionation is not supported by either cultures or models. If diatoms do not fractionate Ge/Si, then late Pleistocene (Ge/Si)_opal variations in piston cores are caused not by changes in local biosiliceous production and silica utilization (Mortlock et al., 1991) but rather by whole ocean changes in (Ge/Si)_seawater. The marine (Ge/Si)_opal record of the last 450 kyr can be modeled as transient oceanic responses to instantaneous continental climate transitions of consistent with the chemical weathering model of Murnane and Stallard (1990). Glacial periods are characterized by lower continental weathering intensity, lower (Ge/Si)_riv, and two-fold higher dissolved silica river fluxes. Marine (Ge/Si)_opal records thus contain a history of ocean silica chemistry that reflect rapid global changes in continental weathering.

Galloway, J.N., J.E. Penner, C.S. Atherton, J.M. Prospero, H. Rodhe, R.S. Artz, Y.J. Balkanski, H.G. Bingemer, R.A. Brost, S. Burgermeister, G.R. Carmichael, J.S. Chang, R.J. Charlson, S. Cober, W.G. Ellis, Jr., C.J. Fischer, J.M. Hales, D.R. Hastie, T. Iversen, D.J. Jacob, K. John, J.E. Johnson, P.S. Kasibhatla, J. Langner, J. Lelieveld, H. Levy, III, R. Lipschultz, J.T. Merrill, A.F. Michaels, J.M. Miller, J.L. Moody, J. Pinto, A.A.P. Pszenny, P.A. Spiro, L. Tarrason, S.M. Turner, and D.M. Whelpdale. Sulfur and nitrogen levels in the North Atlantic Ocean's atmosphere: A synthesis of field and modeling results. Global Biogeochemical Cycles, 6(2):77-100 (1992).

In April 1990, 42 scientists from eight countries attended a workshop at the Bermuda Biological Station for Research to compare field measurements with model estimates of the distribution and cycling of sulfur and nitrogen species in the North Atlantic Ocean's atmosphere. Data sets on horizontal and vertical distributions of sulfur and nitrogen species and their rates of deposition were available from ships' tracks and island stations. These data were compared with estimates produced by several climatological and event models for two case studies: (1) sulfate surface distributions and deposition; and (2) nitrate surface distributions and deposition. Highlights of the conclusions of the case studies were that the measured concentrations and model results of nitrate and non-seasalt sulfate depositions appeared to be in good agreement at some locations but in poor agreement for some months at other locations. The case studies illustrated the need for the measurement and modeling communities to interact not only to compare results, but also to cooperate in improving the designs of the models and the field experiments.

Garraffo, Z., S.L. Garzoli, W. Haxby, and D.B. Olson. Analysis of a general circulation model. Part 2: Distribution of kinetic energy in the South Atlantic and Kuroshio/Oyashio systems. Journal of Geophysical Research-Oceans, 97(C12):20,139-20,153 (1992).

The energy of the model transient eddies at 37.5 m is compared with GEOSAT altimeter observations for the South Atlantic Ocean and for the Kuroshio system. The model shows areas of transient motions overlapping the ones obtained from GEOSAT altimeter data. For the South Atlantic Ocean, the modeled eddy kinetic energy is smaller than the one observed with GEOSAT, by a factor of 3 for area average on the whole South Atlantic region, and by a factor of 4 for its western boundary. On the Agulhas system, transient eddy activity develops in the region where the Agulhas Current retroflects. In the western South Atlantic, the modeled eddy activity is concentrated on the Confluence front; observed variability along a more extended region following the topography is not resolved in the model. For the Kuroshio region, the energy level of the modeled transient motions is comparable with GEOSAT observations, but the model eddy activity is more concentrated in the Kuroshio Current and not in the Kuroshio extension. The observations show the opposite. For the South Atlantic Ocean, a comparison is also done between model eddy kinetic energy (defined as including standing and transient eddy contributions) with values obtained from surface driftnets. The analysis shows differences in the western boundary, and good agreement across the South Atlantic Ocean between 35°S and 45°S. In this formulation, the model mean energy level is smaller than that observed with drifters from the First GARP Global Experiment; differences might be due to an overestimation in the values obtained with the drifters.

Garzoli, S.L. The Atlantic Equatorial Countercurrent: Models and observations. Journal of Geophysical Research-Oceans, 97(C11):17,931-17,946 (1992).

An analysis of the dynamic height and volume transport variability of the North Equatorial Countercurrent (NECC) in the western tropical Atlantic (west of 38°W) is presented. The study is based upon a subset of the data (16 month-long series of dynamic height obtained with an array of inverted echo sounders) collected in the tropical Atlantic during 1987 and 1988 as part of the National Science Foundation/Tropical Ocean-Global Atmosphere array. Results are compared with those from a previous work in the center of the basin (28°W); a wind product for 1987-1988 is jointly analyzed for further interpretation of the results. In order to obtain transports from the echo sounder data, which do not provide information on the vertical structure of the geostrophic velocities, the product from the Community Model Experiment (CME) is analyzed. In this way the present work follows the objectives: to provide a description of the dynamics of the NECC in a region where maximum reversal is predicted, compare the results with those in the center of the basin, and to validate the product of the CME model.

Garzoli, S.L., Z. Garraffo, G. Podesta, and O.B. Brown. Analysis of a general circulation model product. Part 1: Frontal systems in the Brazil/Malvinas and Kuroshio/Oyashio regions. Journal of Geophysical Research-Oceans, 97(C12):20,117-20,138 (1992).

In the present paper, the product of the Semtner and Chervin general circulation model (GCM) is compared with available observations in the frontal areas of the Brazil/Malvinas and the Kuroshio/Oyashio confluences. The dimensionality of the systems studied is reduced by using the empirical orthogonal functions (EOF) and frontal density methods. The two sets of data utilized to validate the model are the sea surface temperature (SST) from the satellite observations and temperature fields product from the GCM at levels 1 (12.5 m), 2 (37.5 m) and 6 (160 m). Comparisons are made between the dominant empirical modes and the locus of maximum probability for observations and model product. The model reproduces intense thermal fronts at the surface and in the upper layers. In the upper layer (level 1) they are induced by the internal dynamics of the model and not by the restoring of the model to climatology alone. The variability of these fronts is less pronounced in the model than in the observations. The dominant period in the observations is annual with contributions of semiannual and high frequency oscillations. In the model, the dominant variability is also annual at all analyzed levels. A semiannual oscillation contributed to a lower degree and is related to eddies that, in the model, have an annual and semiannual periodicity.

Gray, W.M., and C.W. Landsea. African rainfall as a precursor of hurricane-related destruction on the U.S. east coast. Bulletin of the American Meteorological Society, 73:1352-1364 (1992).

This paper describes a predictive relationship between west African rainfall and U.S. hurricane-spawned destruction, which is based on information for the 42-year period 1949-1990. It is shown that above-average rainfall during the previous year along the Gulf of Guinea, in combination with above-average rainfall in the western Sahel during June and July, is linked to hurricane-spawned destruction along the U.S. east coast occurring after 1 August, which is 10-20 times greater than in years when pre-August precipitation for these west African regions is below average. Similar hurricane-spawned damage along the U.S. Gulf coast shows only a negligible relationship with African rainfall. Hurricane-caused deaths for both U.S. coastal regions also show a similar association with west African rainfall.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Predicting Atlantic seasonal hurricane activity 6-11 months in advance. Weather and Forecasting, 7:440-455 (1992).

A surprisingly strong long-range predictive signal exists for Atlantic-basin seasonal tropical cyclone activity. This predictive skill is related to two measures of west African rainfall in the prior year and to the phase of the stratospheric quasi-biennial oscillation of zonal winds at 30 mb and 50 mb, extrapolated ten months into the future. These predictors, both of which are available by 1 December, can be utilized to make skillful forecasts of Atlantic tropical cyclone activity in the following June-November season. Using jackknife methods to provide independent testing of datasets, it is found that these parameters can be used to forecast nearly half of the season-to-season variability for seven indices of Atlantic seasonal tropical cyclone activity as early as late November of the previous year.

Griffin, J.S., R.W. Burpee, F.D. Marks, and J.L. Franklin. Real-time airborne analysis of aircraft data supporting operational hurricane forecasting. Weather and Forecasting, 7(3):480-490 (1992).

The Hurricane Research Division (HRD) has developed a technique for real-time airborne analysis of aircraft data from reconnaissance and research flights in tropical cyclones. The technique uses an onboard workstation that analyzes flight-level observations, radar reflectivity patterns, radial Doppler velocities, and vertical soundings from Omega dropwindsondes (ODWs). Many of the workstation analyses are in storm-relative coordinates that depend upon interactive identification of the cyclone center from the radar reflectivity data. Displays of the lower fuselage reflectivity, composited for 1-2 h, provide an overall perspective of the horizontal patterns of precipitation and a framework for interpretation of thermodynamic and kinematic observations. The workstation runs algorithms for estimation of the horizontal wind field in the hurricane core using radial velocities measured by the airborne Doppler radar during one or more penetrations of the storm center. Interactive software also supports real-time processing of ODW wind and thermodynamic data, objective editing of bad data, and automatic dissemination of mandatory and significant-level data in the standard dropwindsonde code. Plans for the 1992 hurricane season include transmission of subsets of the data to the National Hurricane Center (NHC) through the Geostationary Operational Environmental Satellite (GOES) communications system and display of the aircraft analyses for the forecasters at NHC. With the implementation of these plans, NHC will receive two-dimensional analyses of the mesoscale precipitation and wind structure of the storm core and more frequent estimates of the location and recent motion of tropical cyclones.

Griffin, J.S., R.W. Burpee, F.D. Marks, and J.L. Franklin. Real-time airborne analysis of flight-level and radar data supporting operational hurricane forecasting. Preprints, 8th International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, Atlanta, GA, January 5-10, 1992. American Meteorological Society, Boston, 241-246 (1992).

No abstract.

Hallett, J., W. Hendricks, and P.T. Willis. Evolution of precipitation spectra in a developing convective cloud. Preprints, 11th International Conference on Clouds and Precipitation, Montreal, Canada, August 17-21, 1992. American Meteorological Society, Boston, 216-219 (1992).

No abstract.

Hansen, D.V. Comments on "The significance of half-inertial flow in the eastern equatorial Pacific." Journal of Physical Oceanography, 22(7):811-813 (1992).

It is shown that the instability waves regularly observed in the tropical Pacific and Atlantic Oceans do not necessarily contain oscillations of half the local inertial frequency. Rather, it is hypothesized that the flow approaches the half-inertial conditions only at times when the instability waves develop sufficient baroclinic intensity to saturate the geostrophic vorticity limit of the gradient wind equation for anticyclonic flow.

Houston, S.H., and M.D. Powell. Hurricane Bob's surface wind fields during landfall in New England. Minutes, 46th Annual Interdepartmental Hurricane Conference, Homestead Air Force Base, FL, January 14-17, 1992. NOAA Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-33 (1992).

No abstract.

Houze, R.A., Jr., F.D. Marks, and R.A. Black. Dual-aircraft investigation of the inner core of Hurricane Norbert. Part II: Mesoscale distribution of ice particles. Journal of the Atmospheric Sciences, 49(11):943-962 (1992).

Horizontal fields of cloud microphysical parameters, vertical air motion, and horizontal wind at the 6 km level in Hurricane Norbert (1984) were obtained by mapping and interpolating data collected on board a WP-3D aircraft along numerous flight tracks executed within the central region of the storm. Although the storm was characterized by a strong vortex of winds reaching peak values >50 m s^-1 all around the storm, the precipitation was concentrated on the southwest side of the storm. A sloping eyewall was located within 20-30 km of the eye. Stratiform precipitation dominated the region outside the eyewall. A band of maximum stratiform precipitation was located 60-70 km southwest of the storm center. The ice particles at flight level tended to be relatively large both in the eyewall and in the outer band of stratiform precipitation. Particles were smaller and more numerous (100-300 l^-1) in the zone between the eyewall and outer stratiform band. These particles occurred on the outside edges of the eyewall convective updrafts, indicating that they may have been produced by splintering in association with graupel formation in the updrafts. The large particles in the eyewall tended to be graupel. In the outer stratiform region, characterized by weak, average vertical air motion and an absence of strong convective drafts, the predominant particle type was aggregates. The region of large graupel particles in the eyewall coincided with the radius of maximum tangential wind and was apparently produced by the azimuthal advection of the graupel particles. Since graupel particles fall rapidly, they were not susceptible to advection out of the weaker radial wind component. On the other hand, some of the more slowly falling, less dense aggregates produced in the eyewall region were evidently advected radially as well as azimuthally, thus accounting for the location of the outer region of maximum stratiform precipitation intensity.

Johns, E., R.L. Molinari, and W.D. Wilson. Upper layer circulation in the western tropical Atlantic inferred from climatological temperature and salinity distributions. EOS, Transactions, American Geophysical Union, 72(51):21 (1992).

No abstract.

Kaplan, J., and M. DeMaria. An operational statistical hurricane intensity prediction scheme (SHIPS) for the Atlantic basin. Minutes, 46th Annual Interdepartmental Hurricane Conference, Homestead Air Force Base, FL, January 14-17, 1992. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-22 (1992).

No abstract.

Katsaros, K.B., and S.S. Atakturk. Air-sea interaction and remote sensing. NASA Contract Rept. (NASA-CR-190913), 12 pp. (1992).

The first part of the proposed research was a joint effort between our group and the Applied Physics Laboratory (APL), University of Washington. The author's own research goal is to investigate the relation between the air-sea exchange processes and the sea state over the open ocean and to compare these findings with previous results obtained over a small body of water namely, Lake Washington. The goals of the APL researchers are to study (1) the infrared sea surface temperature (SST) signature of breaking waves and surface slicks, and (2) microwave and acoustic scattering from water surface. The task of the group in this joint effort is to conduct measurements of surface fluxes (of momentum, sensible heat, and water vapor) and atmospheric radiation (longwave and shortwave) to achieve our research goal as well as to provide crucial complementary data for the APL studies. The progress of the project is summarized.

Landsea, C.W., and W.M. Gray. The strong association between western Sahelian monsoon rainfall and intense Atlantic hurricanes. Journal of Climate, 5(5):435-453 (1992).

Seasonal variability of Atlantic basin tropical cyclones is examined with respect to the monsoon rainfall over west Africa. Variations of intense hurricanes are of the most interest, as they are responsible for over three-quarters of United States tropical cyclone spawned destruction, though they account for only one-fifth of all landfalling cyclones. Intense hurricanes have also shown a strong downward trend during the last few decades. It is these storms that show the largest concurrent association with Africa's western Sahelian June-September rainfall for the years 1949-1990. Though the Sahel is currently experiencing a multidecadal drought, the relationship between Atlantic tropical cyclones and western Sahelian rainfall is not dependent on the similar downward trends in both datasets. A detrended analysis confirms that a strong association still exists, though reduced somewhat in variance explained. Additionally, independent data from the years 1899 to 1948 substantiate the existence of the tropical cyclone-western Sahelian rainfall association. The fact that the Sahel periodically experiences multidecadal wet and dry regimes suggests that the current Sahelian drought, which began in the late 1960s, could be a temporary condition that may end in the near future. When this occurs, the Atlantic hurricane basin--especially the Caribbean islands and the United States east coast--will likely see a large increase in intense hurricane activity associated with abundant Sahelian rainfall similar to the period of the late 1940s through the 1960s.

Landsea, C.W., W.M. Gray, P.W. Mielke, and K.J. Berry. Long-term variations of western Sahelian monsoon rainfall and intense U.S. landfalling hurricanes. Journal of Climate, 5(5):1528-1534 (1992).

Western Salelian rainfall during the primary rainy season of June through September is shown to be significantly associated with concurrent intense U.S. landfalling hurricanes during the last 92 years. The most intense hurricanes (i.e., Saffir-Simpson scale category 3, 4, or 5) have an especially strong relationship with Sahelian rainfall, whereas weaker hurricanes show little or no association. The hurricane-Sahelian rainfall association is most evident along the U.S. east coast but is negligible in the U.S. Gulf coast region.

Landsea, C.W., W.M. Gray, P.W. Mielke, and K.J. Berry. Seasonal forecasting of Atlantic basin tropical cyclones by 1 June. Proceedings, 17th Annual Climate Diagnostics Workshop, Norman, OK. NOAA, 388-390 (1992).

No abstract.

Marks, F.D. Kinematic structure of the hurricane inner core as revealed by airborne Doppler radar. Preprints, 5th Conference on Mesoscale Processes, Atlanta, GA, January 5-10, 1992. American Meteorological Society, Boston, 127-132 (1992).

No abstract.

Marks, F.D., R.A. Houze, and J.F. Gamache. Dual-aircraft investigation of the inner core of Hurricane Norbert. Part I: Kinematic structure. Journal of the Atmospheric Sciences, 49(11):919-942 (1992).

A dedicated experiment to study the details ofthe important physical processes and scale interactions operative within the eyewall regions of Hurricane Norbert was carried out on 24-25 September. The two National Oceanic and Atmospheric Administration (NOAA) Aircraft Operations Center (AOC) WP-3D research aircraft were used for the study. One aircraft, equipped with airborne Doppler radar, flew repeated radial penetrations in and out of the eye, mapping the three-dimensional wind field over the region surrounding the eyewall. This data set provides the first complete mapping of the three-dimensional wind field of the hurricane inner core. The three-dimensional wind field within 40 km of the storm center was derived from a "pseudo" dual-Doppler analysis in each quadrant of the storm. The vertical wind components were derived from the mass continuity equation and the horizontal wind field. The Doppler-derived wind fields for the four quadrants were combined to form a storm composite wind field that was 75 × 75 km on a side and centered on the storm circulation center. The wind-field altitude extended from 0.5-12 km. The Norbert wind field was asymmetric, and the asymmetry varied with altitude. The tangential wind maximum sloped upwind with increasing altitude, from the left of the track (azimuths 147°-327°) at 1 km altitude to the right of the storm track (azimuths 327°-147°) at 3 km altitude. The radial wind at 1 km altitude had inflow in front of the storm (327° azimuth) and outflow behind. This pattern in the radial flow disappeared at 3 km altitude, where the radial flow switched from inflow in the rear of the storm to outflow in the front. The vertical velocity maximum was to the left of the storm track at all levels. The maximum sloped downwind with increasing altitude (along the upper boundary of the reflectivity maximum) from in front of, and to the left of, the track at 2 km altitude, to behind and to the right of the track at 8 km altitude. To investigate the nature of the wind-field asymmetry, a technique was devised to partition the horizontal wind components into a horizontal mean wind as a function of the altitude and a perturbation wind. The cylindrical nature of the wind field permitted further partitioning of the perturbation wind into the mean vortex (a function of radius and height-wave number 0) and a perturbation from the mean vortex (including any higher order wave numbers). The wind partitioning was used to describe the structure of the mean vortex and its interaction with the environmental flow. The partition of the horizontal wind pointed out the complex interactions of the wind components in determining storm motion and in forcing mesoscale convergence/divergence patterns that resulted in the vertical velocity asymmetry.

Maul, G.A., D.V. Hansen, and N.J. Bravo. A note on sea level variability at Clipperton Island from GEOSAT and in-situ observations. IUGG Geophysical Monograph Series 69, 11:145-154 (1992).

During the 1986-1989 Exact Repeat Mission (ERM) of GEOSAT, in-situ observations of sea level at Clipperton Island (10°N/109°W) and satellite-tracked, free-drifting drogued buoys in the eastern tropical Pacific Ocean are concurrently available. A map of the standard deviations of GEOSAT sea surface heights (2.9 years) shows a variance maximum along ~12°N from Central America, past Clipperton to ~160°W. Seafloor pressure gauge observations from a shallow (10 m depth) site on Clipperton Island and an ERM crossover point in deep water nearby show a correlation of r = 0.76 with a residual of ±6.7 cm RMS. Approximately 17% of the difference (GEOSAT minus sea level) is characterized by a 4 cm amplitude 0° phase annual harmonic, which is probably caused by unaccounted-for tropospheric water vapor affecting the altimeter and/or ERM orbit error removal. Wintertime anticyclonic mesoscale eddies advecting past Clipperton Island each year have GEOSAT sea surface height and in-situ sea level signals of more than 30 cm, some of which are documented by the satellite-tracked drifters. Meridional profiles of the annual harmonic of zonal geostrophic current from GEOSAT and from the drifters both show synchronous maxima in the North Equatorial Countercurrent and the North Equatorial Current. Other Clipperton sea level maxima seen during late spring of each year may involve anticyclonic vortices formed along Central America the previous winter.

Mestas-Nunez, A.M., D.B. Chelton, and R.A. deSzoeke. Evidence of time-dependent Sverdrup circulation in the South Pacific from the SEASAT scatterometer and altimeter. Journal of Physical Oceanography, 22(8):934-943 (1992).

SEASAT scatterometer and altimeter data are analyzed to investigate time-dependent Sverdrup dynamics in the Southern Ocean (40°S to 60°S) over seasonal time scales. Sverdrup dynamics are shown to be inadequate to describe the circulation in the South Atlantic and Indian oceans. The Sverdrup circulation in the South Pacific is reasonable north of 55°S. The changes in Sverdrup circulation from July to September 1978 indicate an eastward acceleration along 55°S and westward acceleration along 40°S, suggesting a southward shift in the subpolar eastward flow. Sea level in the South Pacific is estimated for July and September 1978 from scatterometer vector wind data based on Sverdrup dynamics assuming a flat-bottom ocean with barotropic flow. The changes in Sverdrup sea level are compared with the changes in sea level observed by the altimeter for the same time period. Both estimates indicate a rise in sea level along a zonal band centered at about 50°S. This sea level rise inferred from both the scatterometer and altimeter data is supported by a similar rise in sea level observed from tide gauge measurements at two locations in New Zealand. The spatial correlation between the two satellite estimates of sea level change is about 0.5. This agreement suggests that time-dependent Sverdrup dynamics may account for about 1/4 of the spatial variance of sea level change in the South Pacific over the three-month SEASAT mission.

Mielke, P.W., K.J. Berry, W.M. Gray, and C.W. Landsea. Cross-validated prediction models for 1 December and 1 August forecasts of seasonal tropical cyclone activity in the Atlantic basin. Preprints, 12th Conference on Probability and Statistics in Atmospheric Sciences, Toronto, Canada. American Meteorological Society, Boston (1992).

No abstract.

Miller, D.K., and K.B. Katsaros. Satellite-derived surface latent heat fluxes in a rapidly intensifying marine cyclone. Monthly Weather Review, 120(7):1093-1107 (1992).

The aim of this article is to estimate surface latent heat fluxes in the vicinity of a rapidly deepening cyclone before and during its period of most rapid intensification. This is done with a bulk parameterization scheme and remotely sensed input data. A method for estimating the difference in specific humidity between the surface and a 10-m height is investigated using the Special Sensor Microwave/Imager (SSM/I)-observed integrated water vapor field and a sea surface temperature analysis. The surface latent heat flux fields generally have estimated errors below 40% south of 40°N and outside the region of high integrated water vapor values associated with frontal bands. The method of estimating surface latent heat fluxes for the case study was found to be usable in most regions of the northwest Atlantic Ocean except for those locations directly adjacent to coastlines in instances of offshore flow and in the vicinity of surface fronts (DBO).

Millero, F.J., and J.-Z. Zhang. Total alkalinity measurements in the South Atlantic. Data Report, University of Miami, 63 pp. (1992).

This report gives the results of our pH, total alkalinity (TA), and total inorganic carbon dioxide (TCO₂) measurements made in the South Atlantic from June 11 to August 6, 1991 on the NOAA R/V Malcolm Baldridge. The results were obtained by a potentiometric titration of seawater samples with HCl. The resulting pH, TA, and TCO₂ are thought to be precise to ± 0.01 in pH, ± 3 µmol/kg in TA, and ± 5 µmol/kg in TCO₂. These results will be combined with the NOAA's measurements made by Rik Wanninkhof to characterize the CO₂ system in this region.

Molinari, R.L., and E. Johns. Upper layer circulation in the western tropical Atlantic inferred from climatological temperature and salinity distributions. EOS, Transactions, American Geophysical Union, 72(51):21 (1992).

No abstract.

Molinari, R.L., R.A. Fine, and E. Johns. The Deep Western Boundary Current in the tropical North Atlantic Ocean. Deep-Sea Research, 39:1967-1984 (1992).

Tracer and CTD data collected on four cruises to the western tropical North Atlantic Ocean during 1987-1989 are used to describe the Deep Western Boundary Current (DWBC). The study area extends along the boundary and east to the Mid-Atlantic Ridge from 14.5°N to just north of the equator. Two cores of recently ventilated (with respect to the chlorofluorocarbon F11) northern hemisphere water are advected through the area. A shallow core is centered at about 1,500 m and a deeper core at about 3,500 m. The upper core of high F11 (bounded by the 3.2°C and 4.7°C potential temperature isotherms) is typically located inshore of the deeper currents,and transports were computed relative to a zero reference velocity on the 4.7°C potential temperature surface. Total transport below the 4.7°C surface for the most intense portion of the DWBC is 26 Sv (1 Sv = 10⁶ m³/s). Of this total, 17 Sv is contained in the two recently ventilated high F11 cores. The Ceara Rise blocks equatorward flow in the DWBC below the 1.8°C potential temperature surface, causing the coldest waters to recirculate back to the north.

Molinari, R.L., E. Johns, W.E. Johns, and R. Zantopp. A comparison of observed and simulated representations of the North Atlantic Deep Western Boundary Current. EOS, Transactions, American Geophysical Union, 72(51):39 (1992).

No abstract.

Peng, T.-H. Possible effects of ozone depletion on global carbon cycle. Radiocarbon, 34(3):772-779 (1992).

The increase of UV-B radiation resulting from ozone depletion is considered to have damaging effects on marine ecosystems. A cutback of marine productivity would tend to reduce the oceanic uptake of atmospheric CO₂. Box models of the global oceans based on the distribution of bomb-produced ¹⁴C are used to evaluate the possible effects of ozone depletion on the atmospheric CO₂ concentration. The maximum effect presumably takes place if the ozone hole reduces the marine productivity to zero in the Antarctic Ocean. In a business-as-usual scenario of future CO₂ emissions, the atmospheric CO₂ partial pressure (pCO₂) would increase by an additional 37 µatm over the course of the next century. This increase corresponds to 4.6% of the projected atmospheric pCO₂ in the year 2090. However, if the damaging effect caused by the destruction of the stratospheric ozone layer is assumed to lower the productivity over the Antarctic Ocean by 10%, the atmospheric pCO₂ would rise by less than 3 µatm over the expected atmospheric level in the next century.

Peng, T.-H., and W.S. Broecker. Reconstruction of radiocarbon distribution in the glacial ocean. In Radiocarbon After Four Decades: An Interdisciplinary Perspective, R.E. Taylor, A. Long, and R.S. Kra (eds.). Springer-Verlag, New York, 75-92 (1992).

No abstract.

Peng, T.-H., W.S. Broecker, and H.G. Ostlund. Dynamic Constraints on CO₂ Uptake by an Iron-Fertilized Antarctic, Modeling The Earth System, D. Ojima (ed.). Global Change Institute, Volume 3, 77-106 (1992).

No abstract.

Petty, G.W., and K.B. Katsaros. Morning-evening differences in global and regional oceanic precipitation as observed by the SSM/I. Purdue University Press, 4 pp. (1992).

For the present preliminary analysis of oceanic rainfall statistics, global oceanic SSM/I data were simply scanned for pixels which exhibited a 37 GHz polarization difference (vertically polarized brightness temperatures minus horizontally polarized brightness temperatures) of less than 15 K. Such a low polarization difference over the open ocean is a completely unambiguous indication of moderate to intense precipitation. Co-located brightness temperatures from all seven channels of the SSM/I were saved for each pixel so identified. Bad scans and geographically mislocated block of data were objectively identified and removed from the resulting data base. The authors collected global oceanic rainfall data for two time periods, each one month in length. The first period (20 July-19 August 1987) coincides with the peak of the Northern Hemisphere summer. The second period (13 January-12 February 1988) coincides with the Northern Hemisphere winter.

Pikula, L., and S. Elswick. Ecosystems of the Florida Keys: A bibliography. Library and Information Services Division, Current References (92-1), National Oceanographic Data Center, 189 pp. (1992).

No abstract.

Post, W.M., F. Chavez, P.J. Mulholland, J. Pastor, T.-H. Peng, K. Prentice, and T. Web. Climate feedbacks in the global carbon cycle. In The Science of Global Change: The Impacts of Human Activities on the Environment, D.A. Dunnette and R.J. O'Brien (eds.). American Chemical Society, 392-412 (1992).

Increasing atmospheric CO₂ is likely to produce chronic changes in global climate, as it may have done in the geologic past. Future CO₂-induced changes in temperature and precipitation distribution changes could equal or exceed the changes which have occurred over the past 160,000 years and have affected the global carbon cycle. We consider ocean and terrestrial processes that could involve large change in carbon fluxes (>2 Pg C·yr^-1) or changes in storage in large carbon pools (>200 Pg C) resulting from CO₂-induced climate changes. These include (1) air-sea exchange of CO₂ in response to changes in temperature and salinity; (2) climate-induced changes in ocean circulation; (3) changes in oceanic new production and regeneration of organic debris caused directly by climate change; (4) altered oceanic nutrient supply needed to support new production due to climate-induced alteration of ocean circulation and river discharge; (5) CaCO₃ compensation in sea water; (6) altered river nutrient flux and effects on coastal organic matter production and sediment accumulation; (7) seasonal balance between GPP and decomposition-respiration in terrestrial ecosystems in response to changes in temperature and precipitation; (8) successional processes in terrestrial ecosystems and formation of new plant associations in response to climatic change; (9) effects on soil nutrient availability, which amplifies ecosystem responses to climate change; (10) and responses of northern forests, tundra, and peatlands which have, until recently, been a sink for CO₂. The potential effect of these processes on the rate of atmospheric CO₂ concentration changes are estimated where possible, but not much quantitative information at a global scale is known, so uncertainty in these estimates is high. Each of these secondary feedbacks, however, has the potential of changing atmospheric CO₂ concentration in magnitude similar to the effects of the direct human processes (fossil fuel burning and land clearing) responsible for the concern about global warming in the first place. It is, therefore, urgent that these uncertainties be resolved. Lines of research to accomplish this are suggested.

Powell, M.D. Surface wind speeds in hurricanes. Proceedings, ASCE Structures, Congress X, San Antonio, TX, April 13-15, 1992. American Society of Civil Engineers, New York, 246-249 (1992).

No abstract.

Powell, M.D., and S.H. Houston. A comparison of surface wind sampling strategies in hurricanes. Minutes, 46th Annual Interdepartmental Hurricane Conference, Homestead Air Force Base, FL, January 14-17, 1992. NOAA Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., A-32 (1992).

No abstract.

Richardson, P.L., S. Arnault, S.L. Garzoli, and J.G. Bruce. Annual cycle of the Atlantic North Equatorial Countercurrent. Deep-Sea Research, 39(6):997-1014 (1992).

An analysis of numerous meridional XBT sections near 28°W reveals that the geostrophic North Equatorial Countercurrent (NECC) continues to flow eastward throughout the year, fastest in fall and slowest in spring. Drifting buoys and historical ship drifts show that the near-surface Countercurrent reverses each spring even when systematic errors due to windage are taken into account. The seasonally fluctuating winds drive an Ekman surface current that is eastward in fall, adding to the geostrophic current, and westward in spring, countering and overwhelming the geostrophic current. The reversal of the Countercurrent in spring occurs in the near-surface layer and is driven by the Northeast Trades. Thus, the near-surface velocity in the Countercurrent is determined by a competition between local wind stress and the larger field of wind stress curl, both of which have large seasonal variations in the tropical Atlantic.

Rona, P.A., H. Bougault, J.L. Charlou, P. Appriou, T.A. Nelsen, J.H. Trefry, G.L. Eberhart, A. Barone, and H.D. Needham. Hydrothermal circulation, serpentinization and degassing at a rift valley-fracture zone intersection: Mid-Atlantic Ridge near 15°N, 45°W. Geology, 20(9):783-786 (1992).

A hydrothermal system characterized by high ratios of methane to both manganese and suspended particulate matter was detected in seawater sampled at the eastern intersection of the rift valley of the Mid-Atlantic Ridge with the Fifteen-Twenty Fracture Zone. This finding contrasts with low ratios in black smoker-type hydrothermal systems that occur within spreading segments. Near-bottom water sampling coordinated with SeaBeam bathymetry and camera-temperature tows detected the highest concentrations of methane at fault zones in rocks with the appearance of altered ultramafic units in a large dome that forms part of the inside corner high at the intersection. The distinct chemical signatures of the two types of hydrothermal systems are inferred to be controlled by different circulation pathways related to reaction of seawater primarily with ultramafic rocks at intersections of spreading segments with fracture zones but with mafic rocks within spreading segments.

Smith, S.D., R.J. Anderson, W.A. Oost, C. Kraan, N. Maat, J. DeCosmo, K.B. Katsaros, K.L. Davidson, K. Bumke et al. Sea surface wind stress and drag coefficients: The HEXOS results. Boundary-Layer Meteorology, 60(1-2):109-142 (1992).

Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October-November 1986. We started out to study eddy flux of water vapor, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.

Thacker, W.C. Oceanographic inverse problems. Physica D, 60:16-37 (1992).

Oceanographic inverse problems are generalizations of the concept of linear regression to encompass the fitting of numerical models based on the partial-differential equations of fluid dynamics to oceanic data by adjusting surface fluxes, initial conditions, and/or transport parameters. The limited resolution of the data requires some sort of regularizing assumptions similar to those needed for spatial interpolation. Computationally, they are nonlinear-least-squares problems involving very many variables. These problems can be ill-conditioned due to the indirect nature of the observations, to the way the dynamics enter, and to the effect of the regularizing assumptions. Solving such large optimization problems requires efficient computation of derivatives of functions defined by computational codes. The adjoint method provides derivatives with respect to all the code's many adjustable inputs for roughly the same cost as computing a single model simulation. Although computationally difficult, model fitting offers the promise of dynamically consistent multivariate analyses of oceanographic data.

Trefry, J.H., R.P. Trocine, S. Metz, T.A. Nelsen, and N. Hawley. Suspended particulate matter on the Louisiana shelf: Concentrations, composition and transport pathways. Proceedings, NECOP Workshop on Nutrient Enhanced Coastal Ocean Productivity, Chauvin, LA, October 2-3, 1991. Texas A&M University Press, College Station, 126-130 (1992).

The concentrations, composition and transport pathways of suspended particulate matter and particulate organic carbon (POC) have a direct bearing on the development and persistence of shelf hypoxia, as well as on the global cycling of carbon. More than 120 CTD-transmissometer profiles and >400 particle samples were collected from the Mississippi River and adjacent Gulf of Mexico on cruises during July-August 1990 and February 1991. River-flow is a dominant factor in controlling particle distributions; however, time-series data show that tides and weather fronts can greatly influence concentrations and movement of suspended matter. Results from chemical analyses show that concentrations of POC range from >80 µmol/L (>1 mg/L) at near river locations to <0.8 µmol/L (<0.01 mg/L) in some deep offshore waters. The organic fraction of the suspended matter increases from <5% of the total mass near the river mouth to >90% along the shelf at about 10 km from the river. The C/N molar ratio in suspended particles from throughout the shelf is near uniform at 6. Plumes of particle-rich water at outer shelf depths of about 100 m, along with transport in near-bottom nepheloid layers, carry a POC burden that can be traced tens of kilometers offshore.

Tsai, J.J., J.R. Proni, W.P. Dammann, and N.C. Kraus. Dredged material disposal at the edge of the Florida Current. Chemistry and Ecology, 6:169-187 (1992).

A field data collection project was undertaken to investigate the short-term fate of dredged material discharged in the designated Miami Ocean Dredged Material Disposal Site (ODMDS) before dredging of the Miami River and the Miami Harbor Turning Basin begins. The designated ODMDS is located in relatively deep water for discharge sites with typical bottom depth of 150 m and is also located in the western boundary region of the Gulf Stream current off Miami. Acoustical backscattering, current, particulate, temperature, and salinity data were gathered over a three-day period from April 24, 1990 through April 26, 1990. The major generic features of shallow-water discharge plumes were observed to be present: (a) the presence of a rapid convective descending plume portion; (b) impact of that plume portion with the ocean bottom and concomitant generation of bottom surge; (c) rapid horizontal width growth of the descending plume through entrainment; and (d) retention of a residual plume portion within the water column. A well-mixed upper water column layer extending to a depth of 40 to 60 m below the surface of the ocean permitted measurements of the plume entrainment coefficient free from bottom boundary, water column density gradient, and vertical current shear effects which are usually present in relatively shallow, e.g., less than 40 m bottom depth, coastal ocean discharge studies. Entrainment coefficient estimates obtained in this study were between 0.5 to 0.7. The residual water plume material was tracked over one-half hour during each of eight discharge events and was transported in a north-northeast direction.

Tziperman, E., W.C. Thacker, R.B. Long, and S.-M. Hwang. Oceanic data analysis using a general circulation model. Part 1: Simulations. Journal of Physical Oceanography, 22(12):1434-1457 (1992).

This paper deals with the solution of inverse problems involving complex numerical models of the oceanic general circulation and large data sets. The goal of these inverse problems is to find values for model inputs consistent with a steady circulation and, at the same time, consistent with the available data. They are formulated as optimization problems, seeking values for the model's inputs that minimize a cost function measuring departure from steady state and from data. The two main objectives of this work are (1) to examine the feasibility of solving inverse problems involving a realistic numerical model of the oceanic general circulation, and (2) to understand how the optimization uses various data to calculate the desired model parameters. The model considered here is similar to the primitive equations model of Bryan (1969) and of Cox (1984), the principal difference being that here the horizontal momentum balance is essentially geostrophic. The model's inputs calculated by the optimization consist of surface fluxes of heat, water, and momentum, as well as the eddy-mixing parameters. In addition, optimal estimates for the hydrography are obtained by requiring the hydrography to be consistent with both other types of data and the model's dynamics. In the examples presented here, the data have been generated by the model from known inputs; in some cases simulated noise has been added. The cost function is a sum of terms quadratic in the differences between the data and their model counterparts and terms quadratic in the temperature and salinity time rate of change as evaluated using the model equations. The different inverse problems considered differ in the choice of the model inputs calculated by the optimization and in the data used in the cost function. Optimal values of the model's inputs are computed using a conjugate-gradient minimization algorithm, with the gradient computed using the so-called adjoint method. In examples without added noise, solutions for the model inputs were found efficiently and accurately. This was not the case when simulated data with randomly generated noise were used. Amplification of noise was especially felt in regions of deep water formation due to the strong vertical mixing in these regions. Away from deep water formation regions, the performance of the optimization with noisy data was still not satisfactory, possibly due to bad conditioning of the problem. The conditioning of the optimization and the difficulties due to the noise amplification are further discussed in part 2 of this work using real oceanographic data for the North Atlantic Ocean.

Tziperman, E., W.C. Thacker, R.B. Long, S.-M. Hwang, and S.R. Rintoul. Oceanic data analysis using a general circulation model, Part 2: A North Atlantic model. Journal of Physical Oceanography, 22(12):1458-1485 (1992).

A general circulation model (GCM) and North Atlantic climatological data of temperature, salinity, wind stress, evaporation minus precipitation, and air-sea heat fluxes are used to examine the possibility of solving inverse problems using a full-scale numerical GCM and real oceanographic data, combined through an optimization approach. In this study several solutions for the model inputs and the structure of the cost function as a function of the model inputs are examined to demonstrate two of the main difficulties confronting such large-scale nonlinear inverse problems (about 30,000 unknowns and a similar number of constraints for the problem examined here). The first is the possible existence of local minima of the cost function, which prevents the convergence of the optimization to the global minimum representing the desired optimal solution for the model inputs. The second difficulty, which seems the dominant one for many of the problems examined in this part as well as in part 1, is the ill conditioning of the inverse problem. Simple model equations are used to analyze the conditioning of the optimization problem and to analyze the role of both dissipation and waves in the model dynamics in conditioning the problem. The analysis suggests what might be an improved formulation of the cost function resulting in better conditioning of the problem. The relation between the optimization approach and the robust diagnostic method of Sarmiento and Bryan (1982) is explicitly demonstrated, and the solution obtained by combining the two methods is used to examine the performance of the GCM used here for the North Atlantic Ocean.

Wanninkhof, R.H. Relationship between gas exchange and wind speed over the ocean. Journal of Geophysical Research,97:7373-7381 (1992).

Relationships between wind speed and gas transfer, combined with knowledge of the partial pressure difference of CO₂ across the air-sea interface are frequently used to determine the CO₂ flux between the ocean and the atmosphere. Little attention has been paid to the influence of variability in wind speed on the calculated gas transfer velocities and the possibility of chemical enhancement of CO₂ exchange at low wind speeds over the ocean. The effect of these parameters is illustrated using a quadratic dependence of gas exchange on wind speed which is fit through gas transfer velocities over the ocean determined by the natural-¹⁴C disequilibrium and the bomb-¹⁴C inventory methods. Some of the variability between different data sets can be accounted for by the suggested mechanisms, but much of the variation appears due to other causes. Possible causes for the large difference between two frequently-used relationships between gas transfer and wind speed are discussed. To determine fluxes of gases other than CO₂ across the air-water interface, the relevant expressions for gas transfer, and the temperature and salinity dependence of the Schmidt number and solubility of several gases of environmental interest, are included in an appendix.

Willis, P.T., J. Hallett, and R.A. Black. Cloud and hydrometeor microphysics at -3°C in a vigorous Florida convective updraft. Preprints, 11th International Conference on Clouds and Precipitation, Montreal, Canada, August 17-21, 1992. American Meteorological Society, Boston, 436-439 (1992).

No abstract.

Willoughby, H.E. Linear motion of a shallow-water barotropic vortex as an initial-value problem. Journal of the Atmospheric Sciences, 49(21):2015-2031 (1992).

This paper revisits calculation of motion for a shallow-water barotropic vortex with fixed mean axisymmetric structure. The algorithm marches the linear primitive equations for the wavenumber 1 asymmetry forward in time using a vortex motion extrapolated from previous calculations. Periodically, it examines the calculated asymmetry for the apparent asymmetry due to mispositioning of the vortex center, repositions the vortex to remove the apparent asymmetry, and passes the corrected vortex motion on to the next cycle. This approach differs from the author's earlier variational determination of the steady-state motion after initial transients had died away. The steady-state approach demonstrated that the vortex had normal modes at zero frequency and, when an annulus of weak anticyclonic flow encircled the cyclonic inner vortex, at the most anticyclonic rotation frequency of the mean flow. Forcing of the former model led to too rapid steady-state poleward motion on a beta plane. At least for the linear problem, the key to more realistic simulation of motion and structure is the normal modes' transient response to diverse forcing: environmental potential vorticity gradients, embedded sources and sinks of mass, and initial asymmetries. The beta effect and other environmental potential vorticity gradients excite the normal modes to induce an acceleration of the vortex center toward and to the left of the direction to maximum environmental vorticity. Times ~100 days would be required to reach the too fast motions predicted in the earlier work. A rotating mass source-sink pair drives the vortex along a cycloidal track, but does not force the normal modes. A nonrotating source-sink forces a motion from the source toward the sink and excites the normal modes, leading to motion that persists after the forcing has ceased. Similarly, initial asymmetries that project onto the normal modes maintain themselves for times >10 days, leading to persistent vortex propagation that evolves as the complex normal-mode frequencies dictate. Understanding of these normal modes can contribute to better tropical cyclone motion forecasts through better initialization of numerical track prediction models.

Wilson, W.D., and E. Johns. Shipboard ADCP current measurements in the North Brazil Current retroflection region. EOS, Transactions, American Geophysical Union, 72(51):21 (1992).

No abstract.

Yvon, S.A., E.S. Saltzman, and D.J. Cooper. Measurements of atmospheric DMS, SO₂ and H₂S over the equatorial Pacific Ocean during IGAC/MAGE. EOS, Transactions, American Geophysical Union, 73(43):81 (1992).

No abstract. **1991**

Aberson, S.D., and M. DeMaria. A nested barotropic hurricane track forecast model (VICBAR). Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 81-86 (1991).

No abstract.

Barnes, G.M., J.F. Gamache, M.A. LeMone, and G.J. Stossmeister. A convective cell in a hurricane rainband. Monthly Weather Review, 119(3):776-794 (1991).

On 10 October 1983 the two NOAA WP-3D aircraft completed a mision designed to provide airborne Doppler radar data for a convective cell embedded in a weak rainband on the trailing side of Hurricane Raymond. Comparisons of the wind field produced from the pseudo-dual Doppler radar technique with in-situ wind measurements suggest that the larger convective-scale features may be resolved if the sampling time is kept to a minimum. The convective cell was found to move downband faster than any environmental winds, but slightly slower than the winds found in the reflectivity core that delineates the cell. In the core of the cell the tangential wind is increased and the radial inflow turns to outflow with respect to the circulation center. The flow field demonstrates that the downband stratiform portion of a rainband is not from cells currently active, since the updraft detrains upwind relative to the cell, but rather it is due to the fallout from ice particles placed into the upper troposphere by clouds that have since dissipated. The mass flux of this cell is estimated to be 5%-10% of the mass flux accomplished by an eyewall of a moderate tropical cyclone. This finding supports the concept that large, convective-active rainbands have a major effect on the subcloud layer air flowing toward the eyewall.

Barnes, G.M., and M.D. Powell. The inflow thermodynamics of Hurricane Gilbert. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 486-489 (1991).

No abstract.

Beryulev, G.P., P.B. Black, and A.V. Litinetski. Intercomparison of wind and temperature data from the research aircraft WP-3D and AN-12BC in Hurricane Gilbert, 1988. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 587-588 (1991).

No abstract.

Black, M.L., R.W. Burpee, and F.D. Marks. Vertical motions in tropical cyclones determined with airborne Doppler radial velocities. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 409-411 (1991).

No abstract.

Black, P.B., and F.D. Marks. The structure of an eyewall meso-vortex in Hurricane Hugo (1989). Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 579-582 (1991).

No abstract.

Broecker, W.S., A. Virgilio, and T.-H. Peng. Radiocarbon age of the deep Atlantic revisited. Geophysical Research Letters, 18(1):1-3 (1991).

No abstract.

Brown, M.G., F.D. Tappert, and G.J. Goni. An investigation of sound ray dynamics in the ocean volume using an area preserving mapping. Wave Motion, 14(1):93-99 (1991).

An area preserving mapping which describes sound ray propagation in a simple range-dependent model of the ocean sound channel is derived and studied. The unbounded ocean model has a bilinear sound speed profile in which the vertical sound speed gradient above the sound channel axis varies sinusoidally in range. It is assumed that the scale of the range-dependent perturbation is small compared to a typical upper loop length of a ray. The explicit mapping which results gives successive iterates of range and upgoing ray angle at the sound channel axis (r_n, theta_n) - (r_n+1, theta_n+1). The degree of stochasticity of the mapping is governed by a single dimensionless parameter, epsilon, the strength of the range-dependent perturbation. Iterates of the mapping indicate that some ray trajectories are chaotic (i.e., exhibit extreme sensitivity to initial conditions) for perturbations comparable in strength to those produced by internal waves in the ocean. The chaotic nature of these rays is confirmed by the calculation of positive Lyapunov exponents.

Burpee, R.W., and P.G. Black. Strong surface winds and mesoscale convective systems in the unnamed tropical storm of 1987. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 412-415 (1991).

No abstract.

Burpee, R.W., J.S. Griffin, J.L. Franklin, and F.D. Marks. Airborne analysis of observations from a NOAA P-3 in support of operational hurricane forecasting. Preprints, 7th International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 195-197 (1991).

No abstract.

Burpee, R.W., J.S. Griffin, J.L. Franklin, and F.D. Marks. Airborne analysis of observations from a P-3 aircraft in support of operational hurricane forecasting. Proceedings, 4th Interagency Airborne Geoscience Workshop, La Jolla, CA, January 29-February 1, 1991. NASA, Washington, D.C., 123-124 (1991).

No abstract.

Carsey, T.P. Marine tropospheric hydrocarbons: An intercomparison exercise. NOAA Data Report, ERL AOML-21 (PB91-223735), 31 pp. (1991).

No abstract.

Carsey, T.P., M.S. Gallagher, M.L. Farmer, and C.S. Moore. PAN in the equatorial Pacific boundary layer. EOS, Transactions, American Geophysical Union, 72:107 (1991).

No abstract.

Charlou, J.L., H. Bougault, P. Appriou, T.A. Nelsen, and P.A. Rona. Different TDM/CH₄ hydrothermal plume signatures: TAG site 26°N and serpentinized ultrabasic diapir at 15°05'N on the Mid-Atlantic Ridge. Geochimica et Cosmochimica Acta, 55(12):3209-3222 (1991).

As a part of the 1988 NOAA VENTS Program, CH₄ and Mn tracers were used to identify and compare hydrothermal plumes found above the TAG field (26°N) and in the rift valley at 15°N close to the eastern intersection of the ridge axis with the 15°20'N Fracture Zone at the Mid-Atlantic Ridge (MAR). Active hydrothermal venting was confirmed at TAG, based on elevated concentrations of total dissolved Mn (TDM up to 30 nmol/kg), high CH₄ concentrations (up to 200 nL/L), and elevated nephelometry signals. Plumes of a different composition were identified at 15°N with high CH₄ concentrations (up to 400 nL/L), low total dissolved Mn concentrations (TDM <1 nmol/kg), and no significant nephelometry signal. The different properties of these tracers and the different tracer ratios can be used to deduce vent fluid characteristics and compare one hydrothermal area to another. TDM/CH₄ and nephel/CH₄ ratios at TAG are of the same order of magnitude as those observed at other spreading axis hydrothermal fields. At 15°N, the low TDM/CH₄ ratio provides evidence of fluid circulation into ultrabasic rocks and offers a potentially useful and single method of exploring for hydrothermal activity associated with serpentinization. Mantle degassing through hydrothermal activity associated with serpentinization is an important process with respect to chemical and thermal exchanges between the upper mantle and the ocean. Different ratios of hydrothermal tracers (i.e., TDM/CH₄) provide a useful framework for identifying subseafloor processes along mid-oceanic ridges.

Cione, J.J., S. Raman, and L.J. Pietrafesa. Effects of marine boundary layer baroclinicity induced by the Gulf Stream on east coast winter storms. Preprints, 5th Conference on Meteorology and Oceanography of the Coastal Zone, Miami, Florida, May 6-9, 1991. American Meteorological Society, Boston, 113-117 (1991).

No abstract.

Dammann, W.P., J.R. Proni, J.F. Craynock, and R. Fergen. Oceanic wastewater outfall plume characteristics measured acoustically. Chemistry and Ecology, 5:75-84 (1991).

A study, called SEFLOE, of the dispersion characteristics of several wastewater outfalls was conducted off the coast of southeast Florida (USA). In this study, the feasibility of utilizing high frequency (20 kHz and 200 kHz) acoustic echoes to characterize the dilution characteristics of the effluent wastewater was examined. It is hypothesized that the background corrected acoustic backscattered intensity may be used to guide chemical/biological sampling, and that one or more plume subfields may be revealed by the scattering strength field. Data from SEFLOE have indicated that the wastewater plume field is divided into regions of higher concentration spatially separated by regions of lower concentration; we call these regions of higher concentration "boluses." When the water column is density stratified, subsurface plumes may peel off of the main rising plume and remain at equilibrium on a density gradient.

DeMaria, M., and R.W. Jones. Optimization of a hurricane track forecast model using the adjoint model equations. Preprints, 9th Conference on Numerical Weather Prediction, Denver, CO, October 14-18, 1991. American Meteorological Society, Boston, 547-550 (1991).

No abstract.

DeMaria, M., and J. Kaplan. A statistical model for predicting tropical cyclone intensity change. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 521-525 (1991).

No abstract.

Dodge, P.P., R.W. Burpee, and F.D. Marks. Airborne Doppler radar analyses of the core of Hurricane Gilbert. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 551-552 (1991).

No abstract.

Enfield, D.B., and L. Cid. Low-frequency changes in El Niño/Southern Oscillation. Journal of Climate, 4:1137-1146 (1991).

Although there are indications from numerical models that El Niño/Southern Oscillation (ENSO) may be an internal mode of the coupled Pacific Ocean/atmosphere system, sensitive to climatic background parameters, it has not yet been possible to find significant changes in ENSO variability between the Little Ice Age and the present. Yet, a number of authors have found qualitative indications in anecdotal and proxy records of shorter, century-scale variations in the return-interval statistics for El Niño episodes. To objectively determine what nonstationarities exist, we statistically examine the El Niño occurrences since 1525, compiled by Quinn et al. (1987). We have stratified the return intervals both for strong events and for all events according to two null hypotheses: (1) return intervals are stationary over periods of 200-500 years; and (2) the intervals are stationary on a centenary time scale, between epochs of contrasting solar variability. Two-parameter Weibull distributions are fit to subsamples of the data using an optimized bootstrap procedure, and the scale parameters are compared between groups. At the 95% significance level, only the null hypothesis for high/low solar levels and strong El Niño events can be rejected. The corresponding hypothesis for all events rejects at the 90% level, while overall stationarity cannot be rejected at any reasonable level, for either class of events. The significant results are that: (a) the El Niño recurrence rate is stationary with respect to long-term climate changes; (b) return intervals of strong El Niño events are significantly nonstationary at centenary time scales; and (c) events of all intensities exhibit the same nonstationarity but less clearly. There is too little data to reject the possibility that the association with solar epochs is coincidental; however, we have advanced this hypothesis to explain such a connection.

Feuer, S.E., and J.L. Franklin. Nested analyses of Hurricane Gloria from dropwindsonde and Doppler radar data. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 130-133 (1991).

No abstract.

Frazel, D.W., G.A. Berberian, J. McElroy, and G.L. Hitchcock. Radiatively Important Trace Species (RITS) 1990: Tropical Pacific Ozone Minimum Expedition--nutrient, chlorophyll-a, and primary productivity data. NOAA Data Report, ERL AOML-19 (PB91-178087), 40 pp. (1991).

During the period of January 3-February 18, 1990, a multifaceted oceanographic research cruise called the RITS 1990 Tropical Pacific Ozone Minimum Expedition was made on the NOAA ship Malcolm Baldrige in the equatorial Pacific Ocean. The objective of the cruise was to study processes controlling radiatively important trace species in the region of the tropical Pacific ozone minimum in the central equatorial Pacific Ocean. Measurements from hydrocasts for nutrients, phytoplankton biomass, and primary productivity were made during this period. This report represents the hydrographic, nutrient, and biological data from this cruise.

Friedman, H.A., and C.A. Arnhols. 1991 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 118 pp. (1991).

No abstract.

Gamache, J.F. Inner core budget studies of Hurricane Norbert (1984). Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 545-550 (1991).

No abstract.

Gamache, J.F., F. Roux, and F.D. Marks. Comparison of three methods to deduce three-dimensional wind fields in a hurricane with airborne Doppler radar. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 462-465 (1991).

No abstract.

Goni, G.J. Chaos in underwater acoustics. In Ocean Variability and Acoustic Propagation, J. Potter and A. Warn-Varnas (eds.). Kluwer Academic Publishers, The Netherlands, 139-160 (1991).

No abstract.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Potential forecast skill for Atlantic seasonal hurricane variability. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 89-95 (1991).

No abstract.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Strong extended range seasonal predictive potential for Atlantic hurricane activity. Proceedings, 16th Annual Climate Diagnostics Workshop, Los Angeles, CA. NOAA, 412-416 (1991).

No abstract.

Griffin, J.S., R.W. Burpee, J.L. Franklin, and F.D. Marks. Preliminary results of airborne analysis of observations in support of operational hurricane forecasting. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 144-147 (1991).

No abstract.

Houston, S.H., and M.D. Powell. Effects of Tropical Storm Marco (1990) on Florida's west coast. Preprints, 5th Conference on Meteorology and Oceanography of the Coastal Zone, Miami, FL, May 6-9, 1991. American Meteorological Society, Boston, 131-133 (1991).

No abstract.

Jones, R.W., and M. DeMaria. A variational method for including persistence in a hurricane track forecast model. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 331-334 (1991).

No abstract.

Kaplan, J., and J.L. Franklin. The relationship between the motion of Tropical Storm Florence (1988) and its environmental flow. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 93-97 (1991).

No abstract.

Lagos, P., D.V. Hansen, and A. Herman. Climatological atlas of the subsurface thermal structure of the eastern tropical South Pacific Ocean. NOAA Technical Report, ERL 444-AOML-34, 303 pp. (1991).

Monthly climatological maps of objectively analyzed fields of temperature are presented at standard oceanographic observation levels from the surface to 300 m depth on a 1° latitude-longitude grid in the region between the equator and 20°S and between the South American coast and 90°W. The temperature data used in this study were from bathythermograph measurements obtained from 1952 to 1987 from Peruvian and other research vessels; they were made available by research institutions in Peru and the United States and by the National Oceanographic Data Center and the Fleet Numerical Oceanographic Center. The data set was blended with recent data to form a data base containing 14,000 observations. The method of analysis consists of optimally interpolating the value at each mapping grid point, using observations taken at known nearby locations. This method, known as Kriging, is a best linear unbiased estimator that also yields an estimate of the uncertainty of each interpolated value. A brief discussion of the major characteristic features of the temperature fields is given, including a comparison of the SST results with results from other SST climatologies.

Landsea, C.W. Intense Atlantic hurricanes and their concurrent/predictive relationships to west African rainfall. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 165-169 (1991).

No abstract.

Landsea, C.W. West African monsoonal rainfall and intense hurricane associations. Colorado State University, Department of Atmospheric Science Paper No. 484, 272 pp. (1991).

No abstract.

Landsea, C.W., and W.M. Gray. Concurrent multidecadal variations of west African monsoonal rainfall and intense Atlantic hurricane activity. Extended Abstracts, 5th Conference on Climate Variations, Denver, CO. American Meteorological Society, Boston, 38-41 (1991).

No abstract.

Landsea, C.W., and W.M. Gray. Predictability of intense Atlantic hurricanes and western Sahel rainfall from west African rainfall. Proceedings, 16th Annual Climate Diagnostics Workshop, Los Angeles, CA. NOAA, 417-422 (1991).

No abstract.

Lee, W.-C., and F.D. Marks. Real-time display of mean three-dimensional hurricane structure using the VTD technique. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 470-473 (1991).

No abstract.

Lee, W.-C., F.D. Marks, and R. Carbone. Real-time display of mean three-dimensional hurricane structure using the VTD technique. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 445-450 (1991).

No abstract.

Lhermitte, R., and P.T. Willis. Small Doppler radar as a precipitation gauge. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 778-781 (1991).

No abstract.

Marks, F.D., and R.A. Houze. Kinematic structure of the eyewall of Hurricane Emily (1987) as determined from an airborne Doppler radar. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 437-440 (1991).

No abstract.

Marks, F.D., D. Atlas, and P.T. Willis. Probability matched Z-R relations for hurricanes from aircraft observations. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 778-781 (1991).

No abstract.

Mayer, D.A., and G.A. Maul. Refinement of the statistical relationship between Straits of Florida sea level difference and Florida-Bahamas cable voltages. Journal of Geopysical Research, 96(C3):4971-4972 (1991).

Analyses of a composite 6.5-year record of Bahamas minus Miami sea level difference (SLD) and Florida-Bahamas volume transport determined from submarine cable voltages (CABLE) support the hypothesis advanced by Maul et al. (1990) that SLD is the better variable for monitoring volume transport than western side sea level alone. In the subseasonal frequency band BW1 (393^-1- 182^-1 cycles per day), modeled CABLE, when using SLD, accounts for 79% of the variance of observed CABLE. Further, the phase relationships of modeled CABLE with respect to SLD in BW1 represent approximately a simple time shift in that SLD leads CABLE by a little more than two weeks.

McMurdie, L.A., and K.B. Katsaros. Satellite-derived integrated water-vapor distribution in oceanic midlatitude storms: Variation with region and season. Monthly Weather Review, 119(3):589-605 (1991).

With the atmospheric water-vapor content information available from the SEASAT and Nimbus-7 Scanning Multichannel Microwave Radiometers (SMMR), differences in water-vapor distribution between cyclonic storms in different regions of the global ocean can be examined in more detail than previously possible from radiosondes. SMMR-derived integrated water vapor is a robust and dependable variable of the same accuracy as integrated radiosonde soundings. In this study, maximum and minimum water-vapor content in the vicinity of cold fronts of 80 storms that occurred in the North Atlantic, North Pacific, and Southern oceans are compared. North Atlantic storms were found to have significantly higher maximum and minimum water-vapor content near cold fronts on average than North Pacific or Southern ocean storms for both the warm and cold seasons. These differences are attributed to warmer sea surface temperatures and air temperatures in the North Atlantic, and higher baroclinity and consequently stronger upward motion in North Atlantic storms. Additionally, some of the differences may be attributed to the fact that the North Atlantic storms generally occur at lower latitudes than the storms in the other regions. Furthermore, the North Pacific storms were found to have significantly higher maximum and minimum water-vapor content near cold fronts on average than the Southern Ocean storms for both the warm and cold seasons. These differences are attributable to warmer sea surface temperatures in the North Pacific during the warm season, and to less moisture transport by Southern Ocean storms and the poleward location of the Southern Ocean storms compared to North Pacific storms during the cold season. Two examples of water-vapor content in a South Atlantic storm are given to contrast with the Southern Ocean cases. The South Atlantic storm had much higher maximum water-vapor content near the cold front than most Southern Ocean storms (DBO).

McPhaden, M.J., D.V.Hansen, and P.L. Richardson. A comparison of ship drift, drifting buoy, and current meter mooring velocities in the Pacific South Equatorial Current. Journal of Geophysical Research, 96(C1):775-781 (1991).

In this note we compare mean seasonal cycles of zonal and meridional velocity in the Pacific South Equatorial Current based on current meter mooring data, drifting buoy data, and ship drift data. Monthly averages of ship drift and drifting buoy data were computed over 2° latitude by 10° longitude rectangles centered at the positions of multiyear current meter moorings near 0°, 110°W, and 0°, 140°. All three representations of the flow field show the basic character of the annual mean and its variations, provided that the sampling characteristics associated with each measurement technique are taken into account. In particular, we find that more than 15 days of drifter data (regardless of year) are required on a 2° latitude by 10° longitude basis to produce monthly mean estimates that agree with moored estimates to within about 5-10 cm s^-1 rms. We also infer that windage affects climatological monthly mean ship drift velocities, although uncertainties in the data limit a precise determination of the windage magnitude. An upper bound appears to be about 3% of the surface wind speed, though the actual effect of windage may be considerably smaller.

Nelsen, T.A., and E.B. Forde. The structure, mass, and interactions of the hydrothermal plumes at 26°N on the Mid-Atlantic Ridge. Earth and Planetary Science Letters, 106:1-16 (1991).

Water-column surveys by combined nephelometer/CTD (NCTD) tows contributed to the 1985 discovery of the first black smokers on the Mid-Atlantic Ridge. Subsequent regional water-column mapping has helped define the extent, mass, and interactions of the suspended particulate matter phase (SPM) of the hydrothermal plumes emanating from the known and other nearby sources. The results of 29 NCTD cast/tows, covering 23-30 km² of ridge segment, indicate the presence of as many as two additional sources based on SPM concentration gradients and plume-top doming over source areas. Plume doming, documented here for the first time from field observations, conforms strikingly with laboratory experiments and can serve as a marker for source field location. A comparison of the plumes' SPM with potential temperature and salinity distributions indicates close correlation in water-column anomaly patterns for each, confirming modification of the regional potential temperature and salinity structure for hydrothermal plumes, which is expressed by wide separation and sloping of isotherms and isohalines.

Ooyama, K.V. A dynamic test of the diagnostic pressure calculation. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 171 (1991).

No abstract.

Oxburgh, R., W.S. Broecker, and R.H. Wanninkhof. The carbon budget of Mono Lake. Global Biogeochemical Cycles, 5:359-372 (1991).

Radiocarbon measurements suggest that ¹⁴C-free carbon enters from beneath Mono Lake at a rate of about 1 mol/m²/yr. An input of this magnitude should be manifested in the inorganic carbon budget of the lake and, with this in mind, we have devised a model to reconstruct the evolution of the partial pressure of CO₂ (pCO₂) over the past 150 years. This encompasses a period (1945 to present) during which major diversions of source water via the Los Angeles aqueduct have been in effect, significantly increasing the salinity of the lake, and hence its pCO₂. The model has been constrained by experimental characterization of the carbonate chemistry of the lake water, by the temperature dependence of pCO₂ for the lake water, and by pCO₂ measurements made on the lake water in 1966, 1969, 1981, and 1989. Our calculations suggest that prior to 1945 the pCO₂ of about 3.3 mol/m²/yr is required. Volcanic activity beneath the lake is a probable source of this input.

Palmer, D.R., T.M. Georges, and R.M. Jones. Classical chaos and the sensitivity of the acoustic field to small-scale ocean structure. Computer Physics Communications, 65:219-233 (1991).

Ray theory is usually the basis of data inversion schemes for acoustic remote sensing of the ocean. Chaotic ray paths are expected to be present whenever the ocean environment possesses small-scale, range-dependent structure. We are studying the implications of their presence for data inversion schemes. Using numerical simulations we consider ray-path characteristics for acoustic remote sensing of the Florida Current. We find small-scale bathymetric structure results in chaotic ray paths and an exponential proliferation of eigenrays. As a result, for each feature in the time-of-arrival pattern, there is associated not a single eigenray but a group, thereby limiting the spatial resolution of a remote sensing system.

Peng, T.-H. Indication of changes in ocean ventilation rates in ¹⁴C/¹²C record of tree-ring and of deep sea sediment. Proceedings, Interaction of the Global Carbon and Climate Systems Symposium, Lake Arrowhead, California, October 24-28, 1988. University of California, 15-1-15-12 (1991).

No abstract.

Peng, T.-H. Oceanic CO₂ uptake and future atmospheric CO₂ concentration. In Air-Water Mass Transfer: Selected Papers from the Second International Symposium on Gas Transfer at Water Surfaces. ASCE, New York, 618-636 (1991).

The global pattern of water column inventories of bomb-produced ¹⁴C suggests that an upwelling of bomb ¹⁴C-free water takes place in the Antarctic, northern Pacific, and equatorial regions, whereas a downwelling of bomb ¹⁴C-rich surface waters occurs in the temperate oceans and northern Atlantic. A global model of the closed ocean- atmosphere system is constructed on the basis of these dynamic flows for the purpose of estimating the oceanic uptake of excess CO₂. To produce a close match between the historical pattern of atmospheric CO₂ predicted by the model and that observed in the Siple ice core and the Mauna Loa record requires that a net release of 90 × 10¹⁵ g of carbon from the terrestrial ecosystem be posited for the period 1800- 1990, in addition to fossil fuel CO₂ input. It is estimated that the ocean takes up, on average 2.4-2.6 × 10¹⁵ g of anthropogenic carbon each year. This net flux of CO₂ into the ocean is equivalent to 44% of the estimated total for anthropogenic CO₂ emissions. The model uses four scenarios of future CO₂ emissions from fossil fuel consumption and tropical deforestation to predict atmospheric CO₂ concentrations. Although the resulting patterns of predicted CO₂ levels are similar to those in the report given by the Intergovernmental Panel on Climate Change (IPCC), the uptake of CO₂ from fossil fuel in the model is more efficient than that in the general box-diffusion models used by IPCC; that is, all predictions from the model are lower than those given by IPCC.

Peng, T.-H., and W.S. Broecker. Dynamical limitations on the Antarctic iron fertilization strategy. Nature, 349(6306):227-229 (1991).

Martin et al. have proposed an ingenious means by which the rise in atmospheric CO₂ content generated by the burning of fossil fuels and deforestation might be partially compensated. The idea is that plant production in the nutrient-rich surface waters of the Antarctic could be stimulated by the addition of dissolved iron, thereby reducing the CO₂ partial pressure in these waters and allowing CO₂ to flow from the atmosphere into the Antarctic Ocean. We have used a box model calibrated with transient tracer data to examine the dynamical aspects of this proposal, and conclude that after 100 years of totally successful fertilization the CO₂ content of the atmosphere would be lowered by only 10 ± 5% below what it would have been in the absence of fertilization. So if after 100 years the CO₂ content of the atmosphere were 500 µatm without fertilization, it would be between 425 and 475 µatm with full fertilization. In other words, if our model calibration is correct, even if iron fertilization worked perfectly it would not significantly reduce the atmospheric CO₂ content.

Peng, T.-H., and W.S. Broecker. Factors limiting the reduction of atmospheric CO₂ by iron fertilization. Limnology and Oceanography, 36(8):1919-1927 (1991).

A limit on the reduction in atmospheric CO₂ partial pressure (pCO₂) in the next century resulting from purposeful Fe fertilization of the Antarctic Ocean is estimated with an advection-diffusion model calibrated with transient tracer distributions. To evaluate the possible increase in atmospheric CO₂ with and without fertilization, we adopt a "business-as-usual" scenario of anthropogenic CO₂ emission. Such increase is computed from the atmospheric pCO₂ in the ocean-atmosphere total C system as it responds to this emission scenario. Assuming completely successful Fe fertilization, we calculate an 8% atmospheric CO₂ reduction for a case with a 3 cm² s^-1 vertical diffusivity and 17.4 Sv upwelling flux, as derived from distribution of bomb-¹⁴C in the ocean. Hence, if atmospheric pCO₂ reaches 800 µatm in the next century, the maximum possible reduction is ~64 µatm. Doubling of upwelling flux to 34.8 Sv results in a reduction of 96 µatm. If we assume the surface area of the Antarctic Ocean is 16% of the total ocean area instead of 10% as used in the standard case, the reduction is ~71 µatm. These results are independent of the respiration function adopted. As we hold the surface water PO₄ content at a near-zero value, it makes no difference at what depth the organic material is oxidized (or whether it falls to the bottom and accumulates). Changes in the gas exchange rate over the Antarctic Ocean also do not have a significant effect on the magnitude of atmospheric CO₂ drawdown. Doubling the gas exchange rate in the Antarctic region after fertilization results in a reduction of 68 µatm. Doubling of vertical diffusivity to 6 cm² s^-1 in Antarctic deep water yields a reduction of 75 µatm. The key parameters are the rate of upwelling in the Antarctic and the fate of this upwelled water. The length of the productive season influences the extent of pCO₂ reduction. For 8 months of productive fertilization our model yields a reduction of 60 µatm, for 4 months a reduction of 50 µatm, and for 2 months a reduction of 40 µatm. The maximum O₂ consumption in our standard case is estimated to be 133 µmol kg^-1 at a depth of 600 m. However, O₂ consumption depends on the reoxidation function in the subsurface water. If the organic flux reoxidizes completely in the upper 2000 m, the maximum consumption of O₂ at 500 m could teach 500 µmol kg^-1. Hence, depending on the reoxidation function, an anoxic Antarctic thermocline could result from Fe fertilization. Both calculations regarding the seasonality of production and those regarding oxygen reduction are highly sensitive to parameters over which we have little control. They are included only to emphasize their potential importance.

Piotrowicz, S.R., H.F. Bezdek, G.R. Harvey, M. Springer-Young, and K.J. Hanson. On the ozone minimum over the equatorial Pacific Ocean. Journal of Geophysical Research, 96(D10):18,679-18,687 (1991).

Since 1977, several ship and aircraft expeditions to the equatorial Pacific have reported extremely low (10 ppbv) or undetectable levels of ozone within the marine boundary layer. Of necessity, field programs from mobile platforms are limited in both their temporal and spatial coverage. However, a 10-year record of observations at the geophysical monitoring for climatic change site in American Samoa suggests that low ozone mixing ratios are a common occurrence and may reflect a spatially variable but permanent region of low ozone in the equatorial Pacific. The spatial and temporal limits of this feature, as well as some aspects of the intensity of the minimum, appear to be maintained by the large-scale atmospheric circulations of the equatorial Pacific. Perturbations in the large-scale circulations, as well as episodic events, are reflected in observations of ozone in the equatorial Pacific. Variations in the large-scale zonal circulation patterns (i.e., Walker circulation) of the equatorial Pacific appear to have a major influence on the spatial distribution of ozone across the equatorial Pacific. The relative importance of variations in large-scale meridional circulation patterns on the distribution of ozone in the tropical Pacific is uncertain; however, they may be important at latitudes somewhat removed from the equator such as at American Samoa.

Post, W.M., V.H. Dale, D.L. DeAngelis, L.K. Mann, P.J. Mulholland, R.V. O'Neill, T.-H. Peng, and M.P. Farrell. Formulating energy policies related to fossil fuel use: Critical uncertainties in the global carbon cycle. Proceedings, 1990 Southeast Climate Symposium, Global Change: A Southern Perspective, October 1990, 77-95 (1991).

No abstract.

Powell, M.D. Surface wind distribution of Hurricane Hugo in the Carolinas. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 441-444 (1991).

No abstract.

Powell, M.D., P.P. Dodge, and M.L. Black. The landfall of Hurricane Hugo in the Carolinas: Surface wind distribution. Weather and Forecasting, 6(3):379-399 (1991).

Hurricane Hugo struck Charleston, South Carolina, on 22 September 1989 as the most intense hurricane to affect the United States since Camille in 1969. The northeastern eyewall, which contained the maximum winds measured by reconnaissance aircraft shortly before landfall, moved inland over a relatively unpopulated area and there were few fatalities. However, no observations were available to document the surface wind distribution in this part of the storm as it continued inland. To improve specification of surface winds in Hugo, empirically adjusted aircraft winds were combined with coastal, offshore, and inland surface observations and were input to the Ooyama objective analysis algorithm. The wind analysis at landfall was then compared with subsequent analyses at 3 and 6 h after landfall. Reconstruction of the surface wind field after landfall suggests that the maximum (~13 min mean) surface wind at the coast was 50 m s^-1 in the Bulls Bay region, ~40 km northeast of Charleston. Surface roughness over land caused wind speeds to drop off rapidly just inland of the coast to only 50% of values measured by reconnaissance aircraft at the same location relative to the storm over water. Despite relatively rapid increases in the central sea-level pressure and decreases in the mean circulation as Hugo progressed inland, hurricane-force wind gusts extended Hugo's damage pattern well past Charlotte, North Carolina, ~330 km inland. Accurate determination of surface wind distribution in landfalling hurricanes is dependent upon the spatial density and quality of surface wind measurements and techniques to adjust reconnaissance flight-level winds to the surface. Improvements should allow forecasters to prepare more accurate warnings and advisories and allow more thorough documentation of poststorm effects. Empirical adjustments to reconnaissance aircraft measurements may replace surface data voids if the vertical profile of the horizontal wind is known. Expanded use of the airborne stepped-frequency microwave radiometer for remote sensing of ocean surface winds could fill data voids without relying upon empirical methods or models. A larger network of offshore, coastal, and inland surface platforms at standard (10 m) elevations with improved sampling strategies is envisioned for better resolution of hurricane wind fields. A rapid-response automatic station network, deployed at prearranged coastal locations by local universities with meteorology and/or wind engineering programs, could further supplement the fixed platform network and avoid the logistical problems posed by sending outside teams into threatened areas.

Roux, F., and F.D. Marks. Eyewall evolution in Hurricane Hugo deduced from successive airborne Doppler observations. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 558-563 (1991).

No abstract.

Roux, F., F.D. Marks, and J.F. Gamache. Three-dimensional circulation in a hurricane from airborne Doppler radar data: Extended velocity track display. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 466-469 (1991).

No abstract.

Roy, R.N., J.-Z. Zhang, and F.J. Millero. The ionization of sulfurous acid in Na-Mg-Cl solutions at 25°C. Journal of Solution Chemistry, 20(4):361-373 (1991).

The stoichiometric pK₁^* and pK₂^* for the ionization of sulfurous acid has been determined from EMF measurements in NaCl solutions with varying concentrations of added MgCl₂ (m = 0.1, 0.2, and 0.3) from I = 0.5 to 6.0 molal at 25°C. These experimental results have been treated using both the ion pairing and Pitzer's specific ion-interaction models. The Pitzer parameters for the interaction of Mg²⁺ with SO₂ and HSO₃^- yielded lambda = 0.085 ± 0.004, beta⁽⁰⁾ = 0.35 ± 0.02, beta⁽¹⁾ = 1.22 ± 0.04, and C^phi = -0.072 ± 0.007. The Pitzer parameters beta⁽⁰⁾ = -2.8 ± 0.4, beta⁽¹⁾ = 12.9 ± 2.9, and beta⁽²⁾ = -201 ± 57 have been determined for the interactions of Mg²⁺ with SO₃^2-. The calculated values of pK₁^* and pK₂^* using Pitzer's equations reproduce the measured values to within ± 0.04 pK units. The ion pairing model with log K_MgSO3 = 2.36 ± 0.02 and log gamma_MgSO3 = 0.1021, reproduces the experimental values of pK₂^* to ± 0.01. These results demonstrate that treating the data by considering the formation of MgSO₃ yields a better fit of the experimental measurements with fewer adjustable parameters. With these derived coefficients obtained from the Pitzer equations and the ion pairing model, it is possible to make reliable estimates of the activity coefficients of HSO₃^- and SO₃^2- in seawater, brines, and marine aerosols containing Mg²⁺ ions.

Roy, R.N., J.-Z. Zhang, M.A. Sibblies, and F.J. Millero. The pK₂^* for the dissociation of H₂SO₃ in NaCl solutions with added Ni²⁺, Co²⁺, Mn²⁺, and Cd²⁺ at 25°C. Journal of Solution Chemistry, 20(5):467-478 (1991).

The pK₂^* for the dissociation of sulfurous acid from I = 0.5 to 6.0 molal at 25°C has been determined from EMF measurements in NaCl solutions with added concentrations of NiCl₂, CoCl₂, MnCl₂, and CdCl₂ (m = 0.1). These experimental results have been treated using both the ion pairing and Pitzer's specific ion-interaction models. The Pitzer parameters for the interactions of M²⁺ with SO₃^2- yielded

beta⁽⁰⁾_NiSO3 = -5.5, beta⁽¹⁾_NiSO3 = 5.8, and beta⁽²⁾_NiSO3 = -138

beta⁽⁰⁾_CoSO3 = -12.3, beta⁽¹⁾_CoSO3 = 31.6, and beta⁽²⁾_CoSO3 = -562

beta⁽⁰⁾_MnSO3 = -8.9, beta⁽¹⁾_MnSO3 = 18.7, and beta⁽²⁾_MnSO3 = -353

beta⁽⁰⁾_CdSO3 = -7.2, beta⁽¹⁾_CdSO3 = 13.8, and beta⁽²⁾_CdSO3 = -489

The calculated values of pK₂^* using Pitzer's equations reproduce the measured values to within ± 0.01 pK units. The ion pairing model yielded

log K_NiSO3 = 2.88 and log gamma_NiSO3 = 0.11I

log K_CoSO3 = 3.08 and log gamma_CoSO3 = 0.05I

log K_MnSO3 = 3.00 and log gamma_MnSO3 = 0.04I

log K_CdSO3 = 3.29 and log gamma_CdSO3 = 0.17I

for the formation of the complex MSO₃. The stability constants for the formation of MSO₃ complexes were found to correlate with the literature values for the formation of MSO₄ complexes.

Shay, L.K., P.B. Black, J.D. Hawkins, R.L. Elsberry, and A.J. Mariano. Sea surface temperature response to Hurricane Gilbert. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 574-578 (1991).

No abstract.

Tappert, F.D., G.J. Goni, and M.G. Brown. Weak chaos in an area-preserving mapping for sound ray propagation. Physics Letters A, 153(4-5):181-185 (1991).

No abstract.

Thacker, W.C. Automatic differentiation from an oceanographer's perspective. Proceedings, Workshop on Automatic Differentiation of Algorithms, Breckenridge, CO, January 6-8, 1991. Society of Industrial and Applied Mathematics, Philadelphia, 191-201 (1991).

An automatic differentiator is a tool that, when given code for evaluating a function, generates additional code for evaluating its derivatives. Within an oceanographic context, the function-defining code often involves the numerical solution of a system of partial-differential equations, and the corresponding derivative-evaluating code involves the solution of the adjoint system. Because the task of preparing the adjoint code is tedious, time-consuming, and error-prone, an automatic differentiator that could serve as an automatic adjoint generator would be most valuable. To be practical, its design should reflect the fact that, for oceanographic applications, efficient use of storage is crucial. In handwritten adjoint codes, data compression is realized by saving expressions rather than values. This expression-saving approach can be automated. The design of the automatic differentiator would resemble that of a compiler, and compiler-building tools could be used to construct it.

Tsai, J.J., and J.R. Proni. Dredged material disposal at the edge of the Florida Current. First International Ocean Pollution Symposium, Mayaguez, Puerto Rico, April 28-May 3, 1991. University of Puerto Rico, Mayaguez, 80 (1991).

A field data collection project was undertaken to evaluate the potential environmental impact of dumping in the designated Miami Ocean Dredged Material Disposal Site before the actual dredging of Miami River and Miami Harbor Turning Basin. Strong Gulf Stream current and relatively deep water depth at the disposal site make the study unique and important. Acoustic remote sensing techniques with current measurements from acoustic Doppler current profiler and in-situ oceanographic measurements were used to monitor the physical processes and the dispersive characteristics. Results indicate that during the period of observations of the study, materials were transported north-northeast away from sensitive reef areas and penetrated the strong pycnoclines to reach the bottom in the first few minutes. For the first time, intercomparison among all field data and numerical prediction provides dispersive characteristics of dredged material disposal at the western edge of the Florida Current.

Tziperman, E., W.C. Thacker, and K. Bryan. Computing the steady oceanic circulation using an optimization approach. Dynamics of Atmospheres and Oceans, 16:379-403 (1991).

The traditional method for computing steady oceanic circulation has been by stepping an oceanic model forward in time until transients are damped by friction. An alternative method, which has the potential for being more economical, is to minimize the sum of the squares of the residuals of the steady model equations. A variety of algorithms might be considered for computing the minimum; attention here is focused on preconditioned conjugate-gradient descent with the gradient computed using an adjoint model. The choice of variables, i.e., the preconditioning transformation used in the optimization process, is found to be critical to the efficiency of the method. An appropriate preconditioning transformation can be suggested by a heuristic analysis similar to that commonly used to test the stability of numerical models. The method is demonstrated within the context of the barotropic vorticity equation, and results indicate that the method can be at least as efficient as time-stepping.

Willis, P.T., and J. Hallett. Microphysical measurements from an aircraft ascending with a growing isolated maritime cumulus tower. Journal of the Atmospheric Sciences, 48(2):283-300 (1991).

The development of precipitation in the top of an isolated marine cumulus is traced by four rapid penetrations with an instrumented aircraft between 400 and 1000 m below the visible top of the growing tower. The hydrometeor distribution evolves from the first appearance of a few large supercooled drops [0.45 l^-1, D > 0.5 m] to well-developed precipitation (largely ice) in 500 s. This development results from accretion and coalescent growth in the cloud top volume, not from advection by the updraft of large drops from below. Large supercooled drops precede the appearance of ice at -9°C near the cloud top. The cloud and precipitation water budgets are computed and compared with observed values, which indicate that, once precipitation is well-developed, the convective tower cannot maintain itself as a steady-state entity. The budget computations demonstrate a sensitivity of cloud evolution to the ice particle density.

Willis, P.T., and A.J. Heymsfield. Trajectories of hydrometeors in Hurricane Emily. Extended Abstracts, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 192-197 (1991).

No abstract.

Willis, P.T., F.D. Marks, and J. Hallett. Tracing the interactions of precipitation evolution and cloud dynamics using airborne Doppler radar and in-situ data. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 916-919 (1991).

No abstract.

Willoughby, H.E. Reply. Journal of the Atmospheric Sciences, 48(9):1209-1212 (1991).

No abstract.

Willoughby, H.E. Semispectral models of moving hurricane-like vortices. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 383-384 (1991).

No abstract.

Yvon, S.A., D.J. Cooper, E.S. Saltzman, and P.K. Quinn. Measurements of atmospheric DMS and SO₂ over the northeast Pacific Ocean during PSI-3. EOS, Transactions, American Geophysical Union, 72(44):104 (1991).

No abstract.

Zhang, J.-Z., and F.J. Millero. The rate of sulfite oxidation in seawater. Geochimica et Cosmochimica Acta, 55:677-685 (1991).

The rate of oxidation of sulfide, S(IV), in seawater was measured as a function of pH (4.0-8.5), temperature (15-45°C), and salinity (0-35). The observed rate constant, k, in seawater at a pH = 8.2 was found to be second order with respect to S(IV) and half order with respect to oxygen:

-d [S(IV)]/dt = k[S(IV)]² [O₂]^0.5.

The resulting values of k (M^-1.5 min^-1) have been fitted to a function of ionic strength, I, and temperature, T(K):

log k = 19.54 - 5069.47/T + 14.74I^0.5 - 2.93I - 2877.0I^0.5/T,

and the standard error is 0.05 in log k. The energy of activation was found to be a function of salinity and has a value of 140 ± 6 kJ mol^-1 at S = 35. The rates measured in 0.57 M NaCl were found to be higher than the rates in seawater. Measurements made in the major sea salts indicate that Ca²⁺, Mg²⁺, and SO₄^2- added to NaCl cause the decrease. Measurements made in artifical seawater (Na⁺, Mg²⁺, Ca²⁺, Cl^-, and SO₄^2-) were found to be in good agreement with the measurements in real seawater. The rate increased from pH 4 to a maximum at pH 6.5 and decreased at higher pH. The effect of Ph on the rates was attributed to the rate-determining step involving the combination of HSO₃^- and SO₃^2-. This yields:

k = k” alpha HSO₃ - alpha SO₃^2-

where alpha_i is the molar fraction of species i. Values of k” equal to 6.66 ± 0.06 and 6.17 ± 0.17 were found for NaCl and seawater, respectively. The larger range of k” in seawater is due to it being a function of pH. The addition of Mn²⁺ was found to increase the rate apparently due to the formation of MnSO₃. Additions of Fe³⁺ and Fe²⁺ have a catalytic effect only before they hydrolyze to colloidal iron.

**1990**

Baringer, M.O., and J.F. Price. A simple model of the descending Mediterranean outflow plume. Proceedings, NATO Advanced Research Institute on the Physical Oceanography of Sea Straits, L.J. Pratt (ed.), Kluwer Academic Publishers, 298-308 (1990).

No abstract.

Bitterman, D.S., P.P. Niiler, Y. Aoustin, and A. de Chaffaut. Drift buoy intercomparison results. NOAA Data Report, ERL AOML-17, 52 pp. (1990).

Detailed tests were carried out aboard the NOAA ship Oceanographer to measure the slippage of several drift buoy designs used in the TOGA Pan Pacific Surface Current study. These included the AOML low-cost tropical drifter, the Scripps Institution of Oceanography Ministar drifter, the MIT Draper Laboratory low-cost drifter, and the IFREMER (Brest, France) thermistor chain buoy. The results of six tests carried out under varying wind and sea conditions are included.

Black, R.A. Radar reflectivity -- ice water content relationships for use above the melting level in hurricanes. Journal of Applied Meteorology, 29(9):955-961 (1990).

Regression of equations linking radar reflectivity (Z_e) and ice water content (IWC) were calculated from airborne radar and particle image data that were collected above the melting level in two hurricanes. The Z_e-IWC equation from the stratiform areas of Hurricane Norbert (1984) is similar to the composite equation for thunderstorm anvils derived by Heymsfield and Palmer. The Z_e-IWC equation from the convective regions of Hurricane Irene (1981) has essentially the same exponent, but a significantly greater coefficient than that from Norbert. The higher density of the graupel and rounded ice in the Hurricane Irene data accounts for the difference in the coefficients. The hurricane Z_e-IWC relations have smaller exponents than most of those from midlatitude clouds, which indicates that small ice particles may be more prevalent in these two hurricanes than in midlatitude clouds.

Black, R.A., and J. Hallett. Electric field and microphysical measurements in vigorous hurricane eyewalls. Preprints, Conference on Cloud Physics, San Francisco, CA, July 23-27, 1990. American Meteorological Society, Boston, 662-665 (1990).

No abstract.

Broecker, W.S., T.-H. Peng, J. Jouzel, and G. Russell. The magnitude of global fresh-water transports of importance to ocean circulation. Climate Dynamics, 4:73-79 (1990).

Water-vapor transport from low to high latitudes in a given ocean and from one ocean to another must be compensated by a net flow of salt through the sea. A comparison is presented which shows that water-vapor fluxes derived from meteorological information, from an atmospheric general circulation model and from a radiocarbon-calibrated ocean box model are in first-order agreement.

Broecker, W.S., T.-H. Peng, S. Trumbore, G. Bonani, and W. Wolfli. The distribution of radiocarbon in the glacial ocean. Global Biogeochemical Cycles, 4:103-117 (1990).

Accelerator mass spectrometric radiocarbon measurements on benthic foraminifera shells, picked from samples on which concordant ages were obtained on the shells of two species of planktonic foraminifera, reveal that the age of deep water in the equatorial Atlantic during glacial time was 675 ± 80 years (compared to today's age of 350 years) and that the age of deep water in the South China Sea was 1670 ± 105 years (compared to today's value of 1600 years). These results demonstrate that the 1.3 to 1.5 times higher radiocarbon content of carbon in glacial surface waters of the Caribbean Sea reconstructed by Bard et al. (1990) was primarily the result of a higher global inventory of radiocarbon rather than a decrease in rate of mixing between surface and deep waters of the ocean. The results are also consistent with the conclusion by Boyle and Keigwin (1987) that the flow of North Atlantic Deep Water was considerably weakened during glacial time, allowing deep waters of Antarctic origin to push much further north into the Atlantic than they do today.

Chelton, D.B., A.M. Mestas-Nunez, and M.H. Freilich. Global wind stress and Sverdrup circulation from the SEASAT scatterometer. Journal of Physical Oceanography, 20(8):1175-1205 (1990).

Three months of vector wind observations from the SEASAT-A satellite scatterometer (SASS) are used to construct gridded fields of monthly average wind stress and wind stress curl over the global ocean. These fields are examined to identify features either poorly resolved or not present in wind stress fields constructed from conventional data. Particular attention is focused on the spatial structures in the high southern latitudes and the tropical regions. The SASS wind stress fields are compared globally with the Hellerman and Rosenstein climatological monthly average surface wind stress fields and with monthly averages of wind stress computed from contemporaneous 1000 mb wind analyses produced by the National Meteorological Center. The potential for satellite scatterometry improving the present knowledge of the global wind stress field and making important contributions to ocean modeling is demonstrated by comparison of global maps of the Sverdrup circlation computed from three-month average SASS and Hellerman and Rosenstein climatological wind stress curl fields. Except for the region south of about 35°S, the two estimates of Sverdrup circulation are generally very similar. The transports of the western boundary currents calculated from the climatological wind stress fields are consistently higher because the drag coefficient used by Hellerman and Rosenstein is too large by approximately 19%. In the Antarctic Circumpolar Current region, the difference between the two estimates of zonal transport is very large, even disagreeing in direction in the region south of Australia and New Zealand. Historical hydrographic data suggest a tendency, albeit less extensive, for the westward Sverdrup transport indicated by the SASS data, suggesting the possibility of deficiencies in the climatological wind stress fields.

DeMaria, M., and R.W. Jones. The use of aircraft observations in a hurricane track forecast model. Preprints, International Symposium on Assimilation of Observations in Meteorology and Oceanography, Clermont-Ferrand, France, July 9-13, 1990. American Meteorological Society, Boston, 191-195 (1990).

No abstract.

Dodge, P.P., J.S. Griffin, F.D. Marks, and R.W. Burpee. Interactive analysis of NOAA P-3 aircraft data in support of operational hurricane forecasting. Preprints, Sixth International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, Anaheim, CA, February 4-9, 1990. American Meteorological Society, Boston, 245-247 (1990).

No abstract.

Franklin, J.L., C.S. Velden, J. Kaplan, and C.M. Hayden. Some comparisons of VAS and dropwindsonde data over the subtropical Atlantic. Monthly Weather Review, 118(9):1869-1887 (1990).

Omega dropwindsonde and other in-situ (INS) data collected during the NOAA/Hurricane Research Division's (HRD) field program are used as a ground truth data set for the evaluation of VISR Atmospheric Sounder (VAS) soundings over the subtropical Atlantic. The experiments were coordinated with the Cooperative Institute for Meteorological Satellite Services at the University of Wisconsin. The focus of this study is to determine whether soundings derived from VAS radiances are an improvement over the first-guess data used as a starting point in the sounding retrieval process. First-guess inputs for this study are provided by NMC's Regional Analysis and Forecast System (RAFS) nested-grid model (NGM). In a case study, an objective algorithm is used to analyze the INS, VAS, and first-guess data at and below 500 mb from an HRD experiment on 1-2 September 1988. The case study is supplemented by a statistical investigation of data composited from other HRD experiments. In particular, we examine VAS estimates of horizontal temperature and moisture gradients to see if they represent improvements over the first guess. The temperature and moisture descriptions in the vicinity of a 500 mb cold low were improved by the VAS in the case study; however, VAS temperature gradients were found to be generally less accurate than those of the first guess. Temperature gradients from the VAS were also consistently stronger than INS or first-guess gradients. The composite study found that large-scale VAS moisture gradients were better than those of the first guess. Other results indicate a preferred mode for VAS modifications to the guess; the primary impact of the VAS radiances on the first guess was to improve the description of the phasing of horizontal features. The VAS representation of the amplitude of features, however, was not consistently an improvement. This suggests that in tropical applications, VAS data may be most suitable for subjective forecasting uses; if VAS data are to be used in numerical weather prediction, strongest weight should be given to the representation of the location of weather features (troughs, ridges, etc.), and relatively weak weight should be given to the representation of the strength of these features.

Frazel, D.W., and G.A. Berberian. Distributions of chlorophyll and primary productivity in relation to water column structure in the eastern North Atlantic Ocean. Global Biogeochemical Cycles, 4(3):241-251 (1990).

Latitudinal variations in the megascale (10³ km) distribution of biological properties are described in relation to water column structure between 60°N and 7°N in the eastern North Atlantic Ocean. Stations were occupied along a meridional transect of stations at 20°W in August-September 1988, during the third leg of the National Oceanic and Atmospheric Administration Global Change Expedition. An additional transect to the south (38°N to 7°N) was occupied to extend the total range of latitudinal observations. Chlorophyll-a concentrations were highest in the northern latitudes (<2.51 mg m^-3), decreasing to >0.2 mg m^-3 in the vicinity of the subtropical gyre, south of 40°N. The nitracline was associated with a shoaling of the pycnocline in the northern latitudes. At 7°N, high chlorophyll concentrations (approximately 0.5 mg m^-3) and enhanced primary productivity (375.5 mg C m^-2 d^-1) were associated with a lens of fresh Amazon River Water.

Friedman, H.A. "Adopt-a-meteorologist" as an educational resource for teachers. Weather Tips (newsletter of the American Meteorological Society Education Office, prototype issue), 3 (1990).

No abstract.

Friedman, H.A. Hurricane names. Weather Tips (newsletter of the American Meteorological Society Education Office, prototype issue), 1-2 (1990).

No abstract.

Friedman, H.A., and C.A. Arnhols. 1990 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 108 pp. (1990).

No abstract.

Gallagher, M.S., T.P. Carsey, and M.L. Farmer. Peroxyacetyl nitrate in the North Atlantic marine boundary layer. Global Biogeochemical Cycles, 4(3):297-308 (1990).

An automated system utilizing packed column gas chromatography and electron capture detection for the determination of peroxyacetyl nitrate (PAN) is described. The system was calibrated with a cryogenic PAN sublimation device, a molybdenum catalyst, and a chemiluminescent nitric oxide detector. Computer control of the analysis resulted in an analytical precision level of ~1%. A total of 1,178 PAN measurements were made from August 6 to September 5, 1988, in the marine boundary layer during the GCE/CASE/WATOC cruise (66°N to 7°N). Overall, PAN concentrations were highest at high latitudes (up to 40 ppt); PAN levels in the lower latitudes of the cruise track were usually <10 ppt. A number of episodes of elevated PAN are described which were characterized by elevated radon concentrations and a discernible diurnal cycle in the PAN concentration. These higher PAN levels are attributed to air masses with some continental influence, and to the enhanced stability of PAN at the cooler temperatures characteristic of the sub-Arctic region. In aged air masses of marine origin, PAN concentrations were significantly less and did not display diel changes; this is interpreted as a measure of the "background" PAN signal.

Gamache, J.F. Microphysical observations in summer MONEX convective and stratiform clouds. Monthly Weather Review, 118(6):1238-1249 (1990).

Two-dimensional images of ice particles observed by a NOAA WP-3D research aircraft during the Summer Monsoon Experiment (SMONEX) are examined. These images were obtained in the temperature interval from -25°C to 0°C. The particle structures and size distributions found in convective and stratiform clouds are compared. Branched crystals were located predominantly in stratiform clouds while column-shaped crystals were located commonly in both stratiform and convective clouds. Stratiform clouds, particularly those observed at temperatures warmer than -7°C, had a much greater percentage concentration of large ice particles (>0.8 mm in diameter), and many of these ice particles were aggregates or branched crystals. The importance of aggregation and deposition above the melting level in stratiform clouds is strongly suggested by these findings. Ice particle number concentrations measured with the cloud probe were often very high in convective clouds, with a maximum value of approximately 800 L^-1. The average convective-cloud concentration was approximately 230 L^-1, while the average concentration in the stratiform clouds was approximately 20 L^-1. Liquid water was almost completely absent in the convective updrafts, at temperatures between -10°C and -22°C. This suggests that the convective updrafts may have been nearly completely glaciated, and the microphysics were dominated by deposition. The high particle concentrations in the convective updrafts suggest that the updrafts may provide most of the ice particles found in the stratiform cloud. Significant modification in particle structures and size distributions has occurred, however, by the time these suspended particles fall out of the stratiform clouds. These modifications appear to arise from aggregation and deposition.

Garzoli, S.L., and C. Simionato. Baroclinic instabilities and forced oscillations in the Brazil/Malvinas confluence front. Deep-Sea Research, 37(6A):1053-1074 (1990).

Observations collected at the confluence between the Brazil and Malvinas Currents are analyzed to study the high-frequency oscillations in the range of periods from 55 to 2 days. The variability in time and space of the thermohaline front originates at the confluence. The meandering of the Brazil Current after the encounter and the presence of an abrupt shelf break create the conditions for the generation of baroclinic and internal waves. Analysis of time-series of dynamic height, wind magnitude, and position of the front indicates the following: in the band from 20 to 55 day periods, two waves propagate with similar characteristics but in the opposite direction; neither of these waves appears to be forced by the wind. The westward-propagating wave (T=37.4 days) is related to the position of the front and is assumed to be forced by its north-south displacement. The eastward-propagating wave (T=29.1 days) has the characteristics of a topographic Rossby wave.

Georges, T.M., and D.R. Palmer. Applications of ocean acoustic remote sensing to climate monitoring. NOAA Technical Memorandum, ERL WPL-85, 9 pp. (1990).

No abstract.

Giese, G.S., D.C. Chapman, P.B. Black, and J.A. Fornshell. Causation of large-amplitude coastal seiches on the Caribbean coast of Puerto Rico. Journal of Physical Oceanography, 20(9):1449-1458 (1990).

Sea-level oscillations at supertidal frequency with amplitudes of the order of the mean tidal range have been reported from the Caribbean coast of Puerto Rico. Analysis of a 10-year time series of digital tide data from Magueyes Island, Puerto Rico, demonstrates that sea-level variance at the fundamental normal mode (seiche) frequency of the shelf has a pronounced fortnightly distribution with a maximum occurring 6-7 days after new and full moon. The seiche variance also shows a bimodal seasonal distribution with an inverse relationship to easterly wind stress. It is argued that the seiches are excited by internal waves generated by strong tides in the southeastern Caribbean. Support is provided by airborne radar imagery showing sea-surface patterns suggesting the presence of internal waves near the southern Aves Ridge, and by the results of two field experiments, carried out during times when large-amplitude seiches were expected, to research for evidence of internal wave forcing near the shelf break. During the first experiment, large negative-amplitude, pulse-like internal waves were recorded 6 km seaward of the shelf break during a period of strong seiche activity. Such pulses were not observed during the second experiment. However, high-frequency temperature variance 2.3 km seaward of the shelf break, possibly resulting from internal surf, increased with depth and reached a maximum 6-7 days following new moon, again suggesting the presence of internal waves. The 10-year time series analysis shows that large tides are necessary, but not sufficient, to generate high seiche activity. This is supported by the two field experiments; during the first, large-amplitude seiches occurred as expected, while during the second experiment they did not. We suggest that this behavior is related to variations in stratification, which, in turn, alter the energy transfer from tides to seiches.

Gray, W.M., C.W. Landsea, P.W. Mielke, and K.J. Berry. Forecasting Atlantic seasonal hurricane variability. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, NC. NOAA, 456-461 (1990).

No abstract.

Hallett, J., and P.T. Willis. Development of precipitation in isolated maritime cumulus. Preprints, Conference on Cloud Physics, San Francisco, CA, July 23-27, 1990. American Meteorological Society, Boston, 74-79 (1990).

No abstract.

Hansen, C., K.B. Katsaros, S.A. Kitaigorodskii, and S.E. Larsen. The dissipation range of wind-wave spectra observed on a lake. Journal of Physical Oceanography, 20(9):1264-1277 (1990).

No abstract.

Hansen, D.V. Subsurface current and temperature patterns in the western tropical Pacific. Proceedings, U.S.-PRC International TOGA Symposium, Beijing, China, November 15-17, 1988. China Ocean Press, Beijing, 121-127 (1990).

No abstract.

Hansen, D.V., and G.A. Maul. Anticyclonic current rings in the eastern tropical Pacific Ocean. Journal of Geophysical Research, 96(C4):6965-6979 (1990).

Observations from satellite-tracked drifting buoys, XBT and CTD data, and GEOSAT altimeter data are used to describe anticyclonic eddies that occur in small numbers off the Pacific coast of Central America. These eddies are similar in many respects to the well-known, warm-core rings that are observed north of the Gulf Stream off the Atlantic coast of North America, except that they occur in an environment that also is warm, and they contain considerably greater kinetic energy. It is hypothesized that they are formed as a result of conservation of potential vorticity when the North Equatorial Countercurrent (NECC) turns northward upon approaching the eastern boundary during its autumnal maximum. The rings so formed have a strongly nonlinear character which causes them to propagate westward between 9°N and 14°N with a speed in excess of that of long Rossby waves. Due to a relatively small available potential energy content, these rings have a dissipation time scale of about six months and perhaps end by collision with and reabsorption into the NECC. The rings account for the observed enhancement of surface kinetic energy, and probably for the seaward transport of waters enriched in copper.

Houze, R.A., Jr., B.F. Smull, and P.P. Dodge. Mesoscale organization of springtime rainstorms in Oklahoma. Monthly Weather Review, 118(3):613-654 (1990).

Radar reflectivity and rain gage data obtained during six springtimes indicates the types of mesoscale organization that occur in association with major rain events in Oklahoma (at least 25 mm of rain in 24 h over an area exceeding 12,500 km²). In these storms, the primary rain area is found to be a contiguous region of precipitation tens to hundreds of kilometers in scale that consists partly of deep convection and partly of stratiform rain. The patterns of rain formed by the convective and stratiform areas comprise a continuous spectrum of mesoscale structures. About two-thirds of the cases examined exhibited variations on the type of organization in which convective cells arranged in a moving line are followed by a region of stratiform rain. Storm organization was graded according to the degree to which it matched an idealized model of this "leading-line/trailing-stratiform" structure. The precipitation pattern was further graded according to whether its structure was relatively symmetric with respect to an axis normal to and passing through the midpoint of the line, or asymmetric, in which case the storm was biased toward having stronger, more discrete convective structure at the upwind (south or southwestern) end of the line and/or the most extensive stratiform precipitation behind the downwind (north to northeastern) end of the line. About one-third of the cases examined displayed much more chaotic, unclassifiable arrangements of convective and stratiform areas. Among the cases with leading-line/trailing-stratiform structure, severe weather was most frequent in systems with (1) a strong degree of leading-line/trailing-strataiform structure, in which a solid, relatively uniform, arc-shaped line had stratiform rain centered symmetrically behind it, and (2) a weaker degree of leading-line/trailing-stratiform structure in which a southwest-northeast line was biased toward having narrow, intensely convective, irregularly spaced cell structure at its southwestern (upwind) end and stratiform rain confined to the region behind the broader northeastern (downwind) portion of the line. Although all mesoscale organization types were characterized by all types of severe weather, the type (2) cases were the most prolific category in terms of tornado and hail production, while type (1) cases were prone to be associated with flooding. The chaotic, unclassifiable cases, which exhibited no line organization, had just as much severe weather as the cases with line organization, but were more likely to produce hail and somewhat less likely to produce tornadoes and flooding than the systems with line structure. Major rain events occurred whenever a mesoscale convective complex (MCC) was dissipating or merely skirting the area. However, 75% of the major rain events occurred under cloud shields that failed to meet the MCC criteria explicitly, although they often resembled MCCs qualitatively. No particular type of mesoscale radar-echo organization was favored when cloud shields meeting the MCC criteria were observed. A slight preference for the more chaotic type of organization was suggested; however, the data sample is not large enough for this finding to be regarded as conclusive. Mean soundings and hodographs generally show no sign of a low-level jet in environments associated with chaotically arranged rain areas that lacked any line structure. On the other hand, a low-level jet and resulting curved hodograph were typically associated with cases in which line organization was evident. The wind shear in the low to midtroposphere, the bulk Richardson number, and other familiar parameters characterizing squall line environments are consistent with results from recent modeling studies. When leading-line/trailing-stratiform structure was present, the cross-line shear in the environment was of a magnitude associated with model simulations in which a rearward sloping updraft circulation favorable to trailing-stratiform anvil formation quickly develops. The along-line componentt of shear was greater when the squall system structure was of the asymmetric type and the degree of leading-line/trailing-stratiform structure was not as strong, i.e., in those mesoscale systems favoring tornado occurrence.

Katsaros, K.B., U. Hammarstrand, and G.W. Petty. Atmospheric water parameters in mid-latitude cyclones observed by microwave radiometry and compared to model calculations. NASA Tech. Pap., 30 pp. (1990).

Existing and experimental algorithms for various parameters of atmospheric water content such as integrated water vapor, cloud water, precipitation, are used to examine the distribution of these quantities in mid latitude cyclones. The data was obtained from signals given by the special sensor microwave/imager (SSM/I) and compared with data from the NIMBUS scanning multichannel microwave radiometer (SMMR) for North Atlantic cyclones. The potential of microwave remote sensing for enhancing knowledge of the horizontal structure of these storms and to aid the development and testing of the cloud and precipitation aspects of limited area numerical models of cyclonic storms is investigated.

Marks, F.D., and P.G. Black. Close encounter with an intense mesoscale vortex within Hurricane Hugo (September 15, 1989). Extended Abstracts, 4th Conference on Mesoscale Processes, Boulder, CO, June 25-29, 1990. American Meteorological Society, Boston, 114-115 (1990).

No abstract.

Maul, G.A., K. Hanson, and H.F. Bezdek. A note on determining potential anthropogenic signals in sea level: An example from Florida and juxtaposed areas. In Towards an Integrated System for Measuring Long-Term Changes in Global Sea Level, H.F. Eden (ed.). Joint Oceanographic Institutions, Inc., Washington, D.C., 17-25 (1990).

No abstract.

Maul, G.A., D.A. Mayer, and M.H. Bushnell. Statistical relationships between local sea level and weather with Florida-Bahamas cable and Pegasus measurements of Florida Current volume transport. Journal of Geophysical Research, 95(C3):3287-3296 (1990).

Straits of Florida sea level is studied as a measure of Florida Current volume transport because sea level provides an independent time series both (1) for detecting changes in the calibration of the Florida-Bahamas submarine cable which has been operating since 1982, and (2) as a measure of the strength of the Gulf Stream system dating to the 1930's when cable measurements were not available. Accordingly, tide gauge records from Haulover Beach (Miami) and Lake Worth, Florida, and from Cat Cay and Settlement Point, The Bahamas, together with Miami weather and cable voltage, are correlated with each other and with discrete volume transport estimated from all Pegasus data taken during the intensive 1982-1984 Subtropical Atlantic Climate Studies (STACS) observations. Time domain linear correlation coefficients between these 132 Pegasus values and cable voltage observations, Cat Cay minus Haulover Beach sea level, and Haulover Beach sea level only, are 0.91, 0.55, and -0.76, respectively, but for the 1982-1988 time series, Cat Cay minus Haulover Beach is better correlated with cable observations (0.62) than is Haulover Beach alone (-0.44). Frequency domain modeling computations reveal that the sea level and cable data are organized in such a way that most of their energy lies below frequencies of 30^-1 cycles per day (cpd). In a subseasonal band (up to and including the semiannual frequency) 49% of the cable energy and 59% of the Haulover Beach energy can be accounted for using 30-day low-passed data. A subseasonal frequency response function has been tentatively identified that relates both Florida sea level and Bahamas-Florida sea level difference to cable observations and can successfully account for more than 60% of the observed cable variance (standard error is ±1 × 10⁶ m³ s^-1). Further, negative Florida sea level only and Bahamas-Florida sea level difference have different phase relationships with cable observations; it is suggested that steric effects could be responsible for the phase shifts.

Mayer, D.A., R.L. Molinari, and R.H. Weisberg. Analysis of volunteer observing ship temperature fields in the tropical Atlantic Ocean. Oceanologica Acta, 13(3):257-264 (1990).

Volunteer observing ship data collected during the FGGE year in 1979 and data from in situ moorings deployed during the SEQUAL/FOCAL experiment in 1983-1984 are used to estimate the dominant temporal and spatial scales of SST variability in the equatorial Atlantic Ocean. Two-dimensional Fourier transforms show that enhanced energy levels in a wave number and frequency band of 1924^-1-825^-1 cycles/km and 37^-1-21^-1 cycles/day respectively, are associated with organized SST structures with wave-like oscillations that are consistent with barotropic instabilities. The oscillations appear on the equator between 1°S and 1°N eastward of 25°W shortly after the springtime intensification of the easterly wind stress and persist into August. They are characterized by a westward phase propagation of about 50 cm s^-1 and a pattern that progresses eastward at approximately 30 cm s^-1.

Molinari, R.L., E. Johns, and J.F. Festa. The annual cycle of meridional heat flux in the Atlantic Ocean at 26.5°N. Journal of Physical Oceanography, 20(3):476-482 (1990).

Total meridional heat flux through a zonal oceanic section at 26.5°N in the Atlantic Ocean is computed from hydrographic, direct current, and surface wind observations. The oceanic current and temperature fields are decomposed into depth-averaged and depth-dependent (including Ekman and geostrophic) components to perform the calculation. The mean annual heat flux is estimated to be 1.21 ± 0.34 PW. Mean monthly values of net heat flux are alsocomputed from the data. The annual cycle of net heat flux determined from these values ranges from a minimum of 0.69 PW in February to a maximum of 1.86 PW in July. Thus, in contrast to an earlier estimate of the annual cycle of oceanic heat flux derived indirectly from surface energy fluxes and upper-layer heat content changes, there is no net southward heat flux during the fall. Results from a simulation of the circulation of the North Atlantic give an annual cycle of heat flux similar to our calculation with a summer maximum and winter minimum. However, the simulated mean value and range of the annual cycle are less than observed.

Molinari, R.L., D. Olson, and G. Reverdin. Surface current distributions in the tropical Indian Ocean derived from compilations of surface buoy trajectories. Journal of Geophysical Research, 95(C5):7217-7238 (1990).

Three different satellite-tracked drifting buoy data sets are compiled and used to generate a monthly climatology of surface currents in the tropical Indian Ocean. Buoys were deployed between 1975 and 1987. The data density is maximum on and near the equator and decreases poleward. Drift characteristics of the different buoy configurations are compared using a structure function analysis. The differences in windage effects are consistent with the buoy designs and small compared with the signals studied. The currents in the tropical Indian Ocean during boreal winter and spring can be characterized as two counterrotating gyres. A southern clockwise rotating gyre is bounded on the south by the South Equatorial Current (SEC) and on the north during winter by the Equatorial Countercurrent (ECC) and during spring by the Equatorial Jet (EJ). A northern counterclockwise rotating gyre is bounded on the south by the ECC and EJ, depending on season, and on the north by the North Equatorial Current (NEC). The two gyre systems break down during boreal summer. During this season, the SEC is located closer to the equator, and the NEC is replaced by the eastward flowing Indian Monsoon Current (IMC). The western boundary circulation becomes more complicated from late spring through early autumn with the observation of two intense smaller scale gyres. The large-scale southern gyre reappears during boreal autumn with the reappearance of the EJ. The northern gyre begins to reappear in December, with the reversal of the IMC and the reappearance of the NEC. The monthly buoy speeds are compared with a monthly climatology generated from ship drift reports. Differences between the two climatologies are, in general, small except in regions of few trajectories. The annual cycles in amplitudes and phases of the major currents in the region are thus comparable.

Ooyama, K.V. A thermodynamic foundation for modeling the moist atmosphere. Journal of the Atmospheric Sciences, 47(21):2580-2593 (1990).

With advances in numerical modeling of the atmosphere, we have experienced that the return to the first principles of physics often enables a model to cope more easily with the complexities of the real atmosphere. The return to the primitive equations of motion from historical balance approximations is an example. This paper proposes a way to return to the "primitive" form of moist thermodynamics, in which prediction is made strictly in terms of conservative properties, such as mass and entropy. There is no conservation law that would apply directly to temperature or pressure. These intensive properties, therefore, should be diagnostically determined by thermodynamics, from the predicted conservative properties. The scope of the paper is limited to the thermodynamics of reversible processes. Irreversible processes, which would make a model alive with real weather, are not discussed here, since each of them requires a separate empirical treatment. It is shown, however, that the proposed formulation of thermodynamics facilitates modularization of various approximations within a model, and among models. For example, both the hydrostatic and nonhydrostatic models can be built under an identical design, differing only in the manner of calculating vertical motion. The proposed formulation is extended to include the ice phase within reversible thermodynamics. Also discussed are numerical problems in the spatial representation of thermodynamic discontinuities, which are caused by the phase transition of water substance.

Palmer, D.R. Book review, "Elastic wave propagation," North-Holland Series in Applied Mathematics and Mechanics, Vol. 35, M.F. McCarthy and M.A. Hayes (eds.). Journal of the Acoustical Society of America, 88:1665 (1990).

No abstract.

Palmer, D.R., and P.A. Rona. Comment on "Acoustic Doppler current profiler observations of a mid-ocean ridge hydrothermal plume." Journal of Geophysical Research, 95(C4):5409-5412 (1990).

No abstract.

Palmer, D.R., T.M. Georges, and R.M. Jones. Chaos in underwater acoustics. Proceedings, Fifth International Symposium on Acoustic Remote Sensing of the Atmosphere and Oceans, S.P. Singal (ed.). New Delhi, India, February 6-9, 1990, Tata McGraw-Hill, 210-215 (1990).

During numerical simulations of acoustic propagation in a weakly range-dependent, deterministic ocean, we find conditions that produce chaotic ray paths. Chaos is an instability which results from the nonlinear nature of the differential equations which determine the ray paths, rather than from externally imposed noise or randomness. It places a fundamental limitation on the range to which an acoustic field can be predicted. We also discuss some new methods for identifying chaotic rays which have advantages over the standard methods. Finally, we note the existence of chaotic rays for propagation in the Straits of Florida.

Palmer, D.R., T.M. Georges, and R.M. Jones. Classical chaos and the sensitivity of the acoustic field to small-scale ocean structure. Proceedings, First International Conference on Computational Physics, Boulder, CO, June 11-15, 1990, North Holland, 8-15 (1990).

Peng, T.-H. Climate change and atmospheric CO₂ variations. Proceedings of the Geological Society of China, 33(4): 391-409 (1990).

A strong correlation between climate change and atmospheric CO₂ variations was revealed through measurements of paleoatmospheric CO₂ in air bubbles trapped in polar ice layers. It was shown that the atmospheric CO₂ increased from 200 to 280 ppm as climate changed from glacial to intergalcial conditions. Many hypotheses have been proposed to explain the cause of these atmospheric CO₂ changes. In most early hypotheses the marine biological activity was considered to be the main mechanism for transferring carbon within ocean-atmosphere-biosphere reservoirs. Unfortunately, these hypotheses have inherent problems of deficient O₂ concentration in glacial deep waters and changes of nutrient content accompanying climate change that are contrary to deep sea sediment records. However, two important factors became clear: (1) the ultimate source of the CO₂ change must lie in the sea, and (2) the most critical waters of the ocean are those at the surface in the polar region. Based on these factors and a recent requirement for an alkalinity increase derived from the observed nutrient deepening in the glacial Atlantic, a polar alkalinity hypothesis was proposed. The hypothesis suggests that the major cause for the 80-ppm change in CO₂ was a 75-µeq · kg^-1 drop in the salinity-normalized alkalinity of Antarctic surface waters at the close of glacial time. This drop stemmed in part from the reinitiation of the Atlantic conveyor circulation system (i.e., North Atlantic Deep Water) and in part from the shallowing of the ocean's nutrient maximum.

Peng, T.-H., T.L. Ku, J. Southon, C. Measures, and W.S. Broecker. Factors controlling the distribution of ¹⁰Be and ⁹Be in the ocean. In From Mantle to Meteorites, A Garland of Perspectives: A Festschrift for Devendra Lal, K. Gopalan, V.K. Gaur, B.L.K. Somayajulu and J.D. Macdougall (eds.). Indian Academy of Sciences, Bangalore, India, 201-204 (1990).

Observations show that while the concentration of ⁹Be in the deep sea is geographically uniform, that of ¹⁰Be increases from Atlantic to Antarctic to Pacific. Using a geochemical ocean box model calibrated by the radiocarbon distribution in the sea, we show that this situation requires (1) that ⁹Be be added preferentially to the Atlantic Ocean and (2) that the residence time for beryllium in the sea be comparable to the oceanic mixing time. Both requirements are consistent with what is known regarding the geochemistry of beryllium.

Peng, T.-H., W.M. Post, D.L. DeAngelis, V.H. Dale, and M.P. Farrell. Atmospheric carbon dioxide and the global carbon cycle: The key uncertainties. In Environmental Problems and Solutions, T.N. Veziroglu (ed.). Hemisphere Pub. Corp., New York, 17-38 (1990).

No abstract.

Piotrowicz, S.R., C.J. Fischer, and R.S. Artz. Ozone and carbon monoxide over the North Atlantic during a boreal summer. Global Biogeochemical Cycles, 4(2):215-224 (1990).

Ozone mixing ratios observed on a cruise from the east coast of North America to Bermuda, to Iceland, to the Azores, and terminating in Barbados in a boreal summer exhibit wide variability. Increases above a North Atlantic background of 10-20 ppbv appear to be associated with transport from terrestrial systems. In the central gyre of the North Atlantic and in the tropical North Atlantic, ozone mixing ratios below 10 ppbv are commonly observed when the air being sampled does not have a recent (10 days) history of terrestrial input. Carbon monoxide mixing ratios within the boundary layer vary latitudinally from an average of 124 ppbv in the westerlies to 88 ppbv in the tropical North Atlantic. Variability in the distribution of CO appears to be dominated by transport from terrestrial source regions.

Post, W.M., T.-H. Peng, W.R. Emanuel, A.W. King, V.H. Dale, and D.L. DeAngelis. The global carbon cycle. American Scientist, 78:310-326 (1990).

No abstract.

Powell, M.D. Boundary layer structure and dynamics in outer hurricane rainbands. Part I: Mesoscale rainfall and kinematic structure. Monthly Weather Review, 118(4):891-917 (1990).

Results of hurricane boundary layer experiments conducted in outer rainbands of Hurricanes Josephine (1984) and Earl (1986) are presented. Comparisons of precipitation and kinematic structures in these storms and in Hurricane Floyd (1981) indicate that principal rainbands have common characteristic mesoscale and convective-scale features in the boundary layer. The two-dimensional mesoscale structure suggests that these rainbands are made up of a linear aggregate of cellular reflectivity elements (on the inner, upshear side of the band) and stratiform rain (on the outer downshear side). The bands are oriented perpendicular to the shear above the boundary layer and cells move downband at about 85% of the density-weighed mean wind speed of the 0.2-6 km layer. The boundary layer windfield is strongly influenced by the rainband with alongband and crossband wind maxima located on the outer side of the band axis, and minima 4-8 km to the inner side. Maximum crossband convergence and cyclonic shear vorticity are also found to the inner side of the rainband axis. Updrafts and downdrafts are preferentially located on the inner side of the band axis, with some downdrafts spreading out at the surface. The band-relative positions of the updraft and perturbation pressure minimum suggest that the minimum may be produced by interaction of the wind shear and the updraft. Outer hurricane rainbands show many similarities to tropical squall lines; major differences are associated with propagation and the structure of the leading and trailing edges.

Powell, M.D. Boundary layer structure and dynamics in outer hurricane rainbands. Part II: Downdraft modification and mixed-layer recovery. Monthly Weather Review, 118(4):918-938 (1990).

Recent aircraft boundary layer measurements in the vicinity of principal hurricane rainbands have confirmed that convective downdrafts are capable of transporting cool, dry, low equivalent potential temperature air to the surface, wher the mixed layer is eliminated. The incorporation of this air into convection near the core of the storm may weaken the storm, depending upon the scale of the disturbance and the processes governing the recovery of the air while it is flowing toward the eyewall. This paper examines the thermodynamic characteristics of the boundary layer in outer convective hurricane rainbands, providing evidence for downdraft modification mechanisms and determining the extent to which disturbed boundary layer air may be restored on its trajectory to the storm.

Powell, M.D. Observations of boundary layer structure and mesoscale wind fields in a midlatitude marine rainband during GALE. Extended Abstracts, 4th Conference on Mesoscale Processes, Boulder, CO, June 25-29, 1990. American Meteorological Society, Boston, 55-56 (1990).

No abstract.

Powell, M.D., and P.G. Black. Meteorological aspects of Hurricane Hugo's landfall in the Carolinas. Shore and Beach, 58(4):3-10 (1990).

No abstract.

Powell, M.D., and P.G. Black. The relationship of hurricane reconnaissance flight-level wind measurements to winds measured by NOAA's oceanic platforms. Journal of Wind Engineering and Industrial Aerodynamics, 36:381-392 (1990).

A well-known problem in hurricane forecasting and in the administration of hazardous weather warnings and advisories concerns what adjustments to make to flight-level reconnaissance wind observations in order to make them representative of sustained surface winds. To solve this problem, a study was initiated comparing NOAA reconnaissance flight-level winds to 10 m level observations from NOAA's oceanic buoys and platforms. A data base was created that consisted of comparisons made whenever the aircraft observation was: (1) within 10 km radial separation from the surface platform (in a storm-relative coordinate system); (2) within ±4 h of the surface observation time; and (3) within ±2 h of the surface observation time. The data base contains all storms flown by NOAA aircraft in the vicinity of the Atlantic and Gulf of Mexico buoy network over the 11-year period from 1975-1986. Comparisons from these criteria are discussed in terms of the ratio of the buoy-measured wind speed (V_B) to the aircraft-measured wind speed V_A. Results indicate that the 10 m level surface winds over water were within 55%-85% of the winds measured by the reconnaissance aircraft. The ratio V_B/V_A depended strongly on the low-level atmospheric stability as indicated by the buoy air-sea temperature.

Provost, C., V. Garcon, and S.L. Garzoli. Sea level variability in the Brazil and Malvinas Confluence region. Advances in Space Research, 9(7):7387-7392 (1990).

No abstract.

Shapiro, L.J., and K.V. Ooyama. Barotropic vortex evolution on a beta plane. Journal of the Atmospheric Sciences, 47(2):170-187 (1990).

A barotropic, primitive equation (shallow water) model is used on the beta plane to investigate the influence of divergence, total relative angular momentum (RAM), and advective nonlinearities on the evolution of a hurricane-like vortex. The multinested numerical model is based on the spectral application of a finite element representation. The undisturbed fluid depth is taken to be 1 km. Scaling of the vorticity equation, in conjunction with a Bessel function spectral decomposition, indicates that divergence should have a very small effect on the hurricane motion. Simulations with an initially symmetric cyclonic vortex in a resting environment confirm this analysis, and contradict previous published studies on the effect of divergence in a barotropic model. During a 120 h simulation, the cyclonic vortex develops asymmetries that have an influence far from the initial circulation. The total RAM within a large circle centered on the vortex decreases with time, and then oscillates about zero. For circles with radii <1000 km, the total RAM approaches, but does not reach, zero. An angular momentum budget indicates that the horizontal angular momentum flux tends to counteract the net Coriolis torque on the vortex. If the total RAM of the initial symmetric vortex is zero, the weak far-field asymmetries are essentially eliminated. The motion of the vortex is not, however, related to the RAM in any simple way. Within a few days the near-vortex asymmetries reach a near-steady state. The asymmetric absolute vorticity (AAV) is nearly uniform within ~350 km of the vortex center. The homogenization of AAV, which occurs within the closed vortex gyre, is likely due to shearing by the symmetric wind, combined with removal of energy at the smallest scales. The homogenization effectively neutralizes the planetary beta effect, as well as the vorticity associated with an environmental wind.

Thacker, W.C. Large least-squares problems and the need for automating the generation of adjoint codes. In Computational Solution of Nonlinear Systems of Equations, E.L. Allgower and K. Georg (eds). American Mathematical Society, Lectures in Applied Mathematics, 26:645-677 (1990).

Some important least-squares problems that arise in oceanography and meteorology are large because they are based on systems of partial-differential equations. The function to be minimized is defined with the aid of a computer code, so the equations stating that the gradient should vanish are not available explicitly. It is possible to construct a second code that evaluates the gradient for a computational effort approximately equal to that of evaluating the function. Since the gradient code can be derived from the function code by following a well-defined set of rules, it should be possible to construct a compiler-like utility to do this task automatically. Such a compiler should find wide applicability, not only within oceanography and meteorology, but for optimization problems in general, as well as for solving systems of nonlinear equations and for checking the sensitivity of outputs of complicated codes to their inputs.

Wilburn, A.M., E. Johns, and M.H. Bushnell. Current velocity and hydrographic observations in the southwestern North Atlantic Ocean: Subtropical Atlantic Climate Study (STACS), 1989. NOAA Data Report, ERL AOML-18, 97 pp. (1990).

No abstract.

Willis, P.T., and A.J. Heymsfield. Microphysical trajectories in tropical cyclones. Preprints, Conference on Cloud Physics, San Francisco, CA, July 23-27, 1990. American Meteorological Society, Boston, 666-671 (1990).

No abstract.

Willoughby, H.E. Gradient balance in tropical cyclones. Journal of the Atmospheric Sciences, 47(2):265-274 (1990).

Analysis of a large inventory of in-situ observations from research aircraft shows that the gradient wind approximates the axisymmetric swirling flow in the free atmosphere within 150 km of the centers of Atlantic hurricanes and tropical storms. In the middle and lower troposphere, the rms difference between azimuthal mean swirling and gradient winds is typically <1.5 m s^-1 with zero bias. This balance prevails only for the azimuthal mean, not locally, nor is balance to be expected in either the surface friction layer or the upper tropospheric outflow layer, where the radial flow is comparable with the swirling flow. It is theoretically possible that axisymmetric supergradient flow may occur in response to rapid radial acceleration where the radial flow slows in the friction layer beneath the eyewall or where it converges into intense diabatically-forced updrafts. Nevertheless, the observations in the free lower and midtroposphere show that systematic departures of the azimuthal mean vortex from balance are too small to measure.

Willoughby, H.E. Linear normal modes of a moving, shallow-water barotropic vortex. Journal of the Atmospheric Sciences, 47(17):2141-2148 (1990).

Calculations with a linear semispectral model of a moving tropical-cyclone-like barotropic vortex (Willoughby, 1988) show that a vortex with cyclonic circulation throughout exhibits unphysically fast poleward motion on a beta plane, but a vortex with enough anticyclonic circulation at its periphery to make the total relative angular momentum (L_R) small moves slowly. The high poleward speed arises because the vortex has a linear normal mode at zero frequency, where the beta effect forces asymmetric perturbations. Advection of planetary vorticity by the axisymmetric circulation forces this normal mode at a rate proportional to L_R. Because the governing equations are third-order in time, as many as three linear normal modes are possible. A completely cyclonic vortex has three repeated stable normal modes at zero frequency, whereas one with small L_R has a single stable mode at zero frequency and a conjugate pair of barotropically unstable modes. The frequency of the unstable modes lies at the most anticyclonic rotation frequency of the axisymmetric circulation, and the growth rate is slow; the e-folding time is typically 75 days. If the fluid is made very shallow, the stable normal mode moves away from zero frequency. In this situation, the beta effect fails to force the resonance, and the vortex propagates westward much as a planetary Rossby wave does. In this model, meridional motion of vortices with L_R = 0 always acts to adjust L_R toward zero through conservation of absolute angular momentum. Since the asymmetric perturbations are Rossby waves that propagate upon the radial gradient of mean relative vorticity, the mode at zero frequency experiences critical--radius absorption where the mean swirling wind is zero--at the boundary between cyclonic and anticyclonic mean circulation and at the edge of the vortex. Regardless of the sign of L_R, the wave momentum convergence is concentrated at these critical radii and weakens the circulation while expanding it spatially. When L_R = 0, waves emanating from the cyclonic and anticyclonic circulations interfere destructively, so that the vortex radiates no angular momentum to its environment.

Willoughby, H.E. Temporal changes of the primary circulation in tropical cyclones. Journal of the Atmospheric Sciences, 47(2):242-264 (1990).

More than 900 radial profiles of in-situ aircraft observations collected in 19 Atlantic hurricanes and tropical storms over 13 years confirm that the usual mechanism of tropical cyclone intensification involves contracting maxima of the axisymmetric swirling wind. Radar shows that annuli of convective echoes accompany the wind maxima. These features, called convective rings, exist and move inward because latent heat released in the rings leads to descent, adiabatic warming, and rapid isobaric height falls in the area they enclose. The radial change in rate of isobaric height fall is concentrated at the inner edge of the wind maximum, causing the gradient wind to increase there and the maximum to contract. Vigorous convection organized in rings invariably causes well-defined, inward-moving wind maxima, but when convection is weak, the rings are also weak or even absent. In this case, the swirling wind may be nearly constant with radius and change slowly in time. Hurricanes that have a single, vigorous, axisymmetric ring strengthen rapidly. Although a series of minor convective rings may support steady strengthening, development is more generally episodic. When asymmetric convection erupts near the center of tropical storms or weak hurricanes, it may cause intensification to falter and the cyclone tracks to become irregular. In intense hurricanes, outer convective rings may form around the pre-existent eyewalls, contract, and strangle the original eyewalls, halting intensification or causing weakening.

Yvon, S.A., E.S. Saltzman, D.J. Cooper, A.M. Thompson, P. Newman, J.E. Johnson, and A.L. Torres. Atmospheric H₂S measurements in the equatorial Pacific from the SAGA-3 cruise. EOS, Transactions, American Geophysical Union, 71(43):1226 (1990).

No abstract. **1989**

Bitterman, D.S., and D.V. Hansen. Direct measurements of current shear in the tropical Pacific Ocean and its effect on drift buoy performance. Journal of Atmospheric and Oceanic Technology, 6(2):274-279 (1989).

Measurements of ocean surface currents derived from drift buoy trajectories are subject to errors caused by slippage of the buoy relative to the surrounding water. This slippage error is caused by a number of forces acting on the buoy and drogue element, one of which is the current shear in the water. Idealized model calculations are used to exemplify some effects of vertical current shear on drogues, and on the performance of drogued buoy systems in current shear. It is shown that shear enhances the performance of drogues, and that long drogues should perform better than short drogues in shear, but shear also can induce slippage by adding drag force to the buoy hull. To establish environmental design parameters, average and rms current shear values between 9.7 m and 22.5 m depth were computed from Doppler acoustic current profiler measurements from the tropical Pacific Ocean. Largest values of shear (~0.25 s^-1 rms) were found near the equator in the eastern Pacific as expected. Elsewhere, the shear was generally less than 0.02 s^-1, mostly less than 0.01 s^-1. Average values of shear were generally less than 0.007 s^-1.

Black, M.L. Signal loss of WSR-57 radars as a function of range in tropical cyclones. Preprints, 24th Conference on Radar Meteorology, Tallahassee, FL, March 27-31, 1989. American Meteorological Society, Boston, 514-517 (1989).

No abstract.

Black, M.L., and F.D. Marks. Concentric eyewalls in Hurricane Gilbert (1988). Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 224-225 (1989).

No abstract.

Black, P.G., L.K. Shay, R.L. Elsberry, and J.D. Hawkins. Response of the Gulf of Mexico to Hurricane Gilbert. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 226-227 (1989).

No abstract.

Broecker, W.S., and T.-H. Peng. The cause of the glacial to interglacial CO₂ change: A polar alkalinity hypothesis. Global Biogeochemical Cycles, 3(3):215-239 (1989).

In an attempt to create a scenario for the cause of the glacial to interglacial CO₂ change recorded in air trapped in polar ice, we call on an increase in the alkalinity of polar surface waters. In this way we circumvent a major deficiency of the polar nutrient scenarios of Sarmiento and Toggweiler (1984), Siegenthaler and Wenk (1984), and Knox and McElroy (1984). Namely, our scenario does not require a drop in the nutrient content of polar surface waters in conformity with the demonstration by Boyle (1988a,b) that the cadmium content of planktonic foraminifera from polar regions did not decrease from late glacial to Holocene time. The rise in alkalinity required by our model is a natural consequence of the demise, during glacial time, of North Atlantic Deep Water as a major force in ocean circulation and of the nutrient maximum deepening of Boyle (1988b). Rather than being original, our hypothesis builds on the concept basic to the polar nutrient hypotheses, namely that the CO₂ partial pressure in polar waters controls that for both the atmosphere and warm surface ocean. It also requires the alkalinity increase in surface waters produced by Boyle's nutrient deepening.

Burpee, R.W., and M.L. Black. Temporal and spatial variations near the centers of two tropical cyclones. Monthly Weather Review, 117(10):2204-2218 (1989).

The Hurricane Research Division collected radar reflectivity data with a portable recorder that was attached to the WSR-57 radar at National Weather Service offices as Hurricane Alicia of 1983 and Elena of 1985 approached the U.S. coastline. The reflectivity data were used to compute rain rates for the eyewall region, including the rain-free eye and the rainbands in the annular area outside the eyewall, but within 75 km of the center of the eye. Area- and time-averaged rain rates (R) in the eyewall region were 5.2 and 6.0 mm h^-1, respectively, for Alicia and Elena. The corresponding averages in the rainband region were 2.8 and 3.4 mm h^-1. The rain rates include reflectivity corrections that were based upon the variation of average returned power with range in four hurricanes. Precipitation was convective in the eyewall region and largely stratiform in the rainband region. Comparison with published results from other tropical cyclones suggests that the corrected R's in the eyewall region are underestimated, but are within a factor of 1.6 of the actual amount. The R's in the rainband region, however, are similar to those from other studies. Alicia's eyewall region represented ~15% of the computational area and contributed ~25% of the total rain rate within 75 km of the center of the eye. Elena's eyewall region comprised ~22% of the area and contributed ~33% of the area-averaged rain rate. The area-averaged rain rate (R) in the eyewall region of both hurricanes varied by up to 4 mm in 1-2 h. In Alicia, the variations of R were caused by the growth and decay of mesoscale convective areas with reflectivity >38 dBZ that achieved maximum areas of 500-800 km². In Elena, life cycles of individual convective cells with maximum reflectivities >48 dBZ also accounted for large changes in the eyewall R. In both hurricanes, the time series of R in the rainband regions were less variable than the eyewall R because the rainband regions included larger areas than the eyewall and had a smaller percentage of area with convective activity. For several hours, the maximum rain rates in the eyewall and rainband regions of Alicia occurred in the left-front quadrant relative to the storm motion. Then the maximum rain rate in the eyewall region shifted to the right-front quadrant and the maximum in the rainband region moved to the right of the storm track. In Elena, the maximum rain rates in the eyewall and rainband regions were in the right-front quadrant throughout the computational period. About 55% of the precipitation in Elena's eyewall region occurred in the right-front quadrant. In both hurricanes, the maximum rain rate in the rainband region was generally oriented to the right of that in the eyewall region.

Burpee, R.W., M.L. Black, and F.D. Marks. Vertical motions measured by airborne Doppler radar in the core of Hurricane Elena. Preprints, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 69-70 (1989).

No abstract.

Carbone, R.E., and F.D. Marks. Velocity track display (VTD): A real-time application for airborne Doppler radar data in hurricanes. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 11-12 (1989).

No abstract.

Carder, K.L., R.G. Steward, G.R. Harvey, and P.B. Ortner. Marine humic and fulvic acids: Their effects on remote sensing of ocean chlorophyll. Limnology and Oceanography, 34(1):68-81 (1989).

Marine humic and fulvic acids were concentrated from about 1,400 liters of seawater from the Gulf of Mexico, and specific absorption coefficients were measured for each from 240 to 675 nmi. Spectral absorption coefficients were then calculated for Gulf of Mexico stations where earlier data on humic and fulvic acid concentrations were available. Marine humic and fulvic acid values have low molecular weights consistent with extrapolations from soil-derived curves of their specific absorption coefficients versus molecular weight. Marine fulvic and humic acids appear to account for most, if not all, water color or Gelbstoff in the offshore regions of the Gulf of Mexico. Based on a remote-sensing reflectance model, it appears that the increase in the Gelbstoff:chlorophyll ratio for waters adjacent to and downstream from regions of high primary productivity accounts for much of the deviation found for such waters from the global chlorophyll algorithm of the Coastal Zone Color Scanner.

Clarke, T.L., J.R. Proni, and L.C. Huff. Joint CGS-AOML acoustical bottom echo-formation research II: Field experiment results and recommendations for echo-sounder design. NOAA Technical Memorandum, ERL AOML-67, 71 pp. (1989).

Field experiments were conducted to test and verify a mathematical model that has been developed to assess the effects of bottom roughness and material properties on bottom echo shape. The physical basis of the model is reviewed and model output is presented. The experiments were conducted in lower Chesapeake Bay and involved taking high resolution acoustic data at a number of frequencies and taking supporting sediment samples. A unique, high-resolution bottom profiler was used to measure bottom roughness profiles for input to the model. While model predictions were in general agreement with the data, fine structure was observed in the echoes that could not be explained by the existing model. An extension to the model has been developed that is able to account for this structure. The essential ingredient of this extension is to consider bottom surface scattering as arising from a number of statistically independent patches within the transducer beam. This revised model should lead to improved predictions of bottom echo waveforms for echo-sounder design. The algorithm developed for removing ship motion from the observations suggests a design for a new type of echo-sounder detector circuit based on an energy threshold. This circuit could be easily implemented with modern digital signal processing (DSP) circuits, and it might be suitable for retro-fitting to existing echo-sounders.

Dodge, P.P. The precipitation structure of Hurricane Elena. Preprints, 24th Conference on Radar Meteorology, Tallahassee, FL, March 27-31, 1989. American Meteorological Society, Boston, 522-524 (1989).

No abstract.

Enfield, D.B. El Niño, past and present. Reviews of Geophysics, 27(1):159-187 (1989).

El Niño events--anomalous warmings of the tropical Pacific with associated climatic and economic impacts around the globe--have occurred at several year intervals since before written records began with the logs of Francisco Pizarro in 1525. In this review, the history of El Niño research is traced from its beginnings through the key innovations of Bjerknes and Wyrtki to the unusual 1982-1983 event. Research research is then reviewed, with detailed discussions of the key processes: instability growth and vacillation between climate states. Throughout the paper there are adjunct discussions of extraregional teleconnections, ecological impacts, and research on El Niño in the ancient record. The final section discusses the present paradigm for vacillations between El Niño and non-El Niño states and speculates on the possible chaotic nature of El Niño. El Niño and its atmospheric counterpart, the Southern Oscillation, appear to occur as an internal cycle of positive and negative feedbacks within the coupled ocean-atmosphere climate system of the tropical Pacific, although hypotheses based on external forcing also exist. All events are preceded by westerly wind anomalies on the equator near the date line. Baroclinic equatorial Kelvin waves are generated, propagating eastward toward South America where they depress the thermocline and raise sea level, while the deep, upper ocean reservoir of warm water in the western Pacific is depleted. Sea surface temperature (SST) anomalies in the cool eastern Pacific occur primarily because the normal source of cold water is depressed below the reach of mixing and upwelling processes. In the central equatorial Pacific, eastward advection by anomalous zonal flows is the principal mechanism. Nonlinear heat transfer to the lower atmosphere creates a positive ocean-atmosphere feedback resulting in the unstable growth of anomalies along the equator. Much of the present research aims at determining how the ocean-atmosphere system vacillates between the El Niño and non-El Niño states. Coupled models suggest that a longer time scale, negative-feedback process produces the transitions: at the apex of an El Niño development an anomalous atmospheric convection above the areas of reduced upper layer thickness in the off-equatorial ocean, which slowly propagate westward to the western boundary as Rossby waves and back to the central equatorial Pacific as upwelling Kelvin waves, re-establishing the normal cooling process. A similar negative feedback of opposite sign completes the second half of an oscillation, returning again to the El Niño state. However, the notion that El Niño/Southern Oscillation variability results only from an internal feedback process is still highly contentious and a number of external forcing mechanisms have been proposed.

Franklin, J.L., C.S. Velden, C.M. Hayden, and J. Kaplan. A comparison of VAS and ODW data around a subtropical cold low. Preprints, 4th Conference on Satellite Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 141-144 (1989).

No abstract.

Friedman, H.A., and C.A. Arnhols. 1989 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 100 pp. (1989).

No abstract.

Gallagher, M.S., T.P. Carsey, and M.L. Farmer. Peroxyacetyl nitrate measurements in the North Atlantic. EOS, Transactions, American Geophysical Union, 70:1041 (1989).

No abstract.

Gamache, J.F. Retrieval of thermodynamic and microphysical variables from airborne Doppler observations in Hurricane Norbert (1984). Preprints, 24th Conference on Radar Meteorology, Tallahassee, FL, March 27-31, 1989. American Meteorological Society, Boston, 525-528 (1989).

No abstract.

Gamache, J.F. The eyewall water budget of Hurricane Norbert (1984) as determined from airborne Doppler radar. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 73-74 (1989).

No abstract.

Garzoli, S.L., and Z. Garraffo. Transports, frontal motions, and eddies at the Brazil-Malvinas Currents Confluence. Deep-Sea Research, 36(5A):681-703 (1989).

Three inverted echo sounders were deployed to study the dynamics of the western South Atlantic Brazil-Malvinas Confluence region. Using a simple model, the location of the thermal front is obtained from the time series of the depth of the thermocline. Results show that the main motion of the front is an east-west displacement for distances of about 100 km; the observed period occurs with a periodicity of 12 months and is related to a variability in the latitude of maximum northward penetration of the Malvinas Current. Motions of the front, with a period of 1-2 months, are probably related to a north-south variation of the latitude of return of the Brazil Current.

Garzoli, S.L., and P.L. Richardson. Low-frequency meandering of the Atlantic North Equatorial Countercurrent. Journal of Geophysical Research-Oceans, 94(C2):2079-2090 (1989).

Four 19-month time series of indirect measurements of dynamic height were obtained in the tropical Atlantic along 28°W at 0°, 3°N, 6°N, and 9°N with three inverted echo sounders and one current meter mooring. The series were analyzed to study the time-latitude variability of the North Equatorial Countercurrent (NECC). The eastward flow associated with the NECC was present at 28°W from 3°N to 9°N during most of the observed period except in March-April 1983 and April-May 1984, periods that coincided with the onset of the wind at the equator. The amplitude of the NECC's annual cycle was maximum at 6°N and was larger in 1983 than in 1984. The analysis of the time-latitude variability of differences in dynamic height shows a long-period meridional shift of the NECC. The core of the current attains its northernmost location during August-September in both years and its southernmost location during March-April in 1983 and March in 1984. The location of the core is directly related to the position of the intertropical convergence zone. From the time series of dynamic height obtained from the indirect measurements, geostrophic velocities and transports were estimated and compared with direct observations of currents and values obtained from hydrographic casts.

Goni, G.J., F.D. Tappert, and M.G. Brown. Numerical experiments in the standard mapping. RSMAS Technical Report 89-005 (1989).

No abstract.

Hansen, D.V. Physical aspects of the El Niño event of 1982-1983. In Global Ecological Consequences of the 1982-1983 El Niño-Southern Oscillation, P.W. Glynn (ed.). Elsevier Oceanography Series (1989).

El Niño events are marked by the appearance of anomalously warm ocean waters and unusual rainfall in normally arid coastal regions of Ecuador and Peru. During the past century such events have occurred at about four-year intervals on average, and nine of the events have been described as strong or very strong. In the spring of 1982 the heavy rainfall that normally characterizes the Indo-Pacific archipelago began to shift eastward toward the central Pacific. During the following year the region of anomalous rainfall traversed the ocean to the coast of South America, in phase with anomalous winds, currents, and sea surface temperatures. At the peak of the event in the eastern tropical Pacific, Peru and Ecuador experienced record-setting rainfall leading to flooding and avalanches, near surface ocean currents reversed from their normal direction, sea surface temperature rose to 5°C or more above normal, the thermocline plunged to 100 m or more below normal, and sea level rose to nearly half a meter above normal. Upon reaching the coast, many of the oceanic perturbations propagated poleward along the continental margins in both hemispheres, carrying the signs and effects of El Niño to middle and high latitudes in the Pacific. The magnitude of this event made it the "event of the century" in most variables, and the event of several centuries in some. The magnitude of perturbation of the atmosphere in the tropical Pacific sector certainly carried anomalies also in distant regions of the atmosphere, and thereby secondarily in other parts of the ocean. At greater distance, however, it becomes increasingly difficult to distinguish between anomalies resulting from El Niño and those arising from other kinds of variations of the atmospheric circulation.

Hansen, D.V., and A. Herman. A seasonal isotherm depth climatology for the eastern tropical Pacific. NOAA Technical Report, ERL 434 AOML-33, 35 pp. (1989).

A seasonal climatology of the depths of the 10°C, 15°C, and 20°C isotherms in the eastern tropical Pacific is presented. The analyses used Kriging, which is a method for optimal interpolation of data fields. The data set consisted of 10,505 expendable bathythermograph (XBT) and conductivity-temperature-depth (CTD) stations collected during non-El Niño years. Results are presented on shaded contour maps with values overprinted at 2° intervals. The method of analysis also yields an estimate of the uncertainty of each interpolated point.

Hansen, D.V., and A. Herman. Evolution of isotherm depth anomalies in the eastern tropical Pacific Ocean during the El Niño event of 1982-1983. Journal of Geophysical Research, 94(C10):14,461-14,473 (1989).

Subsurface temperature data collected from research vessels, aircraft, and vessels of opportunity are used to describe the evolution of the major El Niño event in the tropical Pacific from September 1982 through September 1983. Optimum interpolation is used to create six analysis mas of the anomalous depths of the 20°C, 15°C, and 10°C isothermal surfaces. The regions analyzed is 20°N to 20°S and 140°W to the coast of the Americas. Each analysis is based on data accumulated over about a month, and the analysis periods are separated by about a month. The depths of the 20°C isotherm are used to compute zonal thermoclinic transports across 100°W of the North and South Equatorial Currents and the North Equatorial Countercurrent.

Hansen, D.V., and A. Herman. Temporal sampling requirements for surface drifting buoys in the tropical Pacific. Journal of Atmospheric and Oceanic Technology, 6(4):599-607 (1989).

Drifting buoy data from the eastern tropical Pacific Ocean are used to evaluate the degradation of sea surface temperature and current information incurred by reducing the number of transmissions from drifting buoys using the ARGOS system for position finding. Buoy locations are interpolated at uniform time intervals using an optimum interpolation method known as Kriging, which provides also an estimate of the rms position error. It is found that the published standard for surface current measurement for the TOGA Program (5 cm s^-1) can be met with transmissions on one day of three in the Southern Hemisphere. Due to stronger mesoscale variability in the Northern Hemisphere, the standard would be jeopardized by reducing transmissions even to one day of two. The standard for observation of sea surface temperature (0.1°C) can be met in either hemisphere with transmissions on one day of four. The Lagrangian decorrelation times for the Northern Hemisphere region of the eastern tropical Pacific are estimated as four days in the meridional direction, and 14 days in the zonal direction. It is recommended that transmissions be made on one day of three, and the time scale for the TOGA standard be revised accordingly.

Hirsh, M.A., and H.A. Friedman. Creating an awareness of the hurricane problem in at-risk coastal communities of south Florida. Preprints, Second International Conference on School and Popular Meteorological and Oceanographic Education, Crystal City, Virginia, July 12-16, 1989. American Meteorological Society, Boston, 160-162 (1989).

No abstract.

Houde, E.D., P.B. Ortner, L. Lubbers, and S.R. Cummings. Test of a camera-net system to determine abundance and heterogeneity in anchovy egg distributions. Rapports et Proces-Verbaux des Reunions Cons. Int. Explor. Mer., 191:112-118 (1989).

A prototype, in-situ camera-net system was deployed in Chesapeake Bay to test its ability to estimate abundances and delineate fine-scale vertical and horizontal distributions of bay anchovy Anchoa mitchilli eggs and larvae. Hydrographic variables were measured synoptically by electronic sensors on the system. Comparison catch data were obtained by simultaneous deployment of a conventional plankton net. The camera subsampled 1.9% of the water that entered the system and photographed part of the catch at 2-m intervals along the tow. Densities of anchovy eggs, which averaged 99.0 m^-3 during six trial tows, were estimated at 1, 5, and 10 m depths. Anchovy larvae were uncommon (0.34 m^-3) and not sampled effectively. The system detected increasing egg abundances between the surface and 10 m depth and horizontal patchiness over 10-100 m distances. In the configuration used, the system has potential where mean egg or larval densities exceed ca. 5 m^-3. Its advantages are that it can (1) reduce the need to collect and sort plankton samples, (2) provide photographic data for image analysis, and (3) synoptically assess fine-scale distributions of ichthyoplankton, environmental variables, and co-occurring predators and prey.

Johns, E., and R.L. Molinari. Recent current and watermass observations along the western boundary of the tropical North Atlantic Ocean. EOS, Transactions, American Geophysical Union, 70(15):360 (1989).

No abstract.

Johns, E., D.R. Watts, and H.T. Rossby. A test of geostrophy in the Gulf Stream. Journal of Geophysical Research, 94(C3):3211-3222 (1989).

In July 1982 two detailed sections of density and absolute velocity were taken across the Gulf Stream northeast of Cape Hatteras to conduct an accurate test of geostrophy in a strong current. The sections, which were taken about four days apart, were each completed within 48 hours, using one ship to make closely spaced (12 km) conductivity-temperature-depth measurements to 2000 m, and a second ship to simultaneously take Pegasus absolute velocity profiles to the ocean bottom. The Gulf Stream path and curvature were also surveyed. The dynamically inferred velocity profiles were made absolute by matching their velocities to the Pegasus profiles at 2000 m. The geostrophic method (properly referenced) underestimated the observed velocities by 10-25 cm s^-1 in the core of the current above 500 m where speeds exceeded 150 cm s^-1. The difference is a factor of 2, larger than the sampling and measurement errors in corresponding parts of the current, estimated to be 5-10 cm s^-1, well within the uncertainties of the method. The transport above 2000 m is less sensitive to curvature effects; it agrees to within 3 Sv before and 1 Sv after correcting for curvature, or approximately 2% of the total 93 Sv transport. The deep velocity field below 1000 m had significant changes (10-20 cm s^-1) in structure, and even reversals, in the four days between the sections, with cross-stream scales of 50-100 km. This deep variability, attributed to topographic Rossby waves, introduces more than 10 Sv uncertainty in defining the total volume transport of the Gulf Stream.

Katsaros, K.B., G.W. Petty, I. Bhatti, and D. Miller. Application of special sensor microwave/imager data for analysis of cyclonic storms in midlatitudes over the sea. Contract Report 00014-86-K-0453. Naval Environmental Prediction Research Facility, Monterey, CA, 42 pp. (1989).

This report is concerned with currently operating microwave radiometer, the Special Sensor Microwave/Imager (SSM/I) on the F8 satellite in the Defense Meteorological Satellite Program (DMSP). This sensor employs three frequencies with similar characteristics as the ones giving atmospheric water data on SMMR, but not at exactly the same frequencies. For this reason we needed to test the algorithms for identifying fronts with data from this new sensor. In addition, the SSM/I has two channels at 85 GHz which are sensitive to scattering caused by large ice particles and graupel in the clouds. We found that an index of this scattering gives a unique view of the deep clouds in frontal zones. We also tested cloud liquid water and wind algorithms developed for SSM/I, and found good qualitative agreement with conventional data.

Landsea, C.W., H.E. Willoughby, and J.M. Masters. Analysis of Hurricane Gilbert at its maximum intensity. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 222-223 (1989).

No abstract.

Leaman, K.D., E. Johns, and H.T. Rossby. The average distribution of volume transport and potential vorticity with temperature at three sections across the Gulf Stream. Journal of Physical Oceanography, 19(1):36-51 (1989).

Average cross sections of downstream velocity and temperature, obtained using PEGASUS current profilers at three locations along the Gulf Stream, have been partioned into 2.5°C temperature intervals to examine the distribution of transport increase versus temperature between the two southern sections (27° and 29°N) and off Cape Hatteras (73°W). Between 27° and 29°N the total transport of the Florida Current over the sections increased only by about 3 × 10⁶ m³ s^-1 (3 Sv) but the current broadens by about 50%. By Cape Hatteras, the transport has increased nearly three-fold to 93.7 Sv, of which two-thirds of the increase is contained in the 19.5°-17.0°C ("18°") layer and in water colder than the 7°C "sill" temperature found at 27°N. Cross-stream distributions of layer transport, potential vorticity, and thickness are estimated. At each section, the 10 × 10^-7 m^-1 s^-1 contour tends to be a boundary (independent of temperature) between the region of relatively uniform layer potential vorticity on the anticyclonic (offshore) side of the current and an area with high lateral potential vorticity gradients on the cyclonic (onshore) side. In the colder (<7°C) waters off Cape Hatteras, layer potential vorticity also tends to be uniform at ~5 × 10^-7 m^-1 s^-1. Layer potential vorticity in the 18° layer is quite uniform with minimum values ~3.5 × 10^-7 m^-1 s^-1 at 27° and 29°N and somewhat less off Cape Hatteras, which is close to where 18°C water is formed in the wintertime. At Cape Hatteras this same layer shows a peak in transport/unit width at the point where the layer begins to thin as one moves into the Gulf Stream core from the southeast. A simple model based on conservation of layer potential vorticity is proposed to describe this transport structure.

Liao, Q., and M.C. Pazos. Drifting buoy data from western tropical Pacific for the period February 1, 1986 through February 28, 1989. NOAA Data Report, ERL AOML-14, 125 pp. (1989).

No abstract.

Long, R.B., and W.C. Thacker. Data assimilation into a numerical equatorial ocean model, Part 1: The model and the assimilation algorithm. Dynamics of Atmospheres and Oceans, 13:379-412 (1989).

Numerical modeling provides a powerful tool for the study of the dynamics of oceans and atmospheres. However, the relevance of modeling results can only be established by reference to observations of the system being modeled. Typical oceanic observation sets are sparse, asynoptic, of mixed type and limited reliability, generally inadequate in some respects, and redundant and inconsistent in others. An optimal procedure for interfacing such data sets with a numerical model is the so-called adjoint method. This procedure effectively assimilates the observations into a run of the numerical model by finding that solution to the model equations that best fits all observations made within some specified space-time interval. The method requires the construction of the adjoint of the numerical model, a process made practical for models by finding that solution to the model equations that best fits all observations made within some specified space-time interval. The method requires the construction of the adjoint of the numerical model, a process made practical for models of realistic complexity by the work of Thacker and Long (1988). In the present paper, the first of two parts, we illustrate the application of Thacker and Long's approach by constructing a data-assimilating version of an equatorial ocean model incorporating the adjoint method. The model is subsequently run for five years to near-steady state, and exhibits many of the features known to be characteristic of equatorial oceanic flows. Using the last 54 days of the run as a control, a set of simulated sea level and subsurface density observations are collected, then successfully assimilated to demonstrate that the procedure can recover the control run, given a generous amount of data. In part 2 we conduct a sequence of numerical experiments to explore the ability of more limited sets of observations to fix the state of the modeled ocean; in the process, we examine the potential value of sea level data obtained via satellite altimetry.

Long, R.B., and W.C. Thacker. Data assimilation into a numerical equatorial ocean model, Part 2: Assimilation experiments. Dynamics of Atmospheres and Oceans, 13:413-439 (1989).

A sequence of numerical experiments is conducted using a linear, semi-spectral equatorial ocean model and an advanced data assimilation scheme. The numerical model is based on decomposition of the oceanic fields into Kelvin and Rossby waves belonging to the baroclinic modes of a stratified equatorial ocean. The assimilation procedure finds that solution to the model equations that best fits, in the generalized least-squares sense, all observations made within some specified space-time interval. All experiments are of the "identical twin" type; synthetic data are generated by sampling the observable fields produced by a control run of the model, then the data are assimilated using the same model. The sequence of numerical experiments serves two purposes: to demonstrate the performance of the assimilation procedure in the context of a fully three-dimensional, time-varying equatorial ocean model, and to examine the utility of specified data sets, and in particular, observations of sea level, in estimating the state of the equatorial ocean. The results indicate that the assimilation procedure works very well when sufficient data are provided. However, sea level data alone are not sufficient and must be supplemented with subsurface observations if more than a few baroclinic modes are allowed in the model ocean. The required amount of supplementary subsurface data (in the form of density profiles in these experiments) can be reduced by imposing smoothness constraints on the recovered model solution.

Lyons, W.A., M.G. Venne, P.G. Black, and R.C. Gentry. Hurricane lightning: A new diagnostic tool for tropical storm forecasting? Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 113-114 (1989).

No abstract.

Marks, F.D. Kinematic structure of the inner core of hurricanes as viewed by airborne Doppler radar. Proceedings, Third Interagency Airborne Geosciences Workshop, La Jolla, CA, February 21-24, 1989. American Meteorological Society, Boston, IV-79-IV-81 (1989).

No abstract.

Marks, F.D. Radar observations of tropical weather systems. In Radar in Meteorology, D. Atlas (ed.). American Meteorological Society, Boston, 1024 pp. (1989).

No abstract.

Marks, F.D. Three-dimensional structure of the eyewall of Hurricane Emily (1987) as determined from an airborne Doppler radar. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 71-72 (1989).

No abstract.

Marks, F.D., and S.J. Lord. Kinematic structure of Hurricane Gloria as viewed by airborne Doppler radar and Omega dropwindsondes. Preprints, 24th Conference on Radar Meteorology, Tallahassee, FL, March 27-31, 1989. American Meteorological Society, Boston, 529-532 (1989).

No abstract.

Maul, G.A., D.A. Mayer, M.H. Bushnell, and K. Hanson. Volume transport fluctuations in the Gulf Stream system modeled from Florida sea level records, 1931-1988. Proceedings, Chapman Conference on the Physics of the Gulf of Mexico. EOS, Transactions, American Geophysical Union, 12 (1989).

No abstract.

Maul, G.A., J.R. Proni, M.H. Bushnell, and J.L. Mitchell. Oceanic dynamic height anomaly from GEOSAT: A conceptual model for short collinear orbit segments. Marine Geodesy, 12:259-285 (1989).

A method is derived for extracting oceanic dynamic height anomaly from collinear (exact repeat mission) GEOSAT short (~1,000 km long) orbit segments. The procedure requires at least one year of simultaneous in-situ observations and involves: (1) computing with respect to the ellipsoid, a mean sea surface height (SSH) profile solely from altimetry; (2) linear least-squares removal of tilt and bias from individual SSH profiles with respect to the mean profile; (3) determining an independent mean dynamic height anomaly profile from hydrographic data along the orbit segment; (4) demeaning the tilt-and-bias removed individual SSH profiles and addition of the mean in-situ dynamic height anomaly; and (5) correcting for concurrently observed dynamic height anomaly at two or more suborbital points during satellite transit. Analysis of the concept suggests root sum squared errors of ±5 cm, which can be reduced by smoothing and longer term measurements along the same orbit segment. A one-year comparison between two orbit segments at an open ocean crossover point shows differences of ±2 cm, and comparison with six months of simultaneous in-situ data shows corrections of ±3 cm are required. Space-time plots of demeaned tilt-and-bias removed GEOSAT SSH profiles, compared with similarly processed NMC/CAC numerical circulation model calculations, show good agreement with variability in the South Equatorial Current/North Equatorial Countercurrent system in the eastern Pacific Ocean, and suggest that further development of the concept is warranted.

McCreary, J.P., H.S. Lee, and D.B. Enfield. The response of the coastal ocean to strong offshore winds: With application to circulation in the Gulfs of Tehuantepec and Papagayo. Journal of Marine Research, 47:81-109 (1989).

Two ocean models are used to investigate the response of the coastal ocean to strong offshore winds: a linear 1 1/2-layer model, and a non-linear 1 1/2-layer model that allows entrainment of cool water into the surface layer. The models are forced by wind stress fields similar in structure to the intense wintertime, mountain-pass jets (~20 dyne/cm²) that appear in the Gulfs of Tehuantepec and Papagayo for periods of three to ten days. Solutions are arranged in a hierarchy of increasing dynamical complexity in order to illustrate the important physical processes. They compare favorably with observations in several ways. Some properties of solutions are the following. While the wind strengthens, there is an ageostrophic current (not Ekman drift) that is directed offshore. This offshore drift forces coastal upwelling, thereby lowering the local sea level and sea surface temperature (SST). Although the drop in sea level at the coast can be large and rapid (of the order of 20 cm at the peak of a wind event), none of this signal propagates poleward as a coastally-trapped wave. While the wind weakens, the ageostrophic current is directed onshore, and consequently the coastal ocean readjusts toward its initial state. Throughout the wind event, cyclonic and anticyclonic gyres spin up offshore on either side of the jet axis due to Ekman pumping. Entrainment cools SST offshore on and to the right (looking onshore) of the jet axis, and virtually eliminates the cyclonic gyre. The advection terms intensify the anticyclonic gyre and give it a more circular shape. After a wind event, the anticyclonic gyre propagates westward due to beta. Its propagation speed is enhanced over that of a linear Rossby wave due to the nonlinear terms associated with the increased thickness at the center of the gyre and with the divergence of momentum flux.

Millero, F.J., J.P. Hershey, G. Johnson, and J.-Z. Zhang. The solubility of SO₂ and the dissociation of H₂SO₃ in NaCl solutions. Journal of Atmospheric Chemistry, 8:377-389 (1989).

The pK₁* and pK₂* of H₂SO₃ have been determined in NaCl solutions as a function of ionic strength (0.1 to 6 m) and temperature (5 and 25°C). The extrapolated values in water were found to be in good agreement with literature data. The experimental results have been used to determine the Pitzer interaction parameters for SO₂, HSO₃^-, and SO₃^2- in NaCl solutions. The resultant parameters for NaHSO₃ and Na₂SO₃ were found to be in reasonable agreement with the values for NaHSO₄ and Na₂SO₄. It thus seems reasonable to assume that the interactions of Mg²⁺ and Ca²⁺ with HSO₃^- and SO₃^2- can be estimated from the values with HSO₄^- and SO₄^2- until experimental values are available. Measurements of pK₁* and pK₂* in artificial seawater were found to be in good agreement with the calculated values using the derived Pitzer parameters. It is, thus, possible to make reasonable estimates of the activity coefficients HSO₃^- and SO₃^2- ions and pK₁* and pK₂* for the ionization of H₂SO₃ in marine aerosols.

Ortner, P.B., L.C. Hill, and S.R. Cummings. Zooplankton community structure and copepod species composition in the northern Gulf of Mexico. Continental Shelf Research, 9(4):387-402 (1989).

Zooplankton community structure and copepod species composition are analyzed in samples obtained during spring and winter from three areas of the northern Gulf of Mexico: near the Mississippi River outflow, off Cape San Blas, and in the central Gulf of Mexico. Samples from different regions were distinguishable in correspondence analysis of dominant species and/or functional groups. The near-surface communities of the Mississippi and central Gulf were particularly distinct while Cape San Blas was intermediate in both structure and specific character. Saltier waters directly beneath the Mississippi plume yielded samples similar to those from near-surface waters well offshore. At the same time near-surface waters off the Mississippi and off Cape San Blas to the west were distinguishable even during spring when the outflow from the Mississippi was at its annual peak. These differences are consistent with the discharge and flow patterns of the Mississippi River plume and the northern Gulf and with systematic differences in such parameters as temperature, salinity, and chlorophyll concentration. The implications of these observations upon the feeding environments of the larvae of commercially significant fish species are addressed since both zooplankton prey and larval predators appear to be particularly abundant in the Mississippi River plume environs.

Ooyama, K.V. Thermodynamics in the primitive form for modeling the moist atmosphere. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 157-158 (1989).

No abstract.

Peng, T.-H. Changes in ocean ventiliation rates over the last 7000 years based on ¹⁴C variations in the atmosphere and oceans. Radiocarbon, 31(3):481-492 (1989).

Changes in the ocean ventilation rate may be one of the causes for a net decrease of 100^o/_oo DELTA ¹⁴C in atmospheric CO₂ over the last 8000 years. Ocean ventilation rates of the past can be derived from the ¹⁴C record preserved in planktonic and benthic foraminifera in deep-sea sediments. Results of ¹⁴C dating using accelerator mass spectrometry on deep sea sediments from the South China Sea show that the age differences between planktonic (G sacculifer) and benthic foraminifera increase from 1350 yr ca 7000 yr ago to 1590 yr at present. An 11-box geochemical model of global ocean circulation was used for this study. Both tree-ring-determined atmospheric ¹⁴C values and foraminifera ¹⁴C age differences are used as constraints to place limits on patterns of changes in ocean ventilation rates and in atmospheric ¹⁴C production rates. Results indicate: (1) ¹⁴C production rates in the atmosphere may have decreased by as much as 30% between 7000 and 3000 yr ago, and may have increased again by ca 15% in the past 2000 yr; and (2) the global ocean ventilation rate may not have been at steady state over the last 7000 yr, but may have slowed by as much as 35%.

Peng, T.-H., W.M. Post, D.L. DeAngelis, V.H. Dale, and M.P. Farrell. Atmospheric carbon dioxide and the global carbon cycle. The key uncertainties. In Alternative Energy Sources VIII, Volume 2: Research and Development, T.N. Veziroglu (ed.). Hemisphere Pub. Corp., New York, 707-728 (1989).

No abstract.

Peterson, D.H., D.R. Cayan, J.F. Festa, F.H. Nichols, R.A. Walters, J. V. Slack, S.E. Hager, and L.E. Schemel. Climate variability in an estuary: Effects of riverflow on San Francisco Bay. In: Aspects of Climate Variability in the Pacific and Western Americas, D.H. Peterson, editor, Geophysical Monograph 55, 419-442 (1989).

No abstract.

Piotrowicz, S.R., R.A. Rasmussen, K.J. Hanson, and C.J. Fischer. Ozone in the boundary layer of the equatorial Atlantic Ocean. Tellus, 41B:314-322 (1989).

Shipboard (~7) ozone and carbon monoxide measurements made in the equatorial Atlantic Ocean south of the inter-tropical convergence zone between 5°N and 10°S and 10°-30°W in August and September of 1986 exhibited variability in excess of a factor of 2. Ozone mixing ratios ranged from <25 to over 50 ppbv while carbon monoxide mixing ratios ranged from <50 to over 120 ppbv along the western edge of the equatorial Atlantic in spite of the fact that the prevailing surface winds were from the east to southeast at between 5 and 15 m/sec. Ozone and carbon monoxide mixing ratios were generally lower and exhibited less variability in the eastern tropical Atlantic where a lighter, south to southeasterly wind regime predominated. Isobaric trajectory analyses indicated that the high ozone and carbon monoxide mixing ratios appear to be related to long-range transport off of the African continent. Time series analysis of the ozone data indicates a diel cycle in ozone mixing ratios with a morning maximum and afternoon minimum.

Powell, M.D. Boundary-layer kinematic structure in outer hurricane rainbands. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 67-68 (1989).

No abstract.

Powell, M.D. Boundary-layer structure and dynamics in outer hurricane rainbands. Preprints, 24th Conference on Radar Meteorology, Tallahassee, FL, March 27-31, 1989. American Meteorological Society, Boston, 533-536 (1989).

No abstract.

Proni, J.R., and W.P. Dammann. Observations of acoustic backscatter from oceanic wastewater outfalls. Journal of the Acoustical Society of America, 85:S42 (1989).

Narrow beam echo sounders were used to characterize the spatial distribution of wastewater plume material from six ocean outfalls in the south Florida area. Volume scattering strengths were computed and plotted as a function of depth and horizontal distance for 200 kHz echoes. Reduction in peak scattering strength with increased range from the outfall locations correlated well with reduction in concentration of Rhodamine-WT dye introduced into the undiluted wastewater at a concentration of 1 ppm. Sound power reflection coefficients ranging from 10^-5 to 10^-9 were observed for these wastewater plumes. The data presented demonstrates the degree to which the sound power reflection coefficient for a distribution of scatterers is dependent upon the concentration of those scatterers, and shows the utility of the acoustical method in watermass characterization.

Proni, J.R., W.P. Dammann, J.F. Craynock, and R. Fergen. Oceanic wastewater plume characteristics measured acoustically. Program and Abstracts, Eighth International Ocean Disposal Symposium, Dubrovnik, Yugoslavia, October 9-13, 1989. Inter-University Center of Postgraduate Studies, 18-19 (1989).

The measurement of oceanic wastewater plume features is complex and the obtaining of samples of plume material is difficult. A study, called SEFLOE, has been conducted on wastewater outfalls off the coast of southeast Florida (USA). The wastewater plume field F(r,0,z,t) is considered to be comprised of a set of subfields f_i(r,0,z,t), i.e., F(r,0,z,t) = F(f_i, ..., f_i, ..., f_n); likewise, the oceanic water column field W(r,0,z,t), into which the wastewater plume is injected, is considered to be comprised of a set of subfields; i.e., W(r,0,z,t) = W(W₁, ..., w_i, ..., w_n). In this study, the feasibility of utilizing high-frequency acoustics to provide an estimator field I(r,0,z,t) for one or more of the wastewater plume subfields f_i(r,0,z,t) is examined. It is hypothesized that the water-column background corrected acoustical backscattered intensity I(r,0,z,t) where I(r,0,z,t) = <I_f(r,0,z,t)> - <I_w(r,0,z,t)> may be used to guide chemical/biological sampling and the physical structure of at least one wastewater plume subfield is revealed by the structure of I(r,0,z,t) (the brackets denote a measured quantity). Data from SEFLOE have indicated that the wastewater plume field is divided into regions of higher concentration, spatially separated by regions of lower concentration; we call these regions of higher concentration "boluses." When the water column is density stratified, a "peeling-off" effect of the outer portions of the rising wastewater plume is observed. The outer portions "peel-off" into a vertical series of subsurface plumes at different depths within the water column. The rate of dilution with range for a purely surficial plume which existed in January 1988 is compared within the rate of dilution with range of subsurface plume which existed in June of 1988. In the surface plume, a much slower dilution rate is observed for acoustical, dye and fecal streptococcal subfields, while a somewhat slower dilution rate was observed for the fecal coliform. In the subsurface plume, a much slower dilution rate is observed. In addition to dilution with range, mean value, standard deviation and the peak-to-mean values are presented as a function of range for a specific ship transect.

Ramos, P.A., and D.R. Palmer. Comments on the Deep Six Sound Channel. Journal of the Acoustical Society of America, 85:1767 (1989).

Some features of the Deep Six Sound Channel [J.C. Miller, J. Acoust. Soc. Am., 71:859-862 (1982)], which may be important to those who wish to use the model in various applications, are noted and discussed.

Rao, R.R., R.L. Molinari, and J.F. Festa. Evolution of the climatological near-surface structure of the tropical Indian Ocean. Part I: Description of mean montthly mixed layer depth and sea-surface temperature, surface current, and surface meteorological fields. Journal of Geophysical Research, 94(C8):10,801-10,815 (1989).

Mean monthly mixed layer depth (MLD), sea-surface temperature (SST), and surface current climatologies are generated for the tropical Indian Ocean. In addition, surface meteorological climatologies are produced for those variables which could influence the evolution of the MLD and SST fields. Only the MLD climatology is described in detail, as climatologies for the other variables have appeared previously in the literature. The sum of the annual and semi-annual harmonics account for greater than 75% of the energy in the MLD time series over most of the basin. The amplitude of the annual signal is greater than 20 m between 10°S and 25°S, with deepest MLDs observed during the southern hemisphere winter. The south-central Arabian Sea, between the equator and 10°N, and the northern Arabian Sea are also regions of larger annual harmonic amplitude (>15 m). The amplitude of the semi-annual harmonic is largest in the central Arabian Sea (>25 m). Deepest MLDs are observed there during the height of the two monsoon seasons. Correlation coefficients are computed between MLD and SST and several other oceanographic and meteorological variables to explore possible causal relationships. Net energy flux through the sea surface can account for 75% of the variance in the SST and MLD time series over most of the region south of the equator. Large coefficients are also observed in the northwestern Arabian Sea. Correlations between SST and MLD and surface currents are, in general, small throughout the region with maxima observed in the central Arabian Sea, in the vicinity of the South Equatorial Current and in the extreme eastern equatorial Indian Ocean. These correlations are examined in more detail in Part II of this study in which simple models of mixed layer dynamics are employed.

Rappaport, E.N., and P.G. Black. The utility of special sensor microwave/imager data in the operational analysis of tropical cyclones. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, J21-J24 (1989).

No abstract.

Rosenfeld, L.K., R.L. Molinari, and K.D. Leaman. Observed and modeled annual cycle of transport in the Straits of Florida and east of Abaco Island, the Bahamas (26.5°N). Journal of Geophysical Research, 94(C4):4867-4878 (1989).

Direct velocity observations were collected with a free-fall acoustic velocity profiler along an east-west section extending 65 km offshore of Abaco Island, the Bahamas (26.5°N). The section, which includes five stations, was occupied 14 times between September 1984 and September 1987. The two inshore stations were located on the continental slope, and the three offshore stations were located over the abyssal plain (at depths approaching 4,700 m). The average total section transport between the surface and 2,500 m (the portion of the water column best sampled) was 10 Sv (1 Sv = 10⁶ m³/s) to the south. The range of transports is 40 Sv with maximum northward transport observed during April 1985 (5.3 Sv) and maximum southward transport observed during April 1986 (34.8 Sv). The average flow above 800-900 m is to the north at the four westernmost stations and is to the south below 800-900 m and over most of the easternmost station. The southward flow includes the Deep Western Boundary Current. Strong vertical shears extend to 1,100 m. An approximation for the upper layer (above 1,100 m) baroclinic transport has a mean of 12.2 Sv to the north and a range of 15 Sv. Results from a two-layer and a one-and-a-half-layer wind-driven model are compared with the annual cycles of total and upper layer transport, as determined from the observations. The barotropic transport from the two-layer model has a range of the order of ±10 Sv, with a winter maximum and fall minimum. The range of the baroclinic transport from the one-and-a-half-layer model is an order of magnitude smaller and of opposite sign. Although there are similarities between the observations and the results of both models, the small signal-to-noise ratio precludes definitive confirmation of the annual cycle. The situation east of the Bahamas, where the two models give very different predictions, is compared with the Straits of Florida, where both models predict an annual cycle similar to that observed for the total transport. The roles played by topography and local and remote wind forcing in producing these results are discussed.

Shay, L.K., R.L. Elsberry, and P.G. Black. Vertical structure of the ocean current response to a hurricane. Journal of Physical Oceanography, 19(5):649-669 (1989).

During the passage of Hurricane Norbert in 1984, the Hurricane Research Division of NOAA conducted a planetary boundary-layer experiment that included the deployment of airborne expendable current profilers (AXCP). A total of 16 AXCPs provided, for the first time, high-resolution vertical profiles of currents and temperatures in hurricanes wind conditions. This study focuses on the vertical structure of the near-inertial baroclinic currents excited by the passage of this hurricane. The transient, hurricane-induced currents are isolated from the AXCP profiles in Norbert by subtracting a spatially-averaged current. Near the center of Hurricane Norbert, the WKBJ-scaled vertical wavenumber spectra are a decade greater than the Garrett-Munk spectra (GM75). The first ten linear, baroclinic-free modes are calculated from the spatially-averaged, Brunt-Väisälä frequency. To allow a more direct comparison with the AXCP observations in the high-wind regime, the near-inertial response for the three-dimensional velocities is simulated by superposing a hurricane-like wind stress field onto the first ten baroclinic modes. About 70% of the current variance in Hurricane Norbert can be explained by a sum of only the first four near-inertial modes. Most of the ocean current variability can be accounted for by the wind stress curl, although the direct effect of the wind stress and the stress divergence do contribute to the observed current variance within 30-60 km from the storm. However, these last two effects rapidly diminish after one inertial period. Although the energy input by the hurricane forcing is spread over all of the vertical wavelengths, most of the energy is contained in the gravest four vertical modes which then govern the dynamics in the wake region.

Thacker, W.C. Fitting models to inadequate data by enforcing spatial and temporal smoothness. Journal of Geophysical Research, 93(C9):10,655-10,665 (1989).

When observations are too sparse to determine the state of a dynamical model, it is necessary to make use of prior knowledge or prejudice. The approach discussed here is to require that the model state be the best smooth fit to the sparse data. The requirement of smoothness is enforced by introducing bogus data, which correspond to hypothetical observations that properties such as slope, curvature, or temporal tendency of model fields have zero values within some specified accuracy. The bogus data serve to increase the effective ratio of data to model degrees of freedom. The concept of bogus data allows a bias toward smoothness to be incorporated easily into the adjoint method for fitting time-dependent models to asynoptic data. Computational examples using a simple three-wave model show that reasonable fits can be obtained even when the number of real data is considerably less than the number of model degrees of freedom.

Thacker, W.C. The role of the Hessian matrix in fitting models to measurements. Journal of Geophysical Research, 94:6177-6196 (1989).

A numerical model can be fit to data by minimizing a positive quadratic function of the differences between the data and their model counterparts. The rate at which algorithms for computing the best fit to data converge depends on the size of the condition number and the distribution of eigenvalues of the Hessian matrix, which contains second derivatives of this quadratic function. The inverse of the Hessian can be identified as the covariance matrix that establishes the accuracy to which the model state is determined by the data; the reciprocals of the Hessian's eigenvalues representing the variances of linear combinations of variables determined by its eigenvectors. The aspects of the model state that are most difficult to compute are those about which the data provide the least information. A unified formalism is presented in which the model may be treated as either strong or weak constraints, and methods for computing and inverting the Hessian matrix are discussed. Examples of the uncertainties in the best-fit analyses using an oceanographic model are given for several different sets of hypothetical data.

Tziperman, E., and W.C. Thacker. An optimal control/adjoint equations approach to studying the oceanic general circulation. American Meteorological Society, 19:1471-1485 (1989).

An efficient procedure is presented for analyzing oceanographic observations with the aid of a general circulation model. Poorly known model parameters, such as eddy mixing coefficients, surface forcing and tracer boundary fluxes, can be calculated by fitting model results to observations. Optimal estimates for all model fields, including the observed ones, can then be computed by running the model with the best-fit values of the calculated parameters. Information about the resolution and the error-covariances of the model parameters can be computed. This information is shown to be very valuable for critically evaluating how well the data determine the parameter's values. An adjoint model, similar in structure to the numerical model, uses information on model-data misfit to improve estimates of the unknown model parameters, and improve the fit to observations. The procedure is illustrated using simulated data and a simple, barotropic, nonlinear, quasi-geostrophic model. Examples are discussed in which friction parameters, wind forcing, and the steady-state circulation are determined from simulated vorticity and streamfunction observations.

Venne, M.G., W.A. Lyons, C.S. Keen, P.G. Black, and R.C. Gentry. Explosive supercell growth: A possible indicator of tropical storm intensification? Preprints, 24th Conference on Radar Meteorology, Tallahassee, FL, March 27-31, 1989. American Meteorological Society, Boston, 545-548 (1989).

No abstract.

Willis, P.T., and A.J. Heymsfield. Hurricane microphysical trajectories. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 75-76 (1989).

No abstract.

Willis, P.T., and A.J. Heymsfield. Structure of the melting layer in mesoscale convective system stratiform precipitation. Journal of the Atmospheric Sciences, 46(13):2008-2025 (1989).

This study examines the aircraft observations and theoretical evolution of particles above, through, and below the melting layer in the stratiform region associated with a mesoscale convective system (MCS). The aircraft data were obtained from an advecting spiral descent where the descent rate approximately corresponded to the typical hydrometeor fall speeds. The microphysical and thermodynamic measurements not only allowed us to characterize the particle evolution, but also enabled us to compare them with the theoretical evolution of the particles in the melting layer and to quantify the associated heating and cooling rates. Even though complete melting requires a fairly deep layer, most of the mass melts, and thus most of the cooling occurs, in a thin layer above the location of the radar bright band. Based upon the magnitude of vertical velocity fluctuations, the layers below the melting layer appear to be decoupled from those above. The ice water content above the melting layer is two to three times the liquid water content below the melting layer. The production of a few, very large, aggregates is dramatic after the onset of melting, due in part to a melting-induced increase in the terminal velocity difference between similar-sized hydrometeors. The radar reflectivity maximum (bright band) is due to these relatively few, very large, aggregates that survive to warmer temperatures. The reflectivity maximum is depressed well below the isothermal layer and the level where most of the ice mass is melted. Above the melting layer, small crystals are replenished by a fragmentation or breakup process.

Willis, P.T., and P. Tattleman. Drop-size distributions associated with intense rainfall. Journal of Applied Meteorology, 28(1):3-15 (1989).

The probability of occurrence of extreme rainfall rates is reviewed. The drop-size distributions associated with a range of high rainfall rates are examined using data from tropical storms and hurricanes. Mean drop-size distributions are presented for a range of high rainfall rates, as well as a Gamma-distribution fit to the entire set of normalized drop-size distributions. This fit forms the basis for a model drop-size distribution for intense rain. The goodness of fit of the model is examined by comparing it with independent drop-camera measurements of high-rain-rate distributions from several geographic locations. The slope of exponential fits to the distributions are examined for constancy with rainfall rate and are generally found to decrease with increasing rainfall rate.

Willoughby, H.E., W.P. Barry, and M.E. Rahn. Real-time monitoring of Hurricane Gilbert. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 220-221 (1989).

No abstract.

Willoughby, H.E., J. Masters, and C.W. Landsea. A record minimum sea level pressure observed in Hurricane Gilbert. Monthly Weather Review, 117(12):2824-2828 (1989).

On 13 September 1988, Hurricane Gilbert attained an extreme minimum sea level pressure, estimated to be 885 hPa from aircraft reconnaissance reports at the time. Postseason analysis indicates that the flight-level pressure, P, upon which this figure is based requires correction upward. In typhoons with sea level pressure <900 hPa, comparison between sea level pressures measured by dropsonde and those estimated by the same method used in Gilbert indicates that, in addition to the error in P, the estimation has a bias toward low pressure. Although the aircraft did not release a dropsonde in the eye at minimum pressure, it is possible to calculate hydrostatic sea level pressures by assuming a variety of plausible thermal structures below flight level. With corrected P, both the statistical extrapolation with its bias removed and the hydrostatic calculations show that a revised value of 888 ± 2 hPa is closer to the true minimum sea level pressure. The standard deviation of the various approximations means that the probability is <3% that the actual minimum failed to reach a value below 892 hPa, the old record for a hurricane in the Atlantic Basin set by the Labor Day Hurricane of 1935.

Wilson, W.D., and A. Leetmaa. Acoustic Doppler current profiling in the equatorial Pacific in 1984. Journal of Geophysical Research, 93(C11):13,947-13,966 (1989).

Hydrographic data and acoustic Doppler current profiles collected from 150°W to 85°W in the equatorial Pacific during 1984 showed significant seasonal changes in the temperature and velocity fields. On the equator, the surface current was eastward in April up to 80 cm s^-1, reversing to westward at 100 cm s^-1 by November. Over the same period, the Equatorial Undercurrent (EUC) transport decreased, the equatorial zonal pressure gradient (ZPG) increased, and the depth of the mixed layer and EUC core deepened. Off the equator at 150°W, the North Equatorial Countercurrent (NECC) was absent in April/May but pronounced in October/November. Superimposed on this seasonal variability were smaller-scale (roughly 1,000 km wavelength) correlated fluctuations in the upper ocean temperature and velocity fields. We identify these structures with the 20- to 30-day instability waves (Legeckis, 1977). The coincident high-resolution velocity and temperature data allowed the calculation of Reynold's stresses due to the waves and resultant heat and momentum flux estimates as well as details of of the vertical phase structure. Barotropic instability at the northern edge of the EUC is a likely source of energy for these waves. Estimated EUC transport decreased from 50 in April to 25 × 10⁶ m³ s^-1 in November while the westward wind stress doubled and the 0-/400-dbar ZPG quadrupled. The data were used to estimate terms in the momentum balance in the upper 150 m, and it was found that nonlinear terms were often at least as important as the integrated ZPG in balancing the surface wind stress. East of 120°W, the eastward advection of eastward momentum, UU_x, was particularly important. These momentum equation terms were used to estimate a profile of the coefficient of vertical eddy viscosity; it was similar to profiles estimated by bulk methods and by parameterization by Richardson number.

Wood, V.T., and F.D. Marks. Hurricane Gloria: Simulated land-based Doppler velocities reconstructed from airaborne Doppler radar measurements. Extended Abstracts, 18th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 16-19, 1989. American Meteorological Society, Boston, 115-116 (1989).

No abstract.

Vazquez, F., J.-Z. Zhang, and F.J. Millero. Effect of metals on the rate of the oxidation of H₂S in seawater. Geophysical Research Letters, 16(12):1363-1366 (1989).

Recent measurements on the oxidation of H₂S in the Black Sea yielded rates that were ten times faster than expected. To determine if this increase was due to trace metals, measurements have been made on the oxidation of H₂S in seawater with added transition metals. Below a concentration level of 100 nM, none of the metals except for Fe²⁺ affect the rate of oxidation. At higher concentrations the rates increase for all the metals except Zn²⁺. The increase in the rates followed the order:

Fe²⁺ > Pb²⁺ > Cu²⁺ > Fe³⁺ > Cd²⁺ > Ni²⁺ > Co²⁺ > Mn²⁺.

The increase in the rates below sulfide precipitation appears to be related to the formation of MHS⁺ ion pairs that have a higher rate of oxidation than HS^-. Only Fe²⁺ and Mn²⁺ have concentrations high enough to be effective in influencing the rate of oxidation of H₂S in the waters of anoxic basins and sediments. The estimated rates of oxidation of H₂S in the Black Sea using the laboratory measurements were found to be in reasonable agreement with the measured values. Since CuHS⁺ has a higher rate of oxidation than HS^-, it cannot be used to explain the stability of H₂S in oxic seawaters. A more likely choice is ZnHS⁺.

**1988**

Bitterman, D.S. The NOAA-AOML drift buoy program. Proceedings, International Service ARGOS Users Conference and Exhibit, Greenbelt, MD, September 15-17, 1987, 107-116 (1988).

No abstract.

Black, P.G. Hurricane-ocean interaction near the subtropical front. Preprints, 7th Conference on Ocean-Atmosphere Interaction, Anaheim, CA, January 31-February 5, 1988. American Meteorological Society, Boston, J60 (1988).

No abstract.

Black, P.G., R.L. Elsberry, and L.K. Shay. Airborne surveys of ocean current and temperature perturbations induced by hurricanes. In Advances in Underwater Technology, Ocean Science, and Offshore Engineering, Vol. 16, Oceanology '88. Graham and Trotman, London, 51-58 (1988).

No abstract.

Black, P.G., R.L. Elsberry, L.K. Shay, R.M. Partridge, and J.D. Hawkins. Atmospheric boundary-layer and oceanic mixed-layer observations in Hurricane Josephine obtained from air-deployed drifting buoys and research aircraft. Journal of Atmospheric and Oceanic Technology, 5(6):683-698 (1988).

Three drifting buoys were successfully air dropped ahead of Hurricane Josephine. This deployment resulted in detailed simultaneous measurements of surface wind speed, surface pressure, and subsurface ocean temperature during and subsequent to storm passage. This represents the first time that such a self-consistent data set of surface conditions within a tropical cyclone has been collected. Subsequent NOAA research aircraft overflights of the buoys, as part of a hurricane planetary boundary-layer experiment, showed that aircraft wind speeds, extrapolated to the 20 m level, agreed to within ±2 m s^-1, pressures agreed to within ±1 mb, and sea-surface temperatures agreed to within ±0.8°C of the buoy values. Ratios of buoy peak 1 min wind (sustained wind) to 1/2 h mean wind >1.3 were found to coincide with eyewall and principal rainband features. Buoy trajectories and subsurface temperature measurements revealed the existence of a series of mesoscale eddies in the subtropical front. Buoy data revealed storm-generated, inertia-gravity-wave motions superposed upon mean current fields, which reached a maximum surface speed >1.2 m s^-1 immediately following storm passage. A maximum mixed-layer temperature decrease of 1.8°C was observed to the right of the storm path. A temperature increase of 3.5°C at 100 m and subsequent decrease of 4.8°C following storm passage indicated a combination of turbulent mixing, upwelling, and horizontal advection processes.

Broecker, W.S., D. Oppo, T.-H. Peng, W. Curry, M. Andree, W. Wolfli, and G. Bonani. Radiocarbon-based chronology for the ¹⁸0/¹⁶0 record for the last deglaciation. Paleoceanography, 3(4):509-515 (1988).

A radiocarbon-calibrated box model for today's ocean suggests that a lag of about 1750 years should exist between the arrival of the mid-point of the deglaciation ¹⁸O signal in the deep Atlantic Ocean and its arrival in the deep Pacific Ocean. In order to assess the actual lag, we have carried out accelerator radiocarbon measurements on two cores from the Atlantic Ocean and one core from the Pacific Ocean. Although the results are not definitive, there is a suggestion that the actual time lag was about 1000 years.

Broecker, W.S., R.H. Wanninkhof, G. Mathieu, T.-H. Peng, S. Stine, S. Robinson, A. Herczeg, and M. Stuiver. The radiocarbon budget for Mono Lake: An unsolved mystery. Earth and Planetary Science Letters, 88:16-26 (1988).

Since 1957 the ¹⁴C/C ratio of the dissolved inorganic carbon in Mono Lake has risen by about 60%. The magnitude of this increase is about four times larger than that expected from the invasion of bomb-produced ¹⁴C from the atmosphere. We have eliminated the following explanations: (1) measurement error; (2) an unusually high physical exchange rate for non-reactive gases; (3) inorganic enhancement of the CO₂ exchange rate; and (4) biological enhancement of the CO₂ exchange rate. Clandestine disposal of waste radiocarbon remains a dark-horse explanation. In the course of our investigations we have uncovered evidence for at least one episodic input of radiocarbon-free carbon to the lake over the last 1000 years. We speculate that this injection was related to a hydrothermal event resulting from sublacustrine volcanic activity.

Clarke, T.L., J.R. Proni, D.A. Seem, and J.J. Tsai. Joint CGS-AOML acoustical bottom echo-formation research, I: Literature search and initial modeling results. NOAA Technical Memorandum, ERL AOML-66 (PB88-202007), 73 pp. (1988).

A literature survey has found work dealing with the problem of echo-formation for rough sedimentary bottoms. The main attempts at practical application have been at frequencies lower than those used for echo-sounding work. A model has been formulated that includes the effect of surface scattering and volume scattering in a unified manner. This model has been implemented on the AOML computer and exercised for a variety of bottom types and echo-sounding frequencies.

Colin, C., and S.L. Garzoli. High-frequency variability of in-situ wind, temperature, and current measurements in the equatorial Atlantic during the FOCAL/SEQUAL experiment. Oceanologica Acta, 11(2):139-148 (1988).

The high-frequency variability of in-situ wind measurements in the western (1°N, 29°W) and eastern (0°, 4°W) equatorial Atlantic are described and for the first time compared. The data were obtained from meteorological sensors placed respectively on St. Peter and St. Paul Rocks and at the top of a surface buoy moored in the Gulf of Guinea during the FOCAL/SEQUAL experiment from February 1983 to September 1984.

Dodge, P.P. A climatology of rainbands observed by coastal radars in GALE. Reports of GALE/CASP Preliminary Analysis Workshop, Virginia Beach, VA, November 2-6, 1987. GALE Project Office, NCAR, Boulder, 19-22 (1988).

No abstract.

Enfield, D.B. Is El Niño becoming more common? Oceanography, 1(2):23-27 (1988).

No abstract.

Fine, R.A., and R.L. Molinari. A continuous deep western boundary current between Abaco (26.5°N) and Barbados (13°N). Deep-Sea Research, 35:1441-1450 (1988).

No abstract.

Friedman, H.A., and C.A. Arnhols. 1988 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 120 pp. (1988).

No abstract.

Franklin, J.L., S.J. Lord, and F.D. Marks. Dropwindsonde and radar observations of the eye of Hurricane Gloria (1985). Monthly Weather Review, 116(5):1237-1244 (1988).

Two soundings from the eye of Hurricane Gloria (1985) during a period of rapid deepening are described. The soundings were made by Omega dropwindsondes (ODWs) during research flights of the NOAA Hurricane Research Division on 24-25 September 1985. During the 4.7 h between the two ODW drops, Gloria's minimum sea-level pressure fell from 932 to 922 mb. The ODWs indicate substantial warming due to dry adiabatic descent from 580-660 mb. Descent rates are estimated to be about 11 cm s^-1. Near 500 mb, ascent is indicated. Approximately 60% of the 10 mb pressure fall is associated with thermodynamic changes below 500 mb.

Gamache, J.F., F.D. Marks, and R.A. Black. The bulk water budget of Hurricane Norbert (1984) as determined from thermodynamic and microphysical analyses retrieved from airborne Doppler radar. Preprints, 10th International Cloud Physics Conference, Bad Homburg, Federal Republic of Germany, August 15-20, 1988. American Meteorological Society, Boston, 711-713 (1988).

No abstract.

Georges, T.M., D.R. Palmer, R.M. Jones, and J.P. Riley. A survey of acoustic techniques for monitoring El Niño. NOAA Technical Memorandum, ERL WPL-149 (PB88-157615), 58 pp. (1988).

The challenge of understanding the El Niño-Southern Oscillation (ENSO) cycle in the equatorial Pacific Ocean is a test of our abilities to observe, model, and forecast the processes of global climate change. The only viable technology for monitoring the structure, dynamics, and energetics of the ocean interior on the space-time scales of the ENSO signal appears to be acoustic remote sensing. We, therefore, examine how the following acoustic techniques might be used to monitor ENSO-induced changes in the upper ocean: (1) ocean acoustic tomography; (2) a long-range acoustic thermometer; (3) passive monitoring of ambient acoustic noise level; (4) an occulation technique that depends on bottom absorption; and (5) space-time scintillation analysis. We computed the acoustic properties of ocean models based on the 1982-1983 ENSO event and found out how sensitive different acoustic measurables are to the temperature changes that accompany a strong El Niño. In the eastern Pacific, for example, the largest (and earliest) temperature increases occur between 40 and 100 m depth. For long-range (ducted) sound rays to pass through this region without being absorbed by the bottom, the ocean must be at least 4 km deep. Pulse tomography, applied to vertical ocean slices, could adequately sample the temperature and currents in the upper ocen if appropriate receiving arrays were used. The passive listening scheme could monitor changes in the ambient noise level with the onset of El Niño, but it raised many questions about the natural variability of the noise environment. An occulation scheme that uses a vertical receiving array could economically monitor changes in average thermocline depth. The long-range acoustic thermometer could monitor the heat content of the equatorial ocean, a likely ENSO precursor. The horizontal covariance of acoustic scintillations might be used to measure the structure of transverse currents crossing a long acoustic path. If problems in extending the theoretical model to longer ranges can be solved, scintillation analysis could be used to monitor subsurface equatorial currents that transport heat eastward along the equator. Each technique examined offers some remote-sensing potential, but each also poses problems to be solved before its relative advantages in cost, coverage, or convenience over in-situ methods are clear.

Hansen, D.V., and C.A. Paul. Vertical motion in the eastern equatorial Pacific inferred from drifting buoys. Oceanologica Acta, 6:27-32 (1988).

Surface current measurements have been obtained from the eastern tropical Pacific Ocean by means of drifting buoys tracked by the NIMBUS and ARGOS satellite systems since 1977. Near-equatorial divergence of Ekman transport is indicated qualitatively by persistent avoidance of the equator by drifters. Upwelling velocity and transport were estimated from the horizontal divergence of surface current fields obtained by optimum interpolation of overall and monthly composite data. The estimated divergence is predominantly meridional. Average upwelling velocity and transport in the region 1.5°N-1.5°S, 80°W-130°W are estimated to be 1.5 m da^-1 and 32 × 10⁶ m³ s^-1. Seasonal variation of the estimated upwelling agrees closely in phase but is larger in magnitude than that implied by the annual and semiannual constituents of 14°C isotherm depth variations in the eastern equatorial Pacific.

Houze, R.A., F.D. Marks, and R.A. Black. Mesoscale patterns of ice particle characteristics in Hurricane Norbert. Preprints, 10th International Cloud Physics Conference, Bad Homburg, Federal Republic of Germany, August 15-20, 1988. American Meteorological Society, Boston, 708-710 (1988).

No abstract.

Lautenschlager, M., D.P. Eppel, and W.C. Thacker. Subgrid-parameterization in helical flows. Beiträge zur Physik der Atmosphäre, 61(2):87-97 (1988).

A new parameterization for the turbulent momentum fluxes of an incompressible flow is suggested. Assuming the turbulent field to carry internal structure, the expansion of the subgrid fluxes in terms of average vorticity leads, in addition to subgrid kinetic energy, to subgrid helicity as an extra parameter to characterize this internal structure. In a simple model the expansion coefficients are connected to the resolution scale of the numerical grid model used. It is shown that the new subgrid-helicity dependent terms act against diffusion as they can transport additional rotation into the mean motion. In the limit of vanishing turbulent helicity the new parameterization reproduces the well-known diffusion parameterization of the turbulent fluxes.

Maul, G.A., J.R. Proni, and J.L. Mitchell. On the integration of satellite altimeter data with in-situ oceanographic data to provide precise profiles of absolute dynamic height anomaly. Proceedings, PACON '88, Pacific Congress on Marine Science and Technology, OST2, 9-10 (1988).

In 1984, the U.S. National Academy of Science, and in 1985 the U.S. National Science Foundation, issued reports on global observations and understanding of the general circulation of the oceans, and on the emergence of a unified ocean science. Both reports note that there are certain critical areas in the ocean where horizontal fluxes must be monitored: the Gulf Stream; the Kuroshio; East Australian, Brazil, and Somali Currents; Norwegian and Mediterranean Seas outflows; through the Drake Passage and across the equator at several Pacific and Atlantic sites. These fluxes are required as boundary conditions in numerical models, as verification data for forecasts and remote sensing, and as time series signals to measure changes at climatically sensitive sites. Results from the NOAA Subtropical Atlantic Climate Study (STACS) have shown that volume flux is closely related to changes in sea surface topography across one of the most important of these critical areas: the Florida Current portion of the Gulf Stream system. This paper investigates the role of satellite altimetry in precise determination of the variations of absolute dynamic topography anomaly across critical areas of the Gulf Stream system in the STACS region, and the tropical Pacific in the Equatorial Pacific Ocean Climate Study (EPOCS) region near 110°W. From error budgets for GEOSAT, ERS-1, and TOPEX/POSEIDON, it is clear that satellite altimeters alone cannot provide both the precision and accuracy required to determine absolute dynamic topography anomaly across a critical ocean area. Conversely, for both logistic and financial reasons, no in-situ measuring scheme alone is reasonably able to observe horizontal fluxes, such as volume transport on interannaul time scales. Some combination of remote sensing and in-situ observations will provide the proper mix of technologies; satellite altimetry coupled with independent measures of sea level and/or dynamic height, supplemented by buoy, mooring, and ship-of-opportunity data, is such a mixture. Based on experience with GEOSAT, we are developing sampling strategies that use mixed data inputs to create time series of absolute dynamic topography anomaly along short (~1000 km) exact repeat mission (EER) tracks. RSS accuracies due to media effects are estimated to be less than ± 5 dynamic centimeters (dyn-cm) for the GEOSAT ERM when coupled with in-situ observations. ERS-1 and TOPEX/POSEIDON promise to provide significant improvements over this figure, and should allow monitoring volume transport at the ±1 gigaliter per second (10⁶ m³ sec^-1) level in the subtropics, as well as documenting oceanic equatorial waves and other tropical circulation features such as those associated with ENSO events. In the open ocean, inverted echo sounder/pressure gauge (IES/PG) assemblies have been found to provide in-situ verification data that is accurate within ±3 dyn-cm. However, on more careful examination of the record, a seasonal dependence in the correlation between acoustic travel time and dynamic height anomaly has been discovered. In the equatorial Pacific Ocean, thermistor strings that measure the upper 500 m at 50 m intervals have been found to be as accurate as IES/PGs, with the added benefit of real-time data transmission for nowcasting purposes. In coastal regions, open ocean tide gauges and/or shallow water pressure gauges are shown to provide calibration data at the ±1 dyn-cm precision level, but may have distorted amplitudes of the tidal wave component of instantaneous sea level. This work is conducted as part of the overall NOAA EPOCS and STACS efforts in climate, and as such benefits from other aspects of these programs such as numerical modeling at GFDL, in-situ observations from NOAA ships and moorings, other satellite studies, sea-level/weather stations, and cooperative efforts with several institutes and universities. Using a space-time objective analysis, we show variability in dynamic height derived from GEOSAT, to provide information that is in agreement with in-situ observations, and that is precise at ±5 dyn-cm.

Metz, S., J.H. Trefry, and T.A. Nelsen. History and geochemistry of a metalliferous sediment core from the Mid-Atlantic Ridge at 26°N. Geochimica et Cosmochimica Acta, 52:2369-2378 (1988).

Fourteen thousand years of hydrothermal deposition are recorded in a metalliferous sediment core recovered from the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge at 26°N. An estimated 26% to >96% of the sediment at this core site is hydrothermally derived as determined from the CaCO₃, Al, and Fe data. Layers of essentially pure vent precipitates contain <3% CaCO₃ and <0.5% Al, with high concentrations of Fe (43%), Cu (4.1%), Zn (1.2%), Mn (1.1%), V (480 ppm), Pb (175 ppm), Cd (32 ppm) and Hg (3.8 ppm). Sediment accumulation rates vary from ~1 to >30 g/cm²/1,000 y throughout the core, a function of the intensity of hydrothermal inputs. Distinct hydrothermal events are recorded at 6,000 and 8,500 y B.P. in layers containing >90% vent-derived material. Vertical metal profiles and interelement relationships in the core result from variable deposition of oxides and sulfides, oxidation, and dissolution of sulfide phases and scavenging of metals from seawater.

Molinari, R.L., and K.D. Leaman. Variability of Gulf Stream surface currents in the Straits of Florida. Marine Weather Log, 31(3):10-13 (1988).

No abstract.

Molinari, R.L., and J. Morrison. The separation of the Yucatan Current from the Campeche Bank and the intrusion of the Loop Current into the Gulf of Mexico. Journal of Geophysical Research, 93(C9):10,645-10,654 (1988).

Data collected in the eastern Gulf of Mexico during 1974, 1975, and 1976 show that the penetration of the Loop Current into the Gulf is strongly correlated with the location of the Yucatan Current on the Campeche Bank. The Loop does not penetrate far into the Gulf when the Yucatan Current separates from the bank in the vicinity of the Catoche Tongue (i.e., the eastern Campeche Bank). Deep Loop penetrations are correlated with separations farther west on the bank. The angle of the Yucatan Current at separation is also correlated with separations farther west on the bank. The angle of the Yucatan Current at separation is also correlated with the location of separation (i.e., smaller angles relative to due east are correlated with separations from farther east on the bank). Thus, small angles at separation are correlated with shallow intrusions of the Loop. Historical temperature data collected in the eastern Gulf are reviewed and support these correlations. Simple conservation of potential vorticity considerations can explain the correlation between the angle at separation and the penetration of the Loop.

Palmer, D.R., T.M. Georges, and R.M. Jones. New techniques for investigating the properties of chaotic ray paths. Journal of the Acoustical Society of America, 84:S91 (1988).

It has been established that acoustic ray paths in a range-dependent ocean environment can exhibit chaotic behavior [Palmer et al., Geophys. Res. Lett., 15:569-572 (1988)]. The usual techniques for identifying chaotic rays are the examination of Poincaré sections and power spectra of path depth, as well as the observation of exponential sensitivity to initial conditions. These techniques are not always useful, however, and are not directly related to observable signal characteristics. Travel times, ray elevation angle at axis crossings, and upper and lower turning point depths have practical relevance and provide new insights into the character of chaotic rays. Since this effort involved the numerical calculation of ray paths for both the Helmholtz and parabolic equations, procedures were developed for comparing results obtained for the two equations.

Palmer, D.R., M.G. Brown, F.D. Tappert, and H.F. Bezdek. Chaotic behavior of ray trajectories in a range-dependent ocean environment. Journal of the Acoustical Society of America, 83:S37 (1988).

It has been demonstrated that ray trajectories propagating in a range-dependent ocean environment can exhibit chaotic behavior. A particularly simple sound-speed model was considered consisting of the Munk reference sound-speed profile to which is added a small range-dependent, deterministic perturbation having a harmonic dependence on range and decreasing exponentially with depth. Chaotic ray trajectories were identified from an examination of Poincaré sections and power spectra. The sensitivity of chaotic trajectories to initial conditions and the consequent implications for predictability were investigated by considering the evolution with range of a bundle of rays that initially occupy a very small region in phase space. The largest Lyapunov exponent was determined by considering the spread of the bundle. Since the ray equations define a nonautonomous Hamiltonian system with one degree of freedom, our results can be understood in terms of recent contributions to the study of classical chaos.

Palmer, D.R., M.G. Brown, F.D. Tappert, and H.F. Bezdek. Classical chaos in nonseparable wave propagation problems. Geophysical Research Letters, 15(6):569-572 (1988).

Numerical calculations show that acoustic ray paths in a weakly range-dependent, deterministic ocean model exhibit chaotic behavior, that is, have an exponentially sensitive dependence on initial conditions. Since the ray equations define a nonautonomous Hamiltonian system with one degree of freedom, these results may be understood in terms of recent advances in classical chaos. The Hamiltonian structure of ray equations in general suggests that chaotic ray trajectories will be present in all types of linear wave motion in geophysics when variables do not separate, as in laterally inhomogeneous media.

Palmer, D.R., L.M. Lawson, Y.-H. Daneshzadeh, and D.W. Behringer. Computational studies of the effect of an El Niño/Southern Oscillation event on underwater sound propagation. In Computational Acoustics: Algorithms and Applications, D. Lee, R.L. Sternberg, and M.H. Schultz (eds.). Elsevier Science Publishers B.V. (North-Holland), Amsterdam, 335-356 (1988).

Computer simulations of underwater sound propagation in the equatorial Pacific have been undertaken using a recently-developed program called ULETA. This program was developed to exploit the characteristics of modern computing systems including the clustering of processors, command languages that permit interactive processor communication, and the availability of color graphics hardware and software. It has three modes of operation: a ray-tracing mode; a continuous-wave mode in which transmission loss as a function of depth and range is obtained for a source radiating a single acoustic frequency; and a pulsed mode in which the pressure resulting from a pulsed source is obtained at selected locations as a function of time. The input data for the simulations consisted of a series of sound-speed profiles which reflect the onset, evolution, and cessation of the most recent El Niño/Southern Oscillation (ENSO) event. The results of the computations indicate the presence of a layer of ray-path instability in the ocean, extending from about 50 m to 280 m in depth, which suddenly became very quiet during the ENSO event. Sound which entered this layer or was generated within it could not have traveled on for more than a few tens of kilometers in range without striking the bottom and experiencing the usual severe losses in intensity. While the existence of this layer provides an opportunity to monitor ENSO events using underwater sound, it prevents the straightforward application of the techniques of acoustic tomography to study the dynamics of the ocean in the layer. This is unfortunate since the major temperature anomalies occur within it.

Pazos, M.C. Drifting buoy data from the equatorial Pacific for the period January 1, 1984 through May 31, 1985. NOAA Data Report, ERL AOML-11 (PB88-212824), 100 pp. (1988).

No abstract.

Powell, M.D. Boundary-layer structure and dynamics in outer hurricane rainbands. Ph.D. dissertation, Florida State University, Tallahassee, 227 pp. (1988).

Results of hurricane boundary-layer experiments conducted in outer rainbands of Hurricanes Josephine (1984) and Earl (1986) are presented. Comparisons of precipitation, kinematic, and thermodynamic structures in these storms indicate that principal rainbands have common characteristic mesoscale and convective-scale features in the boundary layer. The two-dimensional mesoscale structure suggests that rainbands are made of a linear aggregate of cellular reflectivity elements (on the inner, upshear side of the band) and stratiform rain (on the outer downshear side). The band is oriented perpendicular to the shear above the boundary layer and cells move downband at about 80% of the maximum wind. Alongband and crossband wind and equivalent potential temperature maxima are located on the outer side of the band axis. Updrafts and downdrafts are preferentially located on the inner side of the band axis. Downdraft transport of cool and dry air from middle levels on the inner side of the rainband was responsible for modifying mixed-layer structure adjacent to the band on alongband scales of 100 km. An undisturbed mixed layer of 500 m was present on the outer side of the band. Application of a mixed-layer model to low-level flow trajectories from the outer rainband to the eyewall indicates that under some conditions, the mixed layer may not recover sufficiently and low surface equivalent potential temperature air may reach the eyewall. These conditions are associated with suppressed flow in a region of positive divergence with moderate rainfall from a middle level anvil cloud. Differential evaporation cooling over the transition layer drives entrainment of dry air, resulting in a drier mixed layer (with lower surface equivalent potential temperature). The model results suggest that incomplete recovery may be responsible for transitional changes in hurricane intensity.

Tappert, F.D., M.G. Brown, D.R. Palmer, and H.F. Bezdek. Chaos in underwater acoustics. Journal of the Acoustical Society of America, 83:S36 (1988).

The problem of predicting sound propagation in range-dependent ocean environments has been investigated, in which it is supposed that the environment (volume and/or boundary) varies smoothly in range and is exactly known with arbitrary precision. Although this problem as stated is deterministic and not intrinsically stochastic, it has been discovered from numerical and analytical studies of physically realistic examples drawn from deep ocean propagation, shallow-water propagation, and surface duct propagation, that ray path solutions exhibit "classical chaos," namely, unpredictable and stochastic behavior. Ray paths are found to have a continuous spectrum characteristic of noisy stochastic processes, and ray paths are found to have an exponentially sensitive dependence on initial conditions and environmental parameters characteristic of chaotic processes. This phenomenon of chaos in underwater acoustics is caused by the exponential proliferation of catastrophes (caustics) due to the loss of control implied by the nonseparability of variables in the eikonal equation. As a consequence, even when the ocean environment is known exactly, there exists a "predictability horizon" that limits the range to which acoustic fields can be predicted.

Thacker, W.C. A cost-function approach to the assimilation of asynoptic data. Journal of Scientific Computing, 2(2):137-158 (1988).

This paper describes a method for reconstructing a synoptic state by fitting dynamics to asynoptic data. The best fit is defined by the minimum of a quadratic cost function and dynamics are enforced through the use of a penalty term. When the coefficient of the penalty term is identified as the inverse of the variance of model error, the method yields the same results as Kalman filtering, and in the limit of infinitely large coefficients, the same as strong-constraint formalisms. The self-adjoint nature of the equations for the best fit motivated the use of a relaxation method for their solution. The method is illustrated within the context of one-dimensional, linear, shallow-water wave dynamics, where computational examples indicate that a synoptic state is properly determined only if the asynoptic data are equivalent to complete initial conditions.

Thacker, W.C., and R.B. Long. Fitting dynamics to data. Journal of Geophysical Research, 93(C2):1227-1240 (1988).

A formalism is presented for fitting dynamic forecast models to asynoptic data. Because of the importance of wind stress forcing in oceanic models and of the inadequacies of wind stress observations, the formalism allows an oceanic model to be fit to both oceanographic and meteorological data. Within the context of this formalism the important question of whether an asynoptic data set contains sufficient information to determine the model state completely and unambiguously is discussed. Becuse the information travels along wave characteristics, it is clear that for the data to be sufficient to determine the model state, they must be distributed so that every feature of the flow is seen at some time or another. Such widespread coverage of the oceans requires a data collection system that relies heavily on satellites. The formalism is illustrated using a highly truncated model of the wind-driven equatorial ocean and computational examples demonstrate how surface elevation and wind stress observations might be used to recover the model state.

No abstract.

Willis, P.T., and A.J. Heymsfield. Melting-layer structure in MCC stratiform precipitation. Preprints, 10th International Cloud Physics Conference, Bad Homburg, Federal Republic of Germany, August 15-20, 1988. American Meteorological Society, Boston, 699-701 (1988).

No abstract.

Willoughby, H.E. Linear motion of a shallow-water, barotropic vortex. Journal of the Atmospheric Sciences, 45(13):1906-1928 (1988).

A shallow-water barotropic model of tropical cyclone motion allows calculation of linear wavenumber one perturbations on a maintained, moving axisymmetric vortex. The perturbations are Rossby waves that depend upon the radial gradient of axisymmetric relative vorticity rather than the meridional gradient of absolute vorticity. Although the motion of the vortex is a parameter for calculation of the perturbations, the motion in a particular situation is determinate because it minimizes the Lagrangian of the system. The motion in an environmental current matches the current, except at frequencies where the vortex is barotropically unstable. Imposed sources and sinks of mass simulate the effects of convection. The "convectively-induced" motions excite the barotropic instability plus a mode that depends upon forcing at the Rossby wave critical radius. This mode has largest amplitude and fastest vortex motion at the orbital frequency of the axisymmetric flow where forcing is imposed. It seems to correspond with the trochoidal motion of real tropical cyclones. For cyclonic frequencies only, perturbation in the stream-function field resembles a solitary Rossby wave and exhibits counterrotating gyres isolated from the relative flow due to the vortex motion. The vortex motion on a beta plane is largely meridional with speed proportional to the total relative angular momentum of the vortex. When the vortex has cyclonic circulation throughout, the northward motion is much too fast. This unreasonable result highlights the importance of nonlinear processes in tropical cyclone motion.

Willoughby, H.E. The dynamics of the tropical cyclone core. Australian Meteorological Magazine, 36(3):183-191 (1988).

The core of a tropical cyclone occupies the inner 100-200 km of the vortex. It is dominated by a cyclonic primary circulation in balance with a nearly axisymmetric, warm core low-pressure anomaly. Superimposed on the primary circulation are weaker asymmetric motions and an axisymmetric secondary circulation. The asymmetries, which may be either internal gravity waves or Rosby waves, modulate precipitation and cloud into trailing spirals. The axisymmetric secondary circulation, driven by latent heat release and surface friction, comprises the following parts: surface inflow that extracts latent heat from the sea and replaces the frictional loss of angular momemtum (M) to the sea; diabatically forced deep inflow that supplies an excess of M above frictional loss; the eyewall, an outward sloping locus of convective ascent; diabatically forced descent inside the eye; and upper tropospheric inflow. The eyewall usually moves inward as a result of differential adiabatic heating across the wind maximum. Eyewall succession occurs in intense cyclones when two concentric eyewalls are present and the outer replaces the inner. Because of their semibalanced dynamics, the primary and sedondary circulations are relatively simple and well understood. These dynamics are not valid in the upper troposphere where the outflow is comparable to the swirling flow, nor do they apply to the asymmetric motions. Since the synoptic-scale environment appears to interact with the vortex core in the upper troposphere by means of the asymmetric motions, future research should emphasize this aspect of the tropical-cyclone dynamics. **1987**

Atakturk, S.S., and K.B. Katsaros. Intrinsic frequency spectra of short gravity-capillary waves obtained from temporal measurements of wave height on a lake. Journal of Geophysical Research, 92(C5):5131-5141 (1987).

Intrinsic frequency spectra of water waves in the range of 6-17 Hz were obtained as a function of both wind speed and wind stress from point measurements of wave height. In a lake with a limited fetch there are two types of surface motions causing Doppler shift in the frequencies of short waves: orbital velocity of long waves and surface wind drift. The former was estimated from long-wave amplitude by using a linear wave theory. The two techniques were found to produce comparable results. Experimental results showed that the spectral energy of short waves rapidly increased in response to increasing winds and jumped up by an order of magnitude when wave breaking occurred.

Baker, E.T., G.J. Massoth, R.W. Collier, J.H. Trefry, D. Kadko, T.A. Nelsen, P.A. Rona, and J.E. Lupton. Evidence for high-temperature hydrothermal venting on the Gorda Ridge, northeast Pacific Ocean. Deep-Sea Research, 34(8):1461-1476 (1987).

The first water-column survey of the axial valley of the Gorda Ridge, a slow- to medium-rate spreading center within 300 km of the coast of Oregon and California, found strong evidence for ongoing hydrothermal venting. At the northern end of the ridge, anomalously high concentrations of helium-3, dissolved manganese, particulate iron, and methane confirmed the hydrothermal origin of the above-bottom plumes identifiable as maxima in light-attenuation profiles. The presence of excess radon-222 and the highly soluble hydrothermal precipitate anhydrite in the plumes require a local vent source; the precipitation of anhydrite requires fluid temperatures of at least 130°C. Indications of hydrothermal activity elsewhere in the axial valley were inconclusive.

Barnes, G.M., G.J. Stossmeister, M.A. LeMone, and J.F. Gamache. A rainband on the trailing side of a fast-moving hurricane. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 377-380 (1987).

No abstract.

Black, M.L., and R.W. Burpee. Temporal and spatial variations of precipitation near the center of tropical cyclones. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 170-173 (1987).

No abstract.

Black, P.G. New measurements within, around, and under tropical cyclones using airborne microwave remote sensors and expendable probes. Program Booklet, Second Airborne Science Workshop, Miami, FL, February 3-6, 1987. NASA, Washington, D.C., 29-30 (1987).

No abstract.

Black, P.G., and F.D. Marks. Environmental interactions associated with hurricane supercells. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 416-419 (1987).

No abstract.

Bluestein, H.B., and F.D. Marks. A note on the structure of the eyewall of Hurricane Diana (1984): Comparison of radar and visual characteristics. Monthly Weather Review, 115(10):2542-2552 (1987).

Features seen in aerial and satellite photographs of the inside edge of the eyewall of Hurricane Diana (1984) are compared with features seen in digitized three-dimensional airborne radar reflectivity data. The photographs show regularly spaced, upwind (downshear) tilted striations in the northeast, east, and southeast sectors of the eyewall that are nearly collocated with upwind (downshear) tilted axes of relative reflectivity maxima of approximately 15 dBZ.

Broecker, W.S., and T.-H. Peng. The oceanic salt pump: Does it contribute to the glacial-interglacial difference in atmospheric CO₂ content? Global Biogeochemical Cycles, 1(3):251-259 (1987).

Sea ice formation drives salt from the surface to the deep sea. In so doing, it lowers the salinity of polar surface waters. We show here that this reduction in turn lowers the CO₂ partial pressure of polar surface waters and hence also of the atmosphere. We propose that during glacial time when more sea ice existed, this pumping action may have been stronger. If so, part of the glacial to interglacial atmospheric CO₂ content change observed in ice cores may have been driven by the ocean's salt pump.

Broecker, W.S., and T.-H. Peng. The role of CaCO₃ compensation in the glacial to interglacial atmospheric CO₂ change. Global Biogeochemical Cycles, 1(1):15-29 (1987).

The only viable explanations put forth to date for the glacial to interglacial change in atmospheric CO₂ content suggested from measurements of the CO₂ content of gas extracted from ice cores involve changes in the ocean's nutrient cycles. Any nutrient change capable of creating the 80 µatm changes in atmosphere CO₂ pressure suggested by the ice core results also creates significant change in the deep ocean's CO₃⁼ content. Evidence from deep sea sediments suggests that these CO₃⁼ changes are compensated on the time scale of a few thousand years by reductions or increases in the amount of CO₃⁼ accumulating in deep sea sediments. This compensation process has two important consequences. First, it significantly increases the magnitude of the CO₂ change per unit of nutrient forcing. Second, it causes a delay in the response of the atmospheric CO₂ change. While the first of these consequences is a boon to those seeking to explain the CO₂ change, the second may prove to be a curse. The ice core CO₂ record shows no evidence of a significant lag between the CO₂ response and the polar warming. In any case it is important that we improve our knowledge of the magnitude and timing of the CaCO₃ preservation events which mark the close of episodes of glaciation and of the dissolution events which mark the onset of these episodes.

Carsey, T.P. LISA: A new aerosol generation system for sampler evaluation. Amer. Ind. Hyg. Assoc. J., 48:710-717 (1987).

No abstract.

Carsey, T.P., S.A. Shulman, and C.D. Lorberau. An investigation of the performance of the 10-mm nylon cyclone. Applied Ind. Hyg., 2:47-52 (1987).

No abstract.

Clarke, T.L., and J.R. Proni. A pattern recognition approach to remote acoustic bottom characterization. In Progress in Underwater Acoustics, H.M. Merklinger (ed.). Plenum Press, New York, 225-229 (1987).

The possibility of extracting useful bottom information from reflected pulse waveforms at customary echo-sounding frequencies has been demonstrated experimentally. The one-dimensional nature of the sediment property continuum should also enable the use of remotely measured acoustical sedimentary properties to predict navigationally important mechanical characteristics. A convenient mathematical model has been developed to assess the effects of bottom roughness and material properties on bottom echo shape. The physical basis of the model is explained and model output is presented. The ability of this model to easily generate sample echoes from a wide range of bottom types permits a pattern recognition approach to be taken to the problem of extracting information from the ehco signals. An adaptive algorithm can be "trained" using model-generated echoes in the same way speech recognition systems are "trained." The linear discriminant algorithm can be trained to distinguish mud from gravel, but has difficulty with mud versus fine sand. A commercially available voice recognition system conversely has difficulty distinguishing sand from gravel. More sophisticated algorithms will be needed for general bottom discrimination.

Clarke, T.L., J.R. Proni, and L. Huff. High temporal resolution observation of high-frequency acoustic bottom echoes. Journal of the Acoustical Society of America, 82:S-122 (1987).

Acoustic bottom echoes at frequencies from 10 to 380 kHz were recorded for a variety of bottom types in southern Chesapeake Bay. Short pulse lengths and direct digital recording allowed temporal resolution of 100 µs to be achieved. Supporting measurements of sediment characteristics and bottom roughness allowed comparison of the measurements with theory. The field observations were in good agreement with the theory after corrections for the interaction of transducer beam patterns with bottom roughness were made.

Colin, C., and S.L. Garzoli. In-situ wind measurements and the ocean response in the equatorial Atlantic during the FOCAL/SEQUAL experiment. Journal of Geophysical Research-Oceans, 92(C4):3741-3750 (1987).

In-situ wind measurements collected as part of the Programme Francais Ocean et Climat dans l'Atlantique Equatorial (FOCAL)/Seasonal Response of the Equatorial Atlantic (SEQUAL) experiment (1983-1984) in the western and eastern parts of the equatorial Atlantic basin are described. They were obtained from meteorological stations placed at St. Peter and St. Paul Rocks (SPP) (1°N, 29°W) and at the top of a surface buoy moored in the Gulf of Guinea (0°N, 4°W). From the wind observations the wind stress was inferred, and results are compared with climatology. The seasonal variations of the temperature both at the surface and below the surface at 28°W and 4°W are interpreted in the light of the results of a nonlinear multilevel model in the cases of a sudden increase and a sudden relaxation of the trade winds.

Cornejo-Rodriguez, M.P., and D.B. Enfield. Propagation and forcing of high-frequency sea level variability along the west coast of South America. Journal of Geophysical Research, 92(C13):14,323-14,334 (1987).

Tide and wind data from coastal and island stations from Buenaventura, Colombia (4°N), to Callao, Peru (12°S), have been analyzed for the 1979-1984 time period to determine the propagation and forcing characteristics of coastal sea level variability at periods of days to weeks, as well as how they vary either with season or between the 1982-1983 El Niño-Southern Oscillation (ENSO) period and non-ENSO years. During four non-ENSO years, the ensemble averaged cross spectra between coastal sea level height (SLH) and local winds show weak evidence of local forcing during the whole year without significant differences between the austral summer and winter seasons, other than a greater energy in the wind fluctuations at Talara during summer. Cross spectra between SLH series from neighboring stations show evidence of poleward phase propagation during winter seasons at speeds of about 20 m s^-1 between La Libertad and Talara at periods of a week or more, and about 2.7 m s^-1 between Talara and Callao at periods of 5-11 days, but no propagation is found during summers. During the 1982-1983 ENSO there is a large increase in SLH energy at most frequencies at all coastal stations, but especially in the 8-11 day band, where energies are enhanced by as much as an order of magnitude above non-ENSO levels. The cross spectra between adjacent SLH stations indicate a nondispersive poleward propagation of events during the 1982-1983 ENSO with phase speeds of 2.2-3.5 m s^-1 from La Libertad to Talara (periods of a week or more) and 3.4-3.6 m s^-1 from Talara to Callao (3.5 days or more). As with the SLH energy, the coherence and phase propagation were much stronger along the Peru coast in 1982-1983 than during non-ENSO periods, especially in the 8-11 day band. The one-third increase in phase speeds during the ENSO over the non-ENSO speeds is found to be consistent with the anomalous depression of the density structure during El Niño. Comparisons between coastal SLH and the local alongshore wind suggest that locally forced SLH variability was obscured during the 1982-1983 ENSO by noncoastally forced, but energetic propagating fluctuations, which probably originated in the equatorial waveguide.

Dammann, W.P., and C.A. Lauter. High-resolution acoustic bottom roughness measurement in support of bottom echo interaction modeling. Journal of the Acoustical Society of America, 82:S-123 (1987).

A high-resolution acoustic bottom profiler using an extremely narrow-beam, three-megahertz echo sounder was developed at the Ocean Acoustics Division of NOAA/AOML. The device was used to measure bottom roughness over a range of scales from less than 1 cm to several meters. Roughness measurements were made in the lower Cheasapeake Bay area over mud, fine to medium grain sand, and course grain sand. The data produced were used to appraise the performance of an acoustic echo formation model that predicts the effects of marine bottom characteristics on a reflected acoustic pulse envelope. Major aspects of the design and use of the system, procedures for processing generated data, and examples of processed output are presented.

Dodge, P.P., M.L. Black, R.W. Burpee, and F.D. Marks. Time-lapse radar imagery from landfalling hurricanes. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 166-169 (1987).

No abstract.

Enfield, D.B. Progress in understanding El Niño. Endeavor, 11(4):197-204 (1987).

Prior to the work of Jacob Bjerknes, the El Niño phenomenon was regarded as an aperiodic climatic event confined to the Pacific coast of South America. Spurred by a growing consciousness of the oceans' role in global climate, there has been an explosion of El Niño research in the last two decades. El Niño is now recognized to be an integral part of a Pacific-wide ocean relaxation, with global climatic impacts and economically important ecological consequences. However, we are still groping for the final prize: the ultimate cause of this climate anomaly and the ability to reliably predict its onset and intensity.

Enfield, D.B. The intraseasonal oscillation in eastern Pacific sea levels: How is it forced? Journal of Physical Oceanography, 17(11):1860-1976 (1987).

No abstract.

Enfield, D.B., M.P. Cornejo-Rodriguez, R.L. Smith, and P.M. Newberger. The equatorial source of propagating variability along the Peru coast during the 1982-1983 El Niño. Journal of Geophysical Research, 92(C13):14,335-14,346 (1987).

Using data obtained from tide gauges in South America, current meters along the equator and the Peru coast, and an array of pressure gauges and inverted echo sounders within and around the Galapagos archipelago, we have analyzed the equatorial origin of coastal trapped waves observed by Cornejo-Rodriguez and Enfield (this issue) along the Peru coast during the intense 1982-1983 El Niño. The propagating fluctuations along the coast were much stronger at that time either before or after the El Niño, and the variability was not locally forced by coastal winds. We find that the coastal variability was also more energetic during previous El Niño occurrences. At periods of one to two weeks the meridional component of currents on the equator was up to an order of magnitude more energetic than the zonal fluctuations and was consistently associated with sea level that fluctuates antisymmetrically between hemispheres. At periods longer than two weeks the zonal velocity component was more energetic and the cross-equatorial sea level variability was symmetric. The meridional and zonal phase structures of cross spectra involving the currents and sea level established the one- to two-week equatorial fluctuations as mixed Rossby-gravity (Yanai) waves of low wave number with infinite phase speed (standing oscillations) in the middle of the band (10 days); the corresponding structures for longer periods were consistent with non-dispersive Kelvin waves. Frequency domain EOF modes of the sea level and current data established the mixed Rossby-gravity waves as the principal source of the strong trapped wave variability in the one- to two-week band along the Ecuador-Peru coast during the 1982-1983 El Niño episode.

Fine, R.A., and R.L. Molinari. Observations of the Deep Western Boundary Current in the subtropical North Atlantic Ocean. EOS, Transactions, American Geophysical Union, 36(16):338 (1987).

No abstract.

Franklin, J.L., K.V. Ooyama, and S.J. Lord. Two improvements in Omega windfinding techniques. Journal of Atmospheric and Oceanic Technology, 4(1):214-219 (1987).

A one-dimensional local spline smoothing technique is applied to Omega navigational signals for the purpose of windfinding. Wind profiles so produced depend largely on two parameters of the smoothing procedure: the nodal spacing, which determines the smallest resolvable scale, and a filtering wavelength, which produces the necessary smoothing of the phase data, and prevents representational distortion of any power from the unresolved scales. Phase "noise" from stationary test sondes is superimposed on synthetic Omega signals to compare wind profiles obtained with this new procedure with profiles computed using other techniques. It is shown that the effect of aircraft maneuvers on Omega wind accuracy is not completely removed by the normal practice of evaluating all phase derivatives at a common time. Additional improvements in accuracy of 2-3 m s^-1 can be obtained by a "rate-aiding" technique using aircraft navigational data.

Friedman, H.A., and C.A. Arnhols. 1987 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 120 pp. (1987).

No abstract.

Gamache, J.F. The bulk water budget of Hurricane Norbert (1984). Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 351-354 (1987).

No abstract.

Garzoli, S.L. Forced oscillations on the equatorial Atlantic basin during the Seasonal Response of the Equatorial Atlantic Program (1983-1984). Journal of Geophysical Research-Oceans, 92(C5): 5089-5100 (1987).

A subset of data from an array of eight inverted echo sounders and a meteorological station deployed and maintained for 15 months in the equatorial Atlantic as part of the Seasonal Response of the Equatorial Atlantic Program are analyzed to determine the variability of forced oscillations of the basin. The analysis is done to study both low- and high-frequency variability. The most significant oceanic oscillations in the inertial gravity band are centered at 5.2 and 3.5 days. From the study of their meridional structure it is concluded that those oscillations correspond to forced inertial gravity waves with meridional structures corresponding to the meridional numbers n=1 and n=3, respectively.

Garzoli, S.L., and A. Bianchi. Time-space variability of the local dynamics of the Malvinas-Brazil confluence as revealed by inverted echo sounders. Journal of Geophysical Research, 92(C2):1914-1922 (1987).

Two inverted echo sounders have been deployed for approximately eight months in the region of the confluence of western boundary currents in the South Atlantic (37°58.7'S, 51°56.4'W and 37°29.3'S, 53°49.3'W). The confluence of the subtropical Brazil Current with the sub-Antarctic Malvinas Current creates a strong, sharp thermohaline front. From the time series obtained with the sounders, two parameters are obtained and analyzed: dynamic height from the surface relative to 800 m and the position of the front. The time series of dynamic height indicates the presence of a cold intrusion during November, the southward extension of the Brazil Current and northward extension of the Malvinas Current during January, and a simulataneous warming of the area at both moored locations (0.04 dyn m/month) from March through June.

Goldenberg, S.B., S.D. Aberson, and R.E. Kohler. An updated, fine-grid version of the operational barotropic hurricane-track prediction model. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 86-89 (1987).

No abstract.

Hansen, D.V., and C.A. Paul. Vertical motion in the eastern equatorial Pacific inferred from drifting buoys. Proceedings, International Symposium on Equatorial Vertical Motion, Paris, France, May 6-10, 1985. Oceanological Acta, 27-32 (1987).

No abstract.

Johns, E. A comparison of observed and modelled transport through the Windward Passage. EOS, Transactions, American Geophysical Union, 68(50):1718 (1987).

No abstract.

Johns, E., and R.L. Molinari. Observations of current variability northeast of the Bahamas. EOS, Transactions, American Geophysical Union, 68(16):338 (1987).

No abstract.

Jones, R.W. A simulation of hurricane landfall with a numerical model featuring latent heating by the resolvable scales. Monthly Weather Review, 115(10):2279-2297 (1987).

A nested grid hurricane model is used to transport a strong vortex over a straight coastline at about 4 m s^-1. The track, at landfall, of the vortex is about 20 km to the left of a control simulation without land. Just before landfall, a 15 km amplitude trochoidal oscillation of the vortex track occurs. This amplitude is nearly double that of similar oscillations of the control simulation. About 10 h before landfall, a spiral rainband nearly surrounds the vortex at radii of about 135 km. This rainband has a weak secondary maximum in the tangential wind and is the model analog of the secondary eyewalls observed by Willoughby et al. in several hurricanes. The rainfall in spiral rainbands diminishes during the 7 h before landfall. However, rainfall in the inner core of the vortex is greater during landfall than in the control simulation. The greatest rainfall accumulation is to the right of the vortex. However, compared with the control simulation, rainfall is greater to the left and less to the right of the vortex. This may be the result of an increase of the relative radial inflow in the boundary layer in the left-front quadrant near landfall. To the extent which is possible, these characteristics of landfall are related to observations.

Katsaros, K.B., S.D. Smith, and W.A. Oost. HEXOS: Humidity Exchange Over the Sea. A program for research on water-vapor and droplet fluxes from sea to air at moderate to high wind speeds. Bulletin of the American Meteorological Society, 68(5): 466-476 (1987).

HEXOS is an international program for the study of evaporation and spray-droplet flux from sea to air. Present accomplishments of the program include an investigation of processes near the air-sea interface in a wind-wave simulation tunnel. The main field experiment, taking place in the autumn of 1986 at and around the Noordwijk platform, includes measurements of the fluxes of water vapor, spray droplets, sensible heat, and momentum, as well as the structure of the planetary boundary layer and the state of the sea.

Komar, P.D., and D.B. Enfield. Short-term sea-level changes and coastal erosion. In Sea-Level Change and Coastal Evolution, D. Nummedal (ed.). Society of Economic Paleontologists and Mineralogists, 41:17-27 (1987).

Investigations of the role of sea level in producing coastal erosion have focused mainly on the long-term rise due to melting of glaciers and thermal expansion of seawater. There are additional shorter term changes in the local sea level produced by a variety of ocean processes. Variations in the coastal currents, for example, can alter the water level at the shoreline due to the geostrophic balance between the current and the offshore sea-surface slope. Other factors which may alter local sea level include changes in atmospheric pressure, winds blowing either in the longshore or cross-shore directions, and the occurrence of upwelling. Because the inclined continental shelf and slope act as a wave guide, the fluctuations often become trapped and propagate over longshore distances beyond where they are actually generated. In that many of these processes are typically seasonal, the responding sea level also has a pronounced seasonal cycle, but frequently there can be significant fluctuations at periodicities of several days to a few weeks. The magnitudes of such changes vary considerably with coastal location but are typically on the order of 10 to 30 cm, achieving a maximum of about 100 cm in the Bay of Bengal. The occurrence of an El Niño in the equatorial Pacific is known to have considerable impact on the erosion of the coasts of California and Oregon. This occurs because associated with an El Niño are shifts in the storm paths and a temporary rise in sea level. An El Niño is a breakdown of the normal equatorial wind and current patterns. This breakdown releases water which is normally set up in the western Pacific by the trade winds. The release creates a "wave" of sea-level rise, which first propagates eastward along the equator and then poleward along the eastern ocean margin. Such "waves" have been measured in the tide records of the western United States, amounting to some 20 to 60 cm and lasting for several months. Such transient sea-level changes have likely played an important role in coastal erosion.

Landsea, C.W. A quantitative comparison of two BASIN lidar images. UCLA Undergraduate Science Journal, 4:49-56 (1987).

No abstract.

Leaman, K.D., and R.L. Molinari. Topographic modification of the Florida Current by Little Bahama and Great Bahama Banks. Journal of Physical Oceanography, 17(10):1724-1736 (1987).

The effect of local topography in modifying the structure and variability of the Florida Current is examined using shipboard acoustic Doppler and Pegasus acoustic current profiler data. Pegasus absolute velocity data were obtained during 16 cruises in the Florida Current at 27°N as part of the Subtropical Atlantic Climate Studies (STACS) program. The ensemble average of all Pegasus velocity data shows that the effect of the constriction imposed on the mean Florida Current by Little Bahama Bank can be detected up to 30 km into the Straits of Florida. A simple model is proposed to explain how this effect can produce the subsurface maximum of northward flow commonly observed in the eastern Straits. Pegasus and acoustic Doppler data obtained during the March 1984 STACS cruise are used to describe the temporal and spatial variability of the flow. It is shown that intermittent southward flow can exist in a band 10-15 km wide off Little Bahama Bank; one such event was detected during this cruise. The Pegasus data suggest that these events are associated with meandering of the Florida Current. These results may explain earlier observations in satellite synthetic aperture radar images of small-scale vortices moving southward across the mouth of Northwest Providence Channel.

Leaman, K.D., R.L. Molinari, and E. Johns. Velocity and transport variability at 26.5°N east of Abaco Island, the Bahamas. EOS, Transactions, American Geophysical Union, 68(16):338 (1987).

No abstract.

Leaman, K.D., R.L. Molinari, and P.S. Vertes. Structure and variability of the Florida Current at 27°N: April 1982-July 1984. Journal of Physical Oceanography, 17:565-583 (1987).

Results of a two-year field experiment as part of the Subtropical Atlantic Climate Studies (STACS) program in the Straits of Florida are presented. Temperature and absolute ocean current observations were obtained by Pegasus acoustic current profilers over 16 cruises during which repeated cross sections of the Florida Current were made at 27°N. Results are shown for the mean velocity and temperature fields, the perturbation horizontal kinetic energy and potential energy fields and for those energy conversion terms that could be computed directly from the data. The barotropic and baroclinic energy conversion terms, although small, indicate that the flow is stable for both types of perturbations. A large part of the variability is contributed by short time scales (one week or less). The average and standard deviation of northward volume transport by the Florida Current during these cruises was (31.7 ± 3.0) × 10⁶ m³ s^-1. Barotropic and baroclinic contributions to the total heat flux across the North Atlantic Ocean at 27°N are computed for each cruise and for the two-year average of all cruises. With the use of previous estimates of the midbasin baroclinic and Ekman heat fluxes, the total average northward heat flux from the obsersvations is (1.29 ± 0.21) × 10¹⁵ W. To compare STACS data with results from a recent numerical model by Anderson and Corry, Florida Current transports are resolved in a simple manner into barotropic and baroclinic modes. Although the barotropic mode is considerably more variable than the baroclinic, the basic annual signal obtained from the model also appears in the STACS observations. In particular, a rapid transport decrease in the fall with a secondary decrease in the spring are found in both model and observations.

Marks, F.D., and R.A. Houze. Inner core structure of Hurricane Alicia from airborne Doppler radar observations. Journal of the Atmospheric Sciences, 44(9):1296-1317 (1987).

Airborne Doppler radar measurements are used to determine the horizontal winds, vertical air motions, radar reflectivity, and hydrometeor fallspeeds over much of the inner-core region (within 40 km of the eye) of Hurricane Alicia (1983). The reconstructed flow field is more complete and detailed than any obtained previously. The data show both the primary (azimuthal) and secondary (radial-height) circulations. The primary circulation was characterized by an outward sloping maximum of tangential wind. The secondary circulation was characterized by a deep layer of radial inflow in the lower troposphere and a layer of intense outflow above the 10 km altitude. The rising branch of the secondary circulation was located in the eyewall and sloped radially outward. Discrete convective-scale bubbles of more intense upward motion were superimposed in this mean rising current, and convective-scale downdrafts were located throughout and below the core of maximum precipitation in the eyewall. Precipitation particles in the eyewall rainshaft circulated 18-20 km downwind as they fell, consistent with the typical upwind slope with increasing altitude of eyewall precipitation cores. Outside the eyewall, the precipitation was predominantly stratiform. A radar bright band was evident at the melting level. Above the melting level, ice particles were advected into the stratiform region from the upper levels of the eyewall and drifted downward through a mesoscale region of ascent. Hypothetical precipitation particle trajectories showed that as these particles fell slowly through the mesoscale updraft toward the melting level, they were carried azimuthally as many as 1 1/2 times around the storm. During this spiraling descent, the particles evidently grew vigorously. The amount of water condensed by the ambient mesoscale ascent exceeded that transported into the stratiform region by the eyewall outflow by a factor of 3. As the particles fell into the lower troposphere, they entered a mesoscale region of subsidence, the top of which coincided with the radar bright band.

Marks, F.D., and R.A. Houze. Three-dimensional structure of the eyewall of Hurricane Norbert as determined from an airborne Doppler radar. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 347-350 (1987).

No abstract.

Maul, G.A., D.A. Mayer, and M.H. Bushnell. Relationships between local sea level and weather with Florida-Bahamas cable and Pegasus measurements of the Florida Current: 1982-1986. EOS, Transactions, American Geophysical Union, 68(16):336-337 (1987).

No abstract.

Molinari, R.L. Air mass modification over the eastern Gulf of Mexico as a function of surface wind fields and Loop Current position. Monthly Weather Review, 115(3):645-652 (1987).

The effects of surface wind patterns and Loop Current position on surface distribution of latent and sensible heat fluxes in the eastern Gulf of Mexico are demonstrated. Mean monthly fields of these fluxes computed from data collected during February 1975 and February 1976 are decomposed into two different modes, a north-wind mode associated with winter outbreaks of dry cold continental air masses and a trade-wind mode associated with advection from the south of warm moist maritime air. The distributions of sensible and latent heat fluxes are different for each mode, with both heat fluxes considerably larger over the northern Gulf, in particular, during times of the northerlies. However, during these two months, trade-wind days are more numerous and the mean monthly flux patterns reflect this preponderance. A simple model of the effect of extreme Loop Current configurations and the associated sea surface temperature distributions on air parcels traversing the Gulf below the inversion layer is presented. Total changes in air parcel temperature and specific humidity are shown to depend on the configuration of the Loop Current parcels which traverse the Gulf and cross the U.S. coastline between Louisiana and Florida during the time of a deep northern Loop intrusion and have 1.3°C higher temperatures and 1.0 g kg^-1 greater specific humidities than parcels which cross the Gulf during a shallow Loop intrusion.

Molinari, R.L. A review of STACS results on Florida Current variability. EOS, Transactions, American Geophysical Union, 68(16):337 (1987).

No abstract.

Molinari, R.L. Ocean-atmosphere relations. In McGraw-Hill Yearbook of Science and Technology. McGraw-Hill, New York, 323-325 (1987).

No abstract.

Molinari, R.L., and D.V. Hansen. Observational studies of near-surface thermal budgets in the tropics: Review, evaluation, and recommendations. In Further Progress in Equatorial Oceanography E.J. Katz and J.M. Witte (eds.). Nova University Press, For Lauderdale, 421-438 (1987).

No abstract.

Molinari, R.L., E. Johns, G.A. Maul, D.A. Mayer, J.C. Larsen, R. Fine, K.D. Leaman, T.N. Lee, W.E. Johns, and F.A. Schott. Subtropical Atlantic Climate Studies (STACS). Proceedings, IUGG XIX General Assembly, 3:1013 (1987).

No abstract.

Nelsen, T.A., and E.B. Forde. Spatial and compositional variability of the hydrothermal plume at TAG: Mid-Atlantic Ridge. EOS, Transactions, American Geophysical Union, 68(44):1325 (1987).

No abstract.

Ooyama, K.V. Numerical experiments of steady and transient jets with a simple model of the hurricane outflow layer. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 318-320 (1987).

No abstract.

Ooyama, K.V. Scale-controlled objective analysis. Monthly Weather Review, 115(10):2479-2506 (1987).

The major topic of this paper is the resolvable spatial scales that can be analyzed by statistical interpolation of an undersampled data set. The inquiry was motivated by the need to design the most appropriate procedures for spatial analysis of the upper air sounding data from the GARP Atlantic Tropical Experiment. A reliable representation of horizontal scales in the analyzed wind fields was a matter of utmost concern, since the derived fields of vorticity, divergence, and vertical motion were also of vital interest. To achieve our goal, it was found that the traditional premise of statistical interpolation had to be reexamined. The main conclusions of this theoretical inquiry are: (1) resolvable scales are determined by the geometrical distribution of observing stations; (2) precise knowledge of the second-moment statistics improves the analysis by de-aliasing the amplitude of resolvable scales, but has no effect on the definition of resolvable scales; (3) residual effects of unresolvable signals in the data are removable by a spatial filter and must be so removed; and (4) spatial phases of de-aliased resolvable scales may still be in error. On the basis of these findings, the objective analysis procedures we have developed are targeted on the best achievable analysis of resolvable scales. The procedures include the following: an adequate estimate of "true" statistical fields from the given ensemble of data, a search for the optimum spatial filter by monitoring the targeted error variance, and a rational method of desensitizing the analysis to statistically errant data. In order to reduce the spatial phase error of propagating disturbances, the procedures are extended to the analysis of the time-wise Fourier-transformed data set (actually in the frequency-band analog). Since the wind is a physical vector, the entire procedure for the wind analysis is given in the tensor-invariant form, which is decidedly advantageous for very practical reasons. For example, the tensor approach eliminates the notorious ambiguity in normalization that is encountered in the multivariate approach. The paper also describes, in the Appendix, a method of filtered mechanical interpolation, which is specifically designed, with a variety of optional boundary conditions, for application to analysis in a finite domain.

Palmer, D.R., and R.A. Rona. The acoustics of "black smoker" hydrothermal plumes. 113th Meeting of the Acoustical Society of America, Indianapolis, Indiana, May 11-15, 1987. Journal of the Acoustical Society of America, 81:S50 (1987).

High-temperature "black smoker" hydrothermal plumes occur when seawater that has penetrated into the oceanic crust and assimilated heat from magma is discharged from vents located at the axis of a mid-ocean ridge. The acidic, metal-rich discharge mixes with alkaline, oxidizing seawater,and a fine suspension of sulfide particles is precipitated and convected by the flow. Vent fields have now been found at both fast and slow seafloor spreading centers and may be an ubiquitous feature of mid-ocean ridges. A review of the progress made in using underwater acoustics to study black smoker plumes is presented. Both active and passive techniques are being investigated. Active techniques involve a high-frequency monostatic sonar mounted on a submersible. Analysis of the amplitude and phase of the signal backscattered from the plume provides information about the three-dimensional shape of the plume as well as estimates of the flow-velocity field of the discharging fluid. Passive techniques use bottom-mounted hydrophones to listen to the very low-frequency, hydrodynamic noise generated by a plume. These noise signatures have potential use in locating, characterizing, and monitoring plume sites and in determining the contribution plume noise makes to the overall ambient noise field in the ocean.

Peng, T.-H. Modeling the seasonal variations of surface water CO₂ in the high-latitude North Atlantic Ocean. Proceedings, Marine Sciences Symposium, NSC Symposium Series No. 10, 199-209 (1987).

Seasonal variations in CO₂ partial pressure (pCO₂), total dissolved CO₂ (TCO₂), O₂, nutrients (PO₄, NO₃, and SiO₄), and temperature in surface water have been monitored at two stations, one located to the north and the other to the west of Iceland. Results of observations show that during the summer, pCO₂, TCO₂, and nutrients are the lowest, while the O₂ concentration is the highest. This trend is reversed during the winter. These seasonal variations are mainly the result of a deepening of the mixed layer during the winter and stratification coupled with intense biological activity during the summer. Photosynthetic utilization of the nutrient constituents during the long daylight time of summer in a strongly stratified and shallow surface mixed layer drives these changes. Enhanced mixing of surface water with deeper water during the winter brings the nutrient-rich deep water to the surface. Together with reduced biological activity due to decreased daylight, this mixing brings about higher concentrations of nutrient constituents and a higher TCO₂ and pCO₂. A simple box model representing the upper water column is devised to simulate the seasonal variations in the properties of surface water. It is shown that the model prediction of the seasonal variation of CO₂ and O₂ is consistent with observations.

Peng, T.-H., and W.S. Broecker. C/P ratios in marine detritus. Global Biogeochemical Cycles, 1(2):155-161 (1987).

Until reliable procedures have been developed to preserve the phosphorus contained in particulate matter captured by in-situ pumps and sediment traps and until these procedures are applied over a wide range of locations and depths in the sea, indirect methods will have to be used to determine the C/P ratio in marine detritus. We have taken two such approaches: (1) the use of C/N ratios for particulates captured in the upper thermocline in conjunction with O₂/P and N/P ratios obtained from deconvolutions of ocean chemical data and (2) regression along isopycnals in the deep-sea waters free of fossil fuel CO₂. While neither approach yields a definitive answer, both suggest that a value of 127 carbon atoms per phosphorus atom would be a more appropriate interim value than that of 106 adopted long ago by A.C. Redfield and his associates.

Peng, T.-H., T. Takahashi, W.S. Broecker, and J. Olafsson. Seasonal variability of carbon dioxide, nutrients, and oxygen in the northern North Atlantic surface water: Observations and a model. Tellus, 39B:439-458 (1987).

The seasonal variation of various surface water properties has been monitored at a station located at about 120 miles south of the Iceland-Greenland sill during the two-year period, March 1983 through May 1985. These properties include the temperature, salinity, mixed-layer depth, partial pressure of CO₂ in seawater and the concentrations of dissolved total CO₂, oxygen, and nutrients. It was observed that during the summer, the CO₂ partial pressure and the concentrations of CO₂ and nutrients in surface water were lowest, while the oxygen concentration was highest. This situation was reversed during the winter. The seasonal variation is attributed mainly to the high photosynthetic utilization rate of carbon and nutrients in a strongly stratified and shallow surface mixed layer during the summer. The winter observations are attributed to the upward transport of deep waters rich in total CO₂ and nutrients by deep convective mixing. In order to account for the observed seasonal variation, a vertically one-dimensional, two-box ocean model has been constructed. The vertical mixing between the surface mixed layer and deep water is characterized in terms of changes in the mixed layer thickness with time, and the biological productivity is related to the solar insolation and nutrient concentration in the mixed layer. Gas exchange of oxygen and CO₂ between the mixed layer and the atmosphere is taken into consideration. When this model is calibrated using the observed phosphate concentration in surface water, it yields seasonal variations of carbon and oxygen values consistent with the observations, with an exception of a large excursion of spring time values resulting from phytoplankton blooms. It is shown that the spring bloom effect can be simulated by a short-term reduction of the phosphate residence time and of the gas exchange rate.

Powell, M.D. Boundary-layer structure in convective hurricane rainbands. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 373-376 (1987).

No abstract.

Powell, M.D. Changes in the low-level kinematic and thermodynamic structure of Hurricane Alicia (1983) at landfall. Monthly Weather Review, 115(1):75-99 (1987).

Aircraft, land station, and buoy data were composited with respect to the center of Hurricane Alicia (1983) for three 8 h periods corresponding to prelandfall in the open Gulf of Mexico, landfall in the Galveston area, and postlandfall in the vicinity of Houston. Comparison of the wind analyses before, during, and after landfall emphasizes the land-sea frictional asymmetry at landfall. In addition, other asymmetries in the surface wind field and differences between the flight-level and the surface wind fields are revealed. The asymmetric structure of the surface wind field may be interpreted as having resulted from the combined effects of land-sea roughness differences, background environmental flow, and storm translation. The land-sea frictional difference acted to oppose the mean vortex flow over land and reinforce it over water. The southwest background environmental flow acted nearly parallel to the coastline, producing surface inflow on the left side and outflow on the right side, while the effect of the storm translation increased winds on the right and decreased winds on the left. At landfall, the analysis revealed a broad region of high wind speeds and a mesoscale divergence-convergence couplet along the outer rainband axis just offshore on the northeast (right) side of the storm. The outer rainband axis acted as an obstruction to the surface flow, separating the warmer central core of the storm from the environment through which the storm moved. In contrast to recent numerical model studies, surface convergence was also noted on the left side of the storm just offshore, despite outflow at flight level. Analyses of temperature, dew point, and equivalent potential temperature indicate that loss of the oceanic heat and moisture source, combined with advection of drier air on the landward side of the storm, was responsible for cooling and drying of the inflowing boundary layer air. Upon introduction of this air into the core convection and vertical ascent, a decrease in the release of latent heat could then lead to cooling in the middle levels of the storm and a subsequent increase in the central sea-level pressure.

Powell, M.D., and P.N. Georgiou. Response of the Allied Bank Plaza Tower during Hurricane Alicia (1983). Journal of Wind Engineering and Industrial Aerodynamics, 26:231-254 (1987).

As Hurricane Alicia passed over Houston on August 19, 1983, a record lasting approximately 90 minutes was obtained of the wind-induced accelerations of the tallest building in the downtown area, the Allied Bank Plaza. Coincidently, the building had been the subject of a detailed wind tunnel model study several years earlier, the results of which included the prediction of building accelerations as a function of wind speed and wind direction. From the many wind observations made during Alicia's passage inland, it was possible to reconstruct the wind speeds and directions experienced at the Allied Bank Plaza site which overlapped the period of the acceleration record. This reconstructed wind history was combined with the wind tunnel test data to compute a time series of estimated accelerations sustained by the building during Alicia's passage inland. The resulting favorable comparison of actual and predicted accelerations provides a valuable case study, illustrating the reliability of wind tunnel modeling within the design process for tall buildings.

Sanford, T.B., P.B. Black, J.R. Haustein, J.W. Feeney, G.Z. Forristall, and J.F. Price. Ocean response to a hurricane. Part I: Observations. Journal of Physical Oceanography, 17(11):2065-2083 (1987).

The response of the ocean was investigated using aircraft-deployable expendable current profilers (AXCP). The goals were to observe and separate the surface wave and surface mixed-layer velocities under the storms and to map the across-track and along-track velocity and temperature response in the mixed layer and thermocline. Custom instrumentation was prepared, including slower falling AXCPs, and the AXCP equipment was installed on NOAA WP-3D aircraft. Research flights were made into two 1984 hurricanes: Norbert, in the western Pacific off Baja, California (19°N, 109°W); and Josephine, off the west coast of the U.S. (29°N, 72°W). Thirty-one probes were deployed in each hurricane. All but four AXCPs survived the 220-knot launch and wave-zone impact (surface winds up to 75 knots) and produced basic RF transmissions. About half the AXCPs provided temperature and velocity profiles. Most velocity profiles exhibited strong surface wave contributions, slab-like velocities in the SML, strong shears beneath the SML, and only weak flows in the upper thermocline. Separation of the surface gravity wave velocities from the steady and inertial motions was obtained by fitting the profiles to steady flows and shears in three layers and to a single surface wave at all levels. The velocity profiles displayed large divergences to the horizontal SML velocities in the wake of the hurricanes. The observations show a strong enhancement to the right of the storm as expected from numerical simulations. The largest SML velocities were 1.1 m s^-1 in Norbert and 0.73 m s^-1 in Josephine. Numerical simulations will be compared with the observations in Part II.

Shay, L.K., R.L. Elsberry, and P.B. Black. Mesoscale ocean temperature and current patterns induced by hurricanes. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 388-392 (1987).

No abstract.

Spillane, M.C., D.B. Enfield, and J.S. Allen. Intraseasonal oscillations in sea level along the west coasst of the Americas. Journal of Physical Oceanography, 17:313-325 (1987).

Hourly observations of coastal sea level at stations from Peru to British Columbia are analyzed for low frequency content. A space-time contour plot of sea level, from four years of data during the 1971-75 period, shows the meridional structure of the seasonal cycle and interannual variability associated with the 1972-73 El Niño. Oscillations with intraseasonal periods of 36-73 days are also evident, coherent over alongshore distances of several thousand kilometers. Further investigation using spectral methods and empirical orthogonal function analysis in the frequency domain reveals, in particular, that intraseasonal sea level variability has a peak in spectral density along the coasts of South America, Central America and Mexico, with high coherence from near the equator (Tumaco, 2°N) north to central California (34°N) and south to at least Callao (12°S). Phase propagation north of the equator is poleward at 150-200 kilometers/day. Atmospheric pressure, alongshore wind stress and wind stress curl, derived from Fleet Numerical Oceanography Center data for the Northern Hemisphere, are used to assess the importance of local atmospheric forcing. The low coherence between sea level and these fields in the intraseasonal frequency band suggests that the observed oscillation may be a coastally propagating response to remote processes in the equatorial Pacific waveguide.

Tanner, A., C.T. Swift, and P.B. Black. Operational airborne remote sensing of wind speeds in hurricanes. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 385-387 (1987).

No abstract.

Velden, C.S., and S.B. Goldenberg. The inclusion of high-density satellite wind information in a barotropic hurricane forecast model. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 90-93 (1987).

No abstract.

Wilburn, A.M., E. Johns, and M.H. Bushnell. Current velocity and hydrographic observations in the Straits of Florida, the Caribbean Sea, and offshore of the Antillean Archipelago: Subtropical Atlantic Climate Study (STACS), 1984 and 1985. NOAA Data Report, ERL AOML-8, 1994 pp. (1987a).

No abstract.

Willis, P.T., and F.D. Marks. Convective-scale transports in a mature hurricane. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 343-346 (1987).

No abstract.

Willoughby, H.E. Tropical cyclone track prediction: Some theoretical aspects. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 262-265 (1987).

No abstract.

Willoughby, H.E. Use of aircraft in hurricane research. Program Booklet, Second Airborne Science Workshop, Miami, FL, February 3-6, 1987. NASA, Washington, D.C., 83 (1987).

No abstract.

Willoughby, H.E., and W.P. Barry. Real-time data acquisition and analysis in Hurricane Charley of 1986. Preprints, 17th Conference on Hurricanes and Tropical Meteorology, Miami, FL, April 7-10, 1987. American Meteorological Society, Boston, 341-342 (1987).

No abstract.

Zhang, J.-Z., H. Jiazhen, L. Bianling, and L. Faxi. The kinetics of oxidation of hydrogen sulfide by dissolved oxygen in seawater. Donghai Marine Science, 5(3):71-77 (1987).

The rate of oxidation of hydrogen sulfide by oxygen has been studied in both a 0.5 M NaCl solution and in seawater over a range of pH and temperature in the presence of metal sulfide precipitation. The results indicate that maximum reaction rates in pH appear at about 7 and great reactions rates in pH at between 9 and 12. The activation energy of the reaction at pH 8.5 in 0.5 M NaCl solution was 25 kcal/mol. The visible light did not affect the reaction rate obviously. The catalysis of FeS, MnS, CuS, and NiS on the reaction has been observed in both the 0.5 M NaCl solution and in seawater, but Mg²⁺, Al³⁺, and CdS did not catalyze the reaction. **1986**

Adams, W.L., and H.A. Friedman. 1986 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida (published for limited distribution), 116 pp. (1986).

No abstract.

Andree, M., H. Oeschger, W.S. Broecker, N. Beavan, M. Klas, A. Mix, G. Bonani, H.J. Hoffman, M. Suter, W. Woelfli, and T.-H. Peng. Limits on the ventilation rate for the deep ocean over the last 12,000 years. Climate Dynamics, 1:53-62 (1986).

In this paper we present accelerator radiocarbon measurements on hand-picked benthic and planktonic foraminifera separated from two deep sea cores raised from the South China Sea. From the benthic-planktonic age differences we are able to place limits on the extent to which the ventilation rate of the deep Pacific Ocean has changed over the last 12,000 years. While much work remains to be done before any definitive answers for the global oceans can be given, these results on cores with sedimentation rates suitably high to avoid major corrections for bioturbation effects suggest that the ventilation rate of the deep Pacific Ocean has remained nearly the same throughout Holocene time. Further, there is no suggestion that the rate was slower during the period of major glacial retreat. These results confirm that the changes in atmospheric ¹⁴C/C ratio over the last 10,000 years owe their origin to radiocarbon production rate changes.

Bitterman, D.S., and D.V. Hansen. The design of a low cost tropical drifter buoy. Proceedings, '86 Marine Data Systems International Symposium, New Orleans, LA, April 30-May 2, 1986. The Marine Technology Society, 575-581 (1986).

Since 1979, the NOAA/Atlantic Oceanographic and Meteorological Laboratory (NOAA/AOML) has been deploying satellite-tracked drift buoys in the tropical Atlantic and Pacific Oceans in support of various long-term laboratory field programs. In order to reduce the cost and eliminate the long procurement lead times associated with commercially available buoys, a simple, relatively inexpensive drift buoy was designed for use in these equatorial areas. This paper describes the construction of the buoy, the results of field tests of the drogue to directly measure its effectiveness under various wind and sea conditions, and illustrates the results of buoy deployments in the open ocean as part of the scientific program.

Black, P.G., F.D. Marks, and R.A. Black. Supercell structure in tropical cyclones. Preprints, 23rd Conference on Radar Meteorology, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, JP255-JP259 (1986).

No abstract.

Black, P.G., R.A. Black, J. Hallett, and W.A. Lyons. Electrical activity of the hurricane. Preprints, 23rd Conference on Radar Meteorology, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, J277-J280 (1986).

No abstract.

Black, P.G., R.W. Burpee, N.M. Dorst, and W.L. Adams. Appearance of the sea surface in tropical cyclones. Weather and Forecasting, 1(1&2):102-107 (1986).

No abstract.

Black, R.A. Microphysical investigations above the melting level in Hurricane Norbert (1984). Preprints, 23rd Conference on Cloud Physics, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, JP252-JP254 (1986).

No abstract.

Black, R.A., and J. Hallett. Observations of the distribution of ice in hurricanes. Journal of Atmospheric Science, 43(8):802-822 (1986).

Observations of the type and distribution of particles above the 0°C isotherm in three Atlantic hurricanes are presented. Supercooled drops, graupel, columns, and aggregated snowflakes were observed. The supercooled drops were found only in convective updrafts stronger than 5 m s^-1, but not all updrafts >5 m s^-1 contained appreciable liquid. Graupel was found in all updrafts at temperatures <-2°C, and small columns were sometimes found in downdrafts. Nonconvective rainbands contained 15-30 L^-1 of snow composed of columns and what appeared to be large aggregates. Other stratiform regions contained 1-15 L^-1 of medium and large aggregates; columns were occasionally found there also but only within about 15 km of convection. Hurricane convection is almost completely glaciated at the -5°C level. It is suggested that the ice particles observed at 6 km inside the convection result primarily from downward mixing on both sides of the eyewall updraft of ice formed in the convective areas at higher, colder levels. The ice in the stratiform areas is believed to have fallen from the high-level (6 km and higher) eyewall outflow.

Broecker, W.S., and T.-H. Peng. Carbon cycle: 1985. Glacial to interglacial changes in the operation of the global carbon cycle. Radiocarbon, 28(2A):309-327 (1986).

The hottest topic for those interested in the earth's carbon cycles is the change in atmospheric CO₂ content between glacial and interglacial time. What caused it? What is its role in glacial cycles? We evaluate here the hypotheses that have been put forward to explain the CO₂ change with evidence from deep sea sediments. We conclude that all the hypotheses have serious drawbacks and that much effort will have to be expended in gathering more data from ice cores and ocean sediments before we will be pointed toward the correct scenario. Also, thoughtful modeling aimed at depicting the ties between pCO₂, O₂, ¹³C/¹²C, ¹⁴C/¹²C, and nutrient constituents in the sea for various modes of circulation will have to be done before the evidence from ocean cores can be properly interpreted.

Broecker, W.S., T.-H. Peng, and G. Ostlund. The distribution of bomb tritium in the ocean. Journal of Geophysical Research, 91(C12):14,331-14,344 (1986).

A global picture of the water column inventories of bomb-produced tritium is constructed from the GEOSECS data set. This picture is compared with that obtained by combining the bomb tritium input function of Weiss and Roether (1980) with the bomb radiocarbon calibrated lateral redistribution model of Broecker et al. (1985). While differences between the calculated and observed distribution exist, they are surprisingly small. Tritium distributions calculated using the lateral redistribution model provide predictions of the changes to be expected in the next few decades. Such predictions are essential to the design of sound strategies for continued monitoring of the tritium transient.

Broecker, W.S., J.R. Ledwell, T. Takahashi, R. Weiss, L. Merlivat, L. Memery, T.-H. Peng, B. Jahne, and K.O. Munnich. Isotopic versus micrometeorologic ocean CO₂ fluxes: A serious conflict. Journal of Geophysical Research, 91(C9):10,517-10,527 (1986).

Eddy correlation measurements over the ocean give CO₂ fluxes an order of magnitude or more larger than expected from mass balance measurements using radiocarbon and radon 222. In particular, Smith and Jones (1985) reported large upward and downward fluxes in a surface zone at supersaturations of 15% and attributed them to the equilibration of bubbles at elevated pressures. They argue that even on the open ocean such bubble injection may create steady state CO₂ supersaturations and that inferences of fluxes based on air-sea pCO₂ differences and radon exchange velocities must be made with caution. We defend the global average CO₂ exchange rate determined by three independent radioisotopic means: prebomb radiocarbon inventories; global surveys of mixed layer radon deficits; and oceanic uptake of bomb-produced radiocarbon. We argue that laboratory and lake data do not lead one to expect fluxes as large as reported from the eddy correlation technique; that the radon method of determining exchange velocities is indeed useful for estimating CO₂ fluxes; that supersaturations of CO₂ due to bubble injection on the open ocean are negligible; that the hypothesis that Smith and Jones advance cannot account for the fluxes that they report; and that the pCO₂ values reported by Smith and Jones are likely to be systematically much too high. The CO₂ fluxes for the ocean measured to date by the micrometeorological method can be reconciled with neither the observed concentrations of radioisotopes of radon and carbon in the oceans nor the tracer experiments carried out in lakes and in wind/wave tunnels.

Chelton, D.B., and D.B. Enfield. Ocean signals in tide gauge records. Journal of Geophysical Research, 91:9081-9098 (1986).

Tide gauges are designed to measure changes in water level relative to land. However, vertical motions of the earth's crust manifest themselves as apparent water level changes in tide gauge records. These crustally-induced changes are often small in amplitude relative to the wide range of oceanic processes which affect water level in coastal regions. Vertical crustal motion can best be studied by first removing oceanic variability from the time series. In this paper we summarize the major oceanic signals in tide gauge records. We take the approach that the oceanic signals are unwanted "noise" in the data. Methods are described for removing or at least reducing the various oceanic signals. These oceanic signals span a broad range of time scales from tides to interannual variability associated with the El Niño phenomenon and secular sea level change from a number of oceanographic effects.

Chew, F., M.H. Bushnell, R.L. Molinari, K.D. Leaman, and S.A. Frisch. A new type of meandering in the Florida Current near latitude 27°N. EOS, Transactions, American Geophysical Union, 67(16):294 (1986).

No abstract.

Clarke, T.L., and J.R. Proni. Remote Acoustical Measurement of Ocean Bottom Parameters: Current Practices and New Technology in Ocean Engineering. OED, Vol. II, Book No. I00206, 145-148 (1986).

The use of acoustics in measuring ocean bottom characteristics has been in progress a number of years. Three of the most widely studied acoustical features have been returned pulse amplitude (genearlly peak amplitude), pulse attenuation, and sub-bottom sound speed. Recently, overall returned pulse shape has been examined as an acoustical feature for sediment classification. An acoustical bottom and sub-bottom sound reflection and scattering model has been developed in NOAA for the purpose of deriving an improved definition of the bottom for charting purposes. A key question being studied is what are those acoustic features relatable to certain bottom physical features such as the shear modulus profile? A discussion of a new application of coherent transverse Doppler to bottom sound speed profile measurements and other profile measurements will be given. A sensitivity analysis of sound speed versus backscattered acoustical intensity will also be presented. Results of the NOAA model will be presented for acoustical frequencies covering the interval from 10 kHz to 200 kHz for various bottom types. Two-dimensional, frequency-time, intensity contours will be presented with particular attention to describing and distinguishing specular reflection, bottom surface-scattering and bottom volumetric scattering regimes. Comparison of typical fluid mud structures with those of sand type bottoms will be given with a discussion of certain esoteric "internal wave" induced "fluid mud like" episodes. Confusion produced in standard echo-sounding systems by such phenomena will be illustrated.

Clarke, T.L., S. Alper, J.R. Proni, and L. Huff. A definition of "ocean bottom" and "ocean bottom depth." Proceedings, Oceans '85, 2:1212-1215 (1986).

The question of the definition of "ocean bottom" for charting and other purposes has been discussed for many years. Intimately associated with the question of the definition of "ocean bottom depth," acoustical echo-sounding has been the dominant approach in making bottom depth estimates. NOAA has undertaken an applied research program to determine the maximum information content available in an acoustical echo from an ocean bottom which may be used to characterize that bottom in terms of texture, particulate type and engineering properties such as the shear modulus of elasticity; the resulting information to be analyzed and synthesized resulting in a scientific/engineering based definition of "bottom" or "bottom-depth." Results shall be presented from a computer model of acoustic information from different bottom types, e.g., of varying surface roughness, porosity, and so on. Initial model data indicate that with appropriate choices of acoustic frequency, bottom-roughness scattering can be less than bottom volumetric scattering, thereby allowing inferences of bottom characterization and engineering parameters.

Enfield, D.B. Zonal and seasonal variability of the equatorial Pacific heat balance. Journal of Physical Oceanography, 16:1038-1054 (1986).

This study calculates a detailed climatological inventory of the oceanic heat balance in the equatorial Pacific. The gridded climatology of Weare et al. is used as an estimate of net surface heating. Zonal and meridional/vertical advection are estimated in a manner similar to that of Wyrtki, using the gridded climatologies for wind stress (Wyrtki and Meyers) and sea surface temperature (Reynolds), plus estimates of zonal transport. In addition, the meridional diffusion of heat into the cold tongue has been estimated from the work of Hansen and Paul and the terms of the heat balance have been resolved by ten-degree longitude zones and by month of the year. The computed residual heat flux has been examined for consistency with expectations about the remaining, vertical diffusion process. The effects of using the alternate climatologies of Esbensen and Kushnir and Reed for the net surface heating are also calculated. The total advective heat flux divergence is calculated to be -27 ± 7, -91 ± 17 and -48 ± 17 W m^-2, respectively, in the western, central and eastern equatorial Pacific with meridional advection and upwelling removing about three times as much heat as zonal advection. The advective contributions are in approximate agreement with Wyrtki's "likely case" estimates for the 100°W-170°E longitude zone. The contributions from zonal advection, meridional advection and meridional diffusion are found to be greatest during the Boreal fall, winter and fall-winter seasons, respectively. Depending on the climatology used for the net surface heat gain, the assumption of a uniform meridional diffusivity of 2 × 10⁴ m² s^-1 leads to physically unrealistic residual flux divergences that imply a heat gain from vertical turbulence in the central Pacific or that vertical turbulence removes much more heat from the western and eastern Pacific than from the central Pacific. Total neglect of the meridional diffusion exacerbates the problems. Increasing the meridional diffusivity to 6 × 10⁴ m² s^-1 in the central Pacific, consistent with direct estimates by Hansen and Paul, gives zonally uniform, negative residuals that are physically consistent with existing measurements of equatorial turbulence. With the model so tuned, the "best guess" heat balance in the central Pacific involves significant contributions from all terms, in the western Pacific between surface heat gain from the atmosphere and losses due to vertical diffusion, and in the eastern Pacific between surface gain and losses due to meridional advection (upwelling) and vertical diffusion.

Friedman, H.A., and O.E. Thompson. First International Conference on School and Popular Meteorological Education, Lady Margaret Hall, Oxford University, July 2-4, 1984. Bulletin of the American Meteorological Society, 67(4):422-425 (1986).

The First International Conference on School and Popular Meteorological Education convened at Lady Margaret Hall, one of the colleges of Oxford University. The conference, held from July 2-4, 1984, was organized by the Royal Meteorological Society (RMS) and was cosponsored by the American Meteorological Society (AMS) and the World Meteorological Organization (WMO). The AMS Board of School and Popular Meteorological and Oceanographic Education (BSPMOE) played an active, though relatively minor, role in helping to structure the conference by developing interest among potential participants in the United States, including educators, meteorological instrument manufacturers and distributors, scientists, school career counselors, representatives of the electronic and print media, and publishers of meteorological and related textbooks and other educational materials. The chairperson of the Conference Organizing Committee was J.M. Walker, education secretary of RMS.

Gamache, J.F. Bulk water-budget components in Hurricane Norbert as determined from airborne radar and Doppler observations. Preprints, 23rd Conference on Radar Meteorology, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, JP244-JP247 (1986).

No abstract.

Gamache, J.F. Particle characteristics in stratiform and convective clouds observed during summer MONEX. Preprints, Conference on Cloud Physics, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, J143-J146 (1986).

No abstract.

Garzoli, S.L., and M.E. Clements. Indirect wind observations in the southwestern Atlantic. Journal of Geophysical Research, 91(C9):10,551-10,556 (1986).

Two time series of wind speed have been inferred from ambient noise measurements obtained with bottom deployed inverted echo sounders in the southwestern Atlantic. The wind records from the two instruments, deployed 181 km apart, show significant differences at low frequencies. The mean speed for the recorded period is 10 m/s. The energy density spectra of the inferred wind records show a decrease in energy with frequency with a slope of -1.7 for frequencies between 0.22 and 20 cpd. The analysis to the spectra from the time series at the two moored locations shows differences in the band of 2-10 days. An increase in the variance is detected in the offshore location at discrete periods corresponding to atmospheric oscillations. These oscillations are considerably less energetic in the continental shelf-slope regime but are coherent in both locations.

Govoni, J.J., P.B. Ortner, F. Alyamani, and L.C. Hill. Selective feeding of spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus) larvae in the northern Gulf of Mexico. Marine Ecology Progress Series, 28:175-183 (1986).

No abstract.

Hayes, S.P., D.W. Behringer, M. Blackmon, D.V. Hansen, N.C. Lau, A. Leetmaa, S.G.H. Philander, E. Pitcher, C.S. Ramage, E.M. Rasmusson, E.S. Sarachik, and B.A. Taft. The Equatorial Pacific Ocean Climate Studies (EPOCS) plans: 1986-1988. EOS, Transactions, American Geophysical Union, 67:442-444 (1986).

No abstract.

Jones, R.W. Mature structure and motion of a model tropical cyclone with latent heating by the resolvable scales. Monthly Weather Review, 114(6):973-990 (1986).

The mature structure of a model tropical cyclone is presented with emphasis on convection in the eyewall and spiral rainbands. Representative patterns of rainband activity occur during the last two days of a 13-day experiment and are shown for 288 h or day 12. These model rainbands seem to be forced by a pair of quasi-stationary spiral bands of upward motion that appear in the low troposphere and boundary layer ahead of and behind the westward moving vortex. These forcing bands, in turn, may be the result of a non-linear interaction of azimuthal wavenumber one with itself. The convective band elements ahead of the vortex do not reach the outflow layer, but are capped by a mesoscale subsidence band in the upper troposphere. Elements behind the vortex, however, reach the outflow layer and have greater precipitation intensity. During the last two days of the experiment, three times as much rain falls behind the vortex and outside of the inner core as falls in front of the vortex. The mesoscale subsidence band that caps the convection in bands in front of the vortex is the direct result of a characteristic asymmetry of the 250 mb layer. This asymmetry forms between simulation hours 60 to 84 and results from bands outside of the inner core of the vortex. The model vortex structure, in cross-section format, is compared with recent aircraft observations of strong hurricanes (Jorgensen, 1984a,b), particularly Hurricane Allen on 5 August 1980. The model data represent a time and space average with respect to real data. When this averaging is taken into account, reasonable agreement is found between the model and Allen. The model updraft maximum occurs inside of the radius of maximum wind and the precipitation maximum is located outside of the maximum wind at lower levels, in agreement with the real data. The time average motion of the vortex is compared with the mass weighted mean environment current at 990 km radius. For periods of four days or more, the vortex speed agrees with the current speed and the vortex path is mostly to the right of the environment current. For 10 h averages, vortex speed deviations <12% occur and show effects of vortex environment current interactions.

Katz, E.J., P. Hisard, J.-M. Verstraete, and S.L. Garzoli. Annual change of sea surface slope along the equator of the Atlantic Ocean in 1983 and 1984. Nature, 322(6076):245-247 (1986).

The authors describe the sea surface slope derived from three complementary methods: hydrographic stations, pressure gauges, and inverted echo sounders. The latter two have the advantage of yielding continuous time series, but depend on the hydrographic stations for an absolute reference. Together, the three provide a detailed description of the temporal variation of the sea surface slope which is then compared to a wind-stress time series. The dominant signal, in both sea slope and wind stress, is the annual cycle, although amplitude and phase vary interannually. The annual increase in sea surface slope along the equator in the western and central basins lags the onset of the southeast trade wind. During the boreal winter of 1983-1984 a strong rise in sea level occurred against the African coast, accompanied by a leveling of the sea surface to the west. At the same time, an almost complete relaxation of eastward wind stress on the equator was observed near the center of the basin.

Marks, F.D. Three-dimensional wind structure of the eyewall of Hurricane Norbert as determined from an airborne Doppler radar. Preprints, 23rd Conference on Radar Meteorology, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, JP248-JP251 (1986).

No abstract.

Maul, G.A., J.R. Proni, W.P. Dammann, C.A. Lauter, M.H. Bushnell, and D.A. Mayer. Inverted echo sounder/pressure gauge measurements under the Gulf Stream in the offing of Cape Canaveral during the Florida Atlantic Coast Transport Study (FACTS), Vol. 2. Submitted by Florida Institute of Oceanography. Prepared for Minerals Management Service (U.S. Dept. of the Interior), Contract 14-12-001-30082, 330-382 (1986).

Three inverted echo sounder/pressure gauges (IES/PGs) were placed at depths of 140 m, 760 m, and 830 m under the Gulf Stream at latitude 29°N off the Florida Atlantic coast from December 1984 to May 1985. The IES/PGs were unusable due to excessive receiver gain. Volume backscattering from below the surface caused the circuitry to record early returns rather than those from the surface. An experiment in 215 m water depth at 27°N, from July to September 1985, successfully recorded travel times to the surface after the receiver sensitivity was reduced by 30 db. The unit, placed in 830 m water depth, recorded travel times that had a non-Gaussian distribution function, but when processed by using all burst samples in a 25-hour period, gave a 40-hour low passed signal with a net decrease in travel time proportional to an increase in dynamic height of 5 dyn-cm for the five month record. Bottom pressure at the 140 m and 830 m water depth sites had net linear drifts of -178 mb and -77 mb respectively over five months; low frequency comparisons with Florida Current transport measured at the Jupiter, FL to Settlement, Point, Bahama submarine cable were therefore excluded. Linear correlation of detrended bottom pressure at the 140 m site were r = -0.33 with similarly detrended cable transports; coherence squared above 0.65 occurred at 21, 9, and 3 days, all with a phase lag of about 245 degrees.

Mayer, D.A., and J.C. Larsen. Tidal transports in the Florida Current and its relationship to tidal heights and cable voltages. Journal of Physical Oceanography, 16(12):2199-2202 (1986).

A linear relationship between tidal height (sea level of tidal frequencies) and tidal transport near 27°N in the Straits of Florida is confirmed. Transport estimates from this relationship for the O₁ and M₂ constituents are compared with those computed from cable voltages across the Florida Current. These estimates are independent in that the weighted tidal height model (tidal-height transport relationship) was developed using collective sets of current meter and velocity profiler data obtained at different times of the year and in different locations. The cable voltages, however, were calibrated using a quasi-synoptic sectional integration of depth-averaged profiler data. Further, a means is suggested by which changes in the cable calibration can be detected.

McBride, J.L., and H.E. Willoughby. Comment: An interpretation of Kurihara and Kawase's two-dimensional tropical-cyclone development model. Journal of the Atmospheric Sciences, 43:3279-3283 (1986).

This comment presents a detailed examination of the published model results of Kurihara and Kawase (1985) in an attempt to clarify the role of wave-CISK in the development of tropical cyclones. Kurihara and Kawase's model simulates the development of a tropical depression, although the vertical structure differs significantly from observations. The physical roles of vertical shear and nonlinear dynamics in the development in this model are unclear. The authors propose that the nonlinear terms in the equations promote rapid growth by increasing the "inertial stiffness." A major concern, however, is that the enhanced development may occur because the nonlinear terms excite modes with high horizontal wavenumbers. These modes grow rapidly through wave-CISK. From considerations of the climatological importance of horizontal shear to tropical-cyclone development in nature, this model may be less relevant to tropical cyclogenesis than one that allows horizontal shears of the environmental flow. The authors discuss the model's response to changes in the vertical shear of the basic state, which appears to have the opposite effect in the model from what it has in nature.

Molinari, R.L. Subtropical Atlantic Climate Studies (STACS) revisited. EOS, Transactions, American Geophysical Union, 67(5):59-60 (1986).

No abstract.

Molinari, R.L., J.F. Festa, and E. Marmolejo. Heat budget and climatic atlas of the tropical Indian Ocean and Arabian Sea during FGGE (1979). NOAA Technical Memorandum, ERL AOML-63, 76 pp. (1986).

Observations of surface oceanographic and meteorological fields collected during the first GARP Global Experiment (FGGE) in the tropical western Indian Ocean and Arabian Sea have been combined and averaged by month onto a 2° by 2° grid. Monthly distributions of sea-surface temperature, wind speed and direction, air temperature, specific humidity, and cloud cover have been generated for the period from December 1978 through November 1979. Net short-wave and long-wave radiation, and sensible and latent heat flux distributions have been generated from these surface data using the bulk aerodynamic formulas. Standard errors of the mean values have been computed along with monthly contoured plots of each oceanographic and meteorological variable.

Molinari, R.L., J.F. Festa, and J. Swallow. Climatic atlas of mixed layer and thermocline depth climatologies in the western Indian Ocean. NOAA Technical Memorandum, ERL AOML-64 (PB86-154613), 40 pp. (1986).

Mean monthly distributions of the mixed layer depth (defined as the first depth at which the temperature is 0.5°C less than the sea-surface temperature) and thermocline depth (defined as the depth of the 20°C isotherm) are derived from data collected between 1948 and 1981. Approximately 50,000 data points are available to generate the climatologies. Amplitude and phase distributions for the annual and semi-annual signals are computed from the monthly time series. The mixed layer depth distributions are compared to the thermocline depth distributions to identify possible regions where thermocline displacements influence mixed layer displacements.

Molinari, R.L., J.F. Festa, and J. Swallow. Evolution of the near-surface thermal structure in the western Indian Ocean during FGGE, 1979. Journal of Marine Research, 44:739-762 (1986).

The evolution of mixed layer temperature (taken as sea-surface temperature, SST) in the western Indian Ocean north of 20°S and west of 80°E during the First GARP Global Experiment (FGGE), 1979, is described and modeled. The FGGE-year development in time and space of SST is compared to the appropriate climatology. FGGE events occurred in phase with climatology, but some amplitude anomalies were observed. Heat budget computations for the surface mixed layer indicate that over 25% of the region-studied energy fluxes through the sea surface can account for 80% of the observed SST variance. South of the equator, 80% of the variance is accounted for in 36% of the area and north, only 11%. Exceptions are noted along the western boundary, in the central and eastern Arabian Sea, and in a band south of the equator between 6°S and 12°S, east of 60°E. The addition of entrainment through the base of the mixed layer improves the heat budget estimates over most of the region, in particular, along the Arabian coast. Near the northern part of the coast of east Africa, however, inclusion of the effect of horizontal advection gives more improvement. The breakdown of the heat budget computations in the central and eastern Arabian Sea and in the band south of the equator is attributed to a small signal in SST variance and few data in the regions.

Molinari, R.L., S.L. Garzoli, E. Katz, E. Harrison, P. Richardson, and G. Reverdin. A synthesis of the first GARP global experiment (FGGE) in the equatorial Atlantic Ocean. Progress in Oceanography, 16(2):91-112 (1986).

A synthesis of near-surface oceanographic and surface meteorological data collected during the First GARP Global Experiment (FGGE) is presented to portray the oceanic response to the seasonal wind forcing for the period December 1978 to November 1979, inclusive. Major wind events during FGGE are in phase with events given in climatology. In particular, the February-March-April relaxation and May enhancement of equatorial winds occurs within one month of the mean event. Accordingly, the oceanic responses, such as the May, June, July appearance of an equatorial cold water tongue, the acceleration of the South Equatorial Current (SEC), and the vertical displacementt of the equatorial thermocline occur at the average time. Furthermore, the curl distribution in the vicinity of the North Equatorial Countercurrent (NECC) during 1979 is similar to the climatological distribution in terms of phase and amplitude, except for a westward displacement in the position of the maximum curl. As predicted from linear theory, the 1979 thermocline response across the NECC is in phase with the climatological response with a westward displacement of the maximum thermocline movement. Deeper than average equatorial thermoclines and a weaker SEC may, in part, be responsible for the anomalously warm sea-surface temperatures observed on the equator between 10°W and 30°W from June to November.

Nelsen, T.A., and J.H. Trefry. Pollutant-particle relationships in the marine environment: A study of particles and their fate in a major river-delta-shelf system. Rapports et Proces-Verbaux des Reunions, 186:115-127 (1986).

The Pollutant-Paraticle Relationships in the Marine Environment (P-PRIME) program was designed to look at the association between partaicles (lithogenic and biogenic) and selected heavy-metal pollutants for their source-pathway-dispersal patterns and behavior from a major United States river (Mississippi River) to the adjacent continental shelf. Data from four cruises indicate the following: (a) the river's SPM concentration varied on an hourly to seasonal scale; (b) suspended particulate matter in the study area was composed of three distinct suites: a dominant lithogenic suite and two subordinates, but distinct and seasonally variable biogenic (phytoplankton) suites; (c) in order of abundance, the offshore concentration of particulate matter is in the bottom nepheloid layer, the surface turbid layer, and the midwater region; (d) in the nearshore and midshelf zone, rapid removal of river-derived (lithogenic) particles from the water column to the underlying sediments may be "driven" by biopackaging; (e) 210 Pb sediment accumulation-rate support the rapid removal and accumulation of river-derived sediments very near the river mouth; (f) data for sediment pollutant Pb support the concept of rapid sediment burial in the nearshore zone and also indicate no losses of Pb from these particles. These findings indicate that modeling and sediment transport of river/shelf systems such as the ones described above must consider variability on the hourly to seasonal scale to provide an accurate reflection of the natural system. Because of close coupling of pollutants such as Pb with particles, even after burial, future studies of the pathways and sinks of many pollutants can be, to a first approximation, that of the river-derived particles.

Nelsen, T.A., G.P. Klinkhammer, J.H. Trefry, and R.P. Trocine. Real-time observation and tracking of dispersed hydrothermal plumes using nephelometry: Examples from the Mid-Atlantic Ridge. Earth and Planetary Science Letters, 81:245-252 (1986).

As part of the 1984-1985 NOAA VENTS program on the Mid-Atlantic Ridge, nephelometry was used to provide real-time detection and tracking of dispersed hydrothermal plumes. At all nine 1984 study sites, hydrothermal activity was detected by in-situ, real-time nephelometer measurements and later confirmed by dissolved Mn and particulate Fe measurements. These same techniques were employed in a site-specific survey of the Trans-Atlantic Geotraverse (TAG) area in 1985 where large water-column anomalies in turbidity and in dissolved Mn helped lead to the discovery of high-temperature black smokers. The optical response of the nephelometer was to hydrothermally-derived particulate matter. Thus, strong correlations existed between the nephelometer readings and total suspended matter (r = 0.98, n = 34), and particulate Fe (r = 88, n = 32). In addition, digital nephelometer data correlated well with dissolved Mn (r = 0.88, n = 78) throughout a large concentration range (0.2-31.0 nmol/kg). These data provide good evidence for the utility of in-situ nephelometer measurements for locating and surveying plumes from hydrothermal events. It also appears possible, within limits, to predict concentrations of in-situ total suspended matter, of particulate Fe and of dissolved Mn.

Nelsen, T.A., S. Metz, J.H. Trefry, and A. Pimmel. Sedimentology and composition of sediment near a black smoker field on the Mid-Atlantic Ridge. EOS, Transactions, American Geophysical Union, 67:1022 (1986).

A 1.25 m core was recovered in 1985 from the Mid-Atlantic Ridge (26°N) approximately 2 km north-northeast of the newly discovered black smokers in the TAG Hydrothermal Field. Structural evidence within the core suggests that it was recovered from the edge of a small infilling basin. Sediment transport mechanisms for the hydrothermal materials appear to be both by mass movement and grain-by-grain sedimentation. Sediment deposited by the latter mechanism has accumulated at rates varying from 2-30 cm/1,000 years. Relative to mass movement transport, x-radiography reveals a debris-flow deposit capped by an associated fine-grained turbidite. Upcore, two course-grained turbidite deposits of hydrothermal material were identified. These mass flow deposits account for approximately 44% of the recovered sediment. The balance of the recovered sediment was deposited in a grain-by-grain fashion with hydrothermal material dominating these intervals. Hydrothermal input was pulsed, with events ranging from the sub-millimeter scale to layers as thick as 25 cm. Within the top 12 cm, representing approximately the last 4,000 years, interlayering of normal pelagic sediments and hydrothermal material indicates either sporadic deposition of, or intermittent venting of, hydrothermal material. Superimposed on the above, chemical and mineralogical data show considerable variability with time, as well as providing sustaining evidence for the interpretations stated above.

Ooyama, K.V. A spectral prediction model on nested domains and its application to asymmetric flow in the hurricane boundary layer. Extended Abstracts, WMO/IUGG International Symposium on Short and Medium-Range Numerical Weather Prediction, Tokyo, Japan, August 4-8, 1986. PSMP Report Series No. 19, 451-454 (1986).

No abstract.

Palmer, D.R., P.A. Rona, and M.J. Mottl. Acoustic imaging of high-temperature hydrothermal plumes at seafloor spreading centers. Journal of the Acoustical Society of America, 80(3):888-898 (1986).

We explore the possibility of using active sonar techniques to acoustically image high-temperature "black smoker" hydrothermal plumes. We examine recent sonar images of a hydrothermal vent field at 11°N on the East Pacific Rise obtained from DSRV Alvin which may show the presence of plumes. For vent fields on the East Pacific Rise, estimates are obtained of the minimum detectable concentration of precipitates as a function of the range between the sonar and the plume boundary. These estimates are compared with measured concentrations. Some of the anticipated advantages of acoustic imaging are discussed. We conclude that acoustic imaging techniques have the potential of providing a coherent framework for point sampling of physical and chemical properties of hydrothermal plumes and for determining the dynamics of their injection into the surrounding water mass.

Palmer, D.R., L.M. Lawson, Y.-H. Daneshzadeh, and D.W. Behringer. The effect of an El Niño/Southern Oscillation event on underwater sound propagation. 111th Meeting of the Acoustical Society of America, Cleveland, OH, May 12-16, 1986. Journal of the Acoustical Society of America, 79:S69 (1986).

No abstract.

Peng, T.-H. Land use change and carbon exchange in the tropics: II. Estimates for the entire region--Comment. Environmental Management, 10(5):573-575 (1986).

No abstract.

Peng, T.-H. The role of the ocean in the atmospheric CO₂ problem. Science Monthly, 17(8):615-621 (in Chinese) (1986).

No abstract.

Peng, T.-H. Uptake of anthropogenic CO₂ by lateral transport models of the ocean based on the distribution of bomb-produced ¹⁴C. Radiocarbon, 28(2A):363-375 (1986).

The pattern of global water column inventories of bomb-produced ¹⁴C suggests that a sizeable portion of bomb ¹⁴C that entered the Antarctic, northern Pacific, and tropical oceans has been transported to adjacent temperate regions. Models of lateral transport of surface water in the Atlantic, Indian, and Pacific Oceans are based on this distribution pattern. Upwelling of bomb-¹⁴C-free water from below takes place in the Antarctic, northern Pacific, and tropical regions; downwelling of surface water occurs in the temperature oceans and northern Atlantic. Uptake of excess CO₂ by these models is calculated using the observed Mauna Loa pCO₂ record as an input function. Results indicate that 35% of fossil fuel CO₂ is taken up by these model oceans during the period 1958-1980. Considering the observed airborne fraction of 0.55, it appears that ca 10% of the global fossil fuel CO₂ is still missing.

Peng, T.-H., and H.D. Freyer. Revised estimates of atmospheric CO₂ variations based on tree-ring ¹³C record. In The Changing Carbon Cycle: A Global Analysis, J.R. Trabalka and D.E. Reichle (eds.). Springer-Verlag, New York, 151-159 (1986).

No abstract.

Peterson, D.H., D.R. Cayan, and J.F. Festa. Interannual variability in biogeochemistry of partially mixed estuaries: Dissolved silicate cycles in northern San Francisco Bay. Estuarine Variability, 1986:123-138 (1986).

Much of the interannual variability in partially-mixed estuaries in dissolved inorganic nutrient and dissolved oxygen patterns results from an enhancement or reduction of their annual cycle (generally via climatic forcing). In northern San Francisco Bay estuary the annual cycle of dissolved silicate supply peaks in spring and the effect of phytoplankton removal peaks in fall. Because riverine silicate sources are enhanced in wet years and reduced in dry years, the annual silicate cycle is modified accordingly. Effects of phytoplankton removal are reduced and delayed in wet years and enhanced and advanced (seen earlier) in dry years. Similar reasoning can apply to interpreting and understanding other mechanisms and rates.

Piotrowicz, S.R., D.A. Boran, and C.J. Fischer. Ozone in the boundary layer of the equatorial Pacific Ocean. Journal of Geophysical Research, 91:13,113-13,119 (1986).

Shipboard (~7 m) ozone measurements made in the equatorial Pacific Ocean between 20°N and 17°S and 140°W-160°W confirm the existence of a distinct ozone minimum in the vicinity of the equator in the late spring, its decline in the summer, and its absence in autumn. This minimum could not be correlated with high biological activity in surface waters. Coincident aircraft measurements of ozone from near sea surface (50-100 m) to 2 km in altitude were made along 150°W at stations at 10°N, 0°, 5°S, and 12°S in May-June 1984. Aircraft data identified the existence of a distinct ozone maximum between the lifting condensation level (LCL) or cloud base and the trade wind inversion, with ozone mixing ratios amounting to 2-2.5 times the ozone levels in the well-mixed subcloud layer. A gradient of decreasing ozone with decreasing altitude extended from the LCL (or cloud base) to the near-surface superadiabatic region but did not include it.

Powell, M.D. Airborne Doppler radar observations in the hurricane boundary layer. Preprints, 23rd Conference on Radar Meteorology, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, JP260-JP263 (1986).

No abstract.

Reverdin, G., R.L. Molinari, and Y. Du Penhoat. Objective analysis of thermocline depth distributions obtained in the tropical Atlantic Ocean during FGGE, 1979. Deep-Sea Research, 33(1):43-53 (1986).

An objective analysis algorithm is applied to subsurface temperature data collected in the tropical Atlantic Ocean from January to August 1979 to obtain maps of 20°C isotherm topography. Throughout the eight-month period anomalies were essentially aligned with the ridge-trough system characteristic of the climatological thermocline distribution in the region. The anomalies, as large as 30 m, increased the relief of the 1979 ridge-trough system relative to climatology. A simple diagnostic calculation using the results from the algorithm and surface wind data suggests that in the region of the North Equatorial Countercurrent the thermocline responds to the effects of local Ekman pumping and the divergence of geostrophic currents. Both effects are caused by the seasonally varying surface winds.

Rona, P.A., G. Klinkhammer, T.A. Nelsen, J. H. Trefry, and H. Elderfield. Black smokers, massive sulfides, and vent biota at the Mid-Atlantic Ridge. Nature, 321:33-37 (1986).

No abstract.

Shang, E.C., L.M. Lawson, and D.R. Palmer. Source range information loss in waveguides. Journal of the Acoustical Society of America, 79:958-963 (1986).

In a previous study (E.C. Shang, C.S. Clay, and Y.Y. Wang, J. Acoust. Soc. Am., 78, 172 [1985]) a new method of passive source ranging in a layered waveguide was proposed. This paper investigates the reduction (loss) in range information due to phase fluctuations and to an inaccurate description of the environment (waveguide mismatch). The effects of phase fluctuations are investigated using a two-dimensional Gaussian distribution function. A numerical normal mode code is used to study the effects of waveguide mismatching. The loss in range information caused by incorrect descriptions of both the bottom sediment type and the sound speed profile in the water column is calculated. Examples are given for a water depth of 100 m and frequencies in the range from 100-500 Hz.

Trefry, J.H., T.A. Nelsen, R.P. Trocine, S. Metz, and T.W. Vetter. Trace metal fluxes through the Mississippi River delta system. Rapports et Proces-Verbaux des Reunions, 186:277-288 (1986).

River deltas serve as an important sink for many continentally-derived contaminants, thereby restricting their flux through the coastal zone. We have investigated the geochemical cycling of several trace metals, especially Cd, Mn, and Pb, in the Mississippi River delta-Gulf of Mexico system to establish the efficiency of this deltaic sink. Greater than 90% of the Mississippi River trace metal load is associated with detrital particles. As a result, dissolved metal concentrations are very low and appear to be controlled in several instances by a predictable partitioning between dissolved and particulate phases. To model this partitioning, distribution coefficients (K_d) were calculated for several metals using field and laboratory data. Much of the river-borne sediment is deposited within 30-50 km of the river mouth. This is especially evident in the sediment record for Pb which shows a sharp decrease in the depth to which pollutant Pb is found with increasing distance offshore. Sediment Pb profiles and river particulate Pb concentrations also support a 40% decrease in the 1982-1983 Mississippi River burden of pollutant Pb relative to the mid-1970's. Delta sediments are not always the ultimate sink for trace metals. Remobilization of Mn and Cd to the overlying water column leads to a 10-50% net loss of these metals from the sediment. In contrast, the Pb cycle shows rapid, permanent removal to the sediments. The Mississippi delta is thus a near-perfect filter of Pb, and traps much, but not all, of the incoming fluxes of Cd and Mn. The availability and potential reactivity of sediment trace metals were elevated by leaching sediments with a series of buffers at pH 2.2-6.0. Results show that Cu, Fe, and Pb have a much lower tendency towards removal than Cd and Mn.

Willis, P.T. Characteristics of hurricane melting layers. Preprints, 23rd Conference on Radar Meteorology, Snowmass, CO, September 22-26, 1986. American Meteorological Society, Boston, JP264-JP267 (1986).

No abstract.

Wilson, W.D., C. Roffer, and D.S. Bitterman. The shipboard acoustic Doppler current profiling program at AOML. EOS, Transactions, American Geophysical Union, 67(44):1061 (1986).

No abstract.

Zhang, J.-Z., and M. Whitfield. Kinetics of inorganic redox reactions in seawater. Marine Chemistry, 19:121-137 (1986).

The kinetics of the reaction between iodate and bisulfide ions have been considered in seawater over a range of reactant concentrations and at temperatures from 5 to 35°C. The progress of the reaction in a closed vessel was monitored by the potentiometric measurement of pH and pS^2-. In a series of experiments at reagent concentrations approaching those observed in natural systems, samples were drawn off from the closed vessel at regular intervals for polarographic analysis of iodate, [IO₃^-], and total sulfide [S_T]. The stoichiometric measurements, together with observations on the products formed, indicate that the initial reaction is:

5HS^- + 2IO₃^- + 7H⁺ <--> I₂ + 5S + 6H₂O

Measurements using both the potentiometric and polarographic data at constant initial pH suggest an initial rate equation of the form:

(d[S_T]₀/dt)₀ = k' [IO₃^-]₀^0.5 [S_T]₀

At 25°C, pH 8.2 and a salinity of 35 ^o/_oo, potentiometric measurements give k' = 162 mol^-1 min^-1 and polarographic measurements give k' = 105 mol^-1 min^-1. The reaction proceeds more rapidly than the corresponding reaction of bisulfide ions with molecular oxygen and it should, therefore, provide a significant source of molecular iodine in circumstances where oxic and anoxic waters mix (e.g., when estuarine sediments are tidally stirred or during the intermittent seasonal mixing of stratified fjord or lake systems).

**1985**

Benngio, B.L., and T.A. Nelsen. Technical note: Successful instrument array deployments in soft mud bottoms adjacent to the Mississippi Delta. Applied Ocean Research, 7(1):58-60 (1985).

An anchor design for instrument arrays was developed for use in the very soft muddy sediments adjacent to the Mississippi Delta. Because of the low sediment shear strengths and high sensitivities combined with large dynamic loadings due to strong currents, problems in successful deployments and recoveries were anticipated. A total of six deployments were attempted; four were sediment trap arrays and two were current meter/transmissometer arrays. All six deployments and recoveries were successful. The array design presented herein is a safe, easy, and cost effective method for deploying instrument arrays in areas where soft bottoms and strong currents are a consideration.

Bennett, R.H., S.A. Bush, L. Lehman, P. Gritton, E.B. Forde, G.R. Harvey, W.B. Sawyer, and M. Hulbert. Organic carbon and submarine sediment, geotechnical property interrelations. Marine Geotechnology, 6:61-98 (1985).

Total organic carbon content (TOC) and selected geotechnical properties were measured in submarine sediments of the U.S. central east coast and the Mississippi Delta. TOC values in the near-surface Delta sediments were approximately 1% (dry weight). TOC in surficial sediments from the U.S. east coast outer continental shelf upper slope, and upper rise was generally less than 1%, but between the upper slope and the upper rise, values ranged from 1% to 3% and exceeded 3% in patches associated with Norfolk and Washington Canyons. TOC displayed positive linear correlations with water content, liquid limit, plastic limit, plasticity index, and the amount (percent) of fine-grained material. Nevertheless, there appeared to be no strong dependence of geotechnical properties on TOC in these sediments. This was in accord with previously reported studies on terrestrial soils with TOC values of less than 5%. Carbohydrate content was strongly correlated with water content and plasticity index, suggesting that measurement of individual components of the organic material may provide more sensitive indications of the effects of organics on geotechnical properties than measurement of bulk TOC. Selected geotechnical properties and TOC content of U.S. continental margin surficial sediments displayed regional trends related to water depth and morphological setting. These trends are probably related to recent biological, sedimentological, and oceanographic processes active on the outer shelf, slope, and rise.

Bitterman, D.S. Use of ARGOS tracked drifting buoys in the equatorial Pacific Ocean. 1984 Drifting Buoy Workshop, November 1984, Marine Technology Society Gulf Coast Section, 109-111 (1985).

No abstract.

Black, P.G., R.L. Elsberry, L.K. Shay, and R.M. Partridge. Hurricane Josephine (1984) surface winds and ocean response determined from air-deployed drifting buoys and concurrent research aircraft data. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 22-24 (1985).

No abstract.

Black, P.G., R.C. Gentry, V.J. Cardone, and J. Hawkins. Seasat microwave wind and rain observations in severe tropical midlatitude marine storms. In Advances in Geophysics 27, Academic Press, New York, 197-277 (1985).

This overview presents initial results of studies concerning Seasat measurements in and around tropical and severe midlatitude cyclones over the open ocean and provides an assessment of their accuracy and usefulness. Sensors flown on Seasat provided complementary measurements of surface wind speed direction, rainfall rate, significant wave height and wave length, and sea surface temperature. These measurements were made with the Seasat-A Satellite Scatterometer (SASS), the Scanning Multichannel Microwave Radiometer (SMMR), The Seasat altimeter, and the Seasat Synthetic Aperture Radar (SAR). This is the first time that such a sophisticated array of microwave instruments has been used to study tropical cyclones.

Black, R.A. Distribution of particle types above 6.0 km in two Atlantic hurricanes. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston (1985).

No abstract.

Broecker, W.S., T.-H. Peng, and T. Takahashi. Reconstructions of past atmospheric CO₂ content from the chemistry of the contemporary ocean: An evaluation. DOE Technical Report TR020, DOE/OR-857 (1985).

No abstract.

Broecker, W.S., C. Rooth, and T.-H. Peng. Ventilation of the deep northeastern Atlantic. Journal of Geophysical Research, 90(C4):6940-6944 (1985).

Comparison of the 1973 GEOSECS expedition results from the deep eastern basin of the North Atlantic with those for 1981 TTO expedition reveal no firm evidence for change in NO₃, PO₄, or a H₄SiO₄ concentration. While a 2-3 µmol/kg difference is seen for O₂, it is more likely experimental than temporal in origin. The combined TTO-GEOSECS data sets reveal no evidence for ventilation of the bottom waters of the eastern basin by waters from the north.

Broecker, W.S., T.-H. Peng, G. Ostlund, and M. Stuiver. The distribution of bomb radiocarbon in the ocean. Journal of Geophysical Research, 90(C4):6953-6970 (1985).

Water column inventories are calculated for bomb radiocarbon at all the stations occupied during the GEOSECS and NORPAX expeditions and for the available TTO stations. The pattern of global inventories obtained in this way suggests that a sizable portion of the bomb radiocarbon that entered the Antarctic, the northern Pacific, and the tropical ocean has been transported to the adjacent temperature zones. A strategy for utilizing these inventory anomalies as constraints on global ocean circulation models is presented. Essential to this strategy are the improvement of our knowledge of the pattern of wind speed over the ocean, the establishment of the wind speed dependence of the rate of gas exchange between the atmosphere and sea, and the continued mapping of the distribution of bomb-produced radiocarbon in the sea.

Burpee, R.W., R.E. Kohler, and D.G. Marks. An evaluation of Omega dropwindsonde data in track forecasts of Hurricane Josephine. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 162-163 (1985).

No abstract.

Carsey, T.P. Quantitation of vanadium oxides in airborne dusts by x-ray diffraction. Analytical Chemistry, 57:2125-2130 (1985).

No abstract.

Dodge, P.P., R.W. Burpee, and F.D. Marks. Convective-scale and mesoscale structure of hurricanes during landfall. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 7-8 (1985).

No abstract.

Emanuel, W.R., I. Y.-S. Fung, G.G. Killough, B. Moore, and T.-H. Peng. Modeling the global carbon cycle and changes in the atmospheric CO₂ levels. In Atmospheric Carbon Dioxide and the Global Carbon Cycle, J.R. Trabalka (ed.). DOE/ER-0239, 141-174 (1985).

No abstract.

Franklin, J.L., S.J. Lord, L.J. Shapiro, and K.V. Ooyama. An objective analysis of Omega dropwindsonde data from Hurricane Debby (1982). Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 186-187 (1985).

No abstract.

Friedman, H.A. Educational program encourages students to seek hurricane precautions (instructional programs to encourage family involvement). In Hurricane Awareness Workbook: Perspectives on Hurricane Preparedness (a monograph). Federal Emergency Management Agency/National Oceanic and Atmospheric Administration, Washington, D.C., A27-A28 (1985).

No abstract.

Friedman, H.A. Meteorological education as a window on science and technology: Activities of the AMS Board of School and Popular Meteorological and Oceanographic Education. Proceedings, First International Conference on School and Popular Meteorological Education, Oxford, England, July 2-4, 1984, J.M. Walker (ed.). Royal Meteorological Society, Bracknell, Berkshire, United Kingdom, 6-9 (1985).

Many U.S. scientists and educators have long held the belief that our educational system has failed to provide its students with the mathematics and science skills needed to compete successfully in today's technologically-oriented society or to maintain our nation's position of technological leadership in the world. Only recently has this belief motivated members of the meteorological profession, through the American Meteorological Society (AMS) and other scientific organizations, to undertake a number of educationally-related activities designed to reverse the disturbing trend toward math and science illiteracy in the nation's schools. The Board of School and Popular Meteorological and Oceanographic Education (BSPMOE) has joined with other boards of the AMS Education and Manpower Commission to develop a resource guide for use with school-aged children and the general public. The guide is designed to help promote an awareness of meteorology as a science and the importance of "weather" in everyday life. We believe that such awareness will serve as a "window" on mathematics, science, and technology, especially for school-aged children, and will awaken their scientific curiosity, enhance their scientific literacy, and heighten their enthusiasm for continued learning. The activities, accomplishments, and programmatic goals of the BSPMOE are discussed.

Friedman, H.A. School-based and community-wide education and public information programs to increase tropical cyclone awareness and preparedness. Proceedings, First International Conference on School and Popular Meteorological Education, Oxford, England, July 2-4, 1984, J.M. Walker (ed.). Royal Meteorological Society, Bracknell, Berkshire, United Kingdom, 79-85 (1985).

Education and public information are recognized as critical elements in the design, organization, and implementation of effective tropical cyclone warning systems. Decision-makers and citizens must have a clear understanding of the dangers associated with tropical cyclones. Otherwise, even in nations that have a high level of preparedness, citizens are likely to take all measures necessary to protect themselves, or to mitigate against, the destructive effects of future landfalling storms. In response to this recognition, a numer of education, public information, and preparedness programs have been proposed or are now in progress. The goals and strategies of three such programs, namely, (1) a cognitive and effective learning model (CALM), to create an awareness of the hurricane problem in at-risk coastal communities of south Florida (HRD/AOML-NOAA), (2) Pan Caribbean Disaster Preparedness and Prevention Project (CARICOM, UNDRO, WHO), and (3) Tropical Cyclone Programme Project No. 14: Public Information and Education (WMO, UNDRO, LRCS), are discussed in this paper. These efforts represent, respectively, programs with local, regional, and international focus.

Friedman, H.A., and C.J. Nelson. 1985 Hurricane Field Program Plan. U.S. Department of Commerce, NOAA/Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, Florida (published for limited distribution), 109 pp. (1985)

No abstract.

Friedman, H.A., P. Stephens, J. Williams, and O.E. Thompson (eds.). Guide to Establishing School and Public Educational Activities. First edition (limited distribution), American Meteorological Society, Boston, 21 pp. (1985).

The first edition of this guide to local AMS chapters and university departments is designed to help develop school and public educational outreach programs in their communities. The guide was produced cooperatively by the AMS Board of School and Popular Meteorological and Oceanographic Education and the Board on Women and Minorities. The authors invite readers of this document to comment on its usefulness in conducting and implementing community educational outreach programs. Formal publication of the guide is planned.

Garzoli, S.L., and S.G.H. Philander. Validation of an equatorial Atlantic simulation model using inverted echo sounder data. Journal of Geophysical Research, 90(C5):9199-9201 (1985).

No abstract.

Goldenberg, S.B., S.D. Aberson, and R.E. Kohler. Incorporation of Omega dropwindsonde data into SANBAR: An operational barotropic hurricane-track forecast model. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 44-45 (1985).

No abstract.

Govoni, J.J., A.J. Chester, D.E. Hoss, and P.B. Ortner. An observation of episodic feeding and growth of larval Leiostomus xanthurus in the northern Gulf of Mexico. Journal of Plankton Research, 7(1):137-146 (1985).

Four cruises were conducted in the northern Gulf of Mexico over two spawning seasons of the sciaenid fish Leiostomus xanthurus. On only one occasion did unusually high densities of larvae and their principal microzooplanktonic foods co-occur. Peak densities of larvae and microzooplankton were observed in a thin lens of cool surface water that characterized a hydrographic discontinuity, and all larvae contained high numbers of food organisms in their guts. Instantaneous exponential growth rates, estimated from measurements of otolith growth increments, indicated accelerated growth on the day that larvae were collected. A laboratory experiment verified that larval L. xanthurus responds to an increased ration with accelerated growth that is detectable in otoliths. Together these data suggest that the spatial distribution of L. xanthurus larvae and their microzooplanktonic food is patchy and that interactions of larvae and microzooplankton may be episodic.

Hansen, D.V. Eastern tropical Pacific thermocline topography during 1982-1983. In El Niño Atlas, 1982-1983, A. Leetmaa and J. Witte (eds.), Chapter 12, Government Printing Office, 131-134 (1985).

No abstract.

Hansen, D.V. Large-scale aspects of oceanic and atmospheric conditions associated with the 1982-1983 El Niño. Rev. Com. Perm. Pacifico Sur, 15:49-65 (1985).

An unprecedented set of oceanic and atmospheric data are available to complement those made in the ERFEN region for description of the El Niño of 1982-1983. These data show that anomalies of sea level atmospheric pressure, precipitation, and winds appeared in the western Pacific Ocean as early as May 1982, and moved eastward across the ocean to the coast of South America. These atmospheric anomalies were associated with observed sea surface temperature and circulation anomalies in the eastern Pacific Ocean. Movements of satellite-tracked drifting buoys reveal that the South Equatorial Current near the equator flowed with less than normal strength during the entire period from August 1982 through June 1983 and actually reversed dring December 1982 and from mid-April through early June 1983. The temporal evolution of near-equatorial water movements is similar to the sea surface temperature and sea level anomalies observed east of the Galapagos Islands. By December 1983, almost all of the anomalies associated with El Niño had returned to near normal values.

Hansen, D.V., M.C. Pazos, and R. Allen. Movements of satellite-tracked drifting buoys in the eastern equatorial Pacific during 1982-1983. In El Niño Atlas, 1982-1983, A. Leetmaa and J. Witte (eds.), Chapter 8, Government Printing Office, 89-102 (1985).

No abstract.

Hendee, J.C., and G. Mueller. Histology of the adenohypophysis of the kelp greenling, Hexagrammus decagrammus (Hexagrammidae). Journal of Fisheries Biology, 27(3):273-276 (1985).

No abstract.

Houze, R.A., F.D. Marks, R.A. Black, P.T. Willis, and J.F. Gamache. Airborne Doppler and cloud microphysical measurements in Hurricane Norbert. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 5-6 (1985).

No abstract.

Katsaros, K.B., L.A. McMurdie, R.J. Lind, and J.E. deVault. Albedo of a water surface, spectral variation, effects of atmospheric transmittance, sun angle, and wind speed. Journal of Geophysical Research, 90(C4):7313-7321 (1985).

In this study, the authors examine the albedo's dependence on transmittance (cloudiness) and solar altitude using observations obtained from aircraft and a ship in the Joint Air-Sea Interaction (JASIN) experiment, from a ship in the GARP Atlantic Tropical Experiment (GATE, where GARP is the Global Atmospheric Research Program), and from an instrumented mast located in Lake Washington (Seattle, Washington). These results are then analyzed.

Lawson, L.M., D.A. Seem, D.R. Palmer, and Y.-H. Daneshzadeh. A computer code for calculating acoustic ray paths with application to the Straits of Florida. NOAA Technical Memorandum, ERL AOML-62, 142 pp. (1985).

Ocean acoustic tomography is an attractive candidate for monitoring the heat transport in the Florida Current. The feasibility of this application of tomography depends on the ability to identify individual ray paths. Although experience shows that paths can be identified with deep ocean propagation, the ray path structure in the Florida Straits is quite different. There the sound speed is such that a ray path which travels a modest distance necessarily experiences bottom bounces. To investigate the question of ray path identification, a fast, specialized ray-tracing program was developed. Using this code, we analyzed the fluctuations in ray path geometry resulting from small perturbations in the bathymetry. This report describes the computer code, documents the historical data, and the numerous ray-tracings calculated for the Florida Straits.

Leetmaa, A., and W.D. Wilson. A diagnostic analysis of a 1982-1983 El Niño simulation. EOS, Transactions, American Geophysical Union, 66(46):830 (1985).

No abstract.

Leetmaa, A., and W.D. Wilson. Ametek-Straza data from the eastern Pacific. In El Niño Atlas, 1982-1983, A. Leetmaa and J. Witte (eds.), Chapter 13, Government Printing Office, 135-148 (1985).

No abstract.

Leetmaa, A., and W.D. Wilson. Characteristics of near surface circulation patterns in the eastern equatorial Pacific. Progress in Oceanography, 14:339-352 (1985).

Since June 1981 several CTD and velocity profiler sections have been made across the equator at 85°W as part of the Equatorial Pacific Ocean Climate Studies (EPOCS). Two of these sections, those in June 1981 and December 1982, are discussed in order to characterize the circulation patterns that occur when the ocean is forced by meridional wind stress. In this area the winds are predominantly southerly. Use of an Ametek-Straza acoustic Doppler backscatter profiler during the 1982 cruise gave velocity data to a depth of 270 m every 5.5 km along the shiptrack. This allowed the shear and velocity fields to be examined in greater detail than had been possible before. Large areas had shears greater than 0.01 s^-1 were observed. Greatest shears tended to coincide with regions of large vertical density gradients. Comparisons with geostrophic computations suggest that a large fraction of the shear was geostrophic. Richardson number computations indicated that over 40% of the area sampled by theCTD casts had values of less than 1 and about 5% had values less than one quarter. Values of less than one quarter were concentrated in the mixed layer but were not confined to it. Below the mixed layer, regions with low Richardson number were associated with regions where the vertical density gradient was quasi-linear. Since such regions were not confined to the vicinity of the equator, these observations suggest shear mixing as an important mechanism over large areas of the upper ocean. Within the top 40 m of the water column there was a general tendency for motions in the mixed layer to be to the left of the wind in the southern hemisphere and to the right in the northern hemisphere. However, no clear examples were found of Ekman spirals. Most of the veering was confined to the mixed layer which was of relatively constant depth over the whole survey area. South of the equator a large fraction of the shear across the base of the mixed layer appeared to be geostrophic, whereas north of the equator, these shears were ageostrophic. Estimates of the various terms in the momentum equation in the upper ocean indicated that near the equator non-linear effects, such as upwelling and northward advection, were as important as Coriolis forces, pressure gradients, and wind stress. The pressure gradient, integrated over the depth quarter, were concentrated in the mixed layer but were not confined to it. Below the mixed layer, regions with low Richardson number were associated with regions where the vertical density gradient was quasi-linear. Since such regions were not confined to the vicinity of the equator, these observations suggest shear mixing as an important mechanism over large areas of the upper ocean. Within the top 40 m of the water column there was a general tendency for motions in the mixed layer to be to the left of the wind in the southern hemisphere and to the right in the northern hemisphere. However, no clear examples were found of Ekman spirals. Most of the veering was confined to the mixed layer which was of relatively constant depth over the whole survey area. South of the equator a large fraction of the shear across the base of the mixed layer appeared to be geostrophic, whereas north of the equator, these shears were ageostrophic. Estimates of the various terms in the momentum equation in the upper ocean indicated that near the equator non-linear effects, such as upwelling and northward advection, were as important as Coriolis forces, pressure gradients, and wind stress. The pressure gradient, integrated over the depth of the mixed layer, was larger than the stress in the vicinity of the equator and the relative importance of other terms varied from place to place. The horizontal scale of variation was as small as 10 km. Near surface upwelling occurred in shallow cells with horizontal dimensions of 100 km or less.

Lewis, J.M., C.M. Hayden, C.S. Velden, T.R. Stewart, S.J. Lord, S.B. Goldenberg, and S.D. Aberson. The use of VAS winds and temperatures as input to barotropic hurricane-track forecasting. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 40-41 (1985).

No abstract.

Li, Y.-H., T.-H. Peng, and W.S. Broecker. A reply to the paper by Austin and Green, "The role of baroclinic eddies in mixing tritium into the oceanic gyres." Tellus, 37B:186-187 (1985).

No abstract.

Marks, F.D. Evolution of the structure of precipitation in Hurricane Allen (1980). Monthly Weather Review, 113:909-930 (1985).

Reflectivity data from the airborne radar systems on board the three NOAA aircraft were gathered during six consecutive days in Hurricane Allen of 1980. The data have been used to specify the horizontal and vertical precipitation distribution within 111 km radius of the hurricane center. The evolution of the structure and intensity of the precipitation in the storm is described from representative time composite radar maps for seven research flights made during the six-day period. The eyewall was characterized by a narrow ring (12-15 km wide) of intense reflectivity (42-47 dBZ) surrounding the center of the storm at a radius that varied in time from 12-40 km. The eyewall had steep radial gradients of reflectivity (4-5 dB km^-1) and tilted radially outward in height. The rain bands were characterized by areas of enhanced reflectivity embedded in a region of stratiform rainfall that contained a distinct bright band at the height of the 0°C isotherm. The most striking changes in structure during the six-day period were the rapid contraction in eyewall radius and the devleopment of a secondary ring of intense reflectivity 80-100 km from the storm center. These changes in eye radius appeared to be related to the vortex evolution, as discussed by Willoughby and others. Changes in storm intensity, coincident with the eyewall radius changes, seemed to have little effect on the total storm rainfall or latent heat release. The maximum storm rainfall occurred when the storm had a double eyewall structure. After the period of the double eyewall, the mean rain rate in the eyewall increased as the storm approached maximum intensity. However, coincident with the increase in eyewall rain rate, the eyewall area decreased, resulting in little change in the total storm rainfall. The sequence of time composites provided the first opportunity to describe, quantitatively, the precipitation distribution within 111 km of the center of a mature hurricane that was away from land influences. The rainfall analysis showed that the mean rain rates in the eyewall were a factor of 6 greater than those outside the eyewall (11.3 mm h^-1 versus 1.8 mm h^-1), but because the eyewall region encompassed such a small area, it only contributed 40% of the total rainfall within a radius of 1° latitude of the storm center. The precipitation distribution around the storm was asymmetric; more rainfall occurred ahead of the storm than behind. In general, the maximum precipitation in the eyewall region was within 15-20° of the storm track. The maximum rainfall in the rainband region was 40-50° to the right of that in the eyewall.

Marmolejo, E., J.F. Festa, and R.L. Molinari. Heat budget and climatic atlas of the equatorial Atlantic Ocean during FGGE (1979). NOAA Technical Memorandum, ERL AOML-61, 76 pp (1985).

No abstract.

Maul, G.A., D.A. Mayer, and S.R. Baig. Comparisons between a continuous three-year current-meter observation at the sill of the Yucatan Strait, satellite measurements of Gulf Loop Current area, and regional sea level. Journal of Geophysical Research, 90(C5):9089-9096 (1985).

From October 1977 through November 1980 a current-meter mooring was maintained in the Yucatan Strait. The meter was moored halfway between Mexico and Cuba, 145 m above the sill or in 1895 m of water. Motions of low frequency (<14^-1 cycles/day) are oriented approximately parallel to the isobaths, 021°-030° true. Net drift for three years is to the south-southwest at an average velocity of 1.8 cm s^-1. Sustained southward flows at intervals of eight months, which persisted for several months each, have average velocities of 5 cm s^-1, with randomly spaced bursts as high as 15 cm s^-1. Energy in subtidal frequency bands has significant peaks near 38^-1 and 19^-1 cycles/day, with a broad band of energy between 300^-1 and 200^-1 cycles/day. The latter peak is consistent with the approximately eight-month interval between the southward flow events. Comparison with weekly areal coverage of the Gulf Loop Current from Geostationary Operational Environmental Satellite infrared observations shows little covariation, except that eight months is typical of some anticyclonic eddy generation. There is little coherence of sill depth velocities with Naples sea level at subtidal frequencies, but with Miami there is coherence at several frequencies, notably 38^-1 and 19^-1 cycles/day. In the higher frequencies, the principal tidal motions are diurnal and are oriented somewhat across the isobaths toward the northwest, 346°-349° true, with counterrotating O₁ and K₁ constituents. No semidiurnal, inertial, or fortnightly energy is observed above the background continuum.

Maul, G.A., F. Chew, M.H. Bushnell, and D.A. Mayer. Sea level variation as an indicator of Florida Current volume transport: Comparisons with direct measurements. Science, 227(4684):304-307 (1985).

Sea level measurements from tide gauges at Miami, Florida, and Cat Cay, Bahamas, and bottom pressure measurements from a water depth of 50 m off Jupiter, Florida, and a water depth of 10 m off Memory Rock, Bahamas, were correlated with 81 concurrent direct volume transport observations in the Straits of Florida. Daily-averaged sea level from either gauge on the Bahamian side of the Straits was poorly correlated with transport. Bottom pressure off Jupiter had a linear coefficient of determination of r² = 0.93, and Miami sea level, when adjusted for weather effects, had r² = 0.74; the standard errors of estimating transports were ±1.2 × 10⁶ cubic meters per second, respectively. A linear multivariate regression, which combined bottom pressure, weather, and the submarine cable observations between Jupiter and the Bahamas, had r² = 0.94 with a standard error of estimating transport of ±1.1 × 10⁶ cubic meters per second. These results suggest that a combination of easily obtained observations is sufficient to adequately monitor the daily volume transport fluctuations of the Florida Current.

Molinari, R.L. Heat balances of the surface mixed layer in the equatorial Atlantic and Indian Oceans during FGGE. In Proceedings, First National Workshop on the Global Weather Experiment, National Academy Press, 779-789 (1985).

No abstract.

Molinari, R.L., J.F. Festa, and E. Marmolejo. Evolution of sea-surface temperature and surface meteorological fields in the tropical Atlantic Ocean during FGGE, 1979: Part I. Description of surface fields and computation of surface energy fluxes. Progress in Oceanography, 14:401-420 (1985).

Observations of surface oceanographic and meteorological fields collected during the First GARP Global Experiment (FGGE) in the equatorial Atlantic Ocean have been combined and averaged by month onto a 2° × 2° grid. Monthly distributions of sea-surface temperature, wind speed and direction, air temperature, specific humidity, and cloud cover have been generated for the period from December 1978 through November 1979. Net short wave and long wave radiation, and sensible and latent heat flux distributions have been generated from the surface data using the bulk aerodynamic formulas. In 1979, large-scale patterns of all the climatic and heat budget variables are very similar to distributions determined from long-term climatological averages. Positive anomalies of SST in the region of the equatorial cold water tongue represent some region of systematic differences between the 1979 and climatological distributions. The positive SST anomalies are, in general, coincident with negative anomalies in the net oceanic heat gain. Negative heat gain anomalies are primarily caused by positive wind speed anomalies, through increased latent and sensible heat fluxes.

Molinari, R.L., J.F. Festa, and E. Marmolejo. Evolution of sea-surface temperature in the tropical Atlantic Ocean during FGGE, 1979: Part II. Oceanographic fields and heat balance of the mixed layer. Journal of Marine Research, 43:67-81 (1985).

Surface meteorological and surface and subsurface oceanographic data collected during 1979 are used to describe sea-surface temperature, mixed layer depth, zonal current component, and net oceanic heat gain fields and to estimate the terms in a heat balance relation for the mixed layer. The terms are evaluated monthly on a 6° of latitude by 10° of longitude grid which covers the equatorial Atlantic from 9°S to 9°N. The first balance tested is between changes in mixed layer temperature and surface energy fluxes. These fluxes can account for more than 75% of the variance in the original time series of the quadrangles along 6°S. Variance reductions are less along 10° (order of 50%) and 6°N (less than 25%). The addition of zonal advection improves some of the predictions but not significantly. Low variance reductions along 6°N, west of 20°W, are attributed to the uncertainties in the estimates of observed temperature change and surface fluxes. The small variance reductions east of 20°W, at 6°N and along 0°, may be related to the neglect of coastal and equatorial upwelling and meridional advection. A simple model is proposed which assumes an annual cycle for the intensity of mixing across the base of the mixed layer, most intense during summer, least intense during winter. Variance reductions at 0°, 5°W increase from 20% to 60% with the inclusion of mixing. Meridional advection may also account for a portion of the observed variability in mixed layer temperature.

Molinari, R.L., W.D. Wilson, and K. Leaman. Volume and heat transports of the Florida Current: April 1982 through August 1983. Science, 227(4684):295-297 (1985).

Absolute velocity and temperature profiles are used to estimate the volume transport through the Straits of Florida and, in combination with historical midbasin data, to estimate the total meridional heat flux through a section at 27°N. The mean annual volume transport of the Florida Current from April 1982 through August 1983 is 30.5 (+1) × 10⁶ cubic meters per second. The net northward heat flux through the 27°N section is 1.2 (±0.1) × 10¹⁵ watts. The volume transport is characterized by high values in the late spring and early summer and low values in the late fall and early winter. There is a similar cycle in total heat flux.

Molinari, R.L., G.A. Maul, F. Chew, W.D. Wilson, M.H. Bushnell, D.A. Mayer, K. Leaman, F. Schott, T. Lee, R. Zantopp, J. Larsen, and T. Sanford. Reports: Subtropical Atlantic Climate Studies: Introduction. Science, 227(4684):292-294 (1985).

This report is an introduction to the accompanying collection of reports that present the results of a two-year period of intensive monitoring of the Florida Current. Both direct observing systems (ship-deployed current profilers and moored current meters) and indirect observing systems (coastal tide gauge stations, bottom pressure gauge arrays, a submarine cable, acoustic arrays, and radar installations) were used to measure temperature and volume transport.

Oakley, S.A., I.W. Duedall, J.H. Parker, and J.R. Proni. Continuous measurements of the dispersion of sewage sludge. In Wastes in the Ocean, Volume 6, I.W. Duedall, D.R. Kester, P.K. Parke, and B.H. Ketchum (eds.), Wiley, New York (1985).

No abstract.

Ooyama, K.V. The polar representation of tensor cross-spectra of winds. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, 182-183 (1985).

No abstract.

Palmer, D.R., L.M. Lawson, D.A. Seem, and Y.-H. Daneshzadeh. Ray path identification and acoustic tomography in the Straits of Florida. Journal of Geophysical Research, 90(C3):4977-4989 (1985).

The Florida Current, which flows through the Straits of Florida, transports a significant fraction of the heat which must be transferred from low to high latitudes in order for the earth to remain in thermal balance. While ocean acoustic tomography is an attractive candidate for monitoring this heat transport, its use is dependent on being able to identify individual ray paths. All published investigations of tomography have been concerned with deep-ocean propagation where experience has shown that paths can be identified. Propagation in the Straits is quite different from deep-ocean propagation, however. The sound speed is such that a ray path which travels modest distances necessarily experiences bottom bounces. It is not clear, a priori, that paths can be identified in the Straits. We report the results of an investigation of this question. Using a fast, specialized ray-tracing program, we analyzed the fluctuations in ray path geometry resulting from small perturbations in the bathymetry. We found that the topographic features amplify these fluctuations to such a degree that identification of individual rays becomes impossible after only a few bottom bounces. Consequently, there is no adequate interpretive tool for relating an acoustic signal recorded more than a few tens of kilometers from a source to the heat transport, i.e., for carrying out the tomographic inversion. We propose a way of overcoming this identification problem based on the use of acoustic profilers.

Paul, C.A., and M.C. Pazos. Data for EPOCS/FGGE drifting buoys: February 1979 through October 1980. NOAA Data Report, ERL AOML-4, 157 pp. (1985).

No abstract.

Pazos, M.C., and C.E. Acero. Drifting buoy data from the equatorial Pacific Ocean for the period November 1, 1981 through December 31, 1983. NOAA Data Report, ERL AOML-7, 245 pp. (1985).

No abstract.

Peng, T.-H. Application of box models for geochemical modeling of ocean. Journal of the National Bureau of Standards, 90:530 (1985).

No abstract.

Peng, T.-H. Atmospheric CO₂ variations based on tree ring ¹³C data. In The Carbon Cycle and Atmospheric CO₂: Natural Variations--Archean to Present, E.T. Sundquist and W.S. Broecker (eds.). Geophysical Monograph 32, AGU, 123-131 (1985).

The reconstruction of atmospheric CO₂ concentrations over the last 150 years, based on a deconvolution of the tree-ring-based ¹³C record, is reviewed. Assuming that Freyer's latest composite ¹³C record for the northern hemisphere represents global changes in the ¹³C/¹²C ratio of atmospheric CO₂ induced by changes in atmospheric CO₂ concentration due to deforestation, soil manipulation, and combustion of fossil fuels, the deconvolution, using the modified box-diffusion model, gives the following results: (1) the magnitude of the integrated CO₂ release from the terrestrial biosphere since 1800 is about 90% of that from fossil fuel; (2) over the two-decade period covered by the Mauna Loa atmospheric CO₂ record, the input from the forest-soil source is about 15% of that from fossil fuels; (3) the ¹³C/¹²C trend and the atmospheric CO₂ anomaly over the last two decades have been dominated by the input of fossil fueld CO₂; and (4) the pre-1850 atmospheric CO₂ content is estimated to be about 266 ppm. The integrated amount of CO₂ released from the terrestrial biosphere between A.D. 1800 and 1980 is estimated to be 12 × 10¹⁵ mol which is to be compared with the previous estimate of 22 × 10¹⁵ mol on the basis of Freyer and Belacy's (1983) ¹³C data. This indicates that tree-ring ¹³C-based estimates are volatile and further changes are likely.

Peng, T.-H., and W.S. Broecker. PANDORA: An eleven-box geochemical model of the world ocean. In Carbon Dioxide Transfer in the Atmosphere-Ocean-Terrestrial System, R.S. Keir and W.H. Berger (eds.). Scripps Institution of Oceanography, SIO Reference 85-31, 113-121 (1985).

No abstract.

Peng, T.-H., and W.S. Broecker. The utility of multiple tracer distributions in calibrating models for uptake of anthropogenic CO₂ by the ocean thermocline. Journal of Geophysical Research, 90(C4):7023-7035 (1985).

Two-dimensional thermocline ventilation models for the temperate North Atlantic with differing circulation patterns were calibrated to yield a tritium distribution similar to that observed during the GEOSECS survey. These models were then run for ³He, bomb-produced ¹⁴C, radiokrypton, and freons. They were also run for the uptake of fossil fuel CO₂. While the models differ significantly in their ability to match the observed ³He and ¹⁴C distributions, these differences are not large enough to clearly single out one model as superior. This insensitivity of tracer-to-tracer ratio to model design is reflected by the near identity of the fossil fuel CO₂ uptake by the various models. This result suggests that the uptake of CO₂ by the sea is limited more by the rates of physical mixing within the sea than by gas exchange across the sea surface. If so, then the hope that models employing outcropping isopycnals will enhance the CO₂ uptake by the sea and thereby lead to a narrowing in the gap that exists for anthropogenic CO₂ budgets is not well founded. The interim strategy of using reservoir models calibrated by tracer distributions appears to be sound.

Peterson, D.H., and J.F. Festa. Numerical simulation of phytoplankton productivity in partially mixed estuaries. Estuarine, Coastal, and Shelf Science, 19:563-589 (1985).

A two-dimensional steady-state model of light-driven phytoplankton productivity and biomass in partially mixed estuaries has been developed. Effects of variations in river flow, suspended sediment concentration, phytoplankton sinking, self-shading, and growth rates on distributions of phytoplankton biomass and productivity are investigated. Numerical simulation experiments show that biomass and productivity are particularly sensitive to variations in suspended sediment concentrations typical of natural river sources and to variations in loss rates assumed to be realistic but poorly known for real systems. Changes in the loss rate term within the range of empirical error (such as from dark bottle incubation experiments) cause phytoplankton biomass to change by a factor of two. In estuaries with adequate light pentration in the water column, it could be an advantage for phytoplankton to sink. Species that sink increase their concentration and form a phytoplankton maximum in a way similar to the formation of the estuarine turbidity maximum. When attenuation is severe, however, sinking species have more difficultty in maintaining their population.

Philander, G., D. Halpern, D.V. Hansen, R. Legeckis, L. Miller, C.A. Paul, R. Watts, R. Weisberg, and M. Wimbush. Long waves in the equatorial Pacific Ocean. EOS, Transactions, American Geophysical Union, 66(14):154 (1985).

Westward traveling waves with a period of three weeks and a wavelength of 1000 km appear in the central and eastern equatorial Pacific Ocean during periods of intense trade winds and strong surface currents. Recent measurements of the structure of these waves confirm that they are caused by instabilities associated primarily with the latitudinal shear of the surface currents.

Powell, M.D. Airborne Doppler radar observations of the hurricane boundary layer. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, 3-4 (1985).

No abstract.

Ratnaswamy, M., W.D. Wilson, and R.L. Molinari. Current velocity and hydrographic observations in the Straits of Florida: Subtropical Atlantic Climate Study (STACS), 1983-1984. NOAA Data Report, ERL AOML-5, 242 pp. (1985).

No abstract.

Thompson, O.E., P. Stephens, H.A. Friedman, and D. Houghton. Annual Report, 1984: Commission on Education and Manpower. American Meteorological Society, Boston, Massachusetts (published for limited distribution) (1985).

The various boards and committees of the AMS Commission on Education and Manpower were active during 1984, conducting open meetings in conjunction with the annual AMS meeting and transacting business by telephone and mail. The various recommendations, initiatives, activities, and appointments are briefly summarized in sections B-E of this report. Board annual reports and publications of the commission are included as sections F-G and I-K, respectively.

Trefry, J.H., R.P. Trocine, and J.R. Proni. Drilling-fluid discharges into the northwestern Gulf of Mexico. In Wastes in the Ocean, Volume 4, I.W. Duedall, D.R. Kester, P.K. Park, and B.H. Ketchum (eds.), Wiley, New York, 196-222 (1985).

This chapter investigates the dispersion and fate of drilling-fluid components discharged into the marine environmental with special focus on the Texas Flower Garden Banks (Flower Gardens) area of the northwestern Gulf of Mexico. Particulate Ba was found to be the best overall tracer of drilling-fluid dispersion; however, routine monitoring of raw effluent for dissolved and particulate Cr and Fe, total petroleum hydrocarbons, total solids, and one other representative particulate trace metal (As, Cd, Hg, or Pb) is also recommended. During field experiments, we observed: (1) differential settling of the barite and clay components; (2) that the barite component was less susceptible to resuspensoin than was normal sediment; (3) that natural particle-rich layers can be distinguished from drilling-related lenses; and (4) that the long-term, net directional movement of the released fluids can be established. Near the coral reefs of the Flower Gardens, drilling fluids are presently discharged to within 10 m of the bottom, a depth that is at least 100 m below the sea surface and at least 80 m below the top of the reefs. Resuspension processes, even during storms, do not carry bottom sediment, and thus the deposited matter from drilling fluid, onto the living reef. Although the drilling area to the north has higher than normal concentrations of Ba in the sediment and in the suspended matter of the water column, no drilling-fluid movement from that area to the Flower Gardens was observed. In fact, Observed Ba enrichment in some surficial sediment samples taken 3-10 km away from drilling areas may be due to a natural remobilization process. Drilling-fluid-related increases in sedimentation rate and input of different sediment types at the reef base remain as possible concerns.

Trefry, J.H., S.Metz, R.P. Trocine, and T.A. Nelsen. A decline in lead transport by the Mississippi River. Science, 230(4724):439-441 (1985).

Inputs of pollutant lead to the Gulf of Mexico from the Mississippi River have declined by about 40% within the past decade. This decrease has been determined from annual lead loads of the Mississippi River and from the lead record in Mississippi Delta sediments. The observed trend is consistent with reduced consumption of lead in gasoline in the United States. More than 90% of the riverborne lead is associated with suspended sediments. Most of the particle-bound lead is deposited within 50 km of the river mouth and is easily leached at pH values above 3.

Willis, P.T. Microphysics of a stratiform melting layer in Hurricane Alicia. Preprints, 16th Conference on Hurricanes and Tropical Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 14-15 (1985).

No abstract.

Willis, P.T. Reply. Journal of the Atmospheric Sciences, 42:1349-1350 (1985).

No abstract.

Willis, P.T., and P. Tattleman. Model vertical profiles of extreme rainfall rate, liquid water content, and drop-size distribution. Environmental Research Papers, Air Force Geophysics Laboratory, No. 928, AFGL Technical Report 85-022, Hanscom AFB, MA (1985).

This report provides a new model of hydrometeors and associated cloud-water content from the surface to 20 km. The model profiles at altitude were developed based on five surface rainfall rates: 36, 84, 168, 432, and 1872 mm/hr. The first three rates correspond to a frequency of occurrence of 0.5%, 0.1%, and 0.01% of the time during the worst month in the most severe area of the world for intense rainfall. The last two are the 42- and 1-min world record rainfalls. The surface rainfall rates were extrapolated aloft using results from previous studies. A large sample of drop-size distributions from intense rainfall collected during reconnaissance of Atlantic hurricanes/tropical storms was analyzed. The data set was normalized and fit by a gamma distribution. This was used to specify the drop-size distributions and liquid water content for rainfall rates specified at the surface and aloft. Concurrent cloud-water content was estimated. Results are presented at 2 km intervals.

Willoughby, H.E. Confirmatory observations of concentric eyes in hurricanes. Preprints, 16th Conference on Hurricanes and Meteorology, Houston, TX, May 14-17, 1985. American Meteorological Society, Boston, 1-2 (1985).

No abstract.

Willoughby, H.E., D.P. Jorgensen, R.A. Black, and S.L. Rosenthal. Project STORMFURY: A scientific chronicle, 1962-1983. Bulletin of the American Meteorological Society, 66:505-514 (1985).

Between 1962 and 1983, research in hurricane modification centered on an ambitious experimental program, Project STORMFURY. The proposed modification technique involved artificial stimulation of convection outside the eyewall through seeding with silver iodide. The artificially invigorated convection, it was argued, would compete with the convection in the original eyewall, lead to reformation of the eyewall at larger radius, and thus produce a decrease in the maximum wind. Since a hurricane's destructive potential increases rapidly as its maximum wind becomes stronger, a reduction as small at 10% would have been worthwhile. Modification was attempted in four hurricanes on eight different days. On four of these days, the winds decreased by between 10 and 30%. The lack of response on the other days was interpreted to be the result of fault execution of the experiment or poorly selected subjects. These promising results have, however, come into question because recent observations of unmodified hurricanes indicate: (1) that cloud seeding has little prospect of success because hurricanes contain too much natural ice and too little supercooled water; and (2) that the positive results inferred from the seeding experiments in the 1960s probably stemmed from inability to discriminate between the expected effect of human intervention and the natural behavior of hurricanes.

Wilson, W.D., C. Roffer, and G.G. Thomas. Pegasus current profiler measurements collected for EPOCS, 1980-1983. NOAA Data Report, ERL AOML-6, 178 pp. (1985).

Current velocity profiles recorded on nine AOML EPOCS (Equatorial Pacific Ocean Climate Studies) cruises during 1980-1983 using the Pegasus profiler are presented. The data were collected along several equatorial transects from 85°W to 110°W. Station locations and current profiles are shown for each cruise; the instrument and techniques of data acquisition and processing are also described.