**2010
Abdelzaher, A.M., M.E. Wright, C. Ortega, H.M. Solo-Gabriele, G. Miller, S. Elmir, X. Newman, P. Shih, J.A. Bonilla, T.D. Bonilla, C.J. Palmer, T. Scott, J. Lukasik, V.J. Harwood, S. McQuaig, C. Sinigalliano, M. Gidley, L.R.W. Plano, X. Zhu, J.D. Wang, and L.E. Fleming. Presence of pathogens and indicator microbes at a non-point source subtropical recreational marine beach. Applied and Environmental Microbiology, 76(3):724-732 (2010).
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Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in s ubtropical recreational marine waters impacted by non-point source pollution.
Aberson, S.D. Ten years of hurricane synoptic surveillance (1997-2006). Monthly Weather Review, 138(5):1536-1549 (2010).
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In 1997, the National Hurricane Center and the Hurricane Research Division began operational synoptic surveillance missions with the Gulfstream IV-SP jet aircraft to improve the numerical guidance for hurricanes that threaten the continental United States, Puerto Rico, the U. S. Virgin Islands, and Hawaii. During the first ten years, 176 such missions were conducted. Global Positioning System dropwindsondes were released from the aircraft at 150-200 km intervals along the flight track in the environment of each tropical cyclone to obtain wind, temperature, and humidity profiles from flight level (about 150 hPa) to the surface. The observations were processed and formatted aboard the aircraft and sent to the National Centers for Environmental Prediction and the Global Telecommunications System to be ingested into the Global Forecast System, which serves as initial and boundary conditions for regional numerical models that also forecast tropical cyclone track and intensity. The results of an observing system experiment using these data are presented.
Aberson, S.D., J. Cione, C.-C. Wu, M.M. Bell, J. Halverson, C. Fogarty, and M. Weissmann. Aircraft observations of tropical cyclones. In Global Perspectives on Tropical Cyclones: From Science to Mitigation, J.C.L. Chan and J.D. Kepert (ed.). World Scientific Publishing Company, 2nd edition, 227-240 (2010).
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Nine different types of aircraft are currently in use to observe tropical cyclones and their environments for operations and research. The following is a description of those aircraft, their instrumentation, and the field programs with which they have been involved.
Aksoy, A., D.C. Dowell, and C. Snyder. A multicase comparative assessment of the ensemble Kalman filter for assimilation of radar observations, Part II: Short-range ensemble forecasts. Monthly Weather Review, 138(4):1273-1292 (2010).
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The quality of convective-scale ensemble forecasts, initialized from analysis ensembles obtained through the assimilation of radar observations using an ensemble Kalman filter (EnKF), is investigated for cases whose behaviors span supercellular, linear, and multicellular organization. This work is the companion to Part I, which focused on the quality of analyses during the 60-min analysis period. Here, the focus is on 30-min ensemble forecasts initialized at the end of that period. As in Part I, the Weather Research and Forecasting (WRF) model is employed as a simplified cloud model at 2-km horizontal grid spacing. Various observation-space and state-space verification metrics, computed both for ensemble means and individual ensemble members, are employed to assess the quality of ensemble forecasts comparatively across cases. While the cases exhibit noticeable differences in predictability, the forecast skill in each case, as measured by various metrics, decays on a time scale of tens of minutes. The ensemble spread also increases rapidly but significant outlier members or clustering among members are not encountered. Forecast quality is seen to be influenced to varying degrees by the respective initial soundings. While radar data assimilation is able to partially mitigate some of the negative effects in some situations, the supercell case, in particular, remains difficult to predict even after 60 min of data assimilation.
Ali, M.M., G.J. Goni, and V. Jayaraman. Satellite-derived oceanic heat content improves cyclone predictions. Eos, Transactions, American Geophysical Union, 91(43):396 (doi:10.1029/2010EO430009) (2010).
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No abstract.
Amornthammarong, N., P.B. Ortner, and J.-Z. Zhang. A simple, effective mixing chamber used in conjunction with a syringe pump for flow analysis. Talanta, 81(4-5), 1472-1476 (2010).
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A simple, effective mixing chamber used in conjunction with a syringe pump for flow analysis is described and evaluated. A mixing chamber was constructed using a conventional 5 mL pipette tip and its performance compared with a widely used mixing coil. The results demonstrate that the mixing coil does not rapidly and completely mix solutions. Utilizing a configuration that reversed solution positions in the chamber with each mixing cycle, the proposed mixing chamber achieved complete mixing in a significantly shorter time than the mixing coil. The influence of injected sample volume on absorbance signals was evaluated by calculating an S1/2 value for the system. As tested with a minimal rinse, the system has no discernable carryover. Testing this new approach in our previously described silicate measurement system resulted in a more than twofold improvement in sensitivity.
Aoyoma, M., et al., and J.-Z. Zhang. 2008 inter-laboratory comparison study of a reference material for nutrients in seawater. Meteorological Research Institute, Technical Report No 60, Tsukuba, Japan, 134 pp. (2010).
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Autoclaved natural seawater collected in the North Pacific Ocean was used as a reference material for nutrients in seawater (RMNS) during an inter-laboratory comparison (I/C) study conducted in 2008. This study was a follow-up to previous studies conducted in 2003 and 2006. A set of six samples was distributed to each of 58 laboratories in 15 countries around the globe, and results were returned by 54 of those laboratories (15 countries). The homogeneities of samples used in the 2008 I/C study, based on analyses for three determinants, were improved compared to those of samples used in the 2003 and 2006 I/C studies. Results of these I/C studies indicate that most of the participating laboratories have an analytical technique for nutrients that is sufficient to provide data of high comparability. The differences between reported concentrations from the same laboratories in the 2006 and 2008 I/C studies for the same batch of RMNS indicate that most of the laboratories have been maintaining internal comparability for two years. Thus, with the current high level of performance in the participating laboratories, the use of a common reference material and the adaptation of an internationally accepted nutrient scale system would increase comparability among laboratories worldwide, and the use of a certified reference material would establish traceability. In the 2008 I/C study we observed a problem of non-linearity of the instruments of the participating laboratories similar to that observed among the laboratories in the 2006 I/C study. This problem of non-linearity should be investigated and discussed to improve comparability for the full range of nutrient concentrations. For silicate comparability in particular, we see relatively larger consensus standard deviations than those for nitrate and phosphate.
Arndt, D.S., M.O. Baringer, M. R. Johnson (editors). State of the Climate in 2009. Bulletin of the American Meteorological Society, 91(6):S1-S224 (2010).
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This 20th annual State of the Climate report highlights the climate conditions that characterized 2009, including notable extreme events. In total, 37 Essential Climate Variables are reported to more completely characterize the State of the Climate in 2009.
Atlas, R. Application of remotely sensed wind measurements to ocean surface wind analyses. Proceedings, 2010 International Geoscience and Remote Sensing Symposium (IGARSS), Honolulu, HI, July 25-30, 2010. Institute of Electrical and Electronic Engineers, 3 pp. (2010).
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The assimilation and validation of cross-calibrated, multi-satellite ocean surface wind data is described. The principal data set covers the global ocean for the twenty-two year period from 1987 through 2009 with six-hour and 25-km resolution. This data set is produced by combining all ocean surface wind speed observations from SSM/I, AMSR-E, and TMI, and all ocean surface wind vector observations from QuikSCAT and SeaWinds. An enhanced variational analysis method (VAM) performs quality control and combines these data with available ship and buoy data and ECMWF analyses. The VAM analyses fit the data used very closely and contain small-scale structures not present in operational analyses. Comparisons with withheld observations are also shown to be very good. These data should be extremely useful to atmospheric and oceanic research, and to air-sea interaction studies.
Atlas, R. Impact of satellite surface-wind data on weather prediction. SPIE News, doi:10.1117/2.1201007.003120, 2 pp. (2010).
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Microwave remote sensing of ocean-surface winds from space enables improved quantification of their impact on weather analyses and forecasts.
Atlas, R. Review of observing system simulation experiments to evaluate the potential impact of lidar winds on weather prediction. Proceedings, 2010 International Geoscience and Remote Sensing Symposium (IGARSS), Honolulu, HI, July 25-30, 2010. Institute of Electrical and Electronic Engineers, 4 pp. (2010).
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Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. Extensive OSSEs have been conducted at NASA/GSFC and NOAA/AOML in collaboration with Simpson Weather Associates and operational data assimilation centers over the last 25 years. These OSSEs determined correctly the quantitative potential for several proposed satellite observing systems to improve weather prediction prior to their launch, and evaluated trade-offs in orbits, coverage, and accuracy for space-based wind lidars. In this paper, we summarize OSSE methodology and present results from OSSEs to assess the potential impact of lidar winds.
Atlas, R., R.N. Hoffman, S.M. Leidner, and J. Ardizzone. Impact of satellite surface wind observations on ocean surface wind analyses and numerical weather prediction. Proceedings, SPIE Optical Engineering and Applications Conference, August 1-5, 2010, San Diego, CA. International Society of Optical Engineering, 8 pp. (2010).
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Since the 1970s, an extensive series of data impact studies has been performed to evaluate and enhance the impact of satellite surface wind data on ocean surface wind analyses and fluxes, atmospheric and oceanic modeling, and weather prediction. These studies led to the first beneficial impacts of scatterometer winds on numerical weather prediction (NWP), the development of the methodology to assimilate surface wind speeds derived from passive microwave radiometry, and the operational use of satellite surface winds by marine forecasters and NWP models. In recent years, the impact of these data on NWP has decreased as more competing data have become available; however, the results of our recent experiments still show a very significant impact of satellite surface winds on ocean surface wind analyses and on the prediction of selected storms over the oceans.
Baringer, M.O., T.O. Kanzow, C.S. Meinen, S.A. Cunningham, D. Rayner, W.E. Johns, H.L. Bryden, J. J.-M. Hirschi, L.M. Beal, and J. Marotzke. The meridional overturning circulation. In State of the Climate in 2009, D.S. Arndt, M.O. Baringer, and M.R. Johnson (eds.). Bulletin of the American Meteorological Society, 91(6):66-69 (2010).
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No abstract.
Bell, G.D., E.S. Blake, T.B. Kimberlain, C.W. Landsea, R.J. Pasch, J. Schemm, and S.B. Goldenberg. Atlantic basin. In State of the Climate in 2009, D.S. Arndt, M.O. Baringer, and M.R. Johnson (eds.). Bulletin of the American Meteorological Society, 91(6):84-88 (2010).
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No abstract.
Bell, M.M., and M.T. Montgomery. Sheared deep vortical convection in pre-depression Hagupit during TCS08. Geophysical Research Letters, 37(6):L06802, doi:10.1029/2009GL042313 (2010).
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Airborne Doppler radar observations from the recent Tropical Cyclone Structure 2008 (TCS08) field campaign in the western North Pacific reveal the presence of deep, buoyant and vortical convective features within a vertically-sheared, westward-moving pre-depression disturbance that later developed into Typhoon Hagupit. On two consecutive days, the observations document tilted, vertically coherent precipitation, vorticity, and updraft structures in response to the complex shearing flows impinging on and occurring within the disturbance near 18 north latitude. The observations and analyses herein suggest that the low-level circulation of the pre-depression disturbance was enhanced by the coupling of the low-level vorticity and convergence in these deep convective structures on the meso-gamma scale, consistent with recent idealized studies using cloud-representing numerical weather prediction models. Further examination of these new observations is needed to quantify the relative role of these vortical convection features in the tropical cyclone spin up process.
Beron-Vera, F.J., M.J. Olascoaga, and G.J. Goni. Surface ocean mixing inferred from different multisatellite altimetry measurements. Journal of Physical Oceanography, 40(11):2466-2480 (doi:10.1175/2010JPO4458.1) (2010).
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Two sea surface height (SSH) anomaly fields distributed by Archiving, Validation, and Interpretation of Satellite Oceanographic (AVISO) altimetry are evaluated in terms of the effects that they produce on mixing. One SSH anomaly field, tagged REF, is constructed using measurements made by two satellite altimeters; the other SSH anomaly field, tagged UPD, is constructed using measurements made by up to four satellite altimeters. Advection is supplied by surface geostrophic currents derived from the total SSH fields resulting from the addition of these SSH anomaly fields to a mean SSH field. Emphasis is placed on the extraction from the currents of Lagrangian coherent structures (LCSs), which, acting as skeletons for patterns formed by passively advected tracers, entirely control mixing. The diagnostic tool employed to detect LCSs is provided by the computation of finite-time Lyapunov exponents. It is found that currents inferred using UPD SSH anomalies support mixing with characteristics similar to those of mixing produced by currents inferred using REF SSH anomalies. This result mainly follows from the fact that, being more easily characterized as chaotic than turbulent, mixing as sustained by currents derived using UPD SSH anomalies is quite insensitive to spatiotemporal truncations of the advection field.
Borges, A.V., S.R. Alin, F.P. Chavez, P. Vlahos, K.S. Johnson, J.T. Holt, W.M. Balch, N. Bates, R. Brainard, W.-J. Cai, C.T.A. Chen, K. Currie, M. Dai, M. DeGrandpre, B. Delille, A. Dickson, W. Evans, R.A. Feely, G.E. Friederich, G.-C. Gong, B. Hales, N. Hardman-Mountford, J. Hendee, J.M. Hernandez-Ayon, M. Hood, E. Huertas, D. Hydes, D. Ianson, E. Krasakopoulou, E. Litt, A. Luchetta, J. Mathis, W.R. McGillis, A. Murata, J. Newton, J. Olafsson, A. Omar, F.F. Perez, C. Sabine, J.E. Salisbury, R. Salm, V.V.S.S. Sarma, B. Schneider, M. Sigler, H. Thomas, D. Turk, D. Vandemark, R. Wanninkhof, and B. Ward. A global sea surface carbon observing system: Inorganic and organic carbon dynamics in coastal oceans. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 20 pp. (2010).
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Coastal environments are an important component of the global carbon cycle, and probably more vulnerable than the open ocean to anthropogenic forcings. Due to strong spatial heterogeneity and temporal variability, carbon flows in coastal environments are poorly constrained. Hence, an integrated, international, and interdisciplinary program of ship-based hydrography, Voluntary Observing Ship (VOS) lines, time-series moorings, floats, gliders, and autonomous surface vessels with sensors for pCO2 and ancillary variables are recommended to better understand present day carbon cycle dynamics, quantify air-sea CO2 fluxes, and determine future long-term trends of CO2 in response to global change forcings (changes in river inputs, in the hydrological cycle, in circulation, sea-ice retreat, expanding oxygen minimum zones, ocean acidification, ) in the coastal oceans. Integration at the international level is also required for data archiving, management, and synthesis that will require multi-scale approaches including the development of biogeochemical models and use of remotely sensed parameters. The total cost of these observational efforts is estimated at about 50 million U.S. dollars per year.
Bourassa, M.A., A. Stoffelen, H. Bonekamp, P. Chang, D.B. Chelton, J. Courtney, R. Edson, J. Figa, Y. He, H. Hersbach, K. Hilburn, Z. Jelenak, K.A. Kelly, R. Knabb, T. Lee, E.J. Lindstrom, W.T. Liu, D.G. Long, W. Perrie, M. Portabella, M.D. Powell, E. Rodriguez, D.K. Smith, V. Swail, and F.J. Wentz. Remotely sensed winds and wind stresses for marine forecasting and ocean modeling. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 17 pp. (2010).
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No abstract.
Brainard, R.E., D. Butterfield, M. Eakin, R.A. Feely, D.K. Gledhill, E. Kehn, K. Shamberger, A.J. Sutton, O. Vetter, and C. Young. Pacific Islands region ocean acidification research implementation plan, pp. 59-76. In NOAA Ocean and Great Lakes Acidification Research and Implementation Plan, A.J. Sutton (ed.). NOAA Special Report, 143 pp. (2010).
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No abstract.
Brainard, R.E., S. Bainbridge, R. Brinkman, C.M. Eakin, M. Field, J.-P. Gattuso, D. Gledhill, L. Gramer, A. Green, J. Hendee, R.K. Hoeke, S.J. Holbrook, O. Hoegh-Guldberg, M. Lammers, D. Manzello, M. McManus, R. Moffitt, M. Monaco, J.A. Morgan, D. Obura, S. Planes, R.J. Schmitt, C. Steinberg, H. Sweatman, O.J. Vetter, C. Wilkinson, and K.B. Wong. An international network of coral reef ecosystem observing systems (I-CREOS). In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 15 pp. (2010).
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Coral reefs are complex, biologically diverse, and highly valued ecosystems that are declining worldwide due to climate change and ocean acidification, overfishing, land-based sources of pollution, and other anthropogenic threats. To assist policymakers and resource managers at international, national, and local levels in effectively implementing ecosystem approaches to sustainable management and conservation of coral reefs and their biodiversity, it is necessary to have timely, unbiased integrated ecosystem observations about the conditions of coral reefs and the complex physical and biogeochemical processes supporting them. To provide these interdisciplinary ecosystem observations, an International network of Coral Reef Ecosystem Observing Systems (I-CREOS) is proposed that will organize and build upon existing coral reef observation systems being developed around the globe. This paper uses examples of some developing observation systems to demonstrate some of the approaches and technologies available for acquiring biological, physical, and geochemical observations using combinations of visual surveys, moored instrument arrays, spatial-hydrographic and water quality surveys, satellite remote sensing, and hydrodynamic and ecosystem modeling. This fledgling, and hopefully expanding, network of observing systems represents the early stages of an integrated ecosystem observing system for coral reefs capable of providing policymakers, resource managers, researchers, and other stakeholders with essential information products needed to assess various responses of coral reef ecosystems to natural variability and anthropogenic perturbations. While significant challenges and gaps in the I-CREOS network remain, it demonstrably fulfills the requirements of an operational, integrated, interdisciplinary, coastal component of GOOS. Continued support, further development, and open expansion of this emerging network are encouraged and needed to ensure the continually increasing value of the networks observational and predictive capacity. With common goals to maximize versatility, accessibility, and robustness, the existing infrastructure and capacity provide a foundation by which increased global cooperation and coordination could naturally lead to a globally comprehensive I-CREOS.
Brandt, P., V. Hormann, A. Kortzinger, M. Visbeck, G. Krahmann, L. Stramma, R. Lumpkin, and C. Schmid. Changes in the ventilation of the oxygen minimum zone of the tropical North Atlantic. Journal of Physical Oceanography, 40(8):1784-1801 (2010).
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Changes in the ventilation of the oxygen minimum zone (OMZ) of the tropical North Atlantic are studied using oceanographic data from 18 research cruises carried out between 28.5° and 23°W during 1999-2008 as well as historical data referring to the period 1972-85. In the core of the OMZ at about 400-m depth, a highly significant oxygen decrease of about 15 µmol kg-1 is found between the two periods. During the same time interval, the salinity at the oxygen minimum increased by about 0.1. Above the core of the OMZ, within the central water layer, oxygen decreased too, but salinity changed only slightly or even decreased. The scatter in the local oxygen-salinity relations decreased from the earlier to the later period, suggesting a reduced filamentation due to mesoscale eddies and/or zonal jets acting on the background gradients. Here it is suggested that latitudinally alternating zonal jets with observed amplitudes of a few centimeters per second in the depth range of the OMZ contribute to the ventilation of the OMZ. A conceptual model of the ventilation of the OMZ is used to corroborate the hypothesis that changes in the strength of zonal jets affect mean oxygen levels in the OMZ. According to the model, a weakening of zonal jets, which is in general agreement with observed hydrographic evidences, is associated with a reduction of the mean oxygen levels that could significantly contribute to the observed deoxygenation of the North Atlantic OMZ.
Braun, S.A., M.T. Montgomery, K.J. Mallen, and P.D. Reasor. Simulation and interpretation of the genesis of Tropical Storm Gert (2005) as part of the NASA Tropical Cloud Systems and Processes Experiment. Journal of the Atmospheric Sciences, 67(4):999-1025 (2010).
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Several hypotheses have been put forward for the mechanisms of generation of surface circulation associated with tropical cyclones. This paper examines high-resolution simulations of Tropical Storm Gert (2005), which formed in the Gulf of Mexico during NASAs Tropical Cloud Systems and Processes Experiment, to investigate the development of low-level circulation and its relationship to the precipitation evolution. Two simulations are examined: one that better matches available observations but underpredicts the storms minimum sea level pressure and a second one that somewhat overintensifies the storm but provides a set of simulations that encapsulates the overall genesis and development characteristics of the observed storm. The roles of convective and stratiform precipitation processes within the mesoscale precipitation systems that formed Gert are discussed. During 21-25 July, two episodes of convective system development occurred. In each, precipitation system evolution was characterized by intense and deep convective upward motions followed by increasing stratiform-type vertical motions (upper-level ascent, low-level descent). Potential vorticity (PV) in convective regions was strongest at low levels while stratiform-region PV was strongest at midlevels, suggesting that convective processes acted to spin up lower levels prior to the spinup of middle levels by stratiform processes. Intense vortical hot towers (VHTs) were prominent features of the low-level cyclonic vorticity field. The most prominent PV anomalies persisted more than 6 h and were often associated with localized minima in the sea level pressure field. A gradual aggregation of the cyclonic PV occurred as existing VHTs near the center continually merged with new VHTs, gradually increasing the mean vorticity near the center. Nearly concurrently with this VHT-induced development, stratiform precipitation processes strongly enhanced the mean inflow and convergence at middle levels, rapidly increasing the midlevel vorticity. However, the stratiform vertical motion profile is such that while it increases midlevel vorticity, it decreases vorticity near the surface as a result of low-level divergence. Consequently, the results suggest that while stratiform precipitation regions may significantly increase cyclonic circulation at midlevels, convective vortex enhancement at low to mid levels is likely necessary for genesis.
Bunya, S., J.C. Dietrich, J.J. Westerink, B.A. Ebersole, J.M. Smith, J.H. Atkinson, R. Jensen, D.T. Resio, R.A. Luettich, C. Dawson, V.J. Cardone, A.T. Cox, M.D. Powell, H.J. Westerink, and H.J. Roberts. A high-resolution coupled riverine flow, tide, wind, wind wave, and storm surge model for southern Louisiana and Mississippi, Part I: Model development and validation. Monthly Weather Review, 138(2):345-377 (2010).
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A coupled system of wind, wind wave, and coastal circulation models has been implemented for southern Louisiana and Mississippi to simulate riverine flows, tides, wind waves, and hurricane storm surge in the region. The system combines the NOAA Hurricane Research Division Wind Analysis System (H*WIND) and the Interactive Objective Kinematic Analysis (IOKA) kinematic wind analyses, the Wave Model (WAM) offshore and Steady-State Irregular Wave (STWAVE) nearshore wind wave models, and the Advanced Circulation (ADCIRC) basin to channel-scale unstructured grid circulation model. The system emphasizes a high-resolution (down to 50 m) representation of the geometry, bathymetry, and topography; nonlinear coupling of all processes including wind wave radiation stress-induced set up; and objective specification of frictional parameters based on land-cover databases and commonly used parameters. Riverine flows and tides are validated for no storm conditions, while winds, wind waves, hydrographs, and high water marks are validated for Hurricanes Katrina and Rita.
Cai, W.-J., X. Hu, W.-J. Huang, L.-Q. Jiang, Y. Wang, T.-H. Peng, and X. Zhang. Alkalinity distribution in the western North Atlantic Ocean margins. Journal of Geophysical Research, 115:C08014, doi:10.1029/2009JC005482, 15 pp. (2010).
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Total alkalinity (TA) distribution and its relationship with salinity (S) along the western North Atlantic Ocean (wNAO) margins from the Labrador Sea to tropical areas are examined in this study. Based on the observed TA-S patterns, the mixing processes that control alkalinity distribution in these areas can be categorized into a spectrum of patterns that are bracketed by two extreme mixing types, i.e., alongshore current-dominated and river-dominated. Alongshore current-dominated mixing processes exhibit a segmented mixing line with a shared mid-salinity end-member. In such cases (i.e., Labrador Sea, Gulf of Maine, etc.), the y-intercept of the high salinity segment of the mixing line is generally higher than the local river alkalinity values, and it reflects the mixing history of the alongshore current. In contrast, in river-dominated mixing (Amazon River, Caribbean Sea, etc.), good linear relationships between alkalinity and salinity are generally observed, and the zero salinity intercepts of the TA-S regressions roughly match those of the regional river alkalinity values. TA-S mixing lines can be complicated by rapid changes in the river end-member value and by another river nearby with a different TA value (e.g., Mississippi-Atchafalaya/Gulf of Mexico). In the wNAO margins, regression intercepts and river end-members have a clear latitudinal distribution pattern, increasing from a low of ~300 µmol kg-1 in the Amazon River plume to a high value between ~500-1100 µmol kg-1 in the middle and high latitude margins. The highest value of ~2400 µmol kg is observed in the Mississippi River influenced areas. In addition to mixing control, biological processes such as calcification and benthic alkalinity production may also affect ocean margin alkalinity distribution. Therefore, deriving inorganic carbon system information in coastal oceans using alkalinity-salinity relationships, in particular, those of generic nature, may lead to significant errors.
Cai, W.-J., L. Chen, B. Chen, Z. Gao, S.-H. Lee, J. Chen, D. Pierrot, K. Sullivan, Y. Wang, X. Hu, W.-J. Huang, Y. Zhang, S. Xu, A. Murata, J.M. Grebmeier, E.P. Jones, and H. Zhang. Decrease in the CO2 uptake capacity in an ice-free Arctic Ocean basin. Science, 329(5991):556-559 (2010).
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It has been predicted that the Arctic Ocean will sequester much greater amounts of carbon dioxide (CO2) from the atmosphere as a result of sea ice melt and increasing primary productivity. However, this prediction was made on the basis of observations from either highly productive ocean margins or ice-covered basins before the recent major ice retreat. We report here a high-resolution survey of sea-surface CO2 concentration across the Canada Basin, showing a great increase relative to earlier observations. Rapid CO2 invasion from the atmosphere and low biological CO2 drawdown are the main causes for the higher CO2, which also acts as a barrier to further CO2 invasion. Contrary to the current view, we predict that the Arctic Ocean basin will not become a large atmospheric CO2 sink under ice-free conditions.
Carsey, T.P., H. Casanova, C. Drayer, C. Featherstone, C. Fischer, K. Goodwin, J. Proni, A. Saied, C. Sinigalliano, J. Stamates, P. Swart, and J.-Z. Zhang. FACE outfalls survey cruise: October 6-19, 2006. NOAA Technical Report, OAR AOML-38, 130 pp. (CD-ROM) (2010).
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In October 2006, a cruise of the Florida Area Coastal Environment (FACE) program was conducted aboard the NOAA RV Nancy Foster. The cruise visited coastal sites in the vicinity of six treated wastewater boils in south Florida. The outfalls included in this study were those for the South Central, Boca Raton, Broward, Hollywood, Miami-Dade North, and Miami-Dade Central wastewater treatment plants. The boils and associated down-current plumes were studied to produce a data set of ocean currents, ocean chemistry, and microbiology. Seawater was analyzed for nitrate + nitrite, nitrite, ammonia, orthophosphate, and silicate. Samples down-current of each boil were collected by a conductivity-temperature-depth (CTD) rosette at three depths--near-surface, mid-depth, and near-bottom--and from three transects--inshore of the boil, approximately in line with the boil, and further offshore of the boil. Overall, surface samples showed the highest nutrient concentrations versus samples taken at other depths; surface samples taken nearest the boil showed the highest nutrient concentrations in comparison to other samples collected in the vicinity of the outfall. The only exception was Si, which had a maximum observed concentration at an inlet sampling site. The outfall plume was found to be dynamic, irregular, and mainly in the upper 10 m of the water column. Samples were analyzed for a variety of microbes; the detection frequency was higher for the southern boils compared to the northern boils. The CTD data indicated a tendency toward better defined and deeper thermoclines at the 20-30 m depth in the deeper (more offshore) casts; the thermocline showed a tendency to shoal at 10-20 m and become less well defined in more inshore casts.
Coddington, O.M., P. Pilewskie, J. Redemann, S. Platnick, P.B. Russell, K.S. Schmidt, W.J. Gore, J. Livingston, G. Wind, and T. Vukicevic. Examining the impact of overlying aerosols on the retrieval of cloud optical properties from passive remote sensing. Journal of Geophysical Research, 115:D10211, doi:10.1029/2009JD012829 (2010).
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Haywood et al. (2004) showed that an aerosol layer above a cloud can cause a bias in the retrieved cloud optical thickness and effective radius. Monitoring for this potential bias is difficult because space-based passive remote sensing cannot unambiguously detect or characterize aerosol above cloud. We show that cloud retrievals from aircraft measurements above cloud and below an overlying aerosol layer are a means to test this bias. The data were collected during the Intercontinental Chemical Transport Experiment (INTEX-A) study based out of Portsmouth, New Hampshire, United States, above extensive, marine stratus cloud banks affected by industrial outflow. Solar Spectral Flux Radiometer (SSFR) irradiance measurements taken along a lower level flight leg above cloud and below aerosol were unaffected by the overlying aerosol. Along upper level flight legs, the irradiance reflected from cloud top was transmitted through an aerosol layer. We compare SSFR cloud retrievals from below-aerosol legs to satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) in order to detect an aerosol-induced bias. In regions of small variation in cloud properties, we find that SSFR and MODIS-retrieved cloud optical thickness compares within the uncertainty range for each instrument while SSFR effective radius tend to be smaller than MODIS values (by 1-2 µ) and at the low end of MODIS uncertainty estimates. In regions of large variation in cloud properties, differences in SSFR and MODIS-retrieved cloud optical thickness and effective radius can reach values of 10 and 10 µm, respectively. We include aerosols in forward modeling to test the sensitivity of SSFR cloud retrievals to overlying aerosol layers. We find an overlying absorbing aerosol layer biases SSFR cloud retrievals to smaller effective radii and optical thickness while nonabsorbing aerosols had no impact.
Conzemius, R.J., and M.T. Montgomery. Mesoscale convective vortices in multiscale, idealized simulations: Dependence on background state, interdependency with moist baroclinic cyclones, and comparison with BAMEX observations. Monthly Weather Review, 138(4):1119-1139 (2010).
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A set of multiscale, nested, idealized numerical simulations of mesoscale convective systems (MCSs) and mesoscale convective vortices (MCVs) was conducted. The purpose of these simulations was to investigate the dependence of MCV development and evolution on background conditions and to explore the relationship between MCVs and larger, moist baroclinic cyclones. In all experiments, no mesoscale convective system (MCS) developed until a larger-scale, moist baroclinic system with surface pressure amplitude of at least 2 hPa was present. The convective system then enhanced the development of the moist baroclinic system by its diabatic production of eddy available potential energy (APE), which led to the enhanced baroclinic conversion of basic-state APE to eddy APE. The most rapid potential vorticity (PV) development occurred in and just behind the leading convective line. The entire system grew upscale with time as the newly created PV rotated cyclonically around a common center as the leading convective line continued to expand outward. Ten hours after the initiation of deep moist convection, the simulated MCV radii, heights of maximum winds, tangential velocity, and shear corresponded reasonably well to their counterparts in BAMEX. The increasing strength of the simulated MCVs with respect to larger values of background CAPE and shear supports the hypothesis that as long as convection is present, CAPE and shear both add to the strength of the MCV.
Cunningham, S., M. Baringer, W. Johns, J. Toole, S. Osterhus, J. Fischer, A. Piola, E. McDonagh, S. Lozier, U. Send, T. Kanzow, J. Marotzke, M. Rhein, S. Garzoli, S. Rintoul, B. Sloyan, S. Speich, L. Talley, J. Baehr, C. Meinen, A.-M. Treguier, and P. Lherminier. The present and future system for measuring the Atlantic Meridionnal Overturning circulation and heat transport. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 16 pp. (2010).
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The Atlantic Ocean circulation redistributes up to 25% of the global combined atmosphere-ocean heat flux and so is important for the mean climate of the Atlantic sector of the Northern Hemisphere. This meridional heat flux is accomplished by both the Atlantic Meridional Overturning Circulation (AMOC) and by basin-wide horizontal gyre circulations. In the North Atlantic subtropical latitudes the AMOC dominates the meridional heat flux, while in subpolar latitudes and in the subtropical South Atlantic the gyre circulations are also important. Climate models suggest the AMOC will slow over the coming decades as the earth warms, causing widespread cooling in the Northern hemisphere and additional sea-level rise. Monitoring systems for selected components of the AMOC have been in place in some areas for decades, nevertheless the present observational network provides only a partial view of the AMOC, and does not unambiguously resolve the full variability of the circulation. Additional observations, building on existing measurements, are required to more completely quantify the Atlantic meridional heat transport. A basin-wide monitoring array along 26.5°N has been continuously measuring the strength and vertical structure of the AMOC and meridional heat transport since March 31, 2004. The array has demonstrated its ability to observe the AMOC variability at that latitude and also a variety of surprising variability that will require substantially longer time series to understand fully. Here we propose monitoring the Atlantic meridional heat transport throughout the Atlantic at selected critical latitudes that have already been identified as regions of interest for the study of deep water formation and the strength of the subpolar gyre, transport variability of the Deep Western Boundary Current (DWBC) as well as the upper limb of the AMOC, and inter-ocean and intrabasin exchanges with the ultimate goal of determining regional and global controls for the AMOC in the North and South Atlantic Oceans. These new arrays will continuously measure the full depth, basin-wide or choke-point circulation and heat transport at a number of latitudes, to establish the dynamics and variability at each latitude and then their meridional connectivity. Modeling studies indicate that adaptations of the 26.5°N type of array may provide successful AMOC monitoring at other latitudes. However, further analysis and the development of new technologies will be needed to optimize cost effective systems for providing long term monitoring and data recovery at climate time scales. These arrays will provide benchmark observations of the AMOC that are fundamental for assimilation, initialization, and the verification of coupled hindcast/forecast climate models.
Diaz, M.R., J.W. Jacobson, K.D. Goodwin, S.A. Dunbar, and J.W. Fell. Molecular detection of harmful algal blooms (HABs) using locked nucleic acids and bead array technology. Limnology and Oceanography: Methods, 8:269-284 (2010).
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Harmful algal blooms (HABs) are a serious public health risk in coastal waters. As the intensity and frequency of HABs continue to rise, new methods of detection are needed for reliable identification. Herein, we developed a high-throughput, multiplex, bead array technique for the detection of the dinoflagellates Karenia brevis and Karenia mikimotoi. The method combined the Luminex detection system with two novel technologies: locked nucleic acidmodified oligonucleotides (LNA) and Mirus Label IT nucleic acid technology. To study the feasibility of the method, we evaluated the performance of modified and unmodified LNA probes with amplicon targets that were biotin labeled with two different strategies: direct chemical labeling (Mirus Label IT) versus enzymatic end-labeling (single biotinylated primer). The results illustrated that LNA probes hybridized to complementary single-stranded DNA with better affinity and displayed higher fluorescence intensities than unmodified oligonucleotide DNA probes. The latter effect was more pronounced when the assay was carried out at temperatures above 53°C degree. As opposed to the enzymatic 5' terminal labeling technique, the chemical labeling method enhanced the level of fluorescence by as much as ~83%. The detection limits of the assay, which were established with LNA probes and the Mirus Label IT system, ranged from 0.05 to 46 copies of rRNA. This high-throughput method, which represents the first molecular detection strategy to integrate Luminex technology with LNA probes and Mirus Label IT, can be adapted for the detection of other HABs and is well suited for the monitoring of red tides at pre-blooming and blooming conditions.
Dietrich, J.C., S. Bunya, J.J. Westerink, B.A. Ebersole, J.M. Smith, J.H. Atkinson, R. Jensen, D.T. Resio, R.A. Luettich, C. Dawson, V.J. Cardone, A.T. Cox, M.D. Powell, H.J. Westerink, and H.J. Roberts. A high-resolution coupled riverine flow, tide, wind, wind wave, and storm surge model for southern Louisiana and Mississippi, Part II: Synoptic description and analysis of Hurricanes Katrina and Rita. Monthly Weather Review, 138(2):378-404 (2010).
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Hurricanes Katrina and Rita were powerful storms that impacted southern Louisiana and Mississippi during the 2005 hurricane season. In Part I, the authors describe and validate a high-resolution coupled riverine flow, tide, wind, wave, and storm surge model for this region. Herein, the model is used to examine the evolution of these hurricanes in more detail. Synoptic histories show how storm tracks, winds, and waves interacted with the topography, the protruding Mississippi River delta, eastwest shorelines, manmade structures, and low-lying marshes to develop and propagate storm surge. Perturbations of the model, in which the waves are not included, show the proportional importance of the wave radiation stress gradient induced setup.
Di Nezio, P.N., and G.J. Goni. Identifying and estimating biases between XBT and Argo observations using satellite altimetry. Journal of Atmospheric and Oceanic Technology, 27(1):226-240 (2010).
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A methodology is developed to identify and estimate systematic biases between expendable bathythermograph (XBT) and Argo observations using satellite altimetry. Pseudoclimatological fields of isotherm depth are computed by least squares adjustment of in situ XBT and Argo data to altimetry-derived sea height anomaly (SHA) data. In regions where the correlations between isotherm depth and SHA are high, this method reduces sampling biases in the in situ observations by taking advantage of the high temporal and spatial resolution of satellite observations. Temperature profiles from deep XBTs corrected for a bias identified and adopted during the 1990s are considered in this study. The analysis shows that the pseudoclimatological isotherm depths derived from these corrected XBTs are predominantly deeper than the Argo-derived estimates during the 2000-2007 period. The XBT-minus-Argo differences increase with depth consistent with hypothesized problems in the XBT fall-rate equation. The depth-dependent XBT-minus-Argo differences suggest a global positive bias of 3% of the XBT depths. The fact that this 3% error is robust among the different ocean basins provides evidence for changes in the instrumentation, such as changes in the terminal velocity of the XBTs. The value of this error is about the inverse of the correction to the XBT fall-rate equation (FRE) implemented in 1995, suggesting that this correction, while adequate during the 1990s, is no longer appropriate and could be the source of the 3% error. This result suggests that for 2000-2007, the XBT dataset can be brought to consistency with Argo by using the original FRE coefficients without the 1995 correction.
Di Nezio, P.N., A.C. Clement, and G.A. Vecchi. Reconciling differing views of tropical Pacific climate change. Eos, Transactions, American Geophysical Union, 91(16):141-142 (2010).
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No abstract.
Dohan, K., F. Bonjean, L. Centurioni, M. Cronin, G. Lagerloef, D.-K. Lee, R. Lumpkin, N.A. Maximenko, P.P. Niiler, and H. Uchida. Measuring the global ocean surface circulation with satellite and in situ observations. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 14 pp. (2010).
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In the past two decades, the Global Drifter Program (GDP), satellite altimeter missions, precise gravity models and radiometer and scatterometer winds, have provided a detailed resolution of the global sea surface velocity (SSV) and its variability. Out of these has emerged a detailed, unprecedented, description of the surface circulation (calibrated to 15 m depth), including formerly unknown zonal features and an updated global mean dynamic topography. Using the GDP, along with long time series current meter moorings and numerous ship acoustic Doppler current profiler (ADCP) sections for calibration and validation, we can now resolve the spatial and temporal variability of the global surface currents from satellite sea surface topography and vector wind measurements. This record extends from 1993 to present and provides key dynamical insights into the tropical dynamics of ENSO and extra-tropical variations on intra-seasonal to decadal time scales. Beyond the basic oceanographic and climate research applications, the data are useful to marine applications (shipping, fishing, ocean yachting, search and rescue, pollution monitoring, etc.) This paper describes the state of the observing system, data quality and principal scientific insights during the last decade. The synergy of the satellite and in situ components of this observing system has been essential for resolving the circulation on a global synoptic basis. The future observing system requires at a minimum the continuation of these key components. The OceanObs99 GDP requirements (one measurement per month per 5 x 5 degrees) are reviewed for adequacy to define the mean circulation, seasonal to inter-annual variability, calibrate satellite SSV, resolve eddy kinetic energy, coastal processes, and deploying ancillary sensors for surface salinity and PCO2.
Dong, S., S.T. Gille, J. Sprintall, and E.J. Fetzer. Assessing the potential of the Atmospheric Infrared Sounder (AIRS) surface temperature and specific humidity in turbulent heat flux estimates in the Southern Ocean. Journal of Geophysical Research, 115(C5):C05013, doi:10.1029/2009JC005542 (2010).
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Surface air temperature (TA), sea surface temperature (TO), and surface specific humidity (qa) satellite retrievals from the Atmospheric Infrared Sounder (AIRS) are compared with shipboard measurements across Drake Passage for the period from September 2002 to June 2007. The objective is to evaluate whether AIRS retrievals, in conjunction with microwave sea surface temperatures from the Advanced Microwave Scanning Radiometer (AMSRE), can provide sufficiently accurate parameters to estimate sensible and latent heat fluxes in the data-limited Southern Ocean. The collocated data show that both AIRS TA and TO are colder than those from shipboard measurements, with a time mean bias of -2.03°C for TA and -0.22°C for TO. Results show that air-sea temperature difference (TA - TO), qa, and relative humidity (RH) are the major factors contributing to the differences between satellite and shipboard temperature measurements. Differences in AIRS and shipboard TA (DELTA TA) decrease with increasing TA - TO, and DELTA TA increases with increasing RH, whereas differences in AIRS and shipboard TO (DELTA TO) increase with both increasing TA - TO and increasing qa. The time mean qa from AIRS is lower than the shipboard qa by 0.69 g/kg. Statistical analyses suggest that TA - TO, cloud, and qa are the major contributors to the qa difference (DELTA qa). DELTA qa becomes more negative with increasing TA - TO and increasing cloud fraction. DELTA qa also becomes more negative as qa increases. Compared with TA, TO, and TA - TO, from the National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis (NCEP), AIRS-derived and AMSRE-derived variables show more small-scale spatial structure, as is also typical of the ship observations. Although AIRS qa gives a better representation of the full range of values of shipboard qa, its deviation from shipboard qa is relatively large compared to NCEP qa. Compared with several existing gridded flux products, turbulent fluxes estimated from AIRS and AMSRE data using bulk algorithms are better able to represent the full range of flux values estimated from shipboard parameters.
Eakin, C.M., C.J. Nim, R.E. Brainard, C. Aubrecht, C. Elvidge, D.K. Gledhill, F. Muller-Karger, P.J. Mumby,W.J. Skirving, A.E. Strong, M. Wang, S. Weeks, F. Wentz, and D. Ziskin. Monitoring coral reefs from space. Oceanography, 23(4):118-133 (2010).
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Coral reefs are one of the world's most biologically diverse and productive ecosystems. However, these valuable resources are highly threatened by human activities. Satellite remotely-sensed observations enhance our understanding of coral reefs and some of the threats facing them by providing global spatial and time-series data on reef habitats and the environmental conditions influencing them in near-real time. This review highlights many of the ways in which satellites are currently used to monitor coral reefs and their threats, and provides a look toward future needs and capabilities.
Eakin, C.M., J.A. Morgan, S.F. Heron, T.B. Smith, G. Liu, L. Alvarez-Filip, B. Baca, E. Bartels, C. Bastidas, C. Bouchon, M. Brandt, A.W. Bruckner, L. Bunkley-Williams, A. Cameron, B.D. Causey, M. Chiappone, T.R.L. Christensen, M.J.C. Crabbe, O. Day, E. de la Guardia, G. Diaz-Pulido, D. DiResta, D.L. Gil-Agudelo, D.S. Gilliam, R.N. Ginsburg, S. Gore, H.M. Guzman, J.C. Hendee, et al. Caribbean corals in crisis: Record thermal stress, bleaching, and mortality in 2005. PloS ONE, 5(11):e13969 (doi:10.1371/journal.pone.0013969) (2010).
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The rising temperature of the worlds oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watchs Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.
Elipot, S., R. Lumpkin, and G. Prieto. Modifications of inertial oscillations by the mesoscale eddy field. Journal of Geophysical Research, 115:C09010, doi:10.1029/2009JC05679, 20 pp. (2010).
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The modification of near-surface near-inertial oscillations (NIOs) by the geostrophic vorticity is studied globally from an observational standpoint. Surface drifter are used to estimate NIO characteristics. Despite its spatial resolution limits, altimetry is used to estimate the geostrophic vorticity. Three characteristics of NIOs are considered: the relative frequency shift with respect to the local inertial frequency; the near-inertial variance; and the inverse excess bandwidth, which is interpreted as a decay time scale. The geostrophic mesoscale flow shifts the frequency of NIOs by approximately half its vorticity. Equatorward of 30°N and S, this effect is added to a global pattern of blue shift of NIOs. While the global pattern of near-inertial variance is interpretable in terms of wind forcing, it is also observed that the geostrophic vorticity organizes the near-inertial variance; it is maximum for near zero values of the Laplacian of the vorticity and decreases for nonzero values, albeit not as much for positive as for negative values. Because the Laplacian of vorticity and vorticity are anticorrelated in the altimeter data set, overall, more near-inertial variance is found in anticyclonic vorticity regions than in cyclonic regions. While this is compatible with anticyclones trapping NIOs, the organization of near-inertial variance by the Laplacian of vorticity is also in very good agreement with previous theoretical and numerical predictions. The inverse bandwidth is a decreasing function of the gradient of vorticity, which acts like the gradient of planetary vorticity to increase the decay of NIOs from the ocean surface. Because the altimetry data set captures the largest vorticity gradients in energetic mesoscale regions, it is also observed that NIOs decay faster in large geostrophic eddy kinetic energy regions.
Enfield, D.B., and L. Cid-Serrano. Secular and multidecadal warmings in the North Atlantic and their relationships with major hurricane activity. International Journal of Climatology, 30(2):174-184 (2010).
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Analysis of recent literature finds weaknesses in arguments to the effect that the Atlantic multidecadal oscillation (AMO)--roughly 50-90 year fluctuations in North Atlantic sea surface temperatures--is externally forced by anthropogenic aerosols and greenhouse gases rather than an internal climate mode, plus indications from other sources that the contrary may be true. We are led to the conclusion that the AMO is probably comprised of both natural and anthropogenic forcing in ways that preclude a physically based separation of the two, using the limited historical data sets. A straightforward quadratic fitting of trend to temperature data accounts for some of the 20th century nonlinearity in secular warming and separates the secular and multidecadal components of variability without inherent assumptions about the nature of the multidecadal fluctuations. Doing this shows that the 20th century secular ocean warming in the North Atlantic is about equal to the peak-to-peak amplitude of the multidecadal fluctuations. However, over the last quarter-century (1975-2000) the most recent multidecadal warming has been almost three times the secular sea surface temperature (SST) increase over the main development region (MDR) for major Atlantic hurricanes. In the last quarter-century the multidecadal increase in late summer Atlantic warm pool (AWP) size (area of SSTs in excess of 28°C) has been 36%, and the secular increase, 14%. Projections to the year 2025 show that the cumulative change in summer warm pool size since 1975 will depend critically on whether a subsequent cooling in the multidecadal cycle occurs, comparable to the warming between 1975 and 2000 AD. This places a high premium on understanding to what extent the AMO is a man-made or a natural phenomenon.
Feely, R.A., R. Wanninkhof, J. Stein, M.F. Sigler, E. Jewett, F. Arzayus, and D.K. Gledhill (NOAA Ocean Acidification Steering Committee). NOAA Ocean and Great Lakes Acidification Research and Implementation Plan, A.J. Sutton (ed.). NOAA Special Report, 143 pp. (2010).
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No abstract.
Feely, R.A., C.L. Sabine, R. Wanninkhof, S.R. Alin, E. Jewett, D.K. Gledhill, J. Dunne, P. McElhany, A.J. Sutton, D.S. Busch, F. Arzayus, B. Sunda, J. Geubtner, J. Hare, O. Vetter, and S. Hankin. Rationale and strategy for a national ocean acidification program, pp. 3-29. In NOAA Ocean and Great Lakes Acidification Research and Implementation Plan, A.J. Sutton (ed.). NOAA Special Report, 143 pp. (2010).
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No abstract.
Fleisher, J.M., L.E. Fleming, H.M. Solo-Gabriele, J.K. Kish, C.D. Sinigalliano, L.W. Plano, S.M. Elmir, J.D. Wang, K.F. Withum, T. Shibata, M.L. Gidley, A. Abdelzaher, G. He, C. Ortega, X. Zhu, M.D. Wright, J.A. Hollenbeck, and L.C. Backer. The BEACHES Study: Health effects and exposures from nonpoint source microbial contaminants in subtropical recreational marine waters. International Journal of Epidemiology, 39(5):1291-1298 (2010).
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Microbial water quality indicators, found in high concentrations in sewage, are used to determine whether water is safe for recreational purposes. Recently, concerns have been raised about the appropriate use of indicators to regulate recreational water bodies, particularly non-point source sub/tropical recreational marine waters. A group of 1303 adult regular bathers were randomly assigned to bather and non-bather groups, with subsequent follow-up for reported illness, in conjunction with an ongoing extensive environmental sampling of indicator organisms (enterococcus) and pathogens. After controlling for non-water related risk factors/possible confounders, bathers were 1.75 times (95% confidence interval = 0.94-3.26; p = 0.078) more likely to report gastrointestinal illness relative to non bathers; bathers were 4.46 times (0.99-20.97; p = 0.051) more likely to report acute febrile respiratory illness; and bathers were 5.51 times (2.68-11.36; p = 0.<0.0001) more likely to report skin illness relative to non-bathers after seven days of follow up from beach exposure. There was an apparent dose-response relationship between bather exposure to increasing levels of enterococcus and risks of reported skin and gastrointestinal illness, and some evidence of increased risk of respiratory illness among bathers relative to nonbathers. There was a possible threshold effect for gastrointestinal illness at approximately 40 CFU/100 mL of enterococcus; however, no threshold effect was observed for skin illness. Human exposures to and health risks from microbial pollution may occur even in a non-point source recreational marine environment.
Forteza, E. Analysis of governance in Coiba National Park in Panama. M.S. thesis. University of Miami, Rosenstiel School of Marine and Atmospheric Science, 61 pp. (2010).
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This internship is part of a continued effort to contribute to the analysis, discussion and accomplishment of the Management Plan of Coiba National Park, which is located off the Pacific coast of Panama and was declared a UNESCO World Heritage Site in 2005. The National Assembly of Panama adopted legislation, known as Law No. 44, which established Coiba National Park and an adjacent Special Zone of Marine Protection. The Law also established a Governing Council and other working committees. This analysis of governance was based on the revision of legal documents, interviews with members of committees and a review of minutes from meetings of different committees. The analysis covered aspects of relevance as the decision-making process, the interaction between all interested institutions, the participation of the general public and the economic consequences from the establishment of the park for the region. This study revealed that the Governing Council has consolidated his position as the maximum authority in Coiba National Park and was capable of elaborating and approving a renewed Management Plan that will guide conservation goals during the next five years. The analysis also showed that the Governing Council still has many important problems to solve, such as the removal of cattle from Coiba Island, the approval of a Management Plan for the Special Zone of Marine Protection, and the elaboration of a Five-Year Scientific Plan.
Freeland, H.J., D. Roemmich, S.L. Garzoli, P.-Y. Le Traon, M. Ravichandran, S. Riser, V. Thierry, S. Wijffels, M. Belbeoch, J. Gould, F. Grant, M. Ignazewski, B. King, B. Klein, K.A. Mork, B. Owens, S. Pouliquen, A. Sterl, T. Suga, M.-S. Suk, P. Sutton, A. Troisi, P.J. Velez-Belchi, and J. Xi. ARGO: A decade of progress. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 13 pp. (2010).
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No abstract.
Garzoli, S.L., S. Speich, A. Piola, and E. Campos. South Atlantic Meridional Overturning Circulation (SAMOC)Third workshop. CLIVAR Exchanges, 54(4):28-29 (2010).
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No abstract.
Garzoli, S.L., O. Boebel, H. Bryden, R.A. Fine, M. Fukasawa, S. Gladyshev, G. Johnson, M. Johnson, A. MacDonald, C.S. Meinen, H. Mercier, A. Orsi, A. Piola, S. Rintoul, S. Speich, M. Visbeck, and R. Wanninkhof. Progressing towards global sustained deep ocean observations. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306,12 pp. (2010).
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No abstract.
Gledhill, D.K., T. Goedeke, K. Helmle, J. Hendee, A. Hilting, E. Jewett, B. Keller, D. Manzello, M. Miller, E. Rule, B. Sunda, and R. Wanninkhof. Southeast Atlantic and Gulf of Mexico region ocean acidification research implementation plan, pp. 77-91. In NOAA Ocean and Great Lakes Acidification Research Implementation Plan, A.J. Sutton (ed.). NOAA Special Report, 143 pp. (2010).
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No abstract.
Goni, G.J., J.A. Knaff, and I.-I. Lin. TC heat potential. In State of the Climate in 2009, D.S. Arndt, M.O. Baringer, and M.R. Johnson (eds.). Bulletin of the American Meteorological Society, 91(6):99-100 (2010).
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No abstract.
Goni, G., M. DeMaria, J. Knaff, C. Sampson, J. Price, A. Mehra, I. Ginis, I.-I. Lin, P. Sandery, S. Ramos-Buarque, M.M. Ali, F. Bringas, S. Aberson, R. Lumpkin, G. Halliwell, C. Lauer, E. Chassignet, A. Mavume, and K. Kang. The ocean observing system for tropical cyclone intensification forecasts and studies. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 13 pp. (2010).
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No abstract.
Goni, G., D. Roemmich. R. Molinari, G. Meyers, C. Sun, T. Boyer, M. Baringer, V. Gouretski, P. DI NEZIO, F. Reseghetti, G. Vissa, S. Swart, R. Keeley, S. Garzoli, T. Rossby, C. Maes, and G. Reverdin. The Ship of Opportunity Program. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 19 pp. (2010).
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The Ship of Opportunity Program (SOOP) is an international World Meteorological Organization (WMO)-Intergovernmental Oceanographic Commission (IOC) program that addresses both scientific and operational goals to contribute to building a sustained ocean observing system. The SOOP main mission is the collection of upper ocean temperature profiles using eXpendable BathyThermographs (XBTs), mostly from volunteer vessels. The XBT deployments are designated by their spatial and temporal sampling goals or modes of deployment (Low Density, Frequently Repeated, and High Density) and sample along well-observed transects, on either large or small spatial scales, or at special locations such as boundary currents and chokepoints, all of which are complementary to the Argo global broad scale array. A multi-national review of the global upper ocean thermal networks carried out in 1999 [1] and presented at the OceanObs99 conference recommended evolving from broad-scale XBT sampling to increased spatial and temporal transect-based sampling anticipating the implementation of the Argo float network and continued satellite altimetry observations. The objective of the present manuscript is to review the present status of networks against the objectives set during OceanObs99, to present key scientific contributions of XBT observations, and to offer new perspectives for the future of the XBT network. The commercial shipping industry has changed in the past decade, toward fewer routes and more frequent changes of ships and routing impacting the temporal continuity of some XBT transects. In spite of these changes, many routes now have, in addition to XBT sampling, measurements from ThermoSalinoGraphs (TSGs), eXpendable Conductivity Temperature and Depth (XCTD), partial pressure of CO2, Acoustic Doppler Current Profiler (ADCP), Continuous Plankton Recorders (CPR), marine meteorology, fluorescence, and radiometer sensors. In addition, recent studies of the XBT fall rate are being evaluated with the goal of optimizing the XBT historical record for climate research applications. The ongoing value of the Ship Of Opportunity networks is viewed through their extended time series and their integrative relationships with other elements of the ocean observing system including, for example, profiling floats, satellite altimetry, and air-sea flux measurements. Improved capabilities in ocean data assimilation modeling and expansion to support large scale multidisciplinary research will further enhance value in the future.
Gruskin, Z. Structure and evolution of a possible U.S. landfalling tropical cyclone in 2006. Monthly Weather Review, 138(1):265-278 (2010).
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A tropical disturbance made landfall near Morehead City, North Carolina, on 27 June 2006. Surface observations, Air Force reconnaissance, and Doppler velocity data suggest that the disturbance had a closed surface circulation at landfall, with maximum 1-min surface winds >18 m s-1, the threshold of tropical storm strength. A cyclostrophic wind calculation using Doppler velocity data and surface observations indicates that the circulation of the disturbance likely caused the tropical storm force winds observed, rather than an environmental pressure gradient or short-lived convective process. Doppler velocity cross sections of the disturbance further suggest that the disturbance was warm core, and an analysis of the disturbances environment reveals that latent heat of condensation was likely a large source of energy for the disturbance, though there was some baroclinic forcing. These observations and analyses make a compelling case for the upgrade of the disturbance to a tropical storm in the best-track database.
Hamid, S., B.M. Golam Kibria, S. Gulati, M. Powell, B. Annane, S. Cocke, J.-P. Pinelli, K. Gurley, and S.-C. Chen. Predicting losses of residential structures in the state of Florida by the public hurricane loss evaluation model. Statistical Methodology, 7(5):552-573 (2010).
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As an environmental phenomenon, hurricanes cause significant property damage and loss of life in coastal areas almost every year. Although a number of commercial loss projection models have been developed to predict the property losses, only a handful of studies are available in the public domain to predict damage for hurricane prone areas. The state of Florida has developed an open, public model for the purpose of probabilistic assessment of risk to insured residential property associated with wind damage from hurricanes. The model comprises three components; viz. the atmospheric science component, the engineering component and the actuarial science component. The atmospheric component includes modeling the track and intensity life cycle of each simulated hurricane within the Florida threat area. Based on historical hurricane statistics, thousands of storms are simulated allowing determination of the wind risk for all residential zip code locations in Florida. The wind risk information is then provided to the engineering and actuarial components to model damage and average annual loss, respectively. The actuarial team finds the county-wise loss and the total loss for the entire state of Florida. The computer team then compiles all information from atmospheric science, engineering and actuarial components, processes all hurricane related data and completes the project. The model was submitted to the Florida Commission on Hurricane Loss Projection Methodology for approval and went through a rigorous review and was revised as per the suggestions of the commission. The final model was approved for use by the insurance companies in Florida by the commission. At every stage of the process, statistical procedures were used to model various parameters and validate the model. This paper presents a brief summary of the main components of the model (meteorology, vulnerability and actuarial) and then focuses on the statistical validation of the same.
Haus, B.K., D. Jeong, M.A. Donelan, J.A. Zhang, and I. Savelyev. Relative rates of sea-air heat transfer and frictional drag in very high winds. Geophysical Research Letters, 37(7):L07802, doi:10.1029/2009GL042206 (2010).
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Hurricanes are fueled by evaporation and convection from the ocean and they lose energy through the frictional drag of the atmosphere on the ocean surface. The relative rates of these processes have been thought to provide a limit on the maximum potential hurricane intensity. Here we report laboratory observations of these transfers for scaled winds equivalent to a strong Category 1 hurricane (38 ms-1). We show that the transfer coefficient ratio holds closely to a level of ~0.5 even in the highest observed winds, where previous studies have suggested there is a distinct regime change at the air-sea interface. This value is well below the expected threshold value for intense hurricanes of 0.75. Recent three-dimensional model studies also find that the coefficient ratio can be much lower than 0.75, which suggests that other factors such as eyewall and/or vortex dynamics are responsible for the formation of very strong hurricanes.
Huang, X.-L., and J.-Z. Zhang. Spatial variation in sediment-water exchange of phosphorus in Florida Bay: AMP as a model organic compound. Environmental Science and Technology, 44(20):7790-7795 (doi:10.1021/es100057r) (2010).
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Dissolved organic phosphorus (DOP) has been recognized as dominant components in total dissolved phosphorus (TDP) pools in many coastal waters, and its exchange between sediment and water is an important process in biogeochemical cycle of phosphorus. Adenosine monophosphate (AMP) was employed as a model DOP compound to simulate phosphorus exchange across sediment-water interface in Florida Bay. The sorption data from 40 stations were fitted to a modified Freundlich equation and provided a detailed spatial distribution both of the sediments zero equilibrium phosphorus concentration (EPC0-T) and of the distribution coefficient (Kd-T) with respect to TDP. The Kd-T was found to be a function of the index of phosphorus saturation (IPS), a molar ratio of the surface reactive phosphorus to the surface reactive iron oxide content in the sediment, across the entire bay. However, the EPC0-T was found to correlate to the contents of phosphorus in the eastern bay only. Sediment in the western bay might act as a source of the phosphorus in the exchange process due to their high EPC0-T and low Kd-T, whereas sediments in the eastern bay might act as a sink because of their low EPC0-T and high Kd-T. These results strongly support the hypothesis that both phosphorus and iron species in calcareous marine sediments play a critical role in governing the sediment-water exchange of both phosphate and DOP in the coastal and estuarine ecosystems.
Hydes, D.J., M. Aoyama, a. Aminot, K. Bakker, S. Becker, S. Coverly, A. Daniel, A.G. Dickson, O. Grosso, R. Kerouel, J. van Ooijen, K. Sato, T. Tanhua, E.M.S. Woodward, and J.-Z. Zhang. Determination of dissolved nutrients (N, P, Si) in seawater with high precision and inter-comparability using gas-segmented continuous flow analyzers. The GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports and Guidelines, IOCCP Report No. 14, ICPO Publication Series No. 134, Version 1, 87 pp. (2010).
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The Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) brings together scientists with interests in physical oceanography, the carbon cycle, marine biogeochemistry and ecosystems, and other users and collectors of ocean interior data to develop a sustained global network of hydrographic sections as part of the Global Ocean Climate Observing System. A series of manuals and guidelines are being produced by GO-SHIP which update those developed by the World Ocean Circulation Experiment (WOCE) in the early 1990s. Analysis of the data collected in WOCE suggests that improvements are needed in the collection of nutrient data if they are to be used for determining change within the ocean interior. Production of this manual is timely as it coincides with the development of reference materials for nutrients in seawater (RMNS). These RMNS solutions will be produced in sufficient quantities and be of sufficient quality that they will provide a basis for improving the consistency of nutrient measurements both within and between cruises. This manual is a guide to suggested best practice in performing nutrient measurements at sea. It provides a detailed set of advice on laboratory practice for all the procedures surrounding the use of gas-segmented continuous flow analyzers (CFA) for the determination of dissolved nutrients (usually ammonium, nitrate, nitrite, phosphate and silicate) at sea. It does not proscribe the use of a particular instrument or related chemical method as these are well described in other publications. The manual provides a brief introduction to the CFA method, the collection and storage of samples, considerations in the preparation of reagents and the calibrations of the system. It discusses how RMNS solutions can be used to track the performance of a system during a cruise and between cruises. It provides a format for the meta-data that need to be reported alongside the sample data at the end of a cruise so that the quality of the reported data can be evaluated and set in context relative to other data sets. Most importantly the central manual is accompanied by a set of nutrient standard operating procedures (NSOPs) that provide detailed information on key procedures that are necessary if best quality data are to be achieved consistently. These cover sample collection and storage, an example NSOP for the use of a CFA system at sea, high precision preparation of calibration solutions, assessment of the true calibration blank, checking the linearity of a calibration and the use of internal and externally prepared reference solutions for controlling the precision of data during a cruise and between cruises. An example meta-data report and advice on the assembly of the quality control and statistical data that should form part of the meta-data report are also given.
Ismail, S., R.A. Ferrare, E.V. Browell, S.A. Kooi, J.P. Dunion, G. Heymsfield, A. Notari, C.F. Butler, S. Burton, M. Fenn, T.N. Krishnamurti, M.K. Biswas, G. Chen, and B. Anderson. LASE measurements of water vapor, aerosol, and cloud distributions in Saharan air layers and tropical disturbances. Journal of the Atmospheric Sciences, 67(4):1026-1047 (2010).
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The Lidar Atmospheric Sensing Experiment (LASE) on board the NASA DC-8 measured high-resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan air layer (SAL). These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its interactions with AEWs and TCs. Three case studies were selected for detailed analysis: (i) a stratified SAL, with fine structure and layering (unlike a well-mixed SAL), (ii) a SAL with high relative humidity (RH), and (iii) an AEW surrounded by SAL dry air intrusions. Profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in the SAL, convection, and clear air regions. LASE extinction-to-backscatter ratios for the dust layers varied from 35 ± 5 to 45 ± 5 sr, well within the range of values determined by other lidar systems. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively. An analysis of LASE data suggests that the SAL suppresses low-altitude convection. Midlevel convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on 20 August 2008. This interaction is responsible for the transfer of about 7 x 1015 J (or 8 x 103 J m-2) latent heat energy within a day to the SAL. Initial modeling studies that used LASE water vapor profiles show sensitivity to and improvements in model forecasts of an AEW.
Jiang, L.-Q., W.-J. Cai, R.A. Feely, Y. Wang, X. Guo, D.K. Gledhill, X. Hu, F. Arzayus, F. Chen, J. Hartmann, and L. Zhang. Carbonate mineral saturation states along the U.S. east coast. Limnology and Oceanography, 55(6):2424-2432 (2010).
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To assess the impact of ocean acidification on the carbonate chemistry of the shelf waters off the southeastern United States (South Atlantic Bight [SAB]), we measured carbonate mineral saturation states from January 2005 to May 2006. The findings reveal that aragonite (Varag: 2.64.0) and calcite (Vcal: 4.16.0) saturation states were considerably higher than those recently reported along the West Coast of North America. Different water mass age between the Atlantic and Pacific Oceans during global ocean circulation is the primary reason for the higher carbonate mineral saturation states in the SAB than along the west coast. The contrasting water temperatures in the two coasts contribute to such differences. Both upwelling and freshwater discharge also play important roles in controlling saturation state. Carbonate mineral saturation in the surface water of the west coast is strongly controlled by the upwelling of high-salinity, low-temperature, low-oxygen, and low-pH deep water. In comparison, saturation states in the surface water of the SAB coast are rarely affected by upwelling. Instead, they are strongly influenced by the input of low-saturation-state water from rivers. Continued increases of atmospheric CO2 under the Intergovernmental Panel on Climate Change B1 emission scenario will decrease the carbonate mineral saturation states by up to 40% by the end of this century, and aragonite will approach undersaturation near the coast.
Juranek, L.W., R.C. Hamme, J. Kaiser, R. Wanninkhof, and P.D. Quay. Evidence of O2 consumption in underway seawater lines: Implications for air-sea O2 and CO2 fluxes. Geophysical Research Letters, 37:L01601, doi:10.1029/2009GL040423 (2010).
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We observed O2 deficits of 0.5 to 2.0% (1 to 4 µmol/kg) in the underway seawater lines of three different ships. Deficits in O2/Ar and isotopic enrichments in dissolved O2 observed in underway seawater lines indicate a respiratory removal process. A 1% respiratory bias in underway lines would lead to a 2.5-5 µatm (2.5-5 µbar) enhancement in surface water pCO2. If an underway pCO2 bias of this magnitude affected all measurements, the global oceanic carbon uptake based on pCO2 climatologies would be 0.5-0.8 Pg/yr higher than the present estimate of 1.6 Pg/yr. Treatment of underway lines with bleach for several hours and thorough flushing appeared to minimize O2 loss. Given the increasing interest in underway seawater measurements for the determination of surface CO2 and O2 fluxes, respiration in underway seawater lines must be identified and eliminated on all observing ships to ensure unbiased data.
Jury, M.R., and D.B. Enfield. Environmental patterns associated with active and inactive Caribbean hurricane seasons. Journal of Climate, 23(8):2146-2160 (2010).
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This study of hurricanes passing through the Caribbean in the 1950-2005 period reveals that seasons with more intense hurricanes occur with the onset of Pacific La Niña events and when Atlantic SSTs west of Africa are above normal. Composites of NCEP reanalysis fields with regard to Caribbean hurricanes reveal development of an anomalous equatorial Atlantic zonal overturning circulation (upper easterly/lower westerly) that shifts toward the Caribbean coincident with a westward spread of the cold tongue in the east Pacific. Ocean-atmosphere coupling is promoted through interaction of the southern Hadley cell and the Atlantic ITCZ. A heat budget analysis suggests that evaporation governs SSTs in the major development region (MDR) and near Venezuela, but the signal is weak prior to May. Using the knowledge gained, statistical algorithms are developed to predict Caribbean hurricanes at seasonal lead times. These make use of equatorial Pacific SST, subtropical Atlantic SST, and the zonal Walker cell over the Atlantic.
Kanzow, T., S.A. Cunningham, W.E. Johns, J.J-M. Hirschi, J. Marotzke, M.O. Baringer, C.S. Meinen, M.P. Chidichimo, C. Atkinson, L.M. Beal, H.L. Bryden, and J. Collins. Seasonal variability of the Atlantic meridional overturning circulation at 26.5°N. Journal of Climate, 23(21):5678-5698 (doi:10.1175/2010JCL13389.1) (2010).
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The Atlantic meridional overturning circulation (AMOC) makes the strongest oceanic contribution to the meridional redistribution of heat. Here, an observation-based, 48-month-long time series of the vertical structure and strength of the AMOC at 26.5°N is presented. From April 2004 to April 2008, the AMOC had a mean strength of 18.7 ± 2.1 Sv (1 Sv 106 m3 s-1) with fluctuations of 4.8 Sv rms. The best guess of the peak-to-peak amplitude of the AMOC seasonal cycle is 6.7 Sv, with a maximum strength in autumn and a minimum in spring. While seasonality in the AMOC was commonly thought to be dominated by the northward Ekman transport, this study reveals that fluctuations of the geostrophic midocean and Gulf Stream transports of 2.2 and 1.7 Sv rms, respectively, are substantially larger than those of the Ekman component (1.2 Sv rms). A simple model based on linear dynamics suggests that the seasonal cycle is dominated by wind stress curl forcing at the eastern boundary of the Atlantic. Seasonal geostrophic AMOC anomalies might represent an important and previously underestimated component of meridional transport and storage of heat in the subtropical North Atlantic. There is evidence that the seasonal cycle observed here is representative of much longer intervals. Previously, hydrographic snapshot estimates between 1957 and 2004 had suggested a long-term decline of the AMOC by 8 Sv. This study suggests that aliasing of seasonal AMOC anomalies might have accounted for a large part of the inferred slowdown.
Kaplan, J., M. DeMaria, and J.A. Knaff. A revised tropical cyclone rapid intensification index for the Atlantic and eastern North Pacific basins. Weather and Forecasting, 25(1):220-241 (2010).
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A revised rapid intensity index (RII) is developed for the Atlantic and eastern North Pacific basins. The RII uses large-scale predictors from the Statistical Hurricane Intensity Prediction Scheme (SHIPS) to estimate the probability of rapid intensification (RI) over the succeeding 24 h utilizing linear discriminant analysis. Separate versions of the RII are developed for the 25-, 30-, and 35-kt RI thresholds, which represent the 90th (88th), 94th (92nd), and 97th (94th) percentiles of 24-h over water intensity changes of tropical and subtropical cyclones in the Atlantic (eastern North Pacific) basins from 1989 to 2006, respectively. The revised RII became operational at the NHC prior to the 2008 hurricane season. The relative importance of the individual RI predictors is shown to differ between the two basins. Specifically, the previous 12-h intensity change, upper-level divergence, and vertical shear have the highest weights for the Atlantic basin, while the previous 12-h intensity change, symmetry of inner-core convection, and the difference in a systems current and maximum potential intensity are weighted highest in the eastern North Pacific basin. A verification of independent forecasts from the 2006 and 2007 hurricane seasons shows that the probabilistic RII forecasts are generally skillful in both basins when compared to climatology. Moreover, when employed in a deterministic manner, the RII forecasts were superior to all other available operational intensity guidance in terms of the probability of detection (POD) and false alarm ratio (FAR). Specifically, the POD for the RII ranged from 15% to 59% (53% to 73%) while the FAR ranged from 71% to 85% (53% to 79%) in the Atlantic (eastern North Pacific) basins, respectively, for the three RI thresholds studied. Nevertheless, the modest POD and relatively high FAR of the RII and other intensity guidance demonstrate the difficulty of predicting RI, particularly in the Atlantic basin.
Keeley, R., M. Pazos, and B. Bradshaw. Data management system for surface drifters. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 7 pp. (2010).
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The large scale deployment of surface drifters has its origins in the FGGE programme in the late 1970s. Over the course of the next 25 years, surface drifters have become routinely used in all oceans so that now there are more than 1250 operating. The data management systems to handle the data returned from these platforms started with FGGE and have evolved. The main difference between the early years and now from a data system perspective is the volume and timeliness of reporting the data, though more variables are also being measured. Presently there are more than 1 million records reported in real-time and such high volumes are straining processing systems that were originally set up for fewer records and manual scrutiny of the data. The future system will need more sophisticated algorithms for automatic detection of possible errors and these must be developed in cooperation with the scientific and instrument communities. Data must move more quickly through the processing streams and become available to users. Despite the large volumes, there is high demand for on-line access to the entire archive. Strategies must be developed to meet this demand without large data requests swamping data servers. Part of this will involve providing data browse and selection tools that permit a user to refine their request to only the data of interest. Finally, there is an increasing need to use data from different sources to examine a variety of scientific and societal problems. Standard vocabularies for naming variables, instruments, methods, etc., must become widely used to allow easier interoperability of data.
Kelble, C.R. The effect of salinity on the plankton community of Florida Bay. Ph.D. thesis, University of Miami, Rosenstiel School of Marine and Atmospheric Science, 174 pp. (2010).
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The greater Everglades ecosystem, including Florida Bay, has undergone significant anthropogenic manipulation over the past century. These actions resulted in a series of ecologically undesirable events in the Everglades ecosystem, prompting passage of the Comprehensive Everglades Restoration Plan (CERP). It is necessary to understand the variability in, and relationship between, salinity and ecology to fully evaluate the potential effects of CERP on Florida Bay. A seven-year dataset on surface salinity along with eleven-year and eight-year datasets on mesozooplankton and planktivorous fish were analyzed. Overall, mean Bay-wide salinity varied from a low of 24.2 just after the passing of Hurricane Irene in October 1999 to a high of 41.8 near the end of a drought period in July 2001. Bay-wide mean salinity exhibited dramatic decreases, up to 0.5 per day, whereas increases in bay-wide salinity were slower, with a maximum rate of 0.1 per day. Meteorological phenomena, such as tropical cyclones and ENSO, dramatically altered the salinity patterns of Florida Bay on interannual time scales. There was a large degree of spatial heterogeneity in salinity between sub-regions of Florida Bay due to differing freshwater sources and geomorphology. Mesozooplankton abundance displayed interannual variability and a positive correlation with salinity. Both of these features were also closely correlated with abundance of the dominant planktivorous fish, Anchoa mitchilli, indicating the importance of top-down control. The hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance during periods of increased physiological stress. The interaction between mesozooplankton and A. mitchilli, along with its correlation to salinity, was further investigated through the development of a mechanistic model of the populations in Florida Bay. The model indicated predation alone was insufficient to control mesozooplankton populations; rather, it was necessary to incorporate density-dependence utilizing a logistic prey population. With both mechanisms the model was able to replicate the observed interannual variability pattern and positive correlation between mesozooplankton and salinity. A preliminary management scenario evaluation suggests a two to six-fold difference in A. mitchilli and mesozooplankton populations between targeted and general salinity reductions. This suggests alternative freshwater management scenarios could produce drastically different ecological consequences.
Kelble, C.R., P.B. Ortner, G.L. Hitchcock, M.J. Dagg, and J.N. Boyer. Temporal and spatial variability of mesozooplankton in a shallow sub-tropical bay: Influence of top-down control. Estuaries and Coasts, 33(3):727-737 (2010).
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Quantifying the relationship between mesozooplankton and water quality parameters identifies the factors that structure the mesozooplankton community and can be used to generate hypotheses regarding the mechanisms that control the mesozooplankton population and potentially the trophic network. To investigate this relationship, mesozooplankton and water quality data were collected in Florida Bay from 1994 to 2004. Three key characteristics were found in the mesozooplankton community structure: (1) there are significant differences between the four sub-regions of Florida Bay; (2) there is a break in May of 1997 with significant differences before and after this date; and (3) there is a positive correlation between mesozooplankton abundance and salinity. The latter two characteristics are closely correlated with predator abundance, indicating the importance of top-down control. Hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance despite the increased physiological stress.
Keul, N., J.W. Morse, R. Wanninkhof, D.K. Gledhill, and T.S. Bianchi. Carbonate chemistry dynamics of surface waters in the northern Gulf of Mexico. Aquatic Geochemistry, 16(3):337-351 (2010).
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This paper presents the results of two cruises in the northern Gulf of Mexico in 2008 that investigated local and short-term factors influencing the carbonate chemistry dynamics and saturation state with respect to aragonite (OMEGAaragonite) of surface seawater in this region. One cruise covered much of the northern half of the Gulf, and the other focused on the coastal zone west of the Atchafalaya Bay outlet of the Mississippi River--the region where the hypoxic dead zone occurs on the Louisiana shelf. Offshore waters (>100 m depth) exhibited only small variations in CO2 fugacity (fCO2), total alkalinity (TA), and OMEGAaragonite. Values were close to those typically observed in subtropical Atlantic Ocean and Caribbean Sea waters of similar salinity. However, inner shelf waters (<50 m depth) exhibited large variations in fCO2, TA, and OMEGAaragonite that were not directly related to salinity or distance from the Mississippi River plume. Changes in TA values were not the result of simple mixing of end-member freshwater and seawater TA concentrations but exhibited a minimum in values near salinity of 25. This minimum could be the result of microbial recycling across salinity gradients, biological removal of alkalinity by formation of calcium carbonate or mixing of a third end-member with a low alkalinity such as Terrebonne Bay. All waters were supersaturated with respect to aragonite. Offshore waters had an average OMEGAaragoniteof 3.86 with a standard deviation of only ±0.06 and inner shelf waters had a range in OMEGAaragonite values from 3.9 to 9.7 with a median of 4.3. Shelf water OMEGAaragonite values were elevated relative to the offshore as a consequence of both high TA input from Mississippi River and biological drawdown of CO2. A dominant factor controlling OMEGAaragonite distribution in offshore waters with relatively constant temperatures was fCO2, with higher supersaturation occurring in areas with low fCO2.
Kimball, S.K., M.S. Mulekar, S. Cummings, and J. Stamates. The University of South Alabama Mesonet and coastal observing system: A technical and statistical overview. Journal of Atmospheric and Oceanic Technology, 27(9):1417-1439 (2010).
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The University of South Alabama Mesonet consists of 26 sites across the north-central Gulf of Mexico coast. Although the original purpose of the mesonet was monitoring landfalling tropical systems, meteorological data are collected and disseminated every 5 min year-round to serve a multitude of purposes, including weather forecasting, education, and research. In this paper a statistical analysis and like-sensor comparison demonstrates that variables, measured by different sensor types or by sensors at different heights, correlate well. The benefits of sensor redundancy are twofold, offering 1) backup sensors in the case of sensor failure during severe weather and 2) the ability to perform a large number of internal consistency checks for quality control purposes. An oceanographic compliment to the University of South Alabama Mesonet system, which was deployed by NOAAs Atlantic Oceanographic and Meteorological Laboratory (AOML) to measure surface waves and ocean currents in an area south of Mobile, Alabama, is described. A preliminary comparison of mesonet wind data and ocean wave data show good agreement, offering promising opportunities for future research.
Lee, S.-K., and C. Wang. Delayed advective oscillation of the Atlantic thermohaline circulation. Journal of Climate, 23(5):1254-1261 (2010).
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A simple dynamic model is proposed to illustrate the multidecadal oscillation of the Atlantic Ocean thermohaline circulation. The proposed oscillation relies on alternating actions of positive and negative feedbacks, which are operated by a slow adjustment of the ocean circulation and the associated time delay in the advective flux response to a change in meridional density gradient. The key element of the oscillation is the time delay, which is conceptually related to the basin-crossing time of long Rossby waves in the high-latitude North Atlantic. For a sufficiently long time delay, the solution becomes unstable in some regions of model parameter space and oscillates with a period of approximately 2 times the delay time.
Lee, S.-K., C. Wang, and D.B. Enfield. On the impacts of central Pacific warming events on Atlantic tropical storm activity. Geophysical Research Letters, 37:L17702, doi:10.1029/2010GL044459, 5 pp. (2010).
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A recent study by Kim et al. (2009) claim that central Pacific warming (CPW) events in 1969, 1991, 1994, 2002 and 2004 are associated with a greater-than-average frequency of tropical storms and increasing landfall potential along the Gulf of Mexico coast and Central America. Based on an independent data analysis of tropical cyclone activity in the five CPW years, it is shown here that only 1969, 2002, and 2004 were characterized with significantly greater-than-average cyclone activity in the Gulf of Mexico and Caribbean Sea, whereas 1991 and 1994 were characterized with significantly lower-than-average activity. Coincidently, the Atlantic warm pool (AWP) was significantly larger than average during 1969 and 2004, and significantly smaller than average during 1991 and 1994. By performing multiple sets of ensemble model experiments using the NCAR atmospheric general circulation model, it is shown here that the increased tropical storm frequency in 1969 and 2004 can be readily explained by a large AWP and the associated vertical wind shear reduction and enhanced moist convective instability in the main development region for Atlantic hurricanes, without invoking a remote influence from the tropical Pacific. Therefore, we conclude that it is premature to associate CPW events to an increasing frequency of cyclone activity in the Gulf of Mexico and Caribbean Sea.
Leidner, S.M., J. Ardizzone, J.C. Jusem, E. Brin, R.N. Hoffman, and R. Atlas. Ocean-surface wind impacts on hurricane forecasting: Regional and global examples. Proceedings, 14th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS), Atlanta, GA, January 17-21, 2010. American Meteorological Society, Boston, 5 pp. (2010).
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No abstract.
Levina, G.V., and M.T. Montgomery. A first examination of the helical nature of tropical cyclogenesis. Doklady Earth Sciences, 434(1):1285-1289 (2010).
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No abstract.
Lorsolo, S., F.D. Marks, J.F. Gamache, and J.A. Zhang. Estimation and mapping of hurricane turbulent energy using airborne Doppler measurements. Monthly Weather Review, 138(9):3656-3670 (2010).
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Hurricane turbulent kinetic energy (TKE) was computed using airborne Doppler measurements from the NOAA WP-3D tail radars and TKE data were retrieved for a variety of storms at different stages of their lifecycle. The geometry of the radar analysis coupled with the relatively small beam resolution at ranges <8 km allowed for the estimation of sub-kilometer turbulent processes. Two dimensional profiles of TKE were constructed and revealed that the strongest turbulence was in general located in convective regions such as the eyewall with magnitude often exceeding 15 m2 s-2, and in the boundary layer with values of 5-10 m2 s-2 in the lowest km. A correlation analysis showed that the strong turbulence was in general associated with strong horizontal shear of vertical and radial wind components in the eyewall and strong vertical shear of horizontal wind in the boundary layer. Mean vertical profiles of TKE decrease sharply above the hurricane boundary layer and level off at low magnitude for all regions outside the radius of maximum wind. The quality of the retrieval method was evaluated and showed very good agreement with TKE values directly calculated from the three-dimensional wind components of in-situ measurements. The method presented here provides a unique opportunity to assess hurricane turbulence throughout the storm, especially in high wind regions, and can be applied on extensive data sets of past and future airborne hurricane penetrations.
Lumpkin, R., and S. Elipot. Surface drifter pair spreading in the North Atlantic. Journal of Geophysical Research, 115:C12017, 20 pp. (doi:10.1029/2010JC006338) (2010).
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This study examines spreading of surface drifter pairs deployed as part of the CLIVAR Mode Water Dynamic Experiment (CLIMODE) project in the Gulf Stream region. The spreading is resolved at hourly resolution and quantified by relative dispersion and finite-scale Lyapunov exponents. At scales from 1-3 km to 300-500 km, the dispersion follows Richardsons Law, indicating stirring by eddies comparable in scale to the pair separation distance. At larger scales, the spreading becomes a random walk described by a constant diffusivity. The behavior from 1-3 km to the local deformation radius is inconsistent with the enstrophy cascade of 2-D quasigeostrophic turbulence. To test various hypotheses for this result, drifter pair spreading is examined for pairs that were not launched together, pairs deployed in the eastern subtropical North Atlantic, and CLIMODE pairs subsampled to daily temporal resolution. Our results indicate the presence of significant energy at the submesoscale in the Gulf Stream region which flattens the wave number spectrum and dominates surface stirring at this scale range. Results in the less energetic subtropical eastern Atlantic are more equivocal.
Lumpkin, R., G. Goni, and K. Dohan. Surface currents. In State of the Climate in 2009, D.S. Arndt, M.O. Baringer, and M.R. Johnson (eds.). Bulletin of the American Meteorological Society, 91(6):65-66 (2010).
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No abstract.
Luo, D., Z. Zhu, R. Ren, L. Zhong, and C. Wang. Spatial pattern and zonal shift of the North Atlantic Oscillation, Part I: A dynamical interpretation. Journal of the Atmospheric Sciences, 67(9):2805-2826 (2010).
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This paper presents a possible dynamical explanation for why the North Atlantic Oscillation (NAO) pattern exhibits an eastward shift from the period 1958-77 (P1) to the period 1978-97 (P2) or 1998-2007 (P3). Firstly, the empirical orthogonal function analysis of winter-mean geopotential heights during P1, P2, and P3 reveals that the NAO dipole anomaly exhibits a northwest-southeast (NW-SE) tilting during P1, but a northeast-southwest (NE-SW) tilting during P2 (P3). The NAO pattern, especially its northern center, undergoes a more pronounced eastward shift from P1 to P2. The composite calculation of NAO events during P1 and P2 also indicates that the negative (positive) NAO phase dipole anomaly can indeed exhibit such a NW-SE (NE-SW) tilting. Secondly, a linear Rossby wave formula derived in a slowly varying basic flow with a meridional shear is used to qualitatively show that the zonal phase speed of the NAO dipole anomaly is larger (smaller) in higher latitudes and smaller (larger) in lower latitudes during the life cycle of the positive (negative) NAO phases because the core of the Atlantic jet is shifted to the north (south). Such a phase speed distribution tends to cause the different movement speeds of the NAO dipole anomaly at different latitudes, thus resulting in the different spatial tilting of the NAO dipole anomaly depending upon the phase of the NAO. The zonal displacement of the northern center of the NAO pattern appears to be more pronounced because the change of the mean flow between two phases of the NAO is more distinct in higher latitudes than in lower latitudes. In addition, a weakly nonlinear analytical solution, based on the assumption of the scale separation between the NAO anomaly and transient synoptic-scale waves, is used to demonstrate that an eastward shift of the Atlantic storm track eddy activity that is associated with the eastward extension of the Atlantic jet stream is a possible cause of the whole eastward shift of the center of action of the NAO pattern during P2 (P3).
Luo, D., L. Zhong, R. Ren, and C. Wang. Spatial pattern and zonal shift of the North Atlantic Oscillation, Part II: Numerical experiments. Journal of the Atmospheric Sciences, 67(9):2827-2853 (2010).
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In this part, the spatial evolution of an initial dipole anomaly in a prescribed jet is at first investigated by numerically solving linear and nonlinear models without forcing in order to examine how the spatial pattern of a dipole anomaly depends upon the meridional distribution of a specified jet. It is shown that in a linear experiment, an initial symmetric dipole anomaly in the meridional direction can evolve into a northeast-southwest (NE-SW) or northwest-southeast (NW-SE) tilted dipole structure if the core of this jet is in higher latitudes (the north) or in lower latitudes (the south). This is in agreement with the result predicted by the linear Rossby wave theory in a slowly varying media. The conclusion is also held for the nonlinear and unforced experiment. NAO events are then reproduced in a fully nonlinear barotropic model with a wavemaker that mimics the Atlantic storm track eddy activity. In the absence of topography the spatial tilting of the eddy-driven NAO pattern is found to be independent of the NAO phase. The eddy-driven NAO pattern for the positive (negative) phase can exhibit a NE-SW (NW-SE) tilting only when the core of a prescribed jet prior to the NAO is confined in the higher (lower) latitude region. But, in the presence of the wavenumber-two topography (two oceans and continents) in the Northern Hemisphere the spatial tilting of the eddy-driven NAO dipole anomaly can be dependent on the NAO phase. Even when the specified basic flow prior to the NAO is uniform the eddy-driven positive (negative) NAO phase dipole anomaly can also show a NE-SW (NW-SE) tilting because the northward (southward) shift of the excited westerly jet can occur in the presence of topography. In addition, it is found that when the wavemaker is closer to the position of the initial NAO, the eddy-driven positive (negative) NAO phase pattern can display a whole eastward shift and a more distinct NE-SW (NW-SE) tilting. This thus explains why the first empirical orthogonal function of the NAO pattern observed during 1998-2007 exhibits a more pronounced NE-SW tilting than that during 1978-97. It appears that the latitudinal shift of the jet, the large-scale topography and the zonal position of the Atlantic storm track eddy activity are three important factors for controlling the spatial tilting and zonal shift of eddy-driven NAO dipole anomalies.
Majumdar, S.J., K.J. Sellwood, D. Hodyss, Z. Toth, and Y. Song. Characteristics of target areas selected by the Ensemble Transform Kalman Filter for medium-range forecasts of high-impact winter weather. Monthly Weather Review, 138(7):2803-2824 (2010).
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The characteristics of target locations of tropospheric wind and temperature identified by a modified version of the ensemble transform Kalman filter (ETKF), in order to reduce 0-7-day forecast errors over North America, are explored from the perspective of a field program planner. Twenty cases of potential high-impact weather over the continent were investigated, using a 145-member ensemble comprising perturbations from NCEP, ECMWF, and the Canadian Meteorological Centre (CMC). Multiple targets were found to exist in the midlatitude storm track. In half of the cases, distinctive targets could be traced upstream near Japan at lead times of 4-7 days. In these cases, the flow was predominantly zonal and a coherent Rossby wave packet was present over the northern Pacific Ocean. The targets at the longest lead times were often located within propagating areas of baroclinic energy conversion far upstream. As the lead time was reduced, these targets were found to diminish in importance, with downstream targets corresponding to a separate synoptic system gaining in prominence. This shift in optimal targets is sometimes consistent with the radiation of ageostrophic geopotential fluxes and transfer of eddy kinetic energy downstream, associated with downstream baroclinic development. Concurrently, multiple targets arise due to spurious long-distance correlations in the ETKF. The targets were least coherent in blocked flows, in which the ETKF is known to be least reliable. The effectiveness of targeting in the medium range requires evaluation, using data such as those collected during the winter phase of The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Field Campaign (T-PARC) in 2009.
Manzello, D.P. Coral growth with thermal stress and ocean acidification: Lessons from the eastern tropical Pacific. Coral Reefs, 29(3):749-758 (2010).
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The rapid growth of scleractinian corals is responsible for the persistence of coral reefs through time. Coral growth rates have declined over the past 30 years in the western Pacific, Indian, and North Atlantic Oceans. The spatial scale of this decline has led researchers to suggest that a global phenomenon like ocean acidification may be responsible. A multi-species inventory of coral growth from Pacific Panama confirms that declines have occurred in some, but not all species. Linear extension declined significantly in the most important reef builder of the eastern tropical Pacific, Pocillopora damicornis, by nearly one-third from 1974 to 2006. The rate of decline in skeletal extension for P. damicornis from Pacific Panama (0.9% year-1) was nearly identical to massive Porites in the Indo-Pacific over the past 20-30 years (0.89-1.23% year-1). The branching pocilloporid corals have shown an increased tolerance to recurrent thermal stress events in Panama, but appear to be susceptible to acidification. In contrast, the massive pavonid corals have shown less tolerance to thermal stress, but may be less sensitive to acidification. These differing sensitivities will be a fundamental determinant of eastern tropical Pacific coral reef community structure with accelerating climate change that has implications for the future of reef communities worldwide.
Manzello, D.P. Ocean acidification hotspots: Spatiotemporal dynamics of the seawater CO2-system from eastern Pacific coral reefs. Limnology and Oceanography, 55(1):239-248 (2010).
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Seawater CO2 system dynamics were assessed from eastern Pacific reef sites in Panama over five consecutive years (2003-2008) and twice in the Galapagos Islands (2003 and 2009). The seawater CO2 system was highly variable in time and space, but was explained by physical forcing from meteorological (seasonal rainfall) and oceanographic (upwelling, tides) processes interacting with diurnal reef metabolism. Galapagos coral reef communities are naturally exposed to the highest ambient partial pressure of CO2 (pCO2) and lowest aragonite saturation (OMEGAarag) values documented for any coral reef environment to date. During upwelling in the Galapagos, mean pCO2 and mean OMEGAarag at five different sites ranged from 53.1 to 73.5 Pa and 2.27 to 2.86, respectively. Values of pCO2 and OMEGAarag ranged from 21.0 to 48.7 Pa and 2.47 to 4.18, respectively, on the Saboga Reef in the seasonally upwelling Gulf of Panama, with the highest pCO2 and lowest OMEGAarag values occurring during upwelling. The Uva Reef, in the nonupwelling Gulf of Chiriqui of Pacific Panama, had mean OMEGAarag values that were always significantly greater than those at the Saboga Reef. Diurnal changes in the seawater CO2 system from reef metabolism on the Uva Reef were magnified at low tide and highly significant differences were measured over depths as shallow as 15 m because of the shallow thermocline that is pervasive throughout the eastern Pacific. These naturally high-CO2 reefs persist near the OMEGAarag distributional threshold for coral reefs and are thus expected to be the first and most affected by ocean acidification.
McPhaden, M.J., K. Ando, B. Bourles, H.P. Freitag, R. Lumpkin, Y. Masumoto, V.S.N. Murty, P. Nobre, M. Ravichandran, J. Vialard, D. Vousden, and W. Yu. The global tropical moored buoy array. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 17 pp. (2010).
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This paper describes the Global Tropical Moored Buoy Array (GTMBA), which is a multi-national effort to provide data in real time for climate research and forecasting. Components of the global array include the Tropical Atmosphere Ocean/Triangle Trans-Ocean Buoy Network (TAO/TRITON) in the Pacific, the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA), and the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) in the Indian Ocean. The phenomena of primary interest span intraseasonal-to-decadal and longer timescales, including: (1) El Niño/Southern Oscillation and its decadal modulation in the Pacific; (2) the meridional gradient mode and equatorial warm events in the Atlantic; (3) the Indian Ocean Dipole; (4) the mean seasonal cycle, including the Asian, African, Australian, and American monsoons; (5) the intraseasonal Madden-Julian Oscillation, which originates in the Indian Ocean but affects all three ocean basins; and (6) trends that may be related to global warming. Sustained, systematic and comprehensive observations are necessary to advance knowledge of critical processes that govern climate dynamics originating in the tropics. Observations are also needed to develop, initialize, and validate climate forecast models that can be used for advance warning of natural hazards and for many other societal benefits. A global tropical perspective is required not only because of the range and complexity of tropical phenomena that affect the climate system, but also because of basin-to-basin interactions that affect the evolution of climatic fluctuations. This paper reviews expansions and enhancements of moored buoy measurement efforts in the tropics since the October 1999 OceanObs99 Conference in San Rafael, France. We will also highlight major scientific advances enabled by the Global Tropical Moored Buoy Array over the past 10 years.
Meinen, C.S., M.O. Baringer, and R.F.Garcia. Florida Current transport variability: An analysis of annual and longer period signals. Deep-Sea Research, Part I, 57(7):835-846 (2010).
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More than forty years of Florida Current transport estimates are combined to study annual and longer-term variability in this important component of the MOC and subtropical gyre. A detailed analysis with error estimates illustrates the difficulties in extracting annual and longer time scale variability given the strong higher frequency energy present. The annual cycle represents less than 10% of the total Florida Current transport variance in a 16-yr segment of the record, while interannual (13-42 month) variability represents only 13% of the total and periods longer than 42 months represent less than 10% of the total. Given the observed high frequency variability of the Florida Current, in order to get a monthly mean that is accurate to within 0.5 Sv (one standard error level) more than 20 daily observations are needed. To obtain an estimate of the annual climatology that is accurate to within 20% of its own standard deviation, at least 24 yr of data are needed. More than 40 observations spread throughout a year are required to obtain an annual mean that is accurate to within 0.5 Sv. Despite these daunting data requirements, there is sufficient data now to evaluate both the annual cycle of the Florida Current transport with a high degree of accuracy and to begin to determine the longer period transport variability. Comparison of the Florida Current, NAO, and wind stress curl records shows that a recently described Sverdrup-based mechanism explains a significant fraction of the long-period variability primarily during the 1986-1998 time window, with other mechanisms clearly dominating before and after.
Metzl, N., A. Corbiere, G. Reverdin, A. Lenton, T. Takahashi, A. Olsen, T. Johannessen, D. Pierrot, R. Wanninkhof, S.R. Olafsdottir, J. Olafsson, and M. Ramonet. Recent acceleration of the sea surface fCO2 growth rate in the North Atlantic subpolar gyre (1993-2008) revealed by winter observations. Global Biogeochemical Cycles, 24:GB4004, doi:10.1029/2009GB003658, 13 pp. (2010).
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Recent studies based on ocean and atmospheric carbon dioxide (CO2) observations, suggesting that the ocean carbon uptake has been reduced, may help explain the increase in the fraction of anthropogenic CO2 emissions that remain in the atmosphere. Is it a response to climate change or a signal of ocean natural variability or both? Regional process analyses are needed to follow the ocean carbon uptake and to enable better attributions of the observed changes. Here, we describe the evolution of the surface ocean CO2 fugacity (fCO2oc) over the period 1993-2008 in the North Atlantic subpolar gyre (NASPG). This analysis is based primarily on observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) conducted at different seasons in the NASPG between Iceland and Canada. The fCO2oc trends based on DIC and TA data are also compared with direct fCO2oc measurements obtained between 2003 and 2007 in the same region. During winters 1993-2003, the fCO2oc growth rate was 3.7 (±0.6) µatm yr-1, higher than in the atmosphere, 1.8 (±0.1) µatm yr-1. This translates to a reduction of the ocean carbon uptake primarily explained by sea surface warming, up to 0.24 (±0.04) °C yr-1. This warming is a consequence of advection of warm water northward from the North Atlantic into the Irminger basin, which occurred as the North Atlantic Oscillation (NAO) index moved into a negative phase in winter 1995/1996. In winter 2001-2008, the fCO2oc rise was particularly fast, between 5.8 (±1.1) and 7.2 (±1.3) µatm yr-1 depending on the region, more than twice the atmospheric growth rate of 2.1 (±0.2) µatm yr-1, and in the winter of 2007-2008 the area was supersaturated with CO2. As opposed to the 1990s, this appears to be almost entirely due to changes in seawater carbonate chemistry, the combination of increasing DIC and decreasing of TA. The rapid fCO2oc increase was not only driven by regional uptake of anthropogenic CO2 but was also likely controlled by a recent increase in convective processes-vertical mixing in the NASPG and cannot be directly associated with NAO variability. The fCO2oc increase observed in 2001-2008 leads to a significant drop in pH of -0.069 (±0.007) decade-1.
Monteiro, P.M.S., U. Schuster, M. Hood, A. Lenton, M. Metzl, A. Olsen, K. Rogers, C. Sabine, T. Takahashi, B. Tilbrook, J. Yoder, R. Wanninkhof, and A.J. Watson. A global sea surface carbon observing system: Assessment of changing sea surface CO2 and air-sea CO2 fluxes. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 13 pp. (2010).
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No abstract.
Montgomery, M.T., and R.K. Smith. On an analytical model for the rapid intensification of tropical cyclones. Quarterly Journal of the Royal Meteorological Society, 136(647):549-551 (2010).
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Stimulated by recent developments in understanding tropical cyclones, we offer an evaluation of an analytical model that has been proposed to explain the rapid intensification of these storms. We articulate a number of concerns with this model, including the neglect of both the vertical momentum equation and the thermodynamic equation, and conclude that it falls a little short of achieving its stated aims.
Montgomery, M.T., Z. Wang, and T.J. Dunkerton. Coarse, intermediate, and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm. Atmospheric Chemistry and Physics, 10(22):10803-10827 (doi:10.5194/acp-10-10803-2010) (2010).
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Recent work has hypothesized that tropical cyclones in the deep Atlantic and eastern Pacific basins develop from within the cyclonic Kelvin cat's eye of a tropical easterly wave critical layer located equatorward of the easterly jet axis. The cyclonic critical layer is thought to be important to tropical cyclogenesis because its cat's eye provides (i) a region of cyclonic vorticity and weak deformation by the resolved flow, (ii) containment of moisture entrained by the developing flow and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the developing proto-vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. This genesis sequence and the overarching framework for describing how such hybrid wave-vortex structures become tropical depressions/storms is likened to the development of a marsupial infant in its mother's pouch, and for this reason has been dubbed the "marsupial paradigm." Here, we conduct the first multi-scale test of the marsupial paradigm in an idealized setting by revisiting the Kurihara and Tuleya problem examining the transformation of an easterly wave-like disturbance into a tropical storm vortex using the WRF model. An analysis of the evolving winds, equivalent potential temperature, and relative vertical vorticity is presented from coarse (28 km), intermediate (9 km), and high resolution (3.1 km) simulations. The results are found to support key elements of the marsupial paradigm by demonstrating the existence of a rotationally-dominant region with minimal strain/shear deformation near the center of the critical layer pouch that contains strong cyclonic vorticity and high saturation fraction. This localized region within the pouch serves as the "attractor" for an upscale "bottom up" development process while the wave pouch and proto-vortex move together. Implications of these findings are discussed in relation to an upcoming field experiment for the most active period of the Atlantic hurricane season in 2010 that is to be conducted collaboratively between the National Oceanic and Atmospheric Administration (NOAA), the National Science Foundation (NSF), and the National Aeronautics and Space Adminstration (NASA).
Montgomery, M.T., L.L. Lussier, R.W. Moore, and Z. Wang. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experimentPart 1: The role of the easterly wave critical layer. Atmospheric Chemistry and Physics, 10(20):9879-9900 (2010).
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An observational and real-time model forecast study of the genesis of Typhoon Nuri during the Tropical Cyclone Structure 2008 (TCS-08) field campaign in the western North Pacific sector is presented. Analysis and observational data show that the surrounding base state is an easterly trade wind flow and the precursor disturbance to Typhoon Nuri is an easterly wave that originates in the ITCZ in the Central Pacific. This disturbance can be tracked more than 10 days prior to tropical storm formation. An overview of the field data is presented here using a newly proposed dynamical framework for tropical cyclone formation within the critical layer of an easterly wave. Despite propagating through a hostile environment ripe with strong vertical wind shear and relatively dry air, the easterly wave critical layer protects the proto-vortex and allows it to gestate until it reaches a more favorable environment. Within this protective Kelvin cats eye flow located within the waves critical layer existed a sweet spot, defined as the intersection between the wave trough and critical latitude, which is the preferred location for tropical cyclogenesis. Global Forecast System Final Analyses and IR satellite imagery, which shows convective bands wrapping around the sweet spot as genesis nears, confirm that this sweet spot is the location where Typhoon Nuri's dominant low-level circulation emerges. United States Air Force C130 and Naval Research Laboratory P3 research flights on 16 and 17 August collected flight-level, dropwindsonde, and Doppler radar data that allowed an evaluation of the dynamic and thermodynamic processes within the cats eye circulation. The dropwindsonde analyses identifies the precursor easterly wave disturbance on 16 August and identifies an area of weak low-level cyclonic circulation on 17 August. Real-time forecasts were produced using operational global prediction model data to support scientific missions during TCS-08. These forecasts were found to be useful in flight planning discussions and predicted Typhoon Nuri's eventual genesis latitude within 1.5 degrees 72 h in advance.
Munoz, E. The human side of climate change. SACNAC News, 12(2):18-19, 32 (2010).
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No abstract.
Munoz, E., C. Wang, and D. Enfield. The Intra-Americas Sea springtime surface temperature anomaly dipole as fingerprint of remote influences. Journal of Climate, 23(1):43-56 (2010).
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The influence of teleconnections on the Intra-Americas Sea (IAS; Gulf of Mexico and Caribbean Sea) has been mostly analyzed from the perspective of the El Niño-Southern Oscillation (ENSO) on the Caribbean Sea (the latter being an extension of the tropical North Atlantic). This emphasis has overlooked: (1) the influence of other teleconnections on the IAS; and (2) which teleconnections affect the Gulf of Mexico climate variability. In this study, we analyze the different fingerprints that major teleconnection patterns have on the IAS during boreal spring. Indices of teleconnection patterns are regressed and correlated to observations of oceanic temperature and atmospheric data from reanalyses and observational data sets. We find that the Pacific teleconnection patterns that influence the IAS SSTs do so affecting the Gulf of Mexico in an opposite manner to the Caribbean Sea. These Pacific climate patterns analyzed are the Pacific North American (PNA) teleconnection, the Pacific Decadal Oscillation (PDO), and the ENSO. The North Atlantic Oscillation (NAO) is related to a lesser degree with the north-south SST anomaly dipole than are Pacific teleconnection patterns. We also find that the IAS influence from the midlatitude Pacific affects mostly the Gulf of Mexico, whereas the influence from the tropical Pacific affects mostly the Caribbean Sea. Therefore, the combination of a warm ENSO event and a positive PNA event induces a strong IAS SST anomaly dipole between the Gulf of Mexico and the Caribbean Sea during spring. By calculating an index that represents the IAS SST anomaly dipole, we find that the dipole forms mostly in response to changes in the air-sea heat fluxes. In the Gulf of Mexico the dominant mechanisms are the air-sea differences in humidity and temperature. The changes in shortwave radiation also contribute to the dipole of net air-sea heat flux. The changes in shortwave radiation arise, in part, by the cloudiness triggered by the air-sea differences in humidity, and also by the changes in the convection cell that connects the Amazon basin to the IAS. Weaker Amazon convection (e.g., in the event of a warm ENSO event) reduces the subsidence over the IAS and henceforth the IAS cloudiness increases (and the shortwave radiation decreases). This study contributes to a greater understanding of how the IAS is influenced by different Pacific and Atlantic teleconnections.
Park, G.-H., R. Wanninkhof, and J. Trinanes. Procedures to create near real-time seasonal air-sea CO2 flux maps. NOAA Technical Memorandum, OAR AOML-98, 14 pp. (2010).
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Seasonal air-sea carbon dioxide (CO2) flux maps were calculated from wind speed data and the difference in CO2 partial pressure between surface seawater (pCO2SW) and the overlying atmosphere. To infer the seasonal variability of global net air-sea CO2 fluxes over the last three decades, we derived the optimum subannual relationships between pCO2SW and the sea surface temperature (SST). These optimum subannual relationships accounted for the variations between pCO2SW and SST and showed significantly better correlations than previous relationships with fixed monthly boundaries. The derived algorithms were then applied to high-resolution SST data to yield changes in pCO2SW on a monthly basis. The pCO2SW values were also combined with a gas transfer velocity estimate derived from high resolution wind products to estimate seasonal fluxes. The seasonal fluxes that are calculated with a three- to six-month lag from real-time can be obtained at http://cwcgom.aoml.noaa.gov/erddap/griddap/aomlcarbonfluxes.graph. Here, we describe in detail the procedures and uncertainties of this product.
Park, G.-H., R. Wanninkhof, S.C. Doney, T. Takahashi, K. Lee, R.A. Feely, C.L. Sabine, J. Trinanes, and I.D. Lima. Variability of global net sea-air CO2 fluxes over the last three decades using empirical relationships. Tellus B, 62(5):352-368 (doi: 10.1111/j.1600-0889.2010.00498.x) (2010).
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The interannual variability of net sea-air CO2 flux for the period 1982-2007 is obtained from a diagnostic model using empirical subannual relationships between climatological CO2 partial pressure in surface seawater (pCO2SW) and sea surface temperature (SST), along with interannual changes in SST and wind speed. These optimum subannual relationships show significantly better correlation between pCO2SW and SST than the previous relationships using fixed monthly boundaries. Our diagnostic model yields an interannual variability of ±0.14 PgC yr-1 (1 sigma) with a 26-year mean of -1.48 PgC yr-1. The greatest interannual variability is found in the equatorial Pacific, and significant variability is also found at northern and southern high-latitudes, depending in part, on which wind product is used. We provide an assessment of our approach by applying it to pCO2SW and SST output from a prognostic global biogeochemical ocean model. Our diagnostic approach applied to this model output shows reasonable agreement with the prognostic model net sea-air CO2 fluxes in terms of magnitude and phase of variability, suggesting that our diagnostic approach can capture much of the observed variability on regional to global scale. A notable exception is that our approach shows significantly less variability than the prognostic model in the Southern Ocean.
Peng, T.-H., and R. Wanninkhof. Increase of anthropogenic CO2 in the Atlantic Ocean in the last two decades. Deep-Sea Research, Part I, 57(6):755-770 (2010).
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Data from the first systematic survey of inorganic carbon parameters on a global scale, the GEOSECS program, are compared with those collected during WOCE/JGOFS to study the changes in carbon and other geochemical properties, and anthropogenic CO2 increase in the Atlantic Ocean from the 1970s to the early 1990s. This first data-based estimate of CO2 increase over this period was accomplished by adjusting the GEOSECS data set to be consistent with recent high-quality carbon data. Multiple Linear Regression (MLR) and extended Multiple Linear Regression (eMLR) analyses to these carbon data are applied by regressing DIC with potential temperature, salinity, AOU, silica, and PO4 in three latitudinal regions for the western and eastern basins in the Atlantic Ocean. The results from MLR (and eMLR provided in parentheses) indicate that the mean anthropogenic CO2 uptake rate in the western basin is 0.70 (0.53) mol m-2 yr-1 for the region north of 151°N; 0.53 (0.36) mol m-2 yr-1 for the equatorial region between 151°N and 151°S; and 0.83 (0.35) mol m-2 yr-1 in the South Atlantic south of 151°S. For the eastern basin an estimate of 0.57 (0.45) m-2 yr-1 is obtained for the equatorial region, and 0.28 (0.34) mol m-2 yr-1 for the South Atlantic south of 151°S. The results of using eMLR are systematically lower than those from MLR method in the western basin. The anthropogenic CO2 increase is also estimated in the upper thermocline from salinity normalized DIC after correction for AOU along the isopycnal surfaces. For these depths the results are consistent with the CO2 uptake rates derived from both MLR and eMLR methods.
Perez, R.C., M.F. Cronin, and W.S. Kessler. Tropical cells and secondary circulation near the northern front of the equatorial Pacific cold tongue. Journal of Physical Oceanography, 40(9):2091-2106 (2010).
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Shipboard measurements and a model are used to describe the mean structure of meridional-vertical tropical cells (TCs) in the central equatorial Pacific, and a secondary circulation associated with the northern front of the cold tongue. The shape of the front is convoluted by the passage of tropical instability waves (TIWs). When velocities are averaged in a coordinate system centered on the instantaneous position of the northern front, the measurements show a near-surface minimum in northward flow north of the surface front (convergent flow near the front). This convergence and inferred downwelling extend below the surface mixed layer, tilt poleward with depth, and are meridionally bounded by regions of divergence and upwelling. Similarly, the model shows that on average, surface cold tongue water moves northward towards the frontal region and dives below tilted front, while subsurface water north of the front moves southward towards the front, upwells, and then moves northward in the surface mixed layer. The model is used to demonstrate that this mean quasi-adiabatic secondary circulation is not a frozen field that migrates with the front, but is instead highly dependent on the phase of the TIWs: southward-upwelling flow on the warm side of the front tends to occur when the front is displaced southward, while northward-downwelling flow on the cold side of the front occurs when the front is displaced northward. Consequently, when averaged in geographic coordinates, the observed and simulated TCs appear to be equatorially-asymmetric, and show little trace of a secondary circulation near the mean front.
Pierrot, D., P. Brown, S. Van Heuven, T. Tanhua, U. Schuster, R. Wanninkhof, and R.M. Key. CARINA TCO2 data in the Atlantic Ocean. Earth System Science Data, 2(2):177-187 (2010).
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Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged in a new data base: the CARINA (CARbon IN the Atlantic) Project. These data have gone through rigorous quality control (QC) procedures so as to improve the quality and consistency of the data as much as possible. Secondary quality control, which involved objective study of data in order to quantify systematic differences in the reported values, was performed for the pertinent parameters in the CARINA data base. Systematic biases in the data have been tentatively corrected in the data products. The products are three merged data files with measured, adjusted and interpolated data of all cruises for each of the three CARINA regions (Arctic Mediterranean Seas, Atlantic and Southern Ocean). Ninety-eight cruises were conducted in the Atlantic defined as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30°S. Here we report the details of the secondary QC which was done on the total dissolved inorganic carbon (TCO2) data and the adjustments that were applied to yield the final data product in the Atlantic. Procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data, are briefly described. Adjustments were applied to TCO2 measurements for 17 of the cruises in the Atlantic Ocean region. With these adjustments, the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the WOCE Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, regional oceanic carbon inventories, uptake rates, and model validation.
Posselt, D.J., and T. Vukicevic. Robust characterization of model physics uncertainty for simulations of deep moist convection. Monthly Weather Review, 138(5):1513-1535 (2010).
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This study explores the functional relationship between model physics parameters and model output variables for the purpose of (1) characterizing the sensitivity of the simulation output to the model formulation and (2) understanding model uncertainty so that it can be properly accounted for in a data assimilation framework. A Markov chain Monte Carlo algorithm is employed to examine how changes in cloud microphysical parameters map to changes in output precipitation, liquid and ice water path, and radiative fluxes for an idealized deep convective squall line. Exploration of the joint probability density function (PDF) of parameters and model output state variables reveals a complex relationship between parameters and model output that changes dramatically as the system transitions from convective to stratiform. Persistent nonuniqueness in the parameter-state relationships is shown to be inherent in the construction of the cloud microphysical and radiation schemes and cannot be mitigated by reducing observation uncertainty. The results reinforce the importance of including uncertainty in model configuration in ensemble prediction and data assimilation, and they indicate that data assimilation efforts that include parameter estimation would benefit from including additional constraints based on known physical relationships between model physics parameters to render a unique solution.
Pouliquen, S., C. Schmid, A. Wong, S. Guinehut, and M. Belbeoch. ARGO data management. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 5 pp. (2010).
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During the past decade Argo has revolutionized the distribution of ocean data within the research community. People used to go to sea, acquire data, process them, submit one or more publications using these data and finally submit them to their national center that periodically transfers the new data to a World Data Center. WOCE had managed to reduce this exclusivity delay to about 2 years. With Argo, it was stated since the beginning that the data will be freely accessible in real-time both on GTS and Internet to serve the meteorological and oceanographic communities in operational and research capacities. Thanks to a great collaboration between the contributing teams, Argo managed to set up efficient and homogeneous data processing in real-time and in delayed-mode, as well as easy access through two Global Data Centers located in USA and France. Similar data system organization has then been endorsed by other components of the GOOS observing system.
Powell, M.D. Observing and analyzing the near-surface wind field in tropical cyclones. In Global Perspectives on Tropical Cyclones: From Science to Mitigation, J.C.L. Chan and J.D. Kepert (eds.). World Scientific Publishing Company, 2nd edition, 177-199 (2010).
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This paper describes the current state of the art in measuring and analyzing surface winds in tropical cyclones. Observing platforms and strategies will be reviewed, along with their advantages and limitations.
Powell, M.D., S.T. Murillo, P.P. Dodge, E.W. Uhlhorn, J.F. Gamache, V. Cardone, A. Cox, S. Otero, N. Carrasco, B. Annane, and R. St. Fleur. Reconstruction of Hurricane Katrina's wind fields for storm surge and wave hindcasting. Ocean Engineering, 37(1):26-36 (2010).
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As the most costly U.S. natural disaster in history, Hurricane Katrina fostered the IPET forensic study to better understand the event. All available observations from several hundred space-, land-, sea-, and aircraft-based measurement platforms were gathered and processed to a common framework for height, exposure, and averaging time, to produce a series of wind field snapshots at 3 h intervals to depict the wind structure of Katrina when in the Gulf of Mexico. The stepped-frequency microwave radiometer was calibrated against GPS sondes to establish the upper range of the instrument and then used to determine the wind field in the storm's core region in concert with airborne Doppler radar winds adjusted to the surface from near the top of the PBL (500 m). The SFMR data were used to develop a method to estimate surface winds from 3 km level reconnaissance aircraft observations, taking into consideration the observed azimuthal variation of the reduction factor. The SFMR method was used to adjust reconnaissance flight-level measurements to the surface in the core region when SFMR and Doppler winds were not available. A variety of coastal and inland mesonet data were employed, including portable towers deployed by Texas Tech University, University of Louisiana at Monroe, and the Florida Coastal Monitoring Program, as well as fixed mesonet stations from Louisiana State Universities Marine Consortium, University of Southern Mississippi, and Agricultural Networks from Louisiana, Mississippi, and Alabama, and the Coastal Estuarine Network of Alabama and Mississippi. Also included were land- (WSR-88D VAD and GBVTD, ASOS, Metar, LLWAS, HANDAR), space- (QuikScat, GOES cloud drift winds, WindSat), and marine- (GPS sondes, Buoys, C-MAN, ships) platforms. The wind fields serve as an analysis of record and were used to provide forcing for wave and storm surge models to produce hindcasts of water levels in the vicinity of flood control structures.
Reed, D.A., M.D. Powell, and J.M. Westerman. Energy infrastructure damage analysis for Hurricane Rita. Natural Hazards Review, 11(3):102-109 (2010).
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In 2005, Hurricane Rita caused significant damage to the energy infrastructure in the Gulf of Mexico region. In the context of this investigation, the energy infrastructure refers to the offshore oil platforms, refineries, and gasoline supply stations in the region, often referred to as the petroleum infrastructure, the natural gas supply lines, and the delivery of electric power. In this paper, we examine the structural damage to the networks as defined by restoration, resilience, and fragility with a focus on the analysis of the electric power delivery disruptions. Our concern is not on the evaluation of risk, but rather to provide those who assess hurricane risk with relevant structural damage prediction models. We provide correlations of hurricane wind speed data with outages. We conclude that high winds alone can create significant damage to the energy infrastructure system.
Riemer, M., M.T. Montgomery, and M.E. Nicholls. A new paradigm for intensity modification of tropical cyclones: Thermodynamic impact of vertical wind shear on the inflow layer. Atmospheric Chemistry and Physics, 10(7):3163-3188 (2010).
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An important roadblock to improved intensity forecasts for tropical cyclones (TCs) is our incomplete understanding of the interaction of a TC with the environmental flow. In this paper, we re-visit the canonical problem of a TC in vertical wind shear on an f-plane. A suite of numerical experiments is performed with intense TCs in moderate to strong vertical shear. We employ a set of simplified model physics, a simple bulk aerodynamic boundary layer scheme and warm rain microphysics, to foster better understanding of the dynamics and thermodynamics that govern the modification of TC intensity. In all experiments the TC is resilient to shear but significant differences in the intensity evolution occur. The ventilation of the TC core with dry environmental air at mid-levels and the dilution of the upper-level warm core are two prevailing hypotheses for the adverse effect of vertical shear on storm intensity. Here we propose an alternative and arguably more effective mechanism for how cooler and drier (lower thetae) air, anti-fuel for the TC power machine, can enter the core region of the TC. Strong and persistent, shear-induced downdrafts flux low thetae air into the boundary layer from above, significantly depressing the thetae values in the storm's inflow layer. Air with lower thetae values enters the eyewall updrafts, considerably reducing eyewall thetae values in the azimuthal mean. When viewed from the perspective of an idealized Carnot-cycle heat engine, a decrease of storm intensity can thus be expected. Although the Carnot cycle model is, if at all, only valid for stationary and axisymmetric TCs, a close association of the downward transport of low thetae into the boundary layer and the intensity evolution offers further evidence in support of our hypothesis. The downdrafts that flush the boundary layer with low thetae air are tied to a quasi-stationary, azimuthal wave number 1 convective asymmetry outside of the eyewall. This convective asymmetry and the associated downdraft pattern extends outwards to approximately 150 km. Downdrafts occur on the vortex scale and form when precipitation falls out from sloping updrafts and evaporates in the unsaturated air below. It is argued that, to zero order, the formation of the convective asymmetry is forced by frictional convergence associated with the azimuthal wave number 1 vortex Rossby wave structure of the outer-vortex tilt. This work points to an important connection between the thermodynamic impact in the near-core boundary layer and the asymmetric balanced dynamics governing the TC vortex evolution.
Roemmich, D., L. Boehme, H. Claustre, H. Freeland, M. Fukasawa, G. Goni, W.J. Gould, N. Gruber, M. Hood, E. Kent, R. Lumpkin, S. Smith, and P. Testor. Integrating the ocean observing system: Mobile platforms. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 27 pp. (2010).
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No abstract.
Rogers, R.F. Convective-scale structure and evolution during a high-resolution simulation of tropical cyclone rapid intensification. Journal of the Atmospheric Sciences, 67(1):44-70 (2010).
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The role of convective-scale processes in a 1.67-km mesoscale model simulation of the rapid intensification (RI) of Hurricane Dennis (2005) is presented. The structure and evolution of inner-core precipitating areas during RI, the statistical properties of precipitation during times experiencing vigorous convection (termed convective bursts here) and how they differ from nonburst times, possible differences in convective bursts associated with RI and those not associated with RI, and the impacts of precipitation morphology on the vortex-scale structure and evolution during RI are all examined. The onset of RI is linked to an increase in the areal extent of convective precipitation in the inner core, while the inner-core stratiform precipitating area remains unchanged and the intensity increases only after RI has begun. RI is not tied to a dramatic increase in the number of convective bursts nor in the characteristics of the bursts, such as burst intensity. Rather, the immediate cause of RI is a significant increase in updraft mass flux, particularly in the lowest 1.5 km. This increase in updraft mass flux is accomplished primarily by updrafts on the order of 1-2 m s-1, representing the bulk of the vertical motion distribution. However, a period of enhanced updraft mass flux in the midlevels by moderate to strong (>5 m s-1) updrafts located inside the radius of maximum winds occurs ~6 h prior to RI, indicating a synergistic relationship between convective bursts and the background secondary circulation prior to RI. This result supports the assertion that both buoyantly driven updrafts and slantwise near-neutral ascent are important features in eyewall structure, evolution, and intensification, including RI.
Rutherford, B., G. Dangelmayr, J. Persing, M. Kirby, and M.T. Montgomery. Lagrangian mixing in an axisymmetric hurricane model. Atmospheric Chemistry and Physics, 10(14):6777-6791 (2010).
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This paper discusses the extension of established Lagrangian mixing measures to make them applicable to data extracted from a 2-D axisymmetric hurricane simulation. Because of the non-steady and unbounded characteristics of the simulation, the previous measures are extended to a moving frame approach to create time-dependent mixing rates that are dependent upon the initial time of particle integration, and are computed for nonlocal regions. The global measures of mixing derived from finite-time Lyapunov exponents, relative dispersion, and a measured mixing rate are applied to distinct regions representing different characteristic feautures within the model. It is shown that these time-dependent mixing rates exhibit correlations with maximal tangential winds during a quasi-steady state, establishing a connection between mixing and hurricane intensity.
Rutherford, B., G. Dangelmayr, J. Persing, W.H. Schubert, and M.T. Montgomery. Advective mixing in a nondivergent barotropic hurricane model. Atmospheric Chemistry and Physics, 10(2):475-497 (2010).
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This paper studies Lagrangian mixing in a two-dimensional barotropic model for hurricane-like vortices. Since such flows show high shearing in the radial direction, particle separation across shear-lines is diagnosed through a Lagrangian field, referred to as R-field, that measures trajectory separation orthogonal to the Lagrangian velocity. The shear-lines are identified with the level-contours of another Lagrangian field, referred to as S-field, that measures the average shear-strength along a trajectory. Other fields used for model diagnostics are the Lagrangian field of finite-time Lyapunov exponents (FTLE-field), the Eulerian Q-field, and the angular velocity field. Because of the high shearing, the FTLE-field is not a suitable indicator for advective mixing, and in particular does not exhibit ridges marking the location of finite-time stable and unstable manifolds. The FTLE-field is similar in structure to the radial derivative of the angular velocity. In contrast, persisting ridges and valleys can be clearly recognized in the R-field, and their propagation speed indicates that transport across shear-lines is caused by Rossby waves. A radial mixing rate derived from the R-field gives a time-dependent measure of flux across the shear-lines. On the other hand, a measured mixing rate across the shear-lines, which counts trajectory crossings, confirms the results from the R-field mixing rate, and shows high mixing in the eyewall region after the formation of a polygonal eyewall, which continues until the vortex breaks down. The location of the R-field ridges elucidates the role of radial mixing for the interaction and breakdown of the mesovortices shown by the model.
Sabine, C.L., R.A. Feely, R. Wanninkhof, T. Takahashi, S. Khatiwala, and G.-H. Park. The global ocean carbon cycle. In State of the Climate in 2009, D.S. Arndt, M.O. Baringer, and M.R. Johnson (eds.). Bulletin of the American Meteorological Society, 91(6):71-75 (2010).
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No abstract.
Send, U., R. Davis, J. Fischer, S. Imawaki, W. Kessler, C. Meinen, B. Owens, D. Roemmich, T. Rossby, D. Rudnick, J. Toole, S. Wijffels, and L. Beal. A global boundary current circulation observating network. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 16 pp. (2010).
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No abstract.
Sereenonchai, K., S. Teerasong, S. Chan-Eam, P. Saetear, N. Choengchan, K. Uraisin, N. Amornthammarong, S. Motomizu, and D. Nacapricha. A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection. Talanta, 81(3):1040-144 (2010).
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This work presents a flow analysis method for direct quantitation of calcium carbonate in cement without pretreatment of the sample. The method is based on online vaporization of CO2 gas following acidification of the sample inside a small chamber that has a flow of acceptor solution passing around it. Solubilization of the CO2 gas into the acceptor stream changes the conductivity of the acceptor solution, causing an increase of signal at the capacitively coupled contactless conductivity detection (C4D) placed at the outlet of the vaporization chamber. This chamber is an adaption from previous work reported on membraneless vaporization (MBL-VP). The method can be used in the quality control of production of mixed cement. These cement materials usually have calcium carbonate contents at high concentration range (e.g., 33-99% (w/w) CaCO3). Analysis of samples by this method is direct and convenient, as it requires no sample pretreatment. The method is low-cost with satisfactory accuracy and acceptable precision.
Shen, B.-W., W.-K. Tao, W.K. Lau, and R. Atlas. Predicting tropical cyclogenesis with a global mesoscale model: Hierarchical multiscale interactions during the formation of Tropical Cyclone Nargis (2008). Journal of Geophysical Research, 115:D14102, doi:10.1029/2009JD013140, 15 pp. (2010).
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Very severe cyclonic storm Nargis devastated Burma (Myanmar) in May 2008, caused tremendous damage and numerous fatalities, and became one of the 10 deadliest tropical cyclones (TCs) of all time. To increase the warning time in order to save lives and reduce economic damage, it is important to extend the lead time in the prediction of TCs like Nargis. As recent advances in high-resolution global models and supercomputing technology have shown the potential for improving TC track and intensity forecasts, the ability of a global mesoscale model to predict TC genesis in the Indian Ocean is examined in this study with the aim of improving simulations of TC climate. High-resolution global simulations with real data show that the initial formation and intensity variations of TC Nargis can be realistically predicted up to 5 days in advance. Preliminary analysis suggests that improved representations of the following environmental conditions and their hierarchical multiscale interactions were the key to achieving this lead time: (1) a westerly wind burst and equatorial trough; (2) an enhanced monsoon circulation with a zero wind shear line; (3) good upper-level outflow with anti-cyclonic wind shear between 200 and 850 hPa; and (4) low-level moisture convergence.
Shibata, T., H.M. Solo-Gabriele, C.D. Sinigalliano, M.L. Gidley, L.R.W. Plano, J.M. Fleisher, J.D. Wang, S.M. Elmir, G. He, M.E. Wright, A.M. Abdelzaher, C. Ortega, D. Wanless, A.C. Garza, J. Kish, T. Scott, J. Hollenbeck, L.C. Backer, and L.E. Fleming. Evaluation of conventional and alternative monitoring methods for a recreational marine beach with nonpoint source of fecal contamination. Environmental Science and Technology, 44(21):8175-8181 (2010).
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The objectives of this work were to compare enterococci (ENT) measurements based on the membrane filter, ENT(MF) with alternatives that can provide faster results including alternative enterococci methods (e.g., chromogenic substrate (CS), and quantitative polymerase chain reaction (qPCR)), and results from regression models based upon environmental parameters that can be measured in real-time. ENT(MF) were also compared to source tracking markers (Staphylococcus aureus, Bacteroidales human and dog markers, and Catellicoccus gull marker) in an effort to interpret the variability of the signal. Results showed that concentrations of enterococci based upon MF (<2 to 3320 CFU/100 mL) were significantly different from the CS and qPCR methods (p < 0.01). The correlations between MF and CS (r = 0.58, p < 0.01) were stronger than between MF and qPCR (r 0.36, p < 0.01). Enterococci levels by MF, CS, and qPCR methods were positively correlated with turbidity and tidal height. Enterococci by MF and CS were also inversely correlated with solar radiation but enterococci by qPCR was not. The regression model based on environmental variables provided fair qualitative predictions of enterococci by MF in real-time, for daily geometric mean levels, but not for individual samples. Overall, ENT(MF) was not significantly correlated with source tracking markers with the exception of samples collected during one storm event. The inability of the regression model to predict ENT(MF) levels for individual samples is likely due to the different sources of ENT impacting the beach at any given time, making it particularly difficult to predict short-term variability of ENT(MF) for environmental parameters.
Sinigalliano, C.D., J.M. Fleisher, M.L. Gidley, H.M. Solo-Gabriele, T. Shibata, L.R.W. Plano, S.M. Elmir, D. Wanless, J. Bartkowiak, R. Boiteau, K. Withum, A.M. Abdelzaher, G. He, C. Ortega, X. Zhu, M.E. Wright, J. Kish, J. Hollenbeck, T. Scott, L.C. Backer, and L.E. Fleming. Traditional and molecular analyses for fecal indicator bacteria in non-point source subtropical recreational marine waters. Water Research, 44(13):3763-3772 (2010).
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The use of enterococci as the primary fecal indicator bacteria (FIB) for the determination of recreational water safety has been questioned, particularly in sub/tropical marine waters without known point sources of sewage. Alternative FIB (such as the Bacteroidales group) and alternative measurement methods (such as rapid molecular testing) have been proposed to supplement or replace current marine water quality testing methods which require culturing enterococci. Moreover, environmental parameters have also been proposed to supplement current monitoring programs. The objective of this study was to evaluate the health risks to humans from exposure to subtropical recreational marine waters with no known point source. The study reported symptoms between one set of human subjects randomly assigned to marine water exposure with intensive environmental monitoring compared with other subjects who did not have exposure. In addition, illness outcomes among the exposed bathers were compared to levels of traditional and alternative FIB (as measured by culture-based and molecular-based methods) and compared to easily measured environmental parameters. Results demonstrated an increase in self-reported gastrointestinal, respiratory and skin illnesses among bathers versus non-bathers. Among the bathers, a dose-response relationship by logistic regression modeling was observed for skin illness, where illness was positively related to enterococci enumeration by membrane filtration (odds ratio = 1.46 [95% confidence interval = 0.97-2.21] per increasing log10 unit of enterococci exposure) and positively related to 24 hour antecedent rain fall (1.04 [1.01-1.07] per increasing millimeters of rain). Acute febrile respiratory illness was inversely related to water temperature (0.74 [0.56-0.98] per increasing degree of water temperature). There were no significant dose response relationships between report of human illness and any of the other FIB or environmental measures. Therefore, for non-point source subtropical recreational marine waters, this study suggests that humans may be at increased risk of reported illness, and that the currently recommended and investigational FIB may not track gastrointestinal illness under these conditions; the relationship between other human illness and environmental measures is less clear.
Smith, R.H. Atlantic-Caribbean exchange through Windward Passage. M.S. thesis. University of Miami, Rosenstiel School of Marine and Atmospheric Science, 130 pp. (2010).
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Windward Passage, which separates the islands of Cuba and Hispaniola, has been recognized as an important inflow channel to the Caribbean Sea for nearly a century. Despite this fact, few direct measurements of the volume transport through the passage exist. In an effort to gain a more comprehensive understanding of the variability, structure, and mean transport associated with flow through Windward Passage, the University of Miamis Rosenstiel School of Marine and Atmospheric Science (RSMAS) and the National Oceanic and Atmospheric Administration (NOAA)s Atlantic Oceanographic and Meteorological Laboratory (AOML) conducted a targeted research study of the passage and surrounding region from October 2003 through February 2005. The project deployed a moored current meter array across the passage and conducted four regional hydrographic surveys. Velocity sections collected across Windward Passage during the four cruises from lowered and hull-mounted acoustic Doppler current profilers show a highly variable field dominated by small-scale eddy features and other areas of locally-intensified flow. However, when integrated horizontally across the passage, the resulting transport-per unit-depth profiles reveal a remarkably robust vertical shear structure. A net inflow of surface and thermocline waters was observed over the four cruises. Beneath these layers, a persistent outflow of intermediate water was found, intensified along the east side of the passage. Deep inflow, just above the sill depth maximum (1680 m), was observed on cruise #1 and, based on data from the moored current meter record, was determined to be a regular flow feature. Together, project velocity sections and water mass analyses of Windward and surrounding passages suggest that Surface Water (SFC), Subtropical Underwater (SUW), and Central Water (CW) primarily arrive at Windward Passage from the east via the Hispaniola Basin. A majority of SFC and SUW enters the Cayman Basin through Windward Passage, while the arriving CW bifurcates, with slightly more than half bypassing the passage and continuing westward north of Cuba. An intermediate water outflow pathway from the Cayman to the Hispaniola Basin via Windward Passage was also observed. Much of this outflow possessed a salinity signature characteristic of upstream inflow regions immediately to the east and south of the Lesser Antilles. Total Windward Passage transport, calculated from the four ship surveys, was found to be an inflow of 3.0 ± 2.8 Sverdrups (1 Sv equivalent to 106 m3 s-1). Data from the 16-month moored current meter array yielded a larger mean inflow of 5.0 ± 1.6 Sv. These numbers are lower than previous estimates based on regional passage transport differences, and suggest that more transport may be entering the Florida Current system through passages in the Bahamas (the Northwest Providence and Old Bahama Channels) than previously thought, with proportionately less flow entering the system through the Caribbean Sea.
Smith, R.K., and M.T Montgomery. Hurricane boundary-layer theory. Quarterly Journal of the Royal Meteorological Society, 136(652):1665-1670 (doi:10.1002/qj.679) (2010).
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In the light of the plethora of definitions for the hurricane boundary layer, we advocate a dynamical definition based on the distribution of a gradient flow. We seek also to clarify the fundamental role of the boundary layer in the hurricane intensification process. In particular, we contrast the differences between unsteady boundary layers that are able to facilitate the spin-up of the vortex above and steady boundary layers that cannot. If slaved to the time-dependent vortex aloft, the latter can spin up the interior vortex only indirectly by changing its thermodynamic properties through vertical advection of these from below and adjustment to thermal wind balance. These differences are highlighted by an analytical demonstration that the application of a zero-vertical-gradient condition on velocity above a steady boundary layer does not provide a direct means of allowing the boundary layer to determine the flow in the interior vortex. This result assumes that frictional forces are negligible at this boundary. Finally, echoing a few previous insights, we question the applicability of conventional boundary-layer theory at radii of strong ascent into the eyewall, where the flow is akin to that of separation in aerodynamic boundary layers.
Smith, S.R., M.A. Bourassa, E.F. Bradley, C. Cosca, C.W. Fairall, G.J. Goni, J.T. Gunn, M. Hood, D.L. Jackson, E.C. Kent, G. Lagerloef, P. McGillivary, L. Petit de al Villeon, R.T. Pinker, E. Schulz, J. Sprintall, D. Stammer, A. Weill, G.A. Wick, and M.J. Yelland. Automated underway oceanic and atmospheric measurements from ships. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.), Venice, Italy, September 21-25, 2009. European Space Agency Publication, WPP-306,14 pp. (2010).
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Merchant, cruise, and research vessels make unique contributions to marine data collection using automated oceanic and atmospheric monitoring systems. The programs making these observations are reviewed along with the wide range of applications to atmospheric and oceanic research and operations. A vision for the next decade outlines where incremental improvements to instruments, platforms, and data stewardship can benefit the community. A series of recommendations are made to meet the challenges of future-ocean observing.
Sun, C., A. Thresher, R. Keeley, N. Hall, M. Hamilton, P. Chinn, A. Tran, G. Goni, L. Petit de la Villeon, T. Carval, L. Cowen, G. Manzella, V. Gopalahrishna, R. Guerrero, F. Reseghetti, Y. Kanno, B. Klein, L. Rickards, A. Baldoni, S. Lin, F. Ji, and Y. Nagaya. The data management system for the Global Temperature and Salinity Profile Programme. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 8 pp. (2010).
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No abstract.
Swart, P.K., L. Greer, B.E. Rosenheim, C.S. Moses, A.J. Waite, A. Winter, R.E. Dodge, and K. Helmle. The 13C Suess effect in scleractinian corals mirror changes in the anthropogenic CO2 inventory of the surface oceans. Geophysical Research Letters, 37(5):L05604, doi:10.1029/2009GL041397 (2010).
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New delta13C data are presented from 10 coral skeletons collected from Florida and elsewhere in the Caribbean (Dominica, Dominican Republic, Puerto Rico, and Belize). These corals range from 96 to 200 years in age and were collected between 1976 and 2002. The change in the delta13C of the skeletons from these corals between 1900 and 1990 has been compared with 27 other published coral records from the Atlantic, Pacific, and Indian Oceans. The new data presented here make possible, for the first time, a global comparison of rates of change in the delta13C value of coral skeletons. Of these records, 64% show a statistically significant (p < 0.05) decrease in delta13C towards the modern day (23 out of 37). This decrease is attributable to the addition of anthropogenically-derived CO2 (13C Suess effect) to the atmosphere. Between 1900 and 1990, the average rate of change of the delta13C in all the coral skeletons living under open oceanic conditions is approximately -0.01 parts per thousand yr-1. In the Atlantic Ocean the magnitude of the decrease since 1960, -0.019 yr-1 ±0.015 parts per thousand, is essentially the same as the decrease in the delta13C of atmospheric CO2 and the delta13C of the oceanic dissolved inorganic carbon (-0.023 to -0.029 parts per thousand yr-1), while in the Pacific and Indian Oceans the rate is more variable and significantly reduced (-0.007 parts per thousand yr-1 ±0.013). These data strongly support the notion that (i) the delta13C of the atmosphere controls ambient delta13C of the dissolved inorganic carbon which in turn is reflected in the coral skeletons, (ii) the rate of decline in the coral skeletons is higher in oceans with a greater anthropogenic CO2 inventory in the surface oceans, (iii) the rate of delta13C decline is accelerating. Superimposed on these secular variations are controls on the delta13C in the skeleton governed by growth rate, insolation, and local water masses.
Tanhua, T., R. Steinfeldt, R.M. Key, P. Brown, N. Gruber, R. Wanninkhof, F. Perez, A. Kortzinger, A. Velo, U. Schuster, S. van Heuven, J.L. Bullister, I. Stendardo, M. Hoppema, A. Olsen, A. Kozyr, D. Pierrot, C. Schirnick, and D.W.R. Wallace. Atlantic Ocean CARINA data: Overview and salinity adjustments. Earth System Science Data, 2(1):17-34 (2010).
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Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean). The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e., secondary quality control. Systematic biases found in the data have been corrected in the three data products: merged data files with measured, calculated, and interpolated data for each of the three CARINA regions, i.e., the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30°S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control) for salinity for this data set. Procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data, are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.
Teerasong, S., S. Chan-Eam, K. Sereenonchai, N. Amornthammarong, N. Ratanawimarnwong, and D. Nacapricha. A reagent-free SIA module for monitoring of sugar, color, and dissolved CO2 content in soft drinks. Analytica Chimica Acta, 668(1):47-53 (2010).
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This work presents a new sequential injection analysis (SIA) method and a module for simultaneous and real-time monitoring of three key parameters for the beverage industry, i.e., the sugar content (measured in Brix), color, and dissolved CO2. Detection of the light reflection at the liquid interface (the Schlieren effect) of sucrose and water was utilized for sucrose content measurement. A near infrared LED (890 ± 40 nm) was chosen as the light source to ensure that all the ingredients and dyes in the soft drinks did not interfere by contributing light absorption. A linear calibration was obtained for sucrose over a wide concentration range (3.1-46.5 Brix). The same module can be used to monitor the color of the soft drink, as well as the dissolved CO2 during production. For measuring the color, the sample is segmented between air plugs to avoid dispersion. An RGB-LED was chosen as the light source in order to make this module applicable to a wide range of colored samples. The module also has a section where dissolved CO2 is measured via vaporization of the gas from the liquid phase. Dissolved CO2, in a flowing acceptor stream of water resulting in the change of the acceptor conductivity, is detected using an in-house capacitively coupled contactless conductivity detector (C4D). The module includes a vaporization unit that is also used to degas the carbonated drink, prior to the measurements of sucrose and color within the same system. The method requires no chemicals and is therefore completely friendly to the environment.
Teerasong, S., N. Amornthammarong, K. Grudpan, N. Teshima, T. Sakai, D. Nacapricha, and N. Ratanawimarnwong. A multiple processing hybrid flow system for analysis of formaldehyde contamination in food. Analytical Sciences, 26(5):629-633 (2010).
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This work proposes a flow system suitable for the rapid screening of formaldehyde contaminated in food. The system is based on the concept of a flow analyzer with a Hantzsch reaction. An operating procedure was developed for multiple tasking and high sample throughput. This resulted in a significant sample throughput of 51 samples h-1. Under the optimized conditions, linear calibration from 10 to 100 µM was obtained. The system gave a limit of detection and a limit of quantitation of 0.06 and 0.10 mg kg-1, respectively. The system was successfully applied to rehydrated dry squids, vegetables, and mushrooms.
Testor, P., G. Meyers, C. Pattiaratchi, R. Bachmayer, D. Hayes, S. Pouliquen, L. Petit de la Villeon, T. Carval, A. Ganachaud, L. Gourdeau, L. Mortier, H. Claustre, V. Taillandier, P. Lherminier, T. Terre, M. Visbeck, J. Karstensen, G. Krahmann, A. Alvarez, M. Rixen, P.-M. Poulain, S. Osterhus, J. Tintore, S. Ruiz, B. Garau, D. Smeed, G. Griffiths, L. Merckelbach, T. Sherwin, C. Schmid, J.A. Barth. O. Schofield, S. Glenn, J. Kohut, M.J. Perry, C. Eriksen, U. Send, R. Davis, D. Rudnick, J. Sherman, C. Jones, D. Webb, C. Lee, and B. Owens. Gliders as a component of future observing systems. In OceanObs09: Sustained Ocean Observations and Information for Society (Volume 2), J. Hall, D.E. Harrison, and D. Stammer (eds.). European Space Agency Publication, WPP-306, 22 pp. (2010).
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The aim of this community white paper is to make recommendations for a glider component of a global ocean observing system. We first recommend the adoption of an ARGO-like data system for gliders. Then, we argue that combining glider deployments with the other components (ships, moorings, floats and satellites) will considerably enhance our capacity for observing the ocean by filling gaps left by the other observing systems. Gliders could be deployed to sample most of the western and eastern boundary circulations and the regional seas (around 20 basins in the world) which are not well covered by the present global ocean observing system and in the vicinity of fixed point time series stations. These plans already involve people scattered around the world in Australia, Canada, Cyprus, France, Germany, Italy, Norway, Spain, UK,and the USA, and will certainly expand to many other countries. A rough estimate of resources required is about 13M$/Euro for ~20+ gliders permanently at sea during five years in the world ocean, based on present scientific infrastructures.
Tweddle, J.F., P.G. Strutton, D.G. Foley, L. O'Higgins, A.M. Wood, B. Scott, R.C. Everroad, W.T. Peterson, D. Cannon, M. Hunter, and Z. Forster. Relationships among upwelling, phytoplankton blooms, and phycotoxins in coastal Oregon shellfish. Marine Ecology Progress Series, 405:131-145 (2010).
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Climatologies derived from satellite data (1998 to 2007) were used to elucidate seasonal and latitudinal patterns in winds, sea surface temperature (SST), and chlorophyll concentrations (chl) over the Oregon shelf. These were further used to reveal oceanographic conditions normally associated with harmful algal blooms (HABs) and toxic shellfish events along the Oregon coast. South of 43°N, around Cape Blanco, summer upwelling started earlier and finished later than north of 43°N. Spring blooms occur when light limitation is relieved, before the initiation of upwelling, and secondary, more intense blooms occur approximately 2 wk after upwelling is established. North of 45°N, SST and chl are heavily influenced by the Columbia River plume, which delays upwelling-driven cooling of the surface coastal ocean in spring, and causes phytoplankton blooms (as indicated by increased chl) earlier than expected. The presence of saxitoxin in coastal shellfish, which causes paralytic shellfish poisoning, was generally associated with late summer upwelling. The presence of domoic acid in shellfish, which leads to amnesic shellfish poisoning, was greatest during the transition between upwelling and downwelling regimes. This work demonstrates that satellite data can indicate physical situations when HABs are more likely to occur, thus providing a management tool useful in predicting or monitoring HABs.
Vukicevic, T., O. Coddington, and P. Pilewskie. Characterizing the retrieval of cloud properties from optical remote sensing. Journal of Geophysical Research, 115:D20211, doi:10.1029/2009JD012830, 14 pp. (2010).
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This paper presents a new approach to the formal characterization of the optical retrieval of cloud optical thickness and effective droplet radius based on a nonlinear methodology that is derived from a general stochastic inverse problem formulation similar to standard Bayesian estimation theory. The methodology includes efficient use of the precomputed radiative transfer model simulations which are already available in standard retrieval algorithms. Another important property of the methodology is that it does not require performing the retrieval with actual measurements in order to characterize the retrieval results. One utility of this analysis is the quantification of information content in the standard retrieval problem, and the increase of information through adding channels (radiances at different wavelengths) to the inversion. This was demonstrated for the five-wavelength retrieval using airborne hyperspectral shortwave irradiance measurements. The ability of the method to evaluate the impact of observation and radiative transfer model uncertainties on the retrieved cloud properties is also demonstrated. Further benefits from this study will be in its application to the cloud retrieval algorithms to be developed for future space- and airborne instruments. The present study puts forth the framework necessary to quantify that increase in information and to optimize new retrieval algorithms that efficiently accommodate the enhanced measurement space.
Wang, C., and S. Dong. Is the basin-wide warming in the North Atlantic Ocean related to atmospheric carbon dioxide and global warming? Geophysical Research Letters, 37(8):L08707, doi:10.1029/2010GL042743 (2010).
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A basin-wide warming in the North Atlantic Ocean has occurred since the mid-1990s; however, the cause of this basin-wide warming is controversial. Some studies argued that the warming is due to global warming in association with the secular increase of the atmospheric greenhouse gas of carbon dioxide (CO2), while others suggested that it is caused by the Atlantic multidecadal oscillation (AMO), an oscillatory mode occurring in North Atlantic sea surface temperature. Here we show that both global warming and AMO variability make a contribution to the recent basin-wide warming in the North Atlantic and their relative contribution is approximately equal. It is further shown that after removing a linear trend and the seasonal cycle, atmospheric CO2 measured from 1958-2008 varies approximately with the AMO. On the assumption that a linear trend can be removed from the CO2 time series, then there are suggestive similarities between CO2 and AMO temperature anomalies. That is, atmospheric CO2 increases (decreases) when the AMO is in the warm (cold) phase. This would suggest that the recent basin-wide warming of the North Atlantic might contribute to global ocean warming via its associated increase of atmospheric CO2.
Wang, C., and S.-K. Lee. Is hurricane activity in one basin tied to another? Eos, Transactions, American Geophysical Union, 91(10):93-94, doi:10.1029/2009ES002729 (2010).
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No abstract.
Wang, C., S. Dong, and E. Munoz. Seawater density variations in the North Atlantic and the Atlantic meridional overturning circulation. Climate Dynamics, 34(7-8):953-968 (2010).
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Seawater property changes in the North Atlantic Ocean affect the Atlantic meridional overturning circulation (AMOC), which transports warm water northward from the upper ocean and contributes to the temperate climate of Europe, as well as influences climate globally. Previous observational studies have focused on salinity and freshwater variability in the sinking region of the North Atlantic, since it is believed that a freshening North Atlantic basin can slow down or halt the flow of the AMOC. Here we use available data to show the importance of how density patterns over the upper ocean of the North Atlantic affect the strength of the AMOC. For the long-term trend, the upper ocean of the subpolar North Atlantic is becoming cooler and fresher, whereas the subtropical North Atlantic is becoming warmer and saltier. On a multidecadal timescale, the upper ocean of the North Atlantic has generally been warmer and saltier since 1995. The heat and salt content in the subpolar North Atlantic lags that in the subtropical North Atlantic by about 89 years, suggesting a lower latitude origin for the temperature and salinity anomalies. Because of the opposite effects of temperature and salinity on density for both long-term trend and multidecadal timescales, these variations do not result in a density reduction in the subpolar North Atlantic for slowing down the AMOC. Indeed, the variations in the meridional density gradient between the subpolar and subtropical North Atlantic Ocean suggest that the AMOC has become stronger over the past five decades. These observed results are supported by and consistent with some oceanic reanalysis products.
Wang, C., S.-K. Lee, and C.R. Mechoso. Interhemispheric influence of the Atlantic warm pool on the southeastern Pacific. Journal of Climate, 23(2):404-418 (2010).
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The Atlantic warm pool (AWP) is a large body of warm water comprising the Gulf of Mexico, Caribbean Sea, and western tropical North Atlantic. The AWP can vary on seasonal, interannual, and multidecadal time scales. The maximum AWP size is in the boreal late summer and early fall, with the largest extent in the year being about three times the smallest one. The AWP alternates with the Amazon basin in South America as the seasonal heating source for circulations of the Hadley and Walker type in the Western Hemisphere. During the boreal summer/fall, a strong Hadley-type circulation is established, with ascending motion over the AWP and subsidence over the southeastern tropical Pacific. This is accompanied by equatorward flow in the lower troposphere over the southeastern tropical Pacific, as dynamically required by the Sverdrup vorticity balance. It is shown by analyses of observational data and NCAR community atmospheric model simulations that an anomalously large (small) AWP during the boreal summer/fall results in a strengthening (weakening) of the Hadley-type circulation with enhanced descent (ascent) over the southeastern tropical Pacific. It is further demonstratedby using a simple two-level model linearized about a specified background mean statethat the interhemispheric connection between the AWP and the southeastern tropical Pacific depends on the configuration of the background mean zonal winds in the Southern Hemisphere.
Wang, C., H. Liu, and S.-K. Lee. The record-breaking cold temperatures during in the winter of 2009/2010 in the northern hemisphere. Atmospheric Science Letters, 11(3):161-168 (2010).
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In this study, we show that the record-breaking cold temperatures from North America to Europe and Asia during the period of 28 December 2009 to 13 January 2010 were associated with extremely negative values of the North Atlantic Oscillation (NAO) index, which produced northerly surface wind anomalies and caused the southward advection of cold Arctic air. Corresponding to longer-term variations of Pacific and Atlantic sea surface temperatures (SSTs), the downward trend of the NAO has occurred since the early 1990s. It is speculated that if the downward trend of the NAO continues, more frequent cold outbreaks and heavy snow are likely in the coming years.
Wang, G., C. Wang, and R.X. Huang. Interdecadal variability of the Eastward Current in the South China Sea associated with the summer Asian Monsoon. Journal of Climate, 23(22):6115-6123 (doi:10.1175/2010JCLI3607.1) (2010).
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Based on the Simple Ocean Data Assimilation (SODA) dataset and three types of Sverdrup streamfunction, an interdecadal variability of the eastward current in the middle South China Sea (SCS) during summer is identified. Both the pattern and strength of the summer Asian monsoon wind stress curl over the SCS contribute to the interdecadal variability of this current. From 1960 to 1979, the monsoon intensified and the zero wind stress curl line shifted southward. Both the core of positive wind stress curl in the northern SCS and the negative curl in the southern SCS moved southward and thus induced a southward shift of both the southern anticyclonic and northern cyclonic gyres, resulting in a southward displacement of the eastward current associated with these two gyres. In the meantime, the southern (northern) SCS anticyclonic (cyclonic) ocean gyre weakened (strengthened) and therefore also induced the southward shift of the eastward current near the intergyre boundary. In contrast, the eastward current shifted northward from 1980 to 1998 because the monsoon relaxed and the zero wind stress curl line shifted northward. After 1998, the eastward jet moved southward again as the zero wind stress curl line shifted southward and the SCS monsoon strengthened. The eastward current identified from the baroclinic streamfunction moved about 1.7° more southward than that from the barotropic streamfunction, indicating that the meridional position of the eastward current is depth dependent.
Wang, Z., M.T. Montgomery, and T.J. Dunkerton. Genesis of pre-Hurricane Felix (2007), Part 1: The role of the easterly wave critical layer. Journal of the Atmospheric Sciences, 67(6):1711-1729 (2010).
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The formation of pre-Hurricane Felix (2007) in a tropical easterly wave is examined in a two-part study using the Weather Research and Forecasting (WRF) model with a high-resolution nested grid configuration that permits the representation of cloud system processes. The simulation commences during the wave stage of the precursor African easterly-wave disturbance. Here the simulated and observed developments are compared, while in Part II of the study various large-scale analyses, physical parameterizations, and initialization times are explored to document model sensitivities. In this first part, the authors focus on the wave/vortex morphology, its interaction with the adjacent intertropical convergence zone complex, and the vorticity balance in the neighborhood of the developing storm. Analysis of the model simulation points to a bottom-up development process within the wave critical layer and supports the three new hypotheses of tropical cyclone formation proposed recently by Dunkerton, Montgomery, and Wang. It is shown also that low-level convergence associated with the ITCZ helps to enhance the wave signal and extend the wave pouch from the jet level to the top of the atmospheric boundary layer. The region of a quasi-closed Lagrangian circulation within the wave pouch provides a focal point for diabatic merger of convective vortices and their vortical remnants. The wave pouch serves also to protect the moist air inside from dry air intrusion, providing a favorable environment for sustained deep convection. Consistent with the authors earlier findings, the tropical storm forms near the center of the wave pouch via system-scale convergence in the lower troposphere and vorticity aggregation. Components of the vorticity balance are shown to be scale dependent, with the immediate effects of cloud processes confined more closely to the storm center than the overturning Eliassen circulation induced by diabatic heating, the influence of which extends to larger radii.
Wang, Z., M.T. Montgomery, and T.J. Dunkerton. Genesis of pre-Hurricane Felix (2007), Part 2: Warm core formation, precipitation evolution, and predictability. Journal of the Atmospheric Sciences, 67(6):1730-1744 (2010).
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This is the second of a two-part study examining the simulated formation of Atlantic Hurricane Felix (2007) in a cloud-representing framework. Here several open issues are addressed concerning the formation of the storms warm core, the evolution and respective contribution of stratiform versus convective precipitation within the parent waves pouch, and the sensitivity of the development pathway reported in Part I to different model physics options and initial conditions. All but one of the experiments include ice microphysics as represented by one of several parameterizations, and the partition of convective versus stratiform precipitation is accomplished using a standard numerical technique based on the high-resolution control experiment. The transition to a warm-core tropical cyclone from an initially cold-core, lower tropospheric wave disturbance is analyzed first. As part of this transformation process, it is shown that deep moist convection is sustained near the pouch center. Both convective and stratiform precipitation rates increase with time. While stratiform precipitation occupies a larger area even at the tropical storm stage, deep moist convection makes a comparable contribution to the total rain rate at the pregenesis stage, and a larger contribution than stratiform processes at the storm stage. The convergence profile averaged near the pouch center is found to become dominantly convective with increasing deep moist convective activity there. Low-level convergence forced by interior diabatic heating plays a key role in forming and intensifying the near-surface closed circulation, while the midlevel convergence associated with stratiform precipitation helps to increase the midlevel circulation and thereby contributes to the formation and upward extension of a tropospheric-deep cyclonic vortex. Sensitivity tests with different model physics options and initial conditions demonstrate a similar pregenesis evolution. These tests suggest that the genesis location of a tropical storm is largely controlled by the parent waves critical layer, whereas the genesis time and intensity of the protovortex depend on the details of the mesoscale organization, which is less predictable. Some implications of the findings are discussed.
Wanninkhof, R., S.C. Doney, J.L. Bullister, N.M. Levine, M. Warner, and N. Gruber. Detecting anthropogenic CO2 changes in the interior Atlantic Ocean between 1989 and 2005. Journal of Geophysical Research, 115:C11028, 25 pp. (doi:10.1029/2010JC006251) (2010).
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Repeat observations along the meridional Atlantic section A16 from Iceland to 56°S show substantial changes in the total dissolved inorganic carbon (DIC) concentrations in the ocean between occupations from 1989 through 2005. The changes correspond to the expected increase in DIC driven by the uptake of anthropogenic CO2 from the atmosphere, but the DELTA-DIC is more varied and larger, in some locations, than can be explained solely by this process. Concomitant large changes in oxygen (O2) suggest that processes acting on the natural carbon cycle also contribute to DELTA-DIC. Precise partial pressure of CO2 measurements suggest small but systematic increases in the bottom waters. To isolate the anthropogenic CO2 component (DELTA-Canthro) from DELTA-DIC, an extended multilinear regression approach is applied along isopycnal surfaces. This yields an average depth-integrated DELTA-Canthro of 0.53 ± 0.05 mol m-2 yr-1 with maximum values in the temperate zones of both hemispheres and a minimum in the tropical Atlantic. A higher decadal increase in the anthropogenic CO2 inventory is found for the South Atlantic compared to the North Atlantic. This anthropogenic CO2 accumulation pattern is opposite to that seen for the entire Anthropocene up to the 1990s. This change could perhaps be a consequence of the reduced downward transport of anthropogenic CO2 in the North Atlantic due to recent climate variability. Extrapolating the results for this section to the entire Atlantic basin (63°N to 56°S) yields an uptake of 5 ± 1 Pg C decade-1, which corresponds to about 25% of the annual global ocean uptake of anthropogenic CO2 during this period.
Zhang, J.A. Estimation of dissipative heating using low-level in-situ aircraft observations in the hurricane boundary layer. Journal of the Atmospheric Sciences, 67(6):1853-1862 (2010).
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Data collected in the low-level atmospheric boundary layer in five hurricanes by NOAA research aircraft are analyzed to measure turbulence with scales small enough to retrieve the rate of dissipation. A total of 49 flux runs suitable for analysis are identified in the atmospheric boundary layer within 200 m above the sea surface. Momentum fluxes are directly determined using the eddy correlation method, and drag coefficients are also calculated. The dissipative heating is estimated using two different methods: (1) integrating the rate of dissipation in the surface layer; and (2) multiplying the drag coefficient by the cube of surface wind speed. While the latter method has been widely used in theoretical models as well as several numerical models simulating hurricanes, these analyses show that using this method would significantly overestimate the magnitude of dissipative heating. Although the dataset used in this study is limited by the surface wind speed range < 30 m s-1, this work highlights that it is crucial to understand the physical processes related to dissipative heating in the hurricane boundary layer for implementing it into hurricane models.
Zhang, J.A. Spectral characteristics of turbulence in the hurricane boundary layer over ocean between the outer rainbands. Quarterly Journal of the Royal Meteorological Society, 136(649):918-926 (2010).
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Spectra and cospectra of wind velocity, potential temperature, and humidity have been analyzed using data collected in the atmospheric boundary layer in Hurricanes Fabian (2003) and Isabel (2003) during the Coupled Boundary Layer Air- Sea Transfer (CBLAST) hurricane experiment. The spectra and cospectra are normalized following the surface layer scaling methods according to similarity theory. It is found that the CBLAST data gathered in the mixed layer between the outer rain bands below 400 m can be grouped into well-defined curves for spectra of wind velocity, potential temperature and humidity, and for cospectra of momentum and humidity flux. However, the cospectra of sensible heat flux do not exhibit well-defined universal shape. The CBLAST universal shape spectra and cospectra generally resemble the shapes of those from previous studies, but shift to higher frequencies that correspond to smaller wavelengths of turbulent eddies that contain most of the energy. This work highlights the structural difference between the hurricane boundary layer and the standard atmospheric boundary layer over land and ocean.
Zhang, J.-Z., L. Guo, and C.J. Fischer. Abundance and chemical speciation of phosphorus in sediments of the Mackenzie River Delta, the Chukchi Sea, and the Bering Sea: Importance of detrital apatite. Aquatic Geochemistry, 16(3):353-371 (2010).
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Utilizing a sequential extraction technique this study provides the first quantitative analysis on the abundance of sedimentary phosphorus and its partitioning between chemically distinguishable phases in sediments of the Bering Sea, the Chukchi Sea and the Mackenzie River Delta in the western Arctic Ocean. Total sedimentary phosphorus (TSP) was fractionated into five operationally defined phases: (1) adsorbed inorganic and exchangeable organic phosphorus; (2) Fe-bound inorganic phosphorus; (3) authigenic carbonate fluorapatite, biogenic apatite, and calcium carbonate-bound inorganic and organic phosphorus; (4) detrital apatite; and (5) refractory organic phosphorus. TSP concentrations in surface sediments increased from the Chukchi Sea (18 µmol g-1 of dried sediments) to the Bering Sea (22 µmol g-1) and to the Mackenzie River Delta (29 µmol g-1). Among the five pools, detrital apatite phosphorus of igneous or metamorphic origin represents the largest fraction (~43%) of TSP. The second largest pool is the authigenic carbonate fluorapatite, biogenic apatite as well as CaCO3 associated phosphorus (~24% of TSP), followed by the Fe-bound inorganic phosphorus, representing ~20% of TSP. The refractory organic P accounts for ~10% of TSP and the readily exchangeable adsorbed P accounts for only 3.5% of TSP. Inorganic phosphorus dominates all of phosphorus pools, accounting for an average of 87% of the TSP. Relatively high sedimentary organic carbon and total nitrogen contents and low delta13C values in the Mackenzie River Delta together with the dominance of detrital apatite in the TSP demonstrate the importance of riverine inputs in governing the abundance and speciation of sedimentary phosphorus in the Arctic coastal sediments.
**2009**
Aberson, S.D. Regimes or cycles in tropical cyclone activity in the North Atlantic. Bulletin of the American Meteorological Society, 90(1):39-43 (2009).
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The important role of the correct use of statistics in the atmospheric sciences literature is once again emphasized. Despite previous work on this topic, statistical techniques, even very simple ones, continue to be misused or altogether neglected, with the inevitable result of misleading or erroneous conclusions. An example concerning the impact of global climate change and hurricane activity is presented.
Aksoy, A., D.C. Dowell, and C. Snyder. A multicase comparative assessment of the ensemble Kalman filter for assimilation of radar observations, Part I: Storm-scale analyses. Monthly Weather Review, 137(6):1805-1824 (2009).
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The effectiveness of the ensemble Kalman filter (EnKF) for assimilating radar observations at convective scales is investigated for cases whose behaviors span supercellular, linear, and multicellular organization. The parallel EnKF algorithm of the Data Assimilation Research Testbed (DART) is used for data assimilation, while the Weather Research and Forecasting (WRF) Model is employed as a simplified cloud model at 2-km horizontal grid spacing. In each case, reflectivity and radial velocity measurements are utilized from a single Weather Surveillance Radar-1988 Doppler (WSR-88D) within the U.S. operational network. Observations are assimilated every 2 min for a duration of 60 min and correction of folded radial velocities occurs within the EnKF. Initial ensemble uncertainty includes random perturbations to the horizontal wind components of the initial environmental sounding. The EnKF performs effectively and with robust results across all the cases. Over the first 18-30 min of assimilation, the rms and domain-averaged prior fits to observations in each case improve significantly from their initial levels, reaching comparable values of 3-6 m s-1 and 7-10 dBZ. Representation of mesoscale uncertainty, albeit in the simplest form of initial sounding perturbations, is a critical part of the assimilation system, as it increases ensemble spread and improves filter performance. In addition, assimilation of no precipitation observations (i.e., reflectivity observations with values small enough to indicate the absence of precipitation) serves to suppress spurious convection in ensemble members. At the same time, it is clear that the assimilation is far from optimal, as the ensemble spread is consistently smaller than what would be expected from the innovation statistics and the assumed observation-error variance.
Amornthammarong, N., and J.-Z. Zhang. Liquid-waveguide spectrophotometric measurement of low silicate in natural waters. Talanta, 79(3):621-626 (2009).
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This paper describes a robust, sensitive method for measurement of low silicate in natural water. The method is based on the reaction of silicate with ammonium molybdate to form a yellow silicomolybdate complex, which is then reduced to silicomolybdenum blue by ascorbic acid. This method shows no refractive index effect and a small salinity effect that can be corrected for seawater samples. It was found that the use of poly-vinyl alcohol can prevent the precipitation formation in the ammonium molybdate solution and improve the stability of the silicomolybdenum blue complex. The sensitivity of this method is substantially enhanced by using a liquid-waveguide capillary cell. The detection limit is 0.1 M and the working range is 0.1-10 M for using a 2-m liquid-waveguide capillary cell (LWCC). The method can be used for both freshwater and seawater samples and has been used to study the distribution of silicate in surface seawater of Gulf Stream in the Florida Straits.
Amornthammarong, N., D. Nacapricha, K. Sereenonchai, P. Anujarawat, and P. Wilairat. Audible-wave telemetry with PC sound card for remote analysis applications. In Telemetry: Research, Technology, and Applications, D. Barculo and J. Daniels (eds.). Nova Science Publishers, New York, 205-214 (2009).
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This chapter describes the development of a cost-effective telemetric system through a combination of a wireless microphone for signal transmission and a computer sound card for recording of signals in the audible range. Three common communication systems, which are normally used for voice transmission, were compared for data transmission. The final developed telemeter provides a high potential for remote monitoring up to a distance of 30 m with a sampling rate of 10 Hz and 100% accuracy with low noise. The working signal range was from 0 to o2 volts, with resolution of more than a 10 bit A/D. A satisfactorily good precision of 0.1% RSD was achieved. The system works well for wireless monitoring of output from a spectrophotometer and pH meter. This work also demonstrated successful applications of the telemetric system with various chemical analyses in our laboratory.
Ardizonne, J., R. Atlas, R.N. Hoffman, J.C. Jusem, S.M. Leidner, and D.F. Moroni. New multiplatform ocean surface wind product available. EOS, Transactions, American Geophysical Union, 90(27):231 (2009).
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No abstract.
Atlas, R., R.N. Hoffmann, and J. Ardizonne. A cross-calibrated multiple platform ocean surface wind data set. In Ocean Remote Sensing: Methods and Applications, J. Frouin (ed.). Proceedings, SPIE, 7459, doi:10.1117/12.824465, 9 pp. (2009).
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A cross-calibrated, multi-satellite ocean surface wind data is described. It covers the global ocean for the twenty-one year period from 1987 to 2008 with 6-hour and 25-km resolution. This data set is produced using all ocean surface wind speed observations from SSM/I, AMSR-E, and TMI, and all ocean surface wind vector observations from QuikSCAT and SeaWinds. An enhanced variational analysis method (VAM) performs quality control and combines these data with available conventional ship and buoy data and ECMWF analyses. The VAM analyses fit the data used and withheld data very closely and contain small-scale structures not present in operational analyses. These data should be extremely useful to atmospheric and oceanic research, and to air-sea interaction studies.
Atlas, R., R.N. Hoffman, J. Ardizzone, M. Leidner, and J.C. Jusem. Development of a new cross-calibrated, multi-platform (CCMP) ocean surface wind product. Preprint Volume, 13th Conference on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface, Phoenix, AZ, January 11-15, 2009. American Meteorological Society, Boston, 5 pp. (2009).
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No abstract.
Baringer, M.O., C.S. Meinen, G.C. Johnson, T.O. Kanzow, S.A. Cunningham, W.E. Johns, L.M. Beal, J.J.-M. Hirschi, D. Rayner, H.R. Longworth, H.L. Bryden, and J. Marotzke. The meridional overturning circulation. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S59-S62 (2009).
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No abstract.
Bell, G.D., E. Blake, S.B. Goldenberg, T. Kimberlain, C.W. Landsea, R. Pasch, and J. Schemm. Tropical cyclones: Atlantic basin. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S79-S83 (2009).
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No abstract.
Biastoch, A., L.M. Beal, J.R.E. Lutjeharms, and T.G.D. Casal. Variability and coherence of the Agulhas Undercurrent in a high-resolution ocean general circulation model. Journal of Physical Oceanography, 39(10):2417-2435 (2009).
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The Agulhas Current system has been analyzed in a nested high-resolution ocean model and compared to observations. The model shows good performance in the western boundary current structure and the transports off the South African coast. This includes the simulation of the northward-flowing Agulhas Undercurrent. It is demonstrated that fluctuations of the Agulhas Current and Undercurrent around 50-70 days are due to Natal pulses and Mozambique eddies propagating downstream. A sensitivity experiment that excludes those upstream perturbations significantly reduces the variability as well as the mean transport of the undercurrent. Although the model simulates undercurrents in the Mozambique Channel and east of Madagascar, there is no direct connection between those and the Agulhas Undercurrent. Virtual float releases demonstrate that topography is effectively blocking the flow toward the north.
Boehm, A.B., J. Griffith, C. McGee, T.A. Edge, H.M. Solo-Gabriele, R. Whitman, Y. Cao, M. Getrich, J.A. Jay, D. Ferguson, K.D. Goodwin, C.M. Lee, M. Madison, and S.B. Weisberg. Fecal indicator bacteria enumeration in beach sand: A comparison study of extraction methods in medium to coarse sands. Journal of Applied Microbiology, 107(5):1740-1750 (2009).
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The absence of standardized methods for quantifying fecal indicator bacteria (FIB) in sand hinders comparison of results across studies. The purpose of the study was to compare methods for extraction of fecal bacteria from sands and recommend a standardized extraction technique. Twenty-two methods of extracting enterococci and Escherichia coli from sand were evaluated, including multiple permutations of hand shaking, mechanical shaking, blending, sonication, number of rinses, settling time, eluant-to-sand ratio, eluant composition, prefiltration and type of decantation. Tests were performed on sands from California, Florida, and Lake Michigan. Most extraction parameters did not significantly affect bacterial enumeration. ANOVA revealed significant effects of eluant composition and blending; with both sodium metaphosphate buffer and blending producing reduced counts. The simplest extraction method that produced the highest FIB recoveries consisted of 2 min of hand shaking in phosphate-buffered saline or deionized water, a 30-s settling time, one-rinse step and a 10:1 eluant volume to sand weight ratio. This result was consistent across the sand compositions tested in this study but could vary for other sand types.
Boyer, J.N., C.R. Kelble, P.B. Ortner, and D.T. Rudnick. Phytoplankton bloom status: An indicator of water quality condition in the southern estuaries of Florida, USA. Ecological Indicators, 9(6) (Suppl):S56-S67 (2009).
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Altered freshwater inflows have affected circulation, salinity, and water quality patterns of Florida Bay, in turn altering the structure and function of this estuary. Changes in water quality and salinity and associated loss of dense turtle grass and other submerged aquatic vegetation (SAV) in Florida Bay have created a condition in the bay where sediments and nutrients have been regularly disturbed, frequently causing large and dense phytoplankton blooms. These algal and cyanobacterial blooms in turn often cause further loss of more recently established SAV, exacerbating the conditions causing the blooms. Chlorophyll a (CHLA) was selected as an indicator of water quality because it is an indicator of phytoplankton biomass, with concentrations reflecting the integrated effect of many of the water quality factors that may be altered by restoration activities. Overall, we assessed the CHLA indicator as being (1) relevant and reflecting the state of the Florida Bay ecosystem, (2) sensitive to ecosystem drivers (stressors, especially nutrient loading), (3) feasible to monitor, and (4) scientifically defensible. Distinct zones within the bay were defined according to statistical and consensual information. Threshold levels of CHLA for each zone were defined using historical data and scientific consensus. A presentation template of condition of the bay using these thresholds is shown as an example of an outreach product.
Bui, H.-H., R.K. Smith, M.T. Montgomery, and J. Peng. Balanced and unbalanced aspects of tropical cyclone intensification. Quarterly Journal of the Royal Meteorological Society, 135(644):1715-1731 (2009).
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We investigate the extent to which the azimuthally-averaged fields from a three-dimensional, non-hydrostatic, tropical cyclone model can be captured by axisymmetric balance theory. The secondary (overturning) circulation and balanced tendency for the primary circulation are obtained by solving a general form of the Sawyer-Eliassen equation with the diabatic heating, eddy heat fluxes and tangential momentum sources (eddy momentum fluxes, boundary-layer friction and subgrid-scale diffusion) diagnosed from the model. The occurrence of regions of weak symmetric instability at low levels and in the upper-tropospheric outflow layer requires a regularization procedure so that the Sawyer-Eliassen equation remains elliptic. The balanced calculations presented capture a major fraction of the azimuthally-averaged secondary circulation of the three-dimensional simulation except in the boundary layer, where the balanced assumption breaks down and where there is an inward agradient force. In particular, the balance theory is shown to significantly underestimate the low-level radial inflow and therefore the maximum azimuthal-mean tangential wind tendency. In the balance theory, the diabatic forcing associated with the eyewall convection accounts for a large fraction of the secondary circulation. The findings herein underscore both the utility of axisymmetric balance theory and also its limitations in describing the axisymmetric intensification physics of a tropical cyclone vortex.
Burpee, R.W. The Sanders barotropic tropical cyclone track model (SANBAR). In Synoptic-Dynamic Meteorology and Weather Analysis and Forecasting: A Tribute to Fred Sanders, L.F. Bosart and H.B. Bluestein (eds.). Meteorological Monograph, Volume 33, No. 55, American Meteorological Society, 233-240 (2009).
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Sanders designed a barotropic tropical cyclone (TC) track model for the North Atlantic TC basin that became known as SANBAR. It predicted the stream function of the deep layer mean winds (averaged from 1000-100 hPa) that represented the vertically averaged tropical circulations. Originally, the wind input for the operational objective analysis (OA) consisted of winds measured by radiosondes and 44 bogus winds subjectively estimated by analysts at the National Hurricane Center (NHC) that corresponded to the vertically averaged flow over sparsely observed tropical and subtropical oceanic regions. The model covered a fixed regional area and had a grid size of about 154 km. It estimated the initial storm motion solely on the basis of the prevailing flow from the OA, not taking into account the observed storm motion. During 1970, the SANBAR model became the first dynamical TC track model to be run operationally at NHC. The track forecasts of SANBAR were verified from the 1971 TC season when track model verifications began at NHC until its retirement after the 1989 season. The average annual SANBAR forecast track errors are verified relative to CLIPER, the standard no-skill track forecast. Comparison with CLIPER determines the skill of track forecast methods. Verifications are presented for two different versions of the model system used operationally from 1973-84 and 1985-89. In homogeneous comparisons for the former period, SANBARs track forecasts were slightly better than CLIPER at 24-48 h forecast intervals; however, from 1985-89, the average SANBAR track forecast errors from 24-72 h were ~10% more skillful than homogeneous CLIPER track forecasts.
Carsey, T., K.D. Goodwin, J. Hendee, J.R. Proni, C. Sinigalliano, J. Stewart, J.-Z. Zhang, N. Amornthammarong, J. Craynock, S. Cummings, P. Dammann, C. Featherstone, J. Stamates, and K. Sullivan. A glimpse of the Florida Area Coastal Environment (FACE) program. Proceedings, 11th International Coral Reef Symposium, Ft. Lauderdale, FL, July 7-11, 2008. International Society for Reef Studies, 559-563 (2009). (peer reviewed)
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The Florida Area Coastal Environment (FACE) research program gathers a variety of data related to water inputs into the coastal zone of southeast Florida. The water inputs studied include treated wastewater discharges, inlet flows, and upwelling events. Measurements include currents, nutrients, microbial contaminants, and stable isotopes. This report provides a glimpse of the data collected in this program. Data collected from the Boynton inlet point to the significance of this discharge as a source of nutrient and microbiological loads to coastal waters and demonstrate the importance of accounting for all major discharges in order to fully understand the impact of land use and water management decisions on coastal resources.
Casal, T.G.D., L.M. Beal, R. Lumpkin, and W.E. Johns. Structure and downstream evolution of the Agulhas Current system during a quasi-synoptic survey in February-March 2003. Journal of Geophysical Research, 114(C3):C03001, doi:10.1029/2008JC004954 (2009).
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The Agulhas Undercurrent Experiment took place in February-March 2003 off the east coast of South Africa and consisted of four sections of hydrographic and velocity data across the Agulhas Current between 30 and 36°S and connecting offshore sections that formed three closed boxes. An inverse model was applied to the quasi-synoptic data, and results show that the net mass transport at the historical 32°S section had a considerably higher transport of 100 ± 9 Sv than earlier estimates. This high transport falls within the peak-to-peak variability obtained previously from a current meter time series. Several mesoscale cyclonic eddies extending down to intermediate depths were sampled during the survey; in particular, a strong, locally formed shear edge eddy was found inshore of the Agulhas Current at 36°S. Offshore eddies were found to drive considerable onshore-offshore fluxes, resulting in highly variable Agulhas transports from one section to another. After attempting to account for and remove the influence of these eddies on the Agulhas transport, the downstream growth of the Agulhas Current is found to be consistent with the Sverdrup transport variation, within errors. To account for the total magnitude of the Agulhas transport, fluxes from both the Indonesian Throughflow and Indian Ocean overturning must also be taken into account. There is no clear evidence from this study for a significant contribution of inertial recirculation to the Agulhas within this latitude range.
Chassignet, E.P., H.E. Hurlburt, E.J. Metzger, O.M. Smedstad, J.A. Cummings, G.R. Halliwell, R. Bleck, R. Baraille, A.J. Wallcraft, C. Lozano, H.L. Tolman, A. Srinivasan, S. Hankin, P. Cornillon, R. Weisberg, A. Barth, R. He, F. Werner, and J. Wilkin. U.S. GODAE: Global Ocean Prediction with the HYbrid Coordinate Ocean Model (HYCOM). Oceanography, 22(2):64-75 (2009).
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During the past five to ten years, a broad partnership of institutions under NOPP sponsorship has collaborated in developing and demonstrating the performance and application of eddy-resolving, real-time global- and basin-scale ocean prediction systems using the Hybrid Coordinate Ocean Model (HYCOM). The partnership represents a broad spectrum of the oceanographic community, bringing together academia, federal agencies, and industry/commercial entities, and spanning modeling, data assimilation, data management and serving, observational capabilities, and application of HYCOM prediction system outputs. In addition to providing real-time, eddy-resolving global- and basin-scale ocean prediction systems for the U.S. Navy and NOAA, this project also offered an outstanding opportunity for NOAA-Navy collaboration and cooperation, ranging from research to the operational level. This paper provides an overview of the global HYCOM ocean prediction system and highlights some of its achievements. An important outcome of this effort is the capability of the global system to provide boundary conditions to even higher-resolution regional and coastal models.
Chierici, M., A. Olsen, T. Johannessen, J. Trinanes, and R. Wanninkhof. Algorithms to estimate the carbon dioxide uptake in the northern North Atlantic using shipboard observations, satellite, and ocean analysis data. Deep-Sea Research, Part II, 56(8-10):630-639 (2009).
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Observations of the surface-water fugacity of carbon dioxide (fCO2sw) measured during 2005 in the subpolar North Atlantic Ocean (58-62°N, 10-40°W) were used together with in-situ ocean data and remotely sensed data to develop algorithms to estimate fCO2sw. Based on multiple regression, we found that sea-surface temperature (SST), mixed-layer depth (MLD), and chlorophyll a (chl a) contributed significantly to the fit. Two algorithms were developed for periods depending on the presence of chl a data. The correlation coefficient (r2) and the root-mean-square deviation (rms) for the best fit in the period when chl a was observed (20 March-15 October) were 0.720 and ±10.8 µatm, respectively. The best fit for the algorithm for the period when no chl a was present (16 October-19 March) resulted in a r2 of 0.774 and a rms of ±5.6 µatm. Based on these algorithms, we estimated seasonal fields of fCO2sw and the air-sea CO2 flux. The estimated net annual CO2 sink was 0.0058 Gt C yr-1 or 0.6 mol C m-2 yr-1.
Clark, C., D.E. Harrison, M. Johnson, G. Ball, H. Freeland, G.J. Goni, M. Hood, M. McPhaden, D. Meldrum, M. Merrifield, D. Roemmich, C. Sabine, U. Send, R. Weller, S. Wilson, J. Benveniste, H. Bonekamp, C. Donlon, M. Drinkwater, J.-L. Fellous, B.S. Gohil, G. Jacobs, P.-Y. Le Traon, E. Lindstrom, L. Mingsen, K. Nakagawa, and F. Parisot. An overview of the global observing systems relevant to GODAE. Oceanography, 22(3):22-33 (2009).
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A global ocean observing system for the physical climate system, comprising both in situ and satellite components, was conceived largely at the Ocean Observations conference in St. Raphael, France, in October 1999. It was recognized that adequate information was not available on the state of the world ocean or its regional variations to address a range of important societal needs. Subsequent work by the marine carbon community and others in the ocean science and operational communities led to an agreed international plan described in the Global Climate Observing System (GCOS) Implementation Plan (GCOS-92, 2004). This foundation observing system was designed to meet climate requirements, but also supports weather prediction, global and coastal ocean prediction, marine hazard warning systems, transportation, marine environment and ecosystem monitoring, and naval applications. Here, we describe efforts made to reach the goals set out in the international plan. Thanks to these efforts, most of the ice-free ocean above 2000 m is now being observed systematically for the first time, and a global repeat hydrographic survey and selected transport measurements supplement these networks. The system is both integrated and composite. It depends upon in situ and satellite networks that measure the same variable using different sensors. In this way, optimum use is made of all available platforms and sensors to maximize coverage and attain maximum accuracy. Wherever feasible, observations are transmitted in real time or near-real time to maximize their utility, from short-term ocean forecasting to estimation of century-long trends. Because our historical knowledge of oceanic variability is limited, we are learning about the sampling requirements and needed accuracies as the system is implemented and exploited. The system will evolve as technology and knowledge improve. The biggest challenge for the greater oceanographic communityincluding both research and operational componentswill be demonstrating impacts and benefits sufficient to justify the funds needed to complete the observing system, as well as to sustain its funding for the long term.
Conzemius, R.J., and M.T. Montgomery. Clarification on the generation of absolute and potential vorticity in mesoscale convective vortices. Atmospheric Chemistry and Physics, 9(19):7591-7605 (2009).
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In this paper, we clarify several outstanding issues concerning the predominant mechanism of vorticity generation in mesoscale convective vortices (MCVs) in weak to modest baroclinic environments with nonzero Coriolis parameter. We examine also the corresponding diabatic heating profiles of the convective and stratiform components of the MCS and their effects on the concentration and dilution of PV substance.
Dickey, T., N. Bates, R.H. Byrne, G. Chang, F.P. Chavez, R.A. Feely, A.K. Hanson, D.M. Karl, D. Manov, C. Moore, C.L. Sabine, and R. Wanninkhof. The NOPP O-SCOPE and MOSEAN projects: Advanced sensing for ocean observing systems. Oceanography, 22(2):168-181 (2009).
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The National Oceanographic Partnership Program (NOPP) consecutively sponsored the Ocean-Systems for Chemical, Optical, and Physical Experiments (O-SCOPE) and Multi-disciplinary Ocean Sensors for Environmental Analyses and Networks (MOSEAN) projects from 1998 through 2008. The O-SCOPE and MOSEAN projects focused on developing and testing new sensors and systems for autonomous, concurrent measurements of biological, chemical, optical, and physical variables from a diverse suite of stationary and mobile ocean platforms. Design considerations encompassed extended open-ocean and coastal deployments, instrument durability, biofouling mitigation, data accuracy and precision, near-real-time data telemetry, and economythe latter being critical for widespread sensor and system utilization. The complementary O-SCOPE and MOSEAN projects increased ocean sensing and data telemetry capabilities for addressing many societally relevant problems such as global climate change, ocean carbon cycling and sequestration, acidification, eutrophication, anoxia, and ecosystem dynamics, including harmful algal blooms. NOPP support enabled O-SCOPE and MOSEAN to accelerate progress in achieving multiscale, multidisciplinary, sustained observations of the ocean environment. Importantly, both programs produced value-added scientific results, which demonstrated the utility of these new technologies. The NOPP framework fostered strong collaborations among academic, commercial, and government entities, and facilitated technology transfers to the general research community and to long-term observational and observatory programs.
DiNezio, P.N., L.J. Gramer, W.E. Johns, C.S. Meinen, and M.O. Baringer. Observed interannual variability of the Florida Current: Wind forcing and the North Atlantic oscillation. Journal of Physical Oceanography, 39(3):721-736 (2009).
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The role of wind stress curl (WSC) forcing in the observed interannual variability of the Florida Current (FC) transport is investigated. Evidence is provided for baroclinic adjustment as a physical mechanism linking interannual changes in WSC forcing and changes in the circulation of the North Atlantic subtropical gyre. A continuous monthly time series of FC transport is constructed using daily transports estimated from undersea telephone cables near 27°N in the Straits of Florida. This 25-yr-long time series is linearly regressed against interannual WSC variability derived from the NCEPNCAR reanalysis. The results indicate that a substantial fraction of the FC transport variability at 3-12-yr periods is explained by low-frequency WSC variations. A lagged regression analysis is performed to explore hypothetical adjustment times of the wind-driven circulation. The estimated lag times are at least 2 times faster than those predicted by linear beta-plane planetary wave theory. Possible reasons for this discrepancy are discussed within the context of recent observational and theoretical developments. The results are then linked with earlier findings of a low-frequency anticorrelation between FC transport and the North Atlantic Oscillation (NAO) index, showing that this relationship could result from the positive (negative) WSC anomalies that develop between 20° and 30°N in the western North Atlantic during high (low) NAO phases. Ultimately, the observed role of wind forcing on the interannual variability of the FC could represent a benchmark for current efforts to monitor and predict the North Atlantic circulation.
Di Nezio, P.N., A.C. Clement, G.A. Vecchi, B.J. Soden, B.P. Kirtman, and S.-K. Lee. Climate response of the equatorial Pacific to global warming. Journal of Climate, 22(18):4873-4892 (2009).
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The climate response of the equatorial Pacific to increased greenhouse gases is investigated using numerical experiments from 11 climate models participating in the Intergovernmental Panel on Climate Changes Fourth Assessment Report. Multimodel mean climate responses to CO2 doubling are identified and related to changes in the heat budget of the surface layer. Weaker ocean surface currents driven by a slowing down of the Walker circulation reduce ocean dynamical cooling throughout the equatorial Pacific. The combined anomalous ocean dynamical plus radiative heating from CO2 is balanced by different processes in the western and eastern basins: Cloud cover feedbacks and evaporation balance the heating over the warm pool, while increased cooling by ocean vertical heat transport balances the warming over the cold tongue. This increased cooling by vertical ocean heat transport arises from increased near-surface thermal stratification, despite a reduction in vertical velocity. The stratification response is found to be a permanent feature of the equilibrium climate potentially linked to both thermodynamical and dynamical changes within the equatorial Pacific. Briefly stated, ocean dynamical changes act to reduce (enhance) the net heating in the east (west). This explains why the models simulate enhanced equatorial warming, rather than El Niño-like warming, in response to a weaker Walker circulation. To conclude, the implications for detecting these signals in the modern observational record are discussed.
Doney, S.C., I. Lima, R.A. Feely, D.M. Glover, K. Lindsay, N. Mahowald, J.K. Moore, and R. Wanninkhof. Mechanisms governing interannual variability in upper-ocean inorganic carbon system and air-sea CO2 fluxes: Physical climate and atmospheric dust. Deep-Sea Research, Part II, 56(8-10):640-655 (2009).
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We quantify the mechanisms governing interannual variability in the global, upper-ocean inorganic carbon system using a hindcast simulation (1979-2004) of an ecosystem-biogeochemistry model forced with time-evolving atmospheric physics and dust deposition. We analyze the variability of three key, interrelated metrics--air-sea CO2 flux, surface-water carbon dioxide partial pressure pCO2, and upper-ocean dissolved inorganic carbon (DIC) inventory--presenting for each metric global spatial maps of the root mean square (rms) of anomalies from a model monthly climatology. The contribution of specific driving factors is diagnosed using Taylor expansions and linear regression analysis. The major regions of variability occur in the Southern Ocean, tropical Indo-Pacific, and Northern Hemisphere temperate and subpolar latitudes. Ocean circulation is the dominant factor driving variability over most of the ocean, modulating surface dissolved inorganic carbon that in turn alters surface-water pCO2 and air-sea CO2 flux variability (global integrated anomaly rms of 0.34 Pg C yr-1). Biological export and thermal solubility effects partially damp circulation-driven pCO2 variability in the tropics, while in the subtropics, thermal solubility contributes positively to surface-water pCO2 and air-sea CO2 flux variability. Gas transfer and net freshwater inputs induce variability in the air-sea CO2 flux in some specific regions. A component of air-sea CO2 flux variability (global integrated anomaly rms of 0.14 Pg C yr-1) arises from variations in biological export production induced by variations in atmospheric iron deposition downwind of dust source regions. Beginning in the mid-1990s, reduced global dust deposition generates increased air-sea CO2 outgassing in the Southern Ocean, consistent with trends derived from atmospheric CO2 inversions.
Dong, S., S.L. Garzoli, and M.O. Baringer. An assessment of the seasonal mixed layer salinity budget in the Southern Ocean. Journal of Geophysical Research, 114(C12):C12001, doi:10.1029/2008JC005258 (2009).
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The seasonal cycle of mixed layer salinity and its causes in the Southern Ocean are examined by combining remotely sensed and in situ observations. The domain-averaged terms of oceanic advection, diffusion, entrainment, and air-sea freshwater flux (evaporation minus precipitation) are largely consistent with the seasonal evolution of mixed layer salinity, which increases from March to October and decreases from November to February. This seasonal cycle is largely attributed to oceanic advection and entrainment; air-sea freshwater flux plays only a minimal role. Both oceanic advection-diffusion and the freshwater flux are negative throughout the year, i.e., reduce mixed layer salinity, while entrainment is positive year-round, reaching its maximum in May. The advection-diffusion term is dominated by Ekman advection. Although the spatial structure of the air-sea freshwater flux and oceanic processes are similar for the steady state, the magnitude of the freshwater flux is relatively small when compared to that of the oceanic processes. The spatial structure of the salinity tendency for each month is also well captured by the sum of the contributions from the air-sea freshwater flux, advection-diffusion, and entrainment processes. However, substantial imbalances in the salinity budget exist locally, particularly for regions with strong eddy kinetic energy and sparse in situ measurements. Sensitivity tests suggest that a proper representation of the mixed layer depth, a better freshwater flux product, and an improved surface salinity field are all important for closing the mixed layer salinity budget in the Southern Ocean.
Dong, S., S.L. Garzoli, M.O. Baringer, C.S. Meinen, and G.J. Goni. Interannual variations in the Atlantic Meridional Overturning Circulation and its relationship with the net northward heat transport in the South Atlantic. Geophysical Research Letters, 36(20):L20606, doi:10.1029/2009GL039356 (2009).
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Variability of the Atlantic Meridional Overturning Circulation (AMOC) and its effect on the net northward heat transport (NHT) in the South Atlantic are examined using a trans-basin expendable bathythermograph (XBT) high-density line at 35°S (AX18). The time-mean AMOC is 17.9 ± 2.2 Sv during 2002-2007. Although the geostrophic transport dominates the time-mean AMOC, both geostrophic and Ekman transports are important in explaining the AMOC variability. The contributions of geostrophic and Ekman transports to the AMOC show annual cycles, but they are out of phase, resulting in weak seasonal variability of the AMOC. The NHT variability is significantly correlated with the AMOC, where a 1 Sv increase in the AMOC would yield a 0.05 ± 0.01 PW increase in the NHT. Partition of transport into the western and eastern boundaries and interior suggests that, to quantify changes in the AMOC and NHT, it is critical to monitor all three regions.
Dunkerton, T.J., M.T. Montgomery, and Z. Wang. Tropical cyclogenesis in a tropical wave critical layer: Easterly waves. Atmospheric Chemistry and Physics, 9(15):5587-5646 (2009).
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The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a surface low along the wave as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, resembles the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development within the critical layer is given by the intersection of the waves critical latitude and trough axis, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally this marsupial paradigm one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. This translation requires an appropriate gauge that renders translating streamlines and isopleths of translating stream function approximately equivalent to flow trajectories. In the translating frame, the closed circulation is stationary, and a dividing streamline effectively separates air within the critical layer from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because it provides (i) a region of cyclonic vorticity and weak deformation by the resolved flow, (ii) containment of moisture entrained by the gyre and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. These ideas are formulated in three new hypotheses describing the flow kinematics and dynamics, moist thermodynamics and wave/vortex interactions comprising the marsupial paradigm. A survey of 55 named tropical storms in 1998-2001 reveals that actual critical layers sometimes resemble the ideal east-west train of cats eyes, but are usually less regular, with one or more recirculation regions in the translating frame. It is shown that a wave gauge given by the translation speed of the parent wave is the appropriate choice, as well, for isolated proto-vortices carried by the wave. Some implications for entrainment/containment of vorticity and moisture in the cat's eye are discussed from this perspective, based on the observational survey.
Elipot, S., and S.T. Gille. Ekman layers in the Southern Ocean: Spectral models and observations, vertical viscosity and boundary layer depth. Ocean Science, 5(2):115-139 (2009).
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Spectral characteristics of the oceanic boundary-layer response to wind stress forcing are assessed by comparing surface drifter observations from the Southern Ocean to a suite of idealized models that parameterize the vertical flux of horizontal momentum using a first-order turbulence closure scheme. The models vary in their representation of vertical viscosity and boundary conditions. Each is used to derive a theoretical transfer function for the spectral linear response of the ocean to wind stress. The transfer functions are evaluated using observational data. The ageostrophic component of near-surface velocity is computed by subtracting altimeter-derived geostrophic velocities from observed drifter velocities (nominally drogued to represent motions at 15-m depth). Then the transfer function is computed to link these ageostrophic velocities to observed wind stresses. The traditional Ekman model, with infinite depth and constant vertical viscosity is among the worst of the models considered in this study. The model that most successfully describes the variability in the drifter data has a shallow layer of depth O(30-50 m), in which the viscosity is constant and O(100-1000 m2 s-1), with a no-slip bottom boundary condition. The second best model has a vertical viscosity with a surface value O(200 m2 s-1), which increases linearly with depth at a rate O(0.1-1 cm s-1) and a no-slip boundary condition at the base of the boundary layer of depth O(103 m). The best model shows little latitudinal or seasonal variability, and there is no obvious link to wind stress or climatological mixed-layer depth. In contrast, in the second best model, the linear coefficient and the boundary layer depth seem to covary with wind stress. The depth of the boundary layer for this model is found to be unphysically large at some latitudes and seasons, possibly a consequence of the inability of Ekman models to remove energy from the system by other means than shear-induced dissipation. However, the Ekman depth scale appears to scale like the climatological mixed-layer depth.
Elipot, S., and S.T. Gille. Estimates of wind energy input to the Ekman layer in the Southern Ocean from surface drifter data. Journal of Geophysical Research, 114(C6):C06003, doi:10.1029/2008JC005170 (2009).
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The energy input to the upper ocean Ekman layer is assessed for the Southern Ocean by examining the rotary cross spectrum between wind stress and surface velocity for frequencies between 0 and 2 cpd. The wind stress is taken from European Center for Medium-Range Weather Forecasts ERA-40 reanalysis, and drifter measurements from 15 m depth are used to represent surface velocities, with an adjustment to account for the vertical structure of the upper ocean. The energy input occurs mostly through the nonzero frequencies rather than the mean. Phenomenologically, the combination of a stronger anticyclonic wind stress forcing associated with a greater anticyclonic response makes the contribution from the anticyclonic frequencies dominate the wind energy input. The latitudinal and seasonal variations of the wind energy input to the Ekman layer are closely related to the variations of the wind stress, both for the mean and for the time-varying components. The contribution from the near-inertial band follows a different trend, increasing from 30°S to about 45°S and decreasing further south, possibly a consequence of the lack of variance in this band in the drifter and wind stress data.
Elmir, S.M., T. Shibata, H.M. Solo-Gabriele, C.D. Sinigalliano, M.L. Gidley, G. Miller, L.R.W. Plano, J. Kish, K. Withum, and L.E. Fleming. Quantitative evaluation of enterococci and bacteroidales released by adults and toddlers in marine water. Water Research, 43(18):4610-4616 (2009).
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Traditionally, the use of enterococci has been recommended as the fecal indicator bacteria of choice for testing marine recreational water quality, and prior studies have shown that bathers shed large numbers of enterococci into the water. The current study expands upon prior research by evaluating shedding from both toddlers and adults, and by the expansion of measurements to include enterococci shedding via three different methods (membrane filter (MF), chromogenic substrate (CS), and quantitative polymerase chain reaction (qPCR)) and shedding of alternative fecal indicator bacteria (Bacteroidales human markers UCD and HF8 via qPCR). Two sets of experiments were conducted. The first experiment consisted of two groups of 10 adults who bathed together in a large pool. The second study consisted of 14 toddlers who bathed individually in a small pool which allowed for sand recovery. Sand recovery was used to estimate the amount of sand transported on the bodies of toddlers and to estimate the number of fecal indicator bacteria released from this sand. The numbers of estimated enterococci shed per adult ranged from 1.8 x 104 to 2.8 x 106 CFU, from 1.9 x 103 to 4.5 x 106 MPN, and from 3.8 x 105 to 5.5 x 106 GEU based on the MF, CS, and qPCR methods, respectively. The estimated numbers of Bacteroidales human markers ranged from 1.8 x 104 to 1.3 x 106 for UCD, and ranged from the below detection limit to 1.6 x 105 for HF8. The estimated amount of sand transported per toddler (n = 14) into the water column after sand exposure was 8 ± 6 g on average. When normalizing the numbers of enterococci shed from toddlers via sand by the 3.9 body surface area ratio, the differences between toddlers and adults were insignificant. Contributions of sands to the total enterococci (MF) shed per toddler was 3.7 ± 4.4% on average. Although shedding via beach sand may contribute a small fraction of the microbial load during initial bathing, it may have a significant role if bathers go to water repetitively after sand exposure.
Enfield, D.B., C. Wang, and S.-K. Lee. Cross-hemispheric interactions between variability of the American monsoon systems regions. VAMOS Newsletter, 5:11-14 (2009).
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No abstract.
Featherstone, C., J.R. Proni, T.P. Carsey, C. Brown, M. Adler, P. Blackwelder, H. Alsayegh, T. Hood, C. Piela, and D. McCorquodale. Spatial distribution of petroleum hydrocarbons in sediment cores from Blind Pass, St. Pete Beach, Florida. NOAA Technical Memorandum, OAR AOML-97, 252 pp. (CD-ROM) (2009).
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One hundred and one sediment cores were collected to characterize the spatial distribution of petroleum hydrocarbons within and just outside Blind Pass, St. Pete Beach, Florida. Twenty-five percent of the cores exhibited levels of petroleum hydrocarbons above detection limits of the gas chromatograph/flame ionization detector (GC/FID) (0.01 mg/Kg), but at generally low concentrations. Petroleum hydrocarbon speciation studies of these samples (gas chromatography/mass spectroscopy [GC/MS]) indicate above-detection level (1 µg/Kg) petroleum hydrocarbons are similar to the non-volatile petroleum hydrocarbons found in a Bouchard 155 reference sample collected after the 1993 oil spill in the area, but are in a much degraded and weathered state. Individual petroleum hydrocarbons were, in all but one case, below the threshold effective level (TEL) described in the literature (MacDonald, 1994). The petroleum hydrocarbons were primarily found at 100-300 cm depth in Blind Pass cores. Above-detection level petroleum hydrocarbons were generally found in samples from cores in the center of the channel, near the edges of the shoal, and just outside of Blind Pass. A second mixture of hydrocarbons, primarily phthalates, ketones, and ether, was found at relatively shallow core depths (0-99 cm) in the Mid- and North End Channel cores. These suggest a separate source of contamination, possibly storm water runoff. The fuel fluorescence detector (FFD) probe was investigated for its ability to detect petroleum hydrocarbons in marine sediments. When analyzed with the FFD, all sediments from the cores produced peaks of fluorescence, but none above the background levels of Blind Pass native sediments. All but two samples analyzed by GC/FID were below the detection limits (100 ppm) of the FFD. These samples were found in dark-colored sediments. The combination of the detection limits of the instrument, sediment color, and the degraded nature of the heavier weight petroleum hydrocarbons may have resulted in fluorescence outputs below background levels. These studies demonstrate that the distribution of petroleum hydrocarbons within Blind Pass sediments is generally low and patchy. However, 25% of the cores exhibited levels above detection using GC/FID/MS. These cores could be subjected to individual speciation studies which indicate generally below TEL levels and an association of some, but not all, with the 1993 oil spill in Blind Pass. Appendix A provides photographs and tables for sediment subsamples which exhibited total petroleum hydrocarbon concentrations above detection limits, while Appendix B presents the results from fuel fluorescence detector probe analyses. A discussion of the results of the study in relation to sediment quality guidelines and soil cleanup target level guidance documents is included as Appendix C. Some preliminary results using the above techniques on core samples from the nearby Johns Pass are presented in Appendix D.
Fierro, A.O., R.F. Rogers, F.D. Marks, and D.S. Nolan. The impact of horizontal grid spacing on the microphysical and kinematic structures of strong tropical cyclones simulated with the WRF-ARW model. Monthly Weather Review, 137(11):3717-3743 (2009).
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Using the Advanced Weather Research and Forecasting numerical model, the impact of horizontal grid spacing on the microphysical and kinematic structure of a numerically simulated tropical cyclone (TC), and their relationship to storm intensity was investigated with a set of five numerical simulations using input data for the case of Hurricane Rita (2005). The horizontal grid spacing of the parent domain was systematically changed such that the horizontal grid spacing of the inner nest varied from 1 to 5 km by an increment of 1 km, this while keeping geographical dimensions of the domains identical. Within this small range of horizontal grid spacing, the morphology of the simulated storms and the evolution of the kinematic and microphysics field showed noteworthy differences. As grid spacing increased, the model produced a wider, more tilted eyewall, a larger radius of maximum winds, and higher-amplitude, low wavenumber eyewall asymmetries. The coarser-resolution simulations also produced larger volume, areal coverage, and mass flux of updraft speeds 5 m s-1; larger volumes of condensate and ice-phase particles aloft; larger boundary layer kinetic energy; and a stronger secondary circulation. While the contribution of updrafts 5 m s-1 to the total updraft mass flux varied little between the five cases, the contribution of downdrafts 2 m s-1 to the total downdraft mass flux was by far the largest in the finest-resolution simulation. Despite these structural differences, all of the simulations produced storms of similar intensity, as measured by peak 10-m wind speed and minimum surface pressure, suggesting that features in the higher-resolution simulations that tend to weaken TCs (i.e., smaller area of high surface fluxes and weaker total updraft mass flux) compensate for features that favor TC intensity (i.e., smaller-amplitude eyewall asymmetries and larger radial gradients). This raises the possibility that resolution increases in this range may not be as important as other model features (e.g., physical parameterization and initial condition improvements) for improving TC intensity forecasts.
Fierro, A.O., J. Simpson, M.A. LeMone, J.M. Straka, and B.F. Smull. On how hot towers fuel the Hadley cell: An observational and modeling study of line-organized convection in the equatorial trough from TOGA COARE. Journal of the Atmospheric Sciences, 66(9):2730-2746 (2009).
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An airflow trajectory analysis was carried out based on an idealized numerical simulation of the nocturnal 9 February 1993 equatorial oceanic squall line observed over the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) ship array. This simulation employed a nonhydrostatic numerical cloud model, which features a sophisticated 12-class bulk microphysics scheme. A second convective system that developed immediately south of the ship array a few hours later under similar environmental conditions was the subject of intensive airborne quad-Doppler radar observations, allowing observed airflow trajectories to be meaningfully compared to those from the model simulation. The results serve to refine the so-called hot tower hypothesis, which postulated the notion of undiluted ascent of boundary layer air to the high troposphere, which has for the first time been tested through coordinated comparisons with both model output and detailed observations. For parcels originating ahead (north) of the system near or below cloud base in the boundary layer (BL), the model showed that a majority (>62%) of these trajectories were able to surmount the 10-km level in their lifetime, with about 5% exceeding 14-km altitude, which was near the modeled cloud top (15.5 km). These trajectories revealed that during ascent, most air parcels first experienced a quick decrease of equivalent potential temperature (thetae) below 5-km MSL as a result of entrainment of lower ambient thetae air. Above the freezing level, ascending parcels experienced an increase in thetae with height attributable to latent heat release from ice processes consistent with previous hypotheses. Analogous trajectories derived from the evolving observed airflow during the mature stage of the airborne radar-observed system identified far fewer (~5%) near-BL parcels reaching heights above 10 km than shown by the corresponding simulation. This is attributed to both the idealized nature of the simulation and to the limitations inherent to the radar observations of near-surface convergence in the subcloud layer. This study shows that latent heat released above the freezing level can compensate for buoyancy reduction by mixing at lower levels, thus enabling air originating in the boundary layer to contribute to the maintenance of both local buoyancy and the large-scale Hadley cell despite acknowledged dilution by mixing along updraft trajectories. A tropical hot tower should thus be redefined as any deep convective cloud with a base in the boundary layer and reaching near the upper-tropospheric outflow layer.
Gentemann, C.L., P.J. Minnett, J. Sienkiewicz, M. DeMaria, J. Cummings, Y. Jin, J.D. Doyle, L. Gramer, C.N. Barron, K.S. Casey, and C.J. Donlon. MISST: The Multi-sensor Improved Sea Surface Temperature Project. Oceanography, 22(2):76-87 (2009).
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Sea surface temperature (SST) measurements are vital to global weather prediction, climate change studies, fisheries management, and a wide range of other applications. Measurements are taken by several satellites carrying infrared and microwave radiometers, moored buoys, drifting buoys, and ships. Collecting all these measurements together and producing global maps of SST has been a difficult endeavor due in part to different data formats, data location and accessibility, and lack of measurement error estimates. The need for a uniform approach to SST measurements and estimation of measurement errors resulted in the formation of the international Global Ocean Data Assimilation Experiment (GODAE) High Resolution SST Pilot Project (GHRSST-PP). Projects were developed in Japan, Europe, and Australia. Simultaneously, in the United States, the Multi-sensor Improved SST (MISST) project was initiated. Five years later, the MISST project has produced satellite SST data from nine satellites in an identical format with ancillary information and estimates of measurement error. Use of these data in global SST analyses has been improved through research into modeling of the ocean surface skin layer and upper ocean diurnal heating. These data and research results have been used by several groups within MISST to produce high-resolution global maps of SSTs, which have been shown to improve tropical cyclone prediction. Additionally, the new SSTs are now used operationally for marine weather warnings and forecasts.
Gledhill, D.K., R. Wanninkhof, and C.M. Eakin. Observing ocean acidification from space. Oceanography, 22(4):48-60 (2009).
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Space-based observations provide synoptic coverage of surface ocean temperature, winds, sea surface height, and color useful to a wide range of oceanographic applications. These measurements are increasingly applied to monitor large-scale environmental and climate processes that can have an impact on important managed marine resources. From observing the development of harmful algal blooms using ocean color to tracking regions of thermal stress that can induce coral bleaching, satellites are routinely used for environmental monitoring. Here, we demonstrate an approach to monitoring changes in sea surface ocean chemistry in response to ocean acidification as applied to the greater Caribbean region. The method is based on regionally specific empirical algorithms derived from ongoing ship measurements applied to remotely sensed observables. This tool is important for exploring regional to basinwide trends in ocean acidification on seasonal to interannual time scales.
Goni, G.J., and J.A. Knaff. Tropical cyclone heat potential. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S54-S57 (2009).
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No abstract.
Goni, G.J., M. DeMaria, J. Knaff, C. Sampson, I. Ginis, F. Bringas, A. Mavume, C. Lauer, I.-I. Lin, M.M. Ali, P. Sandery, S. Ramos-Buarque, K. Kang, A. Mehra, E. Chassignet, and G.R. Halliwell. Applications of satellite-derived ocean measurements to tropical cyclone intensity forecasting. Oceanography, 22(3):191-197 (2009).
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Sudden tropical cyclone (TC) intensification has been linked with high values of upper ocean heat content contained in mesoscale features, particularly warm ocean eddies, provided that atmospheric conditions are also favorable. Although understanding of air-sea interaction for TCs is evolving, this manuscript summarizes some of the current work being carried out to investigate the role that the upper ocean plays in TC intensification and the use of ocean parameters in forecasting TC intensity.
Goodwin, K.D., and M. Pobuda. Performance of CHROMagarTM Staph aureus and CHROMagarTM MRSA for detection of Staphylococcus aureus in seawater and beach sand: Comparison of culture, agglutination, and molecular analyses. Water Research, 43(19):4802-4811 (2009).
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Beach seawater and sand were analyzed for Staphylococcus aureus and methicillin resistant S. aureus (MRSA) for samples collected from Avalon, and Doheny Beach, CA. Membrane filtration followed by incubation on CHROMagar Staph aureus (SCA) and CHROMagar MRSA (C-MRSA) was used to enumerate S. aureus and MRSA, respectively. Media performance was evaluated by comparing identification via colony morphology and latex agglutination tests to PCR (clfA, 16S, and mecA genes). Due to background color and crowding, picking colonies from membrane filters and streaking for isolation were sometimes necessary. The specificity of SCA and C-MRSA was improved if colony isolates were identified by the presence of a matte halo in addition to mauve color; however routine agglutination testing of isolates did not appear warranted. Using the appearance of a colony on the membrane filter in conjunction with isolate appearance, the positive % agreement, the negative % agreement, and the % positive predictive accuracy for SCA was 84%, 95%, and 99% respectively, and for C-MRSA it was 85%, 98%, and 92%, respectively. Sensitivity and specificity of SCA and C-MRSA with membrane-filtered beach samples were optimized through identification experience, control of filter volume and incubation time, and isolation of colonies needing further identification. With optimization, SCA and C-MRSA could be used for enumeration of S. aureus and MRSA from samples of beach water and sand. For the sites studied here, the frequency of detection of S. aureus ranged from 60 to 76% and 53 to 79% for samples of beach seawater and sand, respectively. The frequency of detection of MRSA ranged from 2 to 9% and 0 to 12% for samples of seawater and sand, respectively.
Goodwin, K.D., L. Matragrano, D. Wanless, C.D. Sinigalliano, and M.J. LaGier. A preliminary investigation of fecal indicator bacteria, human pathogens, and source tracking markers in beach water and sand. Environmental Research Journal, 2(4):395-417 (2009).
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Data suggesting that fecal indicating bacteria may persist and/or regrow in sand has raised concerns that fecal indicators may become uncoupled from sources of human fecal pollution. To investigate this possibility, wet and dry beach sand, beach water, riverine water, canal water, and raw sewage samples were screened by PCR for certain pathogenic microbes and molecular markers of human fecal pollution. The targets included in this study were human specific Bacteroides (HF8 marker), human-specific enterococci (esp gene), Staphylococcus aureus, Escherichia coli 0157:H7, Campylobacter jejuni, and adenovirus. Sewage samples were also tested for Salmonella species. The results were compared to concentrations of enterococci, Escherichia coli, and Bacteroides species, as determined by membrane filtration methods. Molecular analysis yielded positive results for human specific Bacteroides, and S. aureus, in samples of raw sewage. Two of the environmental samples were positive for human specific Bacteroides and one was positive for S. aureus. The PCR screen was negative for other samples and targets, despite exceedance of EPA single sample guidelines for recreational waters on several of the sample dates (5/11 dates). However, estimates of the number of cells delivered to the PCR reaction suggested that few of the samples met the detection limit of the PCR reaction due to a variety of factors. The analysis indicated a need to improve nucleic acid processing in order to enable better delivery of DNA to downstream molecular methods.
Gramer, L.J., E.M. Johns, J.C. Hendee, and C. Hu. Characterization of biologically significant hydrodynamic anomalies on the Florida Reef Tract. Proceedings, 11th International Coral Reef Symposium, Ft. Lauderdale, FL, July 7-11, 2008. International Society for Reef Studies, 470-474 (2009). (peer reviewed)
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The U.S. National Oceanic and Atmospheric Administration (NOAA) Integrated Coral Observing Network (ICON) Project uses artificial-intelligence software to implement heuristic models of coral reef ecosystem response to physical conditions. These models use if-then rules to recognize patterns in environmental data integrated in near real-time from multiple sources. One model is described to detect episodic, biologically significant fluxes acting upon coral reefs in the Florida Reef Tract. Data are gathered from in situ sensors and satellites for three sites near the reef crest: Sombrero Key in the Middle Keys, Molasses Reef in the Upper Keys, and Fowey Rocks off Miami. The model recognizes apparent circulation changes that may impact reef ecology. Criteria are in situ sea-temperature variability at near-tidal frequencies, wind velocity variability, and color-derived satellite chlorophyll-a point data. Model ecological forecasts (ecoforecasts) are verified using secondary data not input to the model, including satellite ocean-color imagery, radar-derived ocean surface currents, and divers reports. Events are characterized as being one of wind-driven upwelling; net transport of eutrophic water from outside the FRT; and interaction of Florida Current frontal features with reef topography, possibly modulated by internal wave-breaking. Multiple events are characterized in a 42-month period in 2005-2008.
Guilyardi, E., A. Wittenberg, A. Fedorov, M. Collins, C. Wang, A. Capotondi, G.J. van Oldenborgh, and T. Stockdale. Understanding El Niño in ocean-atmosphere general circulation models: Progress and challenges. Bulletin of the American Meteorological Society, 90(3):325-340 (2009).
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Determining how El Niño and its impacts may change over the next 10 to 100 years remains a difficult scientific challenge. Ocean-atmosphere coupled general circulation models (CGCMs) are routinely used both to analyze El Niño mechanisms and teleconnections and to predict its evolution on a broad range of time scales, from seasonal to centennial. The ability to simulate El Niño as an emergent property of these models has largely improved over the last few years. Nevertheless, the diversity of model simulations of present-day El Niño indicates current limitations in our ability to model this climate phenomenon and to anticipate changes in its characteristics. A review of the several factors that contribute to this diversity, as well as potential means to improve the simulation of El Niño, is presented.
Halliwell, G.R., A. Barth, R.H. Weisberg, P. Hogan, O.M. Smedstad, and J. Cummings. Impact of GODAE products on nested HYCOM simulations of the West Florida Shelf. Ocean Dynamics, 59(1):139-155 (2009).
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Nested non-assimilative simulations of the West Florida Shelf for 2004-2005 are used to quantify the impact of initial and boundary conditions provided by Global Ocean Data Assimilation Experiment ocean products. Simulations are nested within an optimum interpolation hindcast of the Atlantic Ocean, the initial test of the U.S. Navy Coupled Ocean Data Assimilation system for the Gulf of Mexico, and a global ocean hindcast that used the latter assimilation system. These simulations are compared to one that is nested in a non-assimilative Gulf of Mexico model to document the importance of assimilation in the outer model. Simulations are evaluated by comparing model results to moored Acoustic Doppler Current Profiler measurements and moored sea surface temperature time series. The choice of outer model has little influence on simulated velocity fluctuations over the inner and middle shelf where fluctuations are dominated by the deterministic wind-driven response. Improvement is documented in the representation of alongshore flow variability over the outer shelf, driven in part by the intrusion of the Loop Current and associated cyclones at the shelf edge near the Dry Tortugas. This improvement was realized in the simulation nested in the global ocean hindcast, the only outer model choice that contained a realistic representation of Loop Current transport associated with basin-scale wind-driven gyre circulation and the Atlantic Meridional Overturning Circulation. For temperature, the non-assimilative outer model had a cold bias in the upper ocean that was substantially corrected in the data-assimilative outer models, leading to improved temperature representation in the simulations nested in the assimilative outer models.
Hendee, J.C., L.J. Gramer, D. Manzello, and M. Jankulak. Ecological forecasting for coral reef ecosystems. Proceedings, 11th International Coral Reef Symposium, Ft. Lauderdale, FL, July 7-11, 2008. International Society for Reef Studies, 534-538 (2009). (peer reviewed)
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Assessment of coral reef ecosystems implies the acquisition of precision data and observations appropriate for answering questions about the response of multiple organisms to physical and other environmental stimuli. At the National Oceanic and Atmospheric Administrations Atlantic Oceanographic and Meteorological Laboratory, we model marine organismal response to the environment in terms of a Stimulus/Response Index (S/RI). S/RI is computed using an approach called heuristic programming, from parameters bounded in subjective terms, which are defined numerically by comparing historical data with expert opinion, so as to match research and our understanding of the process in question. The modeled organismal response is called an ecological forecast, or ecoforecast, and relative possibility and intensity of the response is reflected in a rising S/RI. We have had success to date in modeling coral bleaching response to high sea temperatures plus high irradiance and other parameters. The approach requires, a) highly robust instrumentation (in situ, satellite, or other) deployed for long periods and producing high quality data in near real-time, b) a basic understanding of the process, behavior and/or physiology being modeled, and, c) a knowledge of approximate threshold levels for single or synergistically acting environmental parameters that elicit the phenomenon in question.
Heymsfield, A.J., A. Bansemer, G. Heymsfield, and A.O. Fierro. Microphysics of maritime tropical convective updrafts at temperatures from -20° to-60°. Journal of the Atmospheric Sciences, 66(12):3530-3562 (2009).
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Anvils produced by vigorous tropical convection contribute significantly to the earths radiation balance, and their radiative properties depend largely on the concentrations and sizes of the ice particles that form them. These microphysical properties are determined to an important extent by the fate of supercooled droplets, with diameters from 3 to about 20 microns, lofted in the updrafts. The present study addresses the question of whether most or all of these droplets are captured by ice particles or if they remain uncollected until arriving at the -38°C level where they freeze by homogeneous nucleation, producing high concentrations of very small ice particles that can persist and dominate the albedo. Aircraft data of ice particle and water droplet size distributions from seven field campaigns at latitudes from 25°N to 11°S are combined with a numerical model in order to examine the conditions under which significant numbers of supercooled water droplets can be lofted to the homogeneous nucleation level. Microphysical data were collected in pristine to heavily dust-laden maritime environments, isolated convective updrafts, and tropical cyclone updrafts with peak velocities reaching 25 m s-1. The cumulative horizontal distance of in-cloud sampling at temperatures of 20°C and below exceeds 50 000 km. Analysis reveals that most of the condensate in these convective updrafts is removed before reaching the 20°C level, and the total condensate continues to diminish linearly upward. The amount of condensate in small (<50 µm in diameter) droplets and ice particles, however, increases upward, suggesting new droplet activation with an appreciable radiative impact. Conditions promoting the generation of large numbers of small ice particles through homogeneous ice nucleation include high concentrations of cloud condensation nuclei (sometimes from dust), removal of most of the water substance between cloud base and the 38°C levels, and acceleration of the updrafts at mid- and upper levels such that velocities exceed 5-7 m s-1.
Hu, C., F. Muller-Karger, B. Murch, D. Myhre, J. Taylor, R. Luerssen, C. Moses, C. Zhang, L. Gramer, and J. Hendee. Building an automated integrated observing system to detect sea surface temperature anomaly events in the Florida Keys. IEEE Transactions on Geoscience and Remote Sensing, 47(6):1607-1620 (2009).
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Satellite-derived sea surface temperature (SST) images have had limited applications in near-shore and coastal environments due to inadequate spatial resolution, incorrect geocorrection, or cloud contamination. We have developed a practical approach to remove these errors using AVHRR and MODIS 1-km resolution data. The objective was to improve the accuracy of SST anomaly estimates in the Florida Keys and to provide the best quality (in particular, high temporal and spatial resolutions) SST data products for this region. After manual navigation of over 47,000 AVHRR images collected between September 1993 and December 2005, we implemented a cloud-filtering technique that differs from previously published image processing methods. The filter used a 12-year climatology and ±3 day running SST statistics to flag cloud-contaminated pixels. Comparison with concurrent (±0.5 hour) data from the SEAKEYS in situ stations in the Florida Keys showed near-zero bias errors (<0.05°C) in the weekly anomaly for SST anomalies between -3 and 3°C, with standard deviations <0.5°C. The cloud filter was implemented using IDL for near real-time processing of AVHRR and MODIS imagery. The improved SST products were used to detect SST anomalies and to estimate degree-heating-weeks (DHWs) to assess the potential for coral reef stress. The mean, anomaly, and DHW products are updated weekly and accessible on a web site. The SST data at specific geographical locations were also automatically ingested in near real-time into NOAAs Integrated Coral Observing Network (ICON) web-based application to assist in management and decision-making through a novel expert system tool (G2) implemented at NOAA.
Huang, X.-L., and J.-Z. Zhang. Neutral persulfate digestion at sub-boiling temperature in an oven for total dissolved phosphorus determination in natural waters. Talanta, 78(3):1129-1135 (2009).
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A simplified, easily performed persulfate digestion method has been developed to process a large number of water samples for routine determination of total dissolved phosphorus. A neutral potassium persulfate solution (5%, w/v, pH ~6.5) is added to the samples (at 10 mg potassium persulfate per mL of sample), which are then digested at 90°C in an oven for 16 h. This method does not require pH adjustment after digestion because neither an acid nor a base is added to the samples prior to digestion. The full color of phosphoantimonylmolybdenum blue from the digested samples develops within 8 min. Compared with the autoclave method, digestion at sub-boiling temperatures in an oven is safer, and a large number of samples can be heated overnight requiring no constant monitoring. The apparent molar absorptivity (epsilon) of nine organic phosphorus compounds and two condensed inorganic phosphates ranged from 1.17 x 104 to 1.82 x 104L mol-1 cm-1 in both distilled water and artificial seawater matrixes. The average recovery of these phosphorus compounds was 94 ± 11% for the DIW matrix and 90 ± 12% for the ASW matrix. No significant difference in molar absorptivity was observed between the undigested and digested phosphate, especially in the seawater matrix. It is, therefore, suggested that a phosphate solution be directly employed without digestion as the calibration standard for routine determination of total dissolved phosphorus. This method was used to study the spatial distribution of total dissolved phosphorus in the surface waters of Florida Bay.
Jankulak, M., J.C. Hendee, and M. Shoemaker. The instrumental architecture of a Coral Reef Early Warning System (CREWS) station. Proceedings, 11th International Coral Reef Symposium, Ft. Lauderdale, FL, July 7-11, 2008. International Society for Reef Studies, 544-548 (2009). (peer reviewed)
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The Integrated Coral Observing Network (ICON) program has constructed and installed a series of Coral Reef Early Warning System (CREWS) stations which provide a wealth of high-quality meteorological and oceanographic data in near real-time. CREWS stations date back to 2001 with the deployment of an early buoy-type design in the Bahamas. Beginning in 2002, the program shifted to a pylon-type design which was reengineered in 2005, resulting in the modern CREWS stations found in the Bahamas, Puerto Rico, the U.S. Virgin Islands and Jamaica. The CREWS instrumentation architecture described herein has evolved over time into a robust package that, combined with a regimen of regular instrument cleaning and recalibration, has yielded a continuous, long-term, high-quality dataset from these harsh marine environments.
Johnson, G.C., J.M. Lyman, J.K. Willis, S. Levitus, T. Boyer, J. Antonov, C. Schmid, and G.J. Goni. Ocean heat content. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S49-S52 (2009).
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No abstract.
Jones, R.W., H.E. Willoughby, and M.T. Montgomery. Alignment of hurricane-like vortices on f- and beta-planes. Journal of the Atmospheric Sciences, 66(6):1779-1792 (2009).
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A nonlinear, two-layer, vortex-tracking semispectral model (i.e., Fourier transformed in azimuth only) is used to study the evolution of dry, but otherwise hurricane-like, initially tilted vortices in quiescent surroundings on f and beta planes. The tilt projects onto vorticity asymmetries that are dynamically vortex Rossby waves. Since the swirling wind in the principal mean vortex used here decays exponentially outside the eyewall, it has an initial potential vorticity (PV) minimum. The resulting reversal of PV gradient meets the necessary condition for inflectional (i.e., barotropic or baroclinic) instability. Thus, the vortex may be inflectionally stable or unstable. On an f plane, the tilt precesses relatively slowly because the critical radius, where the phase speeds of the waves match the mean swirling flow, is far from the center. An alternative Gaussian-like PV monopole that has a monotonic outward decrease of PV is stable to inflectional instability. It has a smaller critical radius and rapid tilt precession. Generally, vortices with fast tilt precession are more stable, as are stronger vortices in higher latitudes. On a beta plane, the interaction between the symmetric vortex and the planetary PV gradient induces beta gyres that push the vortex poleward and westward. The interaction between the beta gyres and the planetary PV gradient may either create a PV minimum or intensify a minimum inherited from the initial condition. Thus, the nonlinear beta effect reduces the ability of the vortex to recover from initial tilt, relative to the same vortex on an f plane. This result contrasts with previous studies of barotropic vortices on f planes, where the linear and nonlinear solutions were nearly identical.
Katzberg, S.J., and J.P. Dunion. Comparison of reflected GPS wind speed retrievals with dropsondes in tropical cyclones. Geophysical Research Letters, 36(17):L17602, doi:10.1029/2009GL039512 (2009).
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In an earlier communication, data were presented that demonstrated that quasi-specular, L-Band reflection measurements could be used to infer ocean surface winds. Applying an indirect calibration technique, a mean square slope versus surface wind speed was developed and reported. Retrievals using this calibration showed that the resulting surface wind speeds were comparable with other measurements. This report extends the previous results by presenting direct comparisons between GPS dropwindsonde (dropsonde)-reported wind speeds and the Bi-static GPS wind speed retrievals for data sets acquired in 2008. Editing of the Bi-static GPS data will be discussed that takes into effect overland and inside-the-eye winnowing. Data will be presented with a regression line to determine the comparative relationship. It will be shown that good agreement exists between the reflected Bi-static GPS retrieved winds and those reported by the dropsondes when certain well-defined types of data are excluded.
Lee, S.-K., C. Wang, and B.E. Mapes. A simple atmospheric model of the local and teleconnection responses to tropical heating anomalies. Journal of Climate, 22(2):272-284 (2009).
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A minimal complexity model of both the local and remote stationary responses of the atmosphere to tropical heating anomalies is described and demonstrated. Two levels are recast as baroclinic and barotropic components with thermal advection in the tropics neglected. The model is linearized about some idealized and realistic background wind fields and forced with a localized heating for illustration. In the tropics, the baroclinic responses are familiar from the Matsuno-Gill model; these excite barotropic responses by advective interactions with vertical background wind shear. The barotropic signals are in turn transmitted to high latitudes only in the presence of barotropic background westerly winds. For an El Niño-like equatorial heating, the barotropic response has anticyclones to the north and south of the heating reinforcing (opposing) the anticyclonic (cyclonic) baroclinic gyres in the upper (lower) troposphere. With realistic background flows, the model reproduces the hemispheric asymmetry of ENSO teleconnections. Further experiments show that the winter hemisphere is favored mainly because the summer hemispheric subtropical jet is farther from the heating latitude, suggesting that the summer hemisphere can still host robust stationary Rossby waves if the heating occurs in the vicinity of the jet. As an example, it is shown that summer heating over the Atlantic warm pool (AWP) can have a remote influence on the summer climate of North America and Europe.
Lirman, D., and D.P. Manzello. Patterns of resistance and resilience of the stress-tolerant coral Siderastrea radians (Pallas) to sub-optimal salinity and sediment burial. Journal of Experimental Marine Biology and Ecology, 369(1):72-77 (2009).
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The coastal lagoons of south Florida, U.S., experience fluctuating levels of sedimentation and salinity and contain only a subset of the coral species found at the adjacent reefs of the Florida Reef Tract. The dominant species within these habitats is Siderastrea radians, which can reach densities of up to 68 colonies m-2 and is commonly exposed to salinity extremes (< 10 psu to > 37 psu) and chronic sediment burial. In this study, we document the patterns of resistance and resilience of S. radians to sub-optimal salinity levels and sediment burial in a series of short-term, long-term, acute, chronic, single-stressor, and sequential-stressor experiments. S. radians displayed remarkable patterns of resistance and resilience, and mortality was documented only under prolonged (> 48 h) continuous exposure to salinity extremes (15 and 45 psu) and chronic sediment burial. A reduction in photosynthetic rates was documented for all salinity exposures and the decrease in photosynthesis was linearly related to exposure time. Negative impacts on photosynthetic rates were more severe under low salinity (15 psu) than under high salinity (45 psu). Corals exposed to intermediate, low-salinity levels (25 psu) exhibited initial declines in photosynthesis that were followed by temporary increases that may represent transient acclimatization patterns. The impacts of sediment burial were influenced by the duration of the burial period and ranged from a temporary reduction in photosynthesis to significant reductions in growth and tissue mortality. The maintenance of P/R ratios >1 and the rapid (<24 h) recovery of photosynthetic rates after burial periods of 2-24 h indicates that S. radians is able to resist short-term burial periods with minor physiological consequences. However, as burial periods increase and colonies become covered at multiple chronic intervals, sediment burial resulted in extended photosynthetic recovery periods, reduced growth, and mortality. Under normal conditions (i.e., no salinity stress), S. radians was very effective at clearing sediments, and >50% of the colonies surface area was cleared within 1 h. However, clearing rates were influenced by physiological status, and prior exposure to sub-optimal salinity significantly reduced the clearing rates of stressed colonies. The response of S. radians to disturbance documented in this study characterizes this species as highly stress-tolerant and provides an explanation for its present high abundance in both reef and marginal environments. Moreover, the key life-history attributes of S. radians, such as brooding reproductive strategy, small colony size, high stress-tolerance, and high recruitment rates, suggest the potential for this species to replace reef-building taxa under increased disturbance scenarios in Florida and elsewhere in the region.
Lumpkin, R., G.J. Goni, and K. Dohan. Surface current observations. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S57-S59 (2009).
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No abstract.
Manzello, D.P. Reef development and resilience to acute (El Niño warming) and chronic (high-CO2) disturbances in the eastern tropical Pacific: A real-world climate change model. Proceedings, 11th International Coral Reef Symposium, Ft. Lauderdale, FL, July 7-11, 2008. International Society for Reef Studies, 1299-1304 (2009). (peer reviewed)
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It has been recently recognized that eastern tropical Pacific (ETP) coral reefs exist under naturally occurring high-CO2, low carbonate saturation (OMEGA) conditions that encompass the range of expected changes for the entire tropical surface ocean with a doubling and tripling of atmospheric CO2. Holocene reef development positively and linearly tracks OMEGA in the ETP; illustrating the real-world importance of this variable on reef building. Galapagos reef communities have been subject to the most extreme thermal anomalies associated with the El Niño-Southern Oscillation (ENSO) and also experience the lowest OMEGA levels in the ETP. Reef resilience has been so poor in Galapagos that reef structures were completely bioeroded in <10 years after the 1982-83 ENSO. The closure of the Panamanian isthmus 3-3.5 million years ago created the present-day oceanographic conditions responsible for ENSO-related warming events and the upwelling of high-CO2 waters throughout the ETP. These combined acute (ENSO) and chronic (high-CO2) disturbances may help explain why coral reefs are scant and many genera of corals went extinct in the ETP during the late Cenozoic; thus providing a real-world example of the combined thermal and chemical ramifications of climate change on coral reef structure, function, and resilience to disturbance over geologic time.
Manzello, D.P., and J.A. Kleypas. Reef development in a high-CO2 world: Coral reefs of the eastern tropical Pacific. Global Change Newsletter, 73:24 (2009).
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No abstract.
Manzello, D.P. M. Warner, E. Stabenau, J. Hendee, M. Lesser, and M. Jankulak. Remote monitoring of chlorophyll fluorescence in two reef corals during the 2005 bleaching event at Lee Stocking Island, Bahamas. Coral Reefs, 28(1):209-214 (2009).
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Zooxanthellae fluorescence was measured in situ, remotely, and in near real-time with a pulse amplitude modulated (PAM) fluorometer for a colony of Siderastrea siderea and Agaricia tenuifolia at Lee Stocking Island, Bahamas during the Caribbean-wide 2005 bleaching event. These colonies displayed evidence of photosystem II (PS II) inactivation coincident with thermal stress and seasonally high doses of solar radiation. Hurricane-associated declines in temperature and light appear to have facilitated the recovery of maximum quantum yield of PS II within these two colonies, although both corals responded differently to individual storms. PAM fluorometry, coupled with long-term measurement of in situ light and temperature, provides much more detail of coral photobiology on a seasonal time scale and during possible bleaching conditions than sporadic, subjective, and qualitative observations. S. siderea displayed evidence of PS II inactivation over a month prior to the issuing of a satellite-based, sea surface temperature (SST) bleaching alert by the National Oceanic and Atmospheric Administration (NOAA). In fact, recovery had already begun in S. siderea when the bleaching alert was issued. Fluorescence data for A. tenuifolia were difficult to interpret because the shaded parts of a colony were monitored and thus did not perfectly coincide with thermal stress and seasonally high doses of solar radiation as in S. siderea. These results further emphasize the limitations of solely monitoring SST (satellite or in situ) as a bleaching indicator without considering the physiological status of coral-zooxanthellae symbioses.
Marshall, J., A. Andersson, N. Bates, W. Dewar, S. Doney, J. Edson, R. Ferrari, G. Forget, D. Fratantoni, M. Gregg, T. Joyce, K. Kelly, S. Lozier, R. Lumpkin, G. Maze, J. Palter, R. Samelson, K. Silverthorne, E. Skyllingstad, F. Straneo, L. Talley, L. Thomas, J. Toole, and R. Weller. The Climode field campaign: Observing the cycle of convection and restratification over the Gulf Stream. Bulletin of the American Meteorological Society, 90(9):1337-1350 (2009).
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A major oceanographic field experiment is described, which is designed to observe, quantify, and understand the creation and dispersal of weakly stratified fluid known as mode water in the region of the Gulf Stream. Formed in the wintertime by convection driven by the most intense airsea fluxes observed anywhere over the globe, the role of mode waters in the general circulation of the subtropical gyre and its biogeo-chemical cycles is also addressed. The experiment is known as the CLIVAR Mode Water Dynamic Experiment (CLIMODE). Here we review the scientific objectives of the experiment and present some preliminary results.
Masutani, M., R. Atlas, et al. Expanding collaboration in joint OSSEs. Preprint Volume, 13th Conference on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface, Phoenix, AZ, January 11-15, 2009. American Meteorological Society, Boston, 6 pp. (2009).
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No abstract.
Meinen, C.S., D.S. Luther, and M.O. Baringer. Structure, transport, and potential vorticity of the Gulf Stream at 68°W: Revisiting older data sets with new techniques. Deep-Sea Research, Part I, 56(1):41-60 (2009).
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The stream-coordinates mean structure of the Gulf Stream at 68°W is derived using new methods for both defining stream coordinates and interpreting bottom pressure and inverted echo sounder travel times collected during the extensive Synoptic Ocean Prediction Experiment. These new analyses provide pictures of the vertical structure of Gulf Stream flows that are demonstrably dynamically consistent with the density field at all depths, in contrast to previous work that relies on simple vertical interpolations to fill gaps between sparse current meter measurements. This new view of the Gulf Stream suggests a slightly higher total mean transport, with the increases coming from both baroclinic and barotropic components, and slightly stronger recirculation cells, particularly on the southern side. The recirculation of the Gulf Stream appears to have a weak baroclinic component, perhaps 10% of the total. A significant advantage of the methodology is the ability to obtain sensible vertical and horizontal gradients of currents and density so that the vertical and cross-stream structures of the components of the mean potential vorticity can be clearly imaged. One new feature from this calculation is that the along-stream gradient of the cross-stream velocity, a term that is often ignored in potential vorticity analyses, is non-negligible (though small) and is asymmetric about the current axis. Both the derived structure and implied dynamics of the circulation can be significantly altered by small changes to the method of calculating daily stream coordinates, e.g., by carefully filtering out observations in rings or not. Arrays of pressure-equipped inverted echo sounders provide the opportunity (at reasonable cost) for properly defining the stream coordinates of energetic jets such as the Gulf Stream.
Montgomery, M.T., V.S. Nguyen, R.K. Smith, and J. Persing. Do tropical cyclones intensity by WISHE? Quarterly Journal of the Royal Meteorological Society, 135(644):1697-1714 (2009).
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In this paper we seek and obtain a basic understanding of tropical cyclone intensification in three dimensions when precipitation and evaporative-cooling (warm rain) processes are included. Intensification with warm rain physics included is found to be dominated by highly localized deep convective structures possessing strong cyclonic vorticity in their cores, dubbed "Vortical Hot Towers" (VHTs). Unlike previous studies, the findings herein suggest an intensification pathway that is distinct from the "evaporation-wind" feedback mechanism known as wind-induced surface heat exchange (WISHE), which requires a positive feedback between the azimuthal-mean boundary-layer equivalent potential temperature and the azimuthal-mean surface wind speed underneath the eyewall of the storm. Intensification from a finite-amplitude initial vortex is shown to not require this evaporation-wind feedback process. Indeed, when the surface wind speed in the sea-to-air vapour fluxes is capped at a nominal (trade-wind) value, the vortex still intensifies by the same pathway identified in the main experiments via the generation of locally buoyant VHTs and the near-surface convergence that the VHTs induce within the boundary layer. The present findings and interpretations challenge the prevailing view that tropical cyclones are premier examples of vortical systems arising from WISHE. Given the potential significance on our understanding of the dynamics of hurricanes, and given the limitations of the present modelling framework, further tests of these predictions are advocated.
Nolan, D.S., J.A. Zhang, and D.P. Stern. Evaluation of planetary boundary layer parameterizations in tropical cyclones by comparison of in-situ observations and high-resolution simulations of Hurricane Isabel (2003), Part I: Initialization, maximum winds, and the outer core boundary layer. Monthly Weather Review, 137(11):3651-3674 (2009).
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In this study, the first of two parts, the planetary boundary layer (PBL) depicted in high-resolution Weather Research and Forecast Model (WRF) simulations of Hurricane Isabel (2003) is studied and evaluated by direct comparisons with in situ data obtained during the Coupled Boundary Layer and Air-Sea Transfer Experiment (CBLAST). In particular, two boundary layer schemes are evaluated: the Yonsei University (YSU) parameterization and the Mellor-Yamada-Janjic (MYJ) parameterization. Investigation of these schemes is useful since they are available for use with WRF, are both widely used, and are based on entirely different methods for simulating the PBL. In this first part, the model domains and initialization are described. For additional realism of the low-level thermodynamic environment, a simple mixed layer ocean model is used to simulate ocean cooling. The YSU and MYJ schemes are discussed, along with some modifications. Standard measures of the accuracy of the hurricane simulations, such as track, maximum surface wind speed, and minimum surface pressure are described for a variety of parameter choices and for the two parameterizations. The effects on track and intensity of increased horizontal and vertical resolutions are also shown. A modification of the original YSU and MYJ schemes to have ocean roughness lengths more in agreement with recent studies considerably improves the results of both schemes. Instantaneous wind maxima on the innermost grid with 1.33-km resolution are shown to be an accurate representation of the simulated 1-min sustained winds. The simulated boundary layers are evaluated by direct comparison of the PBL as simulated and as observed by in situ data from the CBLAST experiment in the outer core region of the storm. The two PBL schemes and their modified counterparts reproduce the observed PBL remarkably well. Comparisons are also made to the observed vertical fluxes of momentum, heat, and moisture. In Part II, the detailed comparisons of the intensities and structures of the simulated and observed inner-core boundary layers are presented, and the reasons for the differences are discussed.
Nolan, S.D., D.P. Stern, and J.A. ZHANG. Evaluation of planetary boundary layer parameterizations in tropical cyclones by comparison of in-situ observations and high-resolution simulations of Hurricane Isabel (2003), Part II: Inner-core boundary layer and eyewall structure. Monthly Weather Review, 137(11):3675-3698 (2009).
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This is the second of a two-part study of the representation of the planetary boundary layer (PBL) in high-resolution Weather Research and Forecast Model (WRF) simulations of Hurricane Isabel (2003). The Yonsei University (YSU) PBL parameterization and the Mellor-Yamada-Janjic (MYJ) PBL parameterization are evaluated by direct comparison to in situ data obtained by research aircraft. The numerical model, simulation design, details of the PBL schemes, and the representation of the boundary layer in the outer-core were presented in Part I. This part presents a detailed study of the inner-core PBL, including its axisymmetric and asymmetric structures, and comparisons to analyses of dropsonde data from previous studies. Although neither PBL scheme was designed specifically for hurricane conditions, their simulated boundary layers are reasonably good representations of the observed boundary layer. Both schemes reproduce certain unique features of the hurricane boundary layer, such as the separate depths of the well-mixed layer and the inflow layer, and the pronounced wind speed maxima near the top of the inflow layer. Modification of the original YSU and MYJ schemes to have ocean roughness lengths more in agreement with recent studies considerably improves the results of both schemes. Even with these improvements, the MYJ consistently produces larger frictional tendencies in the boundary layer than the YSU scheme, leading to a stronger low-level inflow and a stronger azimuthal wind maximum at the top of the boundary layer. For both schemes, differences in the low-level asymmetries between the simulated and observed wind fields appear to be related to eyewall asymmetries forced by environmental wind shear. The effects of varying horizontal and vertical resolutions are also considered. Increasing the vertical resolution in the PBL results in minor improvements in the inner-core structures. Increasing the horizontal resolution around the eyewall also leads to improved boundary layers, as well as an improvement of the vertical structure of the inner-core wind field. A summary and discussion of the results of both Parts I and II is provided.
Palmer, D.R. Coherent and incoherent scattering by a plume of particles advected by turbulent velocity flow. Journal of the Acoustical Society of America, 126(2):587-598 (2009).
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Studies of acoustic remote sensing of the plumes that result from the injection of particulate matter in the ocean, either naturally or by dumping or dredging activities, have assumed the scattering is incoherent. These plumes are always turbulent, however. The particle density is a passive scalar that is advected by the turbulent velocity flow. The possibility exists, therefore, that the scattered waves from a significant number of particles add coherently as a result of Bragg scattering. In this paper, we investigate this possibility. We derive an expression for the ratio of the coherent intensity to the incoherent one in terms of the turbulent spectrum and the properties of the particles that make up the plume. The sonar is modeled as a high-Q, monostatic, pulsed sonar with arbitrary pulse envelope and arbitrary, but narrow, beam pattern. We apply the formalism to acoustic remote sensing of black smoker hydrothermal plumes. We find that, at most, the coherent intensity is less than 1% of the incoherent one. The implications are that Bragg scattering does not lead to a significant coherent component and in analyses of scattering from this type of plume, one can ignore the complications of turbulence altogether.
Panda, J., M. Sharan, and S.G. Gopalakrishnan. Study of regional-scale boundary layer characteristics over northern India with a special reference to the role of the Thar Desert in regional-scale transport. Journal of Applied Meteorology and Climatology, 48(11):2377-2402 (2009).
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Extensive contrasts of land surface heterogeneities have a pivotal role in modulating boundary layer processes and, consequently, the regional-scale dispersion of air pollutants. The Weather Research and Forecasting (WRF) modeling system has been used to analyze the regional-scale boundary layer features over northern India. Two cases, 9-11 December 2004 and 20-22 May 2005, representing the winter and summer seasons, respectively, are chosen for the simulations. The model results have been compared with the observations from the India Meteorological Department (IMD) and Wyoming Weather Web data archive over three cities: Delhi, Ahmedabad, and Jodhpur. The simulations show that the thermal stratifications and the associated wind patterns are very well supported by land surface characteristics over the region. The results signify that the underlying land surface along with the prevailing hemispheric-scale meteorological processes (synoptic conditions) is the driver of the simulated patterns. The study implies that thermally-driven regional circulations play a major role in the transport of particulate matter from the Thar Desert to Delhi and its neighboring regions during summer.
Pandya, R.E., D.R. Smith, D.J. Charlevoix, W. Hart, M.J. Hayes, S.T. Murillo, K.A. Murphy, D.M. Stanitski, and T.M. Whittaker. A summary of the 16th Symposium on Education. Bulletin of the American Meteorological Society, 90(6):861-865 (2009).
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No abstract.
Pandya, R.E., D.R. Smith, D.J. Charlevoix, S.Q. Foster, R. Hart, M.J. Hayes, M. McGuirk, S.T. Murillo, K.A. Murphy, D.M. Stanitski, and T.M. Whittaker. A summary of the 17th AMS Education Symposium. Bulletin of the American Meteorological Society, 90(10):1545-1548 (2009).
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No abstract.
Peng, G., Z. Garraffo, G.R. Halliwell, O.M. Smedstad, C.S. Meinen, V. Kourafalou, and P. Hogan. Temporal variability of the Florida Current transport at 27°N. In Ocean Circulation and El Niño: New Research, J.A. Long and D.S. Wells (ed.). Nova Science Publishers, New York, 119-137 (2009).
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The variability of the annual cycle of the Florida Current transport and its relationship to the variability of large-scale atmospheric forcing is examined using time series of daily Florida Current transport based on submarine cable voltage measurements from 1982 to 2005. To investigate the impact of large-scale atmospheric forcing variations represented by the North Atlantic Oscillation (NAO), two NAO regimes, strong positive and strong negative, are defined in order to isolate basic characteristics of the annual cycles of the Florida Current transport associated with those two regimes. The strong positive (negative) NAO regime is defined as being when the NAO index is greater (less) than 0.8 (-0.8). A minimum of 30.46 Sv in the Florida Current transport is found in January and a maximum of 33.71 in July with a mean of 32.12 Sv based on daily composites of all cable data, which is consistent with previous studies. A distinct difference between those two opposing NAO regimes occurs in late winter, with a minimum (maximum) for the strong positive (negative) NAOs in March. As for the summer peak, it occurs in May for the strong positive NAOs and in July for the strong negative NAOs, as in the normal year. There is a 5% fluctuation in the mean Florida Current transport values between those two strong NAO regimes. Using daily transport time series for the Florida Current calculated from various model experiments for the year 2004, along with the Florida Current transport derived from cable and in-situ measurements from research cruises, we have shown that the Florida Current transport is not sensitive to the resolution of local atmospheric forcing or to the model vertical resolution. However, the major influence on fluctuations on time scales of a few days to several weeks is found to be linked to basin-scale variability in the North Atlantic Ocean. The decadal variability of the Florida Current transport is examined using a 54-year time series of Florida Current transport anomaly from a 1/3° North Atlantic model simulation. The model Florida Current transport anomaly is found to be loosely correlated with the NAO anomaly. The time series of the sea surface height difference (sshdif) between the subtropical gyre and subpolar gyre, however, is strongly correlated with the NAO anomaly, with NAO leading by about 2.5 years. The results also show that the sshdif is well correlated with the model Florida Current transport anomaly, with sshdif leading by about 3.5 years. This suggests that the decadal variability of the Florida Current transport is largely controlled by the variability of the internal ocean dynamics forced by the NAO variability rather than by the NAO variability itself.
Perez, R.C., and W.S. Kessler. The three-dimensional structure of tropical cells in the central equatorial Pacific Ocean. Journal of Physical Oceanography, 39(1):27-49 (2009).
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The shallow tropical cells (TCs) in the central equatorial Pacific Ocean are characterized by strong equatorial upwelling, near-surface wind-driven poleward flow, downwelling near the cold tongue boundaries, and equatorward flow below the surface mixed layer. Meridional and vertical velocity fluctuations associated with tropical instability waves (TIWs) in the central equatorial Pacific are much larger than those associated with the TCs and can modify the background circulation. OGCM experiments are used to simulate the spinup of the cells along 140°W in response to perturbed trade winds during various phases of the annual cycle. Equatorially modified versions of geostrophy and Ekman theory, and zonal filtering, are used to isolate the large-zonal-scale wind-driven response. Weakening of the trade winds in any season rapidly weakens the TCs, decreases the zonal current shear, and reduces the amplitude and propagation speed of the TIWs. In boreal fall and winter, when the background TCs and TIWs are seasonally strong, the ocean response is equatorially asymmetric (stronger flows north of the equator) and there is evidence of rectification by the modified TIWs onto the TCs. The linear equatorially modified Ekman solutions largely explain the meridional structure and temporal evolution of the anomalous ageostrophic response in the TCs. In fall and winter, however, deviations from the modified Ekman solutions were attributed to interactions with the background TCs and TIWs. An observing system able to quantify the relative contributions of these two processes to the seasonally varying equatorial asymmetry of background circulation would require fine meridional and temporal sampling.
Peterson, T.C., and M.O. Baringer, Editors. State of the climate in 2008. Bulletin of the American Meteorological Society, 90(8):S1-S196 (2009).
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No abstract.
Peterson, T.C., and M.O. Baringer. Introduction. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S13-S15 (2009).
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No abstract.
Pierrot, D., C. Neil, K. Sullivan, R. Castle, R. Wanninkhof, H. Lueger, T. Johannessen, A. Olsen, R.A. Feely, and C.E. Cosca. Recommendations for autonomous underway pCO2 measuring systems and data reduction routines. Deep-Sea Research, Part II, 56(8-10):512-522 (2009).
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In order to facilitate the collection of high quality and uniform surface water pCO2 data, an underway pCO2 instrument has been designed based on community input and is now commercially available. Along with instrumentation, agreements were reached on data reduction and quality control that can be easily applied to data from these systems by using custom-made freeware. This new automated underway pCO2 measuring system is designed to be accurate to within 0.1 µatm for atmospheric pCO2 measurements and to within 2 µatm for seawater pCO2, targeted by the scientific community to constrain the regional air-sea CO2 fluxes to 0.2 Pg C year-1. The procedure to properly reduce the underway pCO2 data and perform the steps necessary for calculation of the fugacity of CO2 from the measurements is described. This system is now widely used by the scientific community on many different types of ships. Combined with the recommended data-reduction procedures, it will facilitate producing data sets that will significantly decrease the uncertainty currently present in estimates of air-sea CO2 fluxes.
Powell, M.D., E.W. Uhlhorn, and J.D. Kepert. Estimating maximum surface winds from hurricane reconnaissance measurements. Weather and Forecasting, 24(3):868-883 (2009).
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Radial profiles of surface winds measured by the Stepped Frequency Microwave Radiometer (SFMR) are compared to radial profiles of flight-level winds to determine the slant ratio of the maximum surface wind speed to the maximum flight-level wind speed, for flight altitude ranges of 2-4 km. The radius of maximum surface wind is found on average to be 0.875 of the radius of the maximum flight-level wind, and very few cases have a surface wind maximum at greater radius than the flight-level maximum. The mean slant reduction factor is 0.84 with a standard deviation of 0.09 and varies with storm-relative azimuth from a maximum of 0.89 on the left side of the storm to a minimum of 0.79 on the right side. Larger slant reduction factors are found in small storms with large values of inertial stability and small values of relative angular momentum at the flight-level radius of maximum wind, which is consistent with Keperts recent boundary layer theories. The global positioning system (GPS) dropwindsonde-based reduction factors that are assessed using this new dataset have a high bias and substantially larger RMS errors than the new technique. A new regression model for the slant reduction factor based upon SFMR data is presented, and used to make retrospective estimates of maximum surface wind speeds for significant Atlantic basin storms, including Hurricanes Allen (1980), Gilbert (1988), Hugo (1989), Andrew (1992), and Mitch (1998).
Prive, N., Y. Xie, T.W. Schlatter, M. Masutani, R. Atlas, Y. Song, J. Woollen, and S. Koch. Observing system simulation experiments for unmanned aircraft systems: Preliminary efforts. Preprint Volume, 13th Conference on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface, Phoenix, AZ, January 11-15, 2009. American Meteorological Society, Boston, 4 pp. (2009).
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No abstract.
Reasor, P.D., M.D. Eastin, and J.F. Gamache. Rapidly intensifying Hurricane Guillermo (1997), Part I: Low-wavenumber structure and evolution. Monthly Weather Review, 137(2):603-631 (2009).
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The structure and evolution of rapidly intensifying Hurricane Guillermo (1997) is examined using airborne Doppler radar observations. In this first part, the low-azimuthal-wavenumber component of the vortex is presented. Guillermo's intensification occurred in an environmental flow with 7-8 m s-1 of deeplayer vertical shear. As a consequence of the persistent vertical shear forcing of the vortex, convection was observed primarily in the downshear left quadrant of the storm. The greatest intensification during the ~6-h Doppler observation period coincided with the formation and cyclonic rotation of several particularly strong convective bursts through the left-of-shear semicircle of the eyewall. Some of the strongest convective bursts were triggered by azimuthally propagating low-wavenumber vorticity asymmetries. Mesoscale budget analyses of axisymmetric angular momentum and relative vorticity within the eyewall are presented to elucidate the mechanisms contributing to Guillermo's structural evolution during this period. The observations support a developing conceptual model of the rapidly intensifying, vertically sheared hurricane in which shear-forced mesoscale ascent in the downshear eyewall is modulated by internally generated vorticity asymmetries yielding episodes of anomalous intensification.
Rodgers, K.B., R.M. Key, A. Gnanadesikan, J.L. Sarmiento, O. Aumont, L. Bopp, S.C. Doney, J.P. Dunne, D.M. Glover, A. Ishida, M. Ishii, A.R. Jacobson, C.L. Monaco, E. Maier-Reimer, H. Mercier, N. Metzl, F.F. Perez, A.F. Rios, R. Wanninkhof, P. Wetzel, C.D. Winn, and Y. Yamanaka. Using altimetry to help to explain patchy changes in hydrographic carbon measurements. Journal of Geophysical Research, 114(C9):C09013, doi:10.1029/2008JC005183 (2009).
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Here we use observations and ocean models to identify mechanisms driving large seasonal to interannual variations in dissolved inorganic carbon (DIC) and dissolved oxygen (O2) in the upper ocean. We begin with observations linking variations in upper ocean DIC and O2 inventories with changes in the physical state of the ocean. Models are subsequently used to address the extent to which the relationships derived from short-timescale (6 months to 2 years) repeat measurements are representative of variations over larger spatial and temporal scales. The main new result is that convergence and divergence (column stretching) attributed to baroclinic Rossby waves can make a first-order contribution to DIC and O2 variability in the upper ocean. This results in a close correspondence between natural variations in DIC and O2 column inventory variations and sea surface height (SSH) variations over much of the ocean. Oceanic Rossby wave activity is an intrinsic part of the natural variability in the climate system and is elevated even in the absence of significant interannual variability in climate mode indices. The close correspondence between SSH and both DIC and O2 column inventories for many regions suggests that SSH changes (inferred from satellite altimetry) may prove useful in reducing uncertainty in separating natural and anthropogenic DIC signals (using measurements from Climate Variability and Predictability's CO2/Repeat Hydrography program).
Roemmich, D., G.C. Johnson, S. Riser, R. Davis, J. Gilson, W.B. Owens, S.L. Garzoli, C. Schmid, and M. Ignaszewski. The Argo Program: Observing the global ocean with profiling floats. Oceanography, 22(2):34-43 (2009).
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The Argo Program has created the first global array for observing the subsurface ocean. Argo arose from a compelling scientific need for climate-relevant ocean data; it was made possible by technology development and implemented through international collaboration. The float program and its data management system began with regional arrays in 1999, scaled up to global deployments by 2004, and achieved its target of 3000 active instruments in 2007. U.S. Argo, supported by the National Oceanic and Atmospheric Administration and the Navy through the National Oceanographic Partnership Program, provides half of the floats in the international array, plus leadership in float technology, data management, data quality control, international coordination, and outreach. All Argo data are freely available without restriction, in real time and in research-quality forms. Uses of Argo data range from oceanographic research, climate research, and education, to operational applications in ocean data assimilation and seasonal-to-decadal prediction. Argos value grows as its data accumulate and their applications are better understood. Continuing advances in profiling float and sensor technologies open many exciting possibilities for Argos future, including expanding sampling into high latitudes and the deep ocean, improving near-surface sampling, and adding biogeochemical parameters.
Roemmich, D., M. Belbeoch, H. Freeland, S.L. Garzoli, W.J. Gould, F. Grant, M. Ignaszewski, B. King, B. Klein, P.-Y. Le Traon, K.A. Mork, W.B. Owens, S. Pouliquen, M. Ravichandran, S. Riser, A. Sterl, T. Suga, M.-S. Suk, P. Sutton, V. Thierry, P.J. Velez-Belchi, S. Wijffels, and J. Xu. Argo: The challenge of continuing 10 years of progress. Oceanography, 22(3):46-55 (2009).
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In only 10 years, the Argo Program has grown from an idea into a functioning global observing system for the subsurface ocean. More than 3000 Argo floats now cover the world ocean. With these instruments operating on 10-day cycles, the array provides 9000 temperature/salinity/depth profiles every month that are quickly available via the Global Telecommunications System and the Internet. Argo is recognized as a major advance for oceanography, and a success for Argos parent programs, the Global Ocean Data Assimilation Experiment and Climate Variability and Predictability, and for the Global Earth Observation System of Systems. The value of Argo data in ocean data assimilation (ODA) and other applications is being demonstrated, and will grow as the data set is extended in time and as experience in using the data set leads to new applications. The spatial coverage and quality of the Argo data set are improving, with consideration being given to sampling under seasonal ice at higher latitudes, in additional marginal seas, and to greater depths. Argo data products of value in ODA modeling are under development, and Argo data are being tested to confirm their consistency with related satellite and in situ data. Maintenance of the Argo Program for the next decade and longer is needed for a broad range of climate and oceanographic research and for many operational applications in ocean state estimation and prediction.
Rogers, R.F., F.D. Marks, and T. Marchok. Tropical cyclone rainfall. In Encyclopedia of Hydrological Sciences, M.G. Anderson (ed.). John Wiley and Sons, Chicester, UK, doi:10.1002/0470848944.hsa030 (2009).
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A brief survey of the relevant research of tropical cyclone (TC) rainfall is presented here. The importance of TC rainfall in global and regional rainfall budgets is discussed, as is its mean characteristics as derived from airborne and satellite observational studies. Discussion is also presented on the physical processes that can modulate TC rainfall distributions, including topography, storm motion, vertical shear, and extratropical transition. Some tools that have been developed to predict and evaluate forecasts of TC rainfall are discussed. Finally, a summary and outlook for the future is presented, including a discussion of opportunities for improving TC rainfall forecasts and conducting research into the role of TC rainfall in intensity and structure changes in TCs.
Rosario, K., E.M. Symonds, C.D. Sinigalliano, J. Stewart, and M. Breitbart. Pepper mild mottle virus as an indicator of fecal pollution. Applied and Environmental Microbiology, 75(22):7261-7267 (2009).
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Accurate indicators of fecal pollution are needed in order to minimize public health risks associated with wastewater contamination in recreational waters. However, the bacterial indicators currently used for monitoring water quality do not correlate with the presence of pathogens. Here we demonstrate that the plant pathogen Pepper mild mottle virus (PMMoV) is widespread and abundant in wastewater from the United States, suggesting the utility of this virus as an indicator of human fecal pollution. Quantitative PCR was used to determine the abundance of PMMoV in raw sewage, treated wastewater, seawater exposed to wastewater, and fecal samples and/or intestinal homogenates from a wide variety of animals. PMMoV was present in all wastewater samples at concentrations greater than 1 million copies per milliliter of raw sewage. Despite the ubiquity of PMMoV in human feces, this virus was not detected in the majority of animal fecal samples tested, with the exception of chicken and seagull samples. PMMoV was detected in four out of six seawater samples collected near point sources of secondary treated wastewater off southeastern Florida, where it co-occurred with several other pathogens and indicators of fecal pollution. Since PMMoV was not found in nonpolluted seawater samples and could be detected in surface seawater for approximately 1 week after its initial introduction, the presence of PMMoV in the marine environment reflects a recent contamination event. Together, these data demonstrate that PMMoV is a promising new indicator of fecal pollution in coastal environments.
Sabine, C.L., R.A. Feely, R. Wanninkhof, and T. Takahashi. The global ocean carbon cycle. In State of the Climate in 2008, T.C. Peterson and M.O. Baringer (eds.). Bulletin of the American Meteorological Society, 90(8):S65-S68 (2009).
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No abstract.
Schmid, C. National workshop on data analysis in Lagos, Nigeria. Argonautics, 11:7 (2009).
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No abstract.
Schmid, C., and S.L. Garzoli. New observations of the spreading and variability of the Antarctic Intermediate Water in the Atlantic. Journal of Marine Research, 67(6):815-843 (2009).
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The new and unique Argo data set currently available, in conjunction with other data previously collected, increases our understanding of the spreading of the Antarctic Intermediate Water in the southern and tropical Atlantic Ocean and to verify previous results. The combination of velocity and salinity data collected with Argo floats verified the main patterns of circulation at intermediate (800 to 1100 dbar) depths. Interesting new features in the pathways are found: (1) the existence of a new, third, branch of westward to northwestward flow that is fed by the Benguela Current; (2) two pathways through which the water from the Benguela Current Extension feeds into the Intermediate Western Boundary Current, one turns north at the western boundary while the other one turns north about 10° farther offshore; (3) the core of the South Atlantic Current is located farther north than was thought earlier (at 35 to 38°S instead of south at about 40°S); (4) significant flow of water from the South Atlantic Current to the Antarctic Circumpolar Current occurs east of the Zapiola Eddy (at about 45°S, 35°W); (5) a quite robust eastward current exists at about 20°S; and (6) there are indications, only in the salinity distribution, for southward spreading of Antarctic Intermediate Water from the equator near the eastern boundary. Transport estimates for the 800 to 1100 dbar layer show that the transports of the zonal currents in the subtropical gyre at intermediate depth increase from east to west, and that this trend is nearly linear. The transport of the South Atlantic Current near the western boundary is between 5 and 10 Sv, while it is close to 1 Sv near the eastern boundary of the Atlantic. The transport of the Benguela Current Extension is about 8 Sv near 45°W and only about 1 Sv near 14°E. It is also found that at the bifurcation of the Benguela Current Extension (at 28.5°S) about two thirds of the Antarctic Intermediate Water recirculate in the subtropical gyre, which is a smaller portion than the three quarters reported previously. Zonally integrated transports in the Antarctic Intermediate Water layer show that, as a meridional average, about 3 Sv are transported northward in the 800 to 1100 dbar layer. At 35°S this transport is 2.8 Sv, which amounts to 16% of the total northward transport of the Meridional Overturning Circulation (18 Sv). An analysis of the variability shows that the confluence of the Malvinas Current and the Brazil Current undergo seasonal variations at intermediate depth. The confluence is at its northernmost location (36°S) in July-September. On average the confluence is at 38°S. Both, the variability and the mean location of the confluence at the depth of Antarctic Intermediate Water is similar to what has been observed at the surface.
Schubert, S., D. Gutzler, H. Wang, A. Dai, T. Delworth, C. Deser, K. Findell, R. Fu, W. Higgins, M. Hoerling, B. Kirtman, R. Koster, A. Kumar, D. Legler, D. Lettenmaier, B. Lyon, V. Magana, K. Mo, S. Nigam, P. Pegion, A. Phillips, R. Pulwarty, D. Rind, A. Ruiz-Barradas, J. Schemm, R. Seager, R. Stewart, M. Suarez, J. Syktus, M. Ting, C. Wang, S. Weaver, and N. Zeng. A U.S. CLIVAR project to assess and compare the responses of global climate models to drought-related SST forcing patterns: Overview and results. Journal of Climate, 22(19):5251-5272 (2009).
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The U.S. Climate Variability and Predictability (CLIVAR) working group on drought recently initiated a series of global climate model simulations forced with idealized SST anomaly patterns, designed to address a number of uncertainties regarding the impact of SST forcing and the role of landatmosphere feedbacks on regional drought. The runs were carried out with five different atmospheric general circulation models (AGCMs) and one coupled atmosphere-ocean model in which the model was continuously nudged to the imposed SST forcing. This paper provides an overview of the experiments and some initial results focusing on the responses to the leading patterns of annual mean SST variability consisting of a Pacific El Niño-Southern Oscillation (ENSO)-like pattern, a pattern that resembles the Atlantic multidecadal oscillation (AMO), and a global trend pattern. One of the key findings is that all of the AGCMs produce broadly similar (though different in detail) precipitation responses to the Pacific forcing pattern, with a cold Pacific leading to reduced precipitation and a warm Pacific leading to enhanced precipitation over most of the United States. While the response to the Atlantic pattern is less robust, there is general agreement among the models that the largest precipitation response over the United States tends to occur when the two oceans have anomalies of opposite signs. Further highlights of the response over the United States to the Pacific forcing include precipitation signal-to-noise ratios that peak in spring, and surface temperature signal-to-noise ratios that are both lower and show less agreement among the models than those found for the precipitation response. The response to the positive SST trend forcing pattern is an overall surface warming over the worlds land areas, with substantial regional variations that are in part reproduced in runs forced with a globally uniform SST trend forcing. The precipitation response to the trend forcing is weak in all of the models. It is hoped that these early results, as well as those reported in the other contributions to this special issue on drought, will serve to stimulate further analysis of these simulations, as well as suggest new research on the physical mechanisms contributing to hydroclimatic variability and change throughout the world.
Scorzetti, G., L.E. Brand, G.L. Hitchcock, K.S. Rein, C.D. Sinigalliano, and J.W. Fell. Multiple simultaneous detection of harmful algal blooms (HABs) through a high throughput bead array technology, with potential use in phytoplankton community analysis. Harmful Algae, 8(2):196-211 (2009).
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As an alternative to traditional, morphology-based methods, molecular techniques can provide detection of multiple species within the HAB community and, more widely, the phytoplankton community in a rapid, accurate and simultaneous qualitative analysis. These methods require detailed knowledge of the molecular diversity within taxa in order to design efficient specific primers and specific probes able to avoid cross-reaction with non-target sequences. Isolates from Florida coastal communities were sequence-analyzed and compared with the GenBank database. Almost 44% of the genotypes obtained did not match any sequence in GenBank, showing the existence of a large and still unexplored biodiversity among taxa. Based on these results and on the GenBank database, we designed 14 species-specific probes and 4 sets of specific primers. Multiple simultaneous detection was achieved with a bead array method based on the use of a flow cytometer and color-coded microspheres, which are conjugated to the developed probes. Following a parallel double PCR amplification, which employed universal primers in a singleplex reaction and a set of species-specific primers in multiplex, detection was performed in a cost effective and highly specific analysis. This multi-format assay, which required less than 4 h to complete from sample collection, can be expanded according to need. Up to 100 different species can be identified simultaneously in a single sample, which allows for additional use of this method in community analyses extended to all phytoplankton species. Our initial field trials, which were based on the 14 species-specific probes, showed the co-existence and dominance of two or more species of Karenia during toxic blooms in Florida waters.
Shen, B.W., W.-K. Tao, J.-D. Chern, R. Atlas, and K. Palaniappan. Scalability improvements in the NASA Goddard multiscale modeling framework for tropical cyclone climate studies. Proceedings, HPC (High Performance Computing) Asia & APAN (Asia-Pacific Advanced Network) 2009 International Conference and Exhibition, March 2-5, 2009, Kaohsiung, Taiwan. National Center for High-Performance Computing, 249-256 (2009).
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A current, challenging topic in tropical cyclone (TC) research is how to improve our understanding of TC interannual variability and the impact of climate change on TCs. Paired with the substantial computing power of the NASA Columbia supercomputer, the newly-developed multi-scale modeling framework (MMF) shows potential for the related studies. The MMF consists of two NASA state-of-the-art modeling components, including the finite-volume General Circulation Model (fvGCM) and the Goddard Cumulus Ensemble model (GCE). For TC climate studies, the MMFs computational issues (e.g., limited scalability) need to be addressed. By introducing a meta-grid system, we integrate the GCEs into a meta-global GCE, and apply a two-dimensional domain decomposition in this grid-point space. A prototype parallelism implementation shows very promising scalability, giving a nearly linear speedup as the number of CPUs is increased from 30 to 364. This scalability improvement makes it more feasible to study TC climate. Future work on further model improvement will be also discussed.
Sinigalliano, C.D., J. Winshell, M.A. Guerrero, G. Scorzetti, J.W. Fell, R.W. Eaton, L. Brand, and K.S. Rein. Viable cell sorting of dinoflagellates by multiparametric flow cytometry. Phycologia, 48(4):249-257 (2009).
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Electronic cell sorting for isolation and culture of dinoflagellates and other marine eukaryotic phytoplankton was compared to the traditional method of manually picking cells using a micropipette. Trauma to electronically sorted cells was not a limiting factor, as fragile dinoflagellates, such as Karenia brevis (Dinophyceae), survived electronic cell sorting to yield viable cells. The rate of successful isolation of large-scale (> 4 litres) cultures was higher for manual picking than for electronic cell sorting (2% vs 0.5%, respectively). However, manual picking of cells is more labor intensive and time consuming. Most manually isolated cells required repicking, as the cultures were determined not to be unialgal after a single round of isolation; whereas, no cultures obtained in this study from electronic single-cell sorting required resorting. A broad flow cytometric gating logic was employed to enhance species diversity. The percentages of unique genotypes produced by manual picking or electronic cell sorting were similar (57% vs 54%, respectively), and each approach produced a variety of dinoflagellate or raphidophyte genera. Alternatively, a highly restrictive gating logic was successfully used to target K. brevis from a natural bloom sample. Direct electronic single-cell sorting was more successful than utilizing a pre-enrichment sort followed by electronic single-cell sorting. The appropriate recovery medium may enhance the rate of successful isolations. Seventy percent of isolated cells were recovered in a new medium (RE) reported here, which was optimized for axenic dinoflagellate cultures. The greatest limiting factor to the throughput of electronic cell sorting is the need for manual postsort culture maintenance and assessment of the large number of isolated cells. However, when combined with newly developed automated methods for growth screening, electronic single-cell sorting has the potential to accelerate the discovery of new algal strains.
Smith, R.K., M.T. Montgomery, and V.S. Nguyen. Tropical cyclone spin-up revisited. Quarterly Journal of the Royal Meteorological Society, 135(642):1321-1335 (2009).
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We present numerical experiments to investigate axisymmetric interpretations of tropical cyclone spin-up in a three-dimensional model. Two mechanisms are identified for the spin-up of the mean tangential circulation. The first involves the convergence of absolute angular momentum above the boundary layer and is a mechanism to spin up the outer circulation, i.e., to increase the vortex size. The second involves the convergence of absolute angular momentum within the boundary layer and is a mechanism to spin up the inner core. It is associated with the development of supergradient wind speeds in the boundary layer. The existence of these two mechanisms provides a plausible physical explanation for certain long-standing observations of typhoons by Weatherford and Gray, which indicate that inner-core changes in the azimuthal-mean tangential wind speed often occur independently from those in the outer core. The unbalanced dynamics in the inner-core region are important in determining the maximum radial and tangential flow speeds that can be attained and are, therefore, important in determining the azimuthal-mean intensity of the vortex. We illustrate the importance of unbalanced flow in the boundary layer with a simple thought experiment. The analyses and interpretations presented are novel and support a recent hypothesis of the boundary layer in the inner-core region.
Takahashi, T., S.C. Sutherland, R. Wanninkhof, C. Sweeney, R.A. Feely, D.W. Chipman, B. Hales, G. Friederich, F. Chavez, C. Sabine, A. Watson, D.C.E. Bakker, U. Schuster, N. Metzl, H. Yoshikawa-Inoue, M. Ishii, T. Midorikawa, Y. Nojiri, A. Kortzinger, T. Steinhoff, M. Hoppema, J. Olafsson, T.S. Arnarson, B. Tilbrook, T. Johannessen, A. Olsen, R. Bellerby, C.S. Wong, B. Delille, N.R. Bates, and H.J.W. de Baar. Climatological mean and decadal change in surface ocean pCO2 and net sea-air CO2 flux over the global oceans. Deep-Sea Research, Part II, 56(8-10):554-577 (2009).
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A climatological mean distribution for the surface water pCO2 over the global oceans in non-El Niño conditions has been constructed with spatial resolution of 4° (latitude) x 5° (longitude) for a reference year 2000 based upon about 3 million measurements of surface water pCO2 obtained from 1970 to 2007. The database used for this study is about 3 times larger than the 0.94 million used for our earlier paper [Takahashi et al., 2002. Global sea-air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects. Deep-Sea Res. II, 49, 1601-1622]. A time-trend analysis using deseasonalized surface water pCO2 data in portions of the North Atlantic, North and South Pacific, and Southern Oceans (which cover about 27% of the global ocean areas) indicates that the surface water pCO2 over these oceanic areas has increased on average at a mean rate of 1.5 µatm y-1 with basin-specific rates varying between 1.2 ± 0.5 and 2.1 ± 0.4 µatm y-1. A global ocean database for a single reference year 2000 is assembled using this mean rate for correcting observations made in different years to the reference year. The observations made during El Niño periods in the equatorial Pacific and those made in coastal zones are excluded from the database. Seasonal changes in the surface water pCO2 and the sea-air pCO2 difference over four climatic zones in the Atlantic, Pacific, Indian, and Southern Oceans are presented. Over the Southern Ocean seasonal ice zone, the seasonality is complex. Although it cannot be thoroughly documented due to the limited extent of observations, seasonal changes in pCO2 are approximated by using the data for under-ice waters during austral winter and those for the marginal ice and ice-free zones. The net air-sea CO2 flux is estimated using the sea-air pCO2 difference and the air-sea gas transfer rate that is parameterized as a function of (wind speed)2 with a scaling factor of 0.26. This is estimated by inverting the bomb 14C data using Ocean General Circulation models and the 1979-2005 NCEP-DOE AMIP-II Reanalysis (R-2) wind speed data. The equatorial Pacific (14°N-14°S) is the major source for atmospheric CO2, emitting about +0.48 Pg-C y-1, and the temperate oceans between 14° and 50° in the both hemispheres are the major sink zones with an uptake flux of -0.70 Pg-C y-1 for the northern and -1.05 Pg-C y-1 for the southern zone. The high-latitude North Atlantic, including the Nordic Seas and portion of the Arctic Sea, is the most intense CO2 sink area on the basis of per unit area, with a mean of -2.5 tons-C month-1 km-2. This is due to the combination of the low pCO2 in seawater and high gas exchange rates. In the ice-free zone of the Southern Ocean (50°-62°S), the mean annual flux is small (-0.06 Pg-C y-1) because of a cancellation of the summer uptake CO2 flux with the winter release of CO2 caused by deepwater upwelling. The annual mean for the contemporary net CO2 uptake flux over the global oceans is estimated to be -1.6 ± 0.9 Pg-C y-1, which includes an undersampling correction to the direct estimate of -1.4 ± 0.7 Pg-C y-1. Taking the pre-industrial steady-state ocean source of 0.4 ± 0.2 Pg-C y-1 into account, the total ocean uptake flux including the anthropogenic CO2 is estimated to be -2.0 ± 1.0 Pg-C y-1 in 2000.
Tao, W.-K., J.-D. Chern, R. Atlas, D. Randall, M. Khairoutdinov, J.-L. Li, D.E. Waliser, A. Hou, X. Lin, C. Peters-Lidard, W. Lau, J. Jiang, and J. Simpson. A multiscale modeling system: Developments, applications, and critical issues. Bulletin of the American Meteorological Society, 9(4):515-534 (2009).
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A multiscale modeling framework (MMF), which replaces the conventional cloud parameterizations with a cloud-resolving model (CRM) in each grid column of a GCM, constitutes a new and promising approach for climate modeling. The MMF can provide for global coverage and two-way interactions between the CRMs and their parent GCM. The CRM allows for explicit simulation of cloud processes and their interactions with radiation and surface processes, and the GCM allows for global coverage. A new MMF has been developed that is based on the NASA Goddard Space Flight Center (GSFC) finite-volume GCM (fvGCM) and the Goddard Cumulus Ensemble (GCE) model. This Goddard MMF produces many features that are similar to another MMF that was developed at Colorado State University (CSU), such as an improved surface precipitation pattern, better cloudiness, improved diurnal variability over both oceans and continents, and a stronger propagating MaddenJulian oscillation (MJO) compared to their parent GCMs using traditional cloud parameterizations. Both MMFs also produce a large and positive precipitation bias in the Indian Ocean and western Pacific during the Northern Hemisphere summer. However, there are also notable differences between the two MMFs. For example, the CSU MMF simulates less rainfall over land than its parent GCM. This is why the CSU MMF simulated less overall global rainfall than its parent GCM. The Goddard MMF simulates more global rainfall than its parent GCM because of the high contribution from the oceanic component. A number of critical issues (i.e., the CRM's physical processes and its configuration) involving the Goddard MMF are discussed in this paper.
Telszewski, M., A. Chazottes, U. Schuster, A.J. Watson, C. Moulin, D.C.E. Bakker, M. Gonzalez-Davila, T. Johannessen, A. Kortzinger, H. Lueger, A. Olsen, A. Omar, X.A. Padin, A.F. Rios, T. Steinhoff, M.Santana-Casiano, D.W.R. Wallace, and R. Wanninkhof. Estimating the monthly pCO2 distribution in the North Atlantic using a self-organizing neural network. Biogeosciences, 6(8):1405-1421 (2009).
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Here we present monthly, basin-wide maps of the partial pressure of carbon dioxide (pCO2) for the North Atlantic on a 1° latitude by 1° longitude grid for years 2004 through 2006 inclusive. The maps have been computed using a neural network technique which reconstructs the non-linear relationships between three biogeochemical parameters and marine pCO2. A self organizing map (SOM) neural network has been trained using 389,000 triplets of the SeaWiFS-MODIS chlorophyll-a concentration, the NCEP/NCAR reanalysis sea surface temperature, and the FOAM mixed layer depth. The trained SOM was labelled with 137,000 underway pCO2 measurements collected in situ during 2004, 2005, and 2006 in the North Atlantic, spanning the range of 208 to 437 µatm. The root mean square error (RMSE) of the neural network fit to the data is 11.6 µatm, which equals to just above 3 per cent of an average pCO2 value in the in situ dataset. The seasonal pCO2 cycle as well as estimates of the interannual variability in the major biogeochemical provinces are presented and discussed. High resolution combined with basin-wide coverage makes the maps a useful tool for several applications such as the monitoring of basin-wide air-sea CO2 fluxes or improvement of seasonal and interannual marine CO2 cycles in future model predictions. The method itself is a valuable alternative to traditional statistical modelling techniques used in geosciences.
Vickery, P.J., F.J. Masters, M.D. Powell, and D. Wadhera. Hurricane hazard modeling: The past, present, and future. Journal of Wind Engineering and Industrial Aerodynamics, 97(7-8):392-405 (2009).
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Hurricane hazard modeling has become a commonly used tool for assessing hurricane risk. The type of hurricane risk considered varies with the user and can be an economic risk, as in the case of the insurance and banking industries, a wind exceedance risk, a flood risk, etc. The most common uses for hurricane hazard models today include: (i) Simulation of wind speed and direction for use with wind tunnel test data to estimate wind loads versus return period for design of structural systems and cladding. (ii) Estimation of design wind speeds for use in buildings codes and standards. (iii) Coastal hazard risk modeling (e.g., storm surge elevations and wave heights vs. return period). (iv) Insurance loss estimation (e.g., probable maximum losses, average annual losses). This paper presents an overview of the past and present work in hurricane modeling. The wind model is the key input to each of the examples presented above and is the focus herein. We discuss the evolution and current state of wind field modeling, modeling uncertainties, and possible future directions of the hurricane risk modeling process.
Vickery, P.J., D. Wadhera, M.D. Powell, and Y. Chen. A hurricane boundary layer and wind field model for use in engineering applications. Journal of Applied Meteorology and Climatology, 48(2):381-405 (2009).
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This article examines the radial dependence of the height of the maximum wind speed in a hurricane, which is found to lower with increasing inertial stability (which in turn depends on increasing wind speed and decreasing radius) near the eyewall. The leveling off, or limiting value, of the marine drag coefficient in high winds is also examined. The drag coefficient, given similar wind speeds, is smaller for smaller-radii storms; enhanced sea spray by short or breaking waves is speculated as a cause. A fitting technique of dropsonde wind profiles is used to model the shape of the vertical profile of mean horizontal wind speeds in the hurricane boundary layer, using only the magnitude and radius of the gradient wind. The method slightly underestimates the surface winds in small but intense storms, but errors are less than 5% near the surface. The fit is then applied to a slab layer hurricane wind field model, and combined with a boundary layer transition model to estimate surface winds over both marine and land surfaces.
Wang, C., and S.-K Lee. Co-variability of tropical cyclones in the North Atlantic and the eastern North Pacific. Geophysical Research Letters, 36:L24702, doi:10.1029/2009GL041469 (2009).
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In the Western Hemisphere, tropical cyclones (TCs) can form and develop in both the tropical North Atlantic (NA) and eastern North Pacific (ENP) Oceans, which are separated by the narrow landmass of Central America. Here it is shown that TC activity in the NA varies out-of-phase with that in the ENP on both interannual and multidecadal timescales. That is, when TC activity in the NA increases (decreases), TC activity in the ENP decreases (increases). Our analyses show that both vertical wind shear and convective instability contribute to the out-of-phase relationship, whereas relative humidity and vorticity variations at the lower troposphere do not seem to cause the relationship. The paper also discusses its association with the Pacific and Atlantic sea surface temperatures. An implication is that seasonal hurricane outlook can be improved by considering the NA and ENP together. It is hoped that this article will stimulate more research regarding TC activity in both the NA and ENP.
Wang, C., and S.-K. Lee. Reply to comment by Joseph J. Barsugli on "Global warming and United States landfalling hurricanes." Geophysical Research Letters, 36(1):L01706, doi:10.1029/2008GL035111 (2009).
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No abstract.
Wang, C., F. Kucharski, R. Barimalala, and A. Bracco. Teleconnections of the tropical Atlantic to the tropical Indian and Pacific Oceans: A review of recent findings. Meteorologische Zeitschrift, 18(4):445-454 (2009).
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Recent studies found that tropical Atlantic variability may affect the climate in both the tropical Pacific and Indian Ocean basins, possibly modulating the Indian summer monsoon and Pacific ENSO events. A warm tropical Atlantic Ocean forces a Gill-Matsuno-type quadrupole response with a low-level anticyclone located over India that weakens the Indian monsoon circulation, and vice versa for a cold tropical Atlantic Ocean. The tropical Atlantic Ocean can also induce changes in the Indian Ocean sea surface temperatures (SSTs), especially along the coast of Africa and in the western side of the Indian basin. Additionally, it can influence the tropical Pacific Ocean via an atmospheric teleconnection that is associated with the Atlantic Walker circulation. Although the Pacific El Niño does not contemporaneously correlate with the Atlantic Niño, anomalous warming or cooling of the two equatorial oceans can form an inter-basin SST gradient that induces surface zonal wind anomalies over equatorial South America and other regions in both ocean basins. The zonal wind anomalies act as a bridge linking the two ocean basins, and in turn reinforce the inter-basin SST gradient through the atmospheric Walker circulation and oceanic processes. Thus, a positive feedback seems to exist for climate variability of the tropical Pacific-Atlantic Oceans and atmospheric system, in which the inter-basin SST gradient is coupled to the overlying atmospheric wind.
Wang, C., Z. Song, F. Qiao, and S. Dong. What signals are removed and retained by using an anomaly field in climatic research? International Journal of Oceanography, 2009:329754, doi:10.1155/2009/329754, 7 pp. (2009).
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Signals in data are often detected by analyzing anomaly field that is calculated by subtracting the mean value over a time length from the data. Here we demonstrate that the anomaly calculation removes signals which satisfy that the ratio between the time length of the mean T and signals' period L is an integer (i.e., T/L = n where n is an integer) and retains other signals if the ratio is not an integer. In climatic and other studies, the time length of the mean is usually chosen as T=12 months from January to December and the mean is called the monthly climatology. Anomaly is calculated by subtracting the monthly climatology from data. This anomaly calculation thus removes the climatic signals with the periods of 12, 6, 4, 3, 2.4, and 2 months which correspond to (12 months)/n with n = 1, 2, 3, 4, 5, and 6, respectively, whereas it retains other signals such as those with the periods of 11, 10, 9, 8, 7, and 5 months. This paper suggests that one should be cautious when an anomaly field is used in research. The conventional notion is that the monthly anomaly calculation removes the annual cycle. However, here we show that the anomaly calculation removes all signals as long as the time length of the mean is an integer multiple of signals period.
Wang, G., Z. Ling, and C. Wang. Influence of tropical cyclones on seasonal ocean circulation in the south China Sea. Journal of Geophysical Research, 114(C10):C10022, doi:10.1029/JC005302 (2009).
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The seasonal variability of South China Sea (SCS) ocean circulation influenced by tropical cyclones (TCs) is studied by using satellite QuikSCAT wind data, Sverdrup theory, and a reduced gravity model. TCs can induce a positive (negative) wind stress curl in the northwestern (southeastern) SCS in summer and a positive wind stress curl for the whole SCS in winter. With these wind stress curls induced by TCs, the cyclonic gyre in the northern SCS and the anticyclonic gyre in the southern SCS are intensified in summer. In winter, the cyclonic gyre in the northern SCS is intensified and the gyre in the southern SCS is weakened except in November and December when both gyres are enhanced. The model results show that the dipole structure off central Vietnam in summer is intensified and the eddy off northwestern Luzon Island in winter is weakened by TCs. The present paper shows that TCs can affect both large-scale and mesoscale SCS ocean circulation, suggesting that studies including the effect of TCs are necessary to help improve our understanding of SCS ocean circulation dynamics.
Wang, Z., M.T. Montgomery, and T.J. Dunkerton. A dynamically-based method for forecasting tropical cyclogenesis location in the Atlantic sector using global model products. Geophysical Research Letters, 36(2):L03801, doi:10.1029/2008GL035586 (2009).
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A real-time forecast method is developed for prediction of the tropical cyclogenesis location over the Atlantic using global model operational products. The method is based on the marsupial theory for tropical cyclogenesis proposed in a recent observational study. A moisture front is usually found ahead of the precursor wave trough, which separates the relatively dry air outside of the wave pouch (a region of closed circulation) from the relatively moist air inside the wave pouch. The propagation speed of the pouch can be determined by tracking the propagation of this moisture front, and the intersection of the critical surface and the trough axis pinpoints the predicted genesis location. Using the global model operational products, the genesis location can be predicted up to three days in advance with an error less than 200 km, which can provide useful guidance for forecasters and flight planning.
Wanninkhof, R., W.E. Asher, D.T. Ho, C.S. Sweeney, and W.R. McGillis. Advances in quantifying air-sea gas exchange and environmental forcing. Annual Reviews in Marine Science, 1:213-244 (2009).
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The past decade has seen a substantial amount of research on air-sea gas exchange and its environmental controls. These studies have significantly advanced the understanding of processes that control gas transfer, led to higher quality field measurements, and improved estimates of the flux of climate-relevant gases between the ocean and atmosphere. This review discusses the fundamental principles of air-sea gas transfer and recent developments in gas transfer theory, parameterizations, and measurement techniques in the context of the exchange of carbon dioxide. However, much of this discussion is applicable to any sparingly soluble, non-reactive gas. We show how the use of global variables of environmental forcing that have recently become available and gas exchange relationships that incorporate the main forcing factors will lead to improved estimates of global and regional air-sea gas fluxes based on better fundamental physical, chemical, and biological foundations.
Watson, A.J., U. Schuster, D.C.E. Bakker, N.R. Bates, A. Corbiere, M. Gonzalez-Davila, T. Friedrich, J. Hauck, C. Heinze, T. Johannessen, A. Kortzinger, N. Metzl, J. Olafsson, A. Olsen, A. Oschlies, X.A. Padin, B. Pfeil, J.M. Santana-Casiano, T. Steinhoff, M. Telszewski, A.F. Rios, D.W.R. Wallace, and R. Wanninkhof. Tracking the variable North Atlantic sink for atmospheric CO2. Science, 326(5958):1391-1393 (2009).
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The oceans are a major sink for atmospheric carbon dioxide (CO2). Historically, observations have been too sparse to allow accurate tracking of changes in rates of CO2 uptake over ocean basins, so little is known about how these vary. Here, we show observations indicating substantial variability in the CO2 uptake by the North Atlantic on time scales of a few years. Further, we use measurements from a coordinated network of instrumented commercial ships to define the annual flux into the North Atlantic, for the year 2005, to a precision of about 10%. This approach offers the prospect of accurately monitoring the changing ocean CO2 sink for those ocean basins that are well covered by shipping routes.
Wright, C.W., E.J. Walsh, W.B. Krabill, W.A. Shaffer, S.R. Baig, M. Peng, L.J. Pietrafesa, A.W. Garcia, F.D. Marks, P.G. Black, J. Sonntag, and B.D. Beckley. Measuring storm surge with an airborne wide-swath radar altimeter. Journal of Atmospheric and Oceanic Technology, 26(10):2200-2215 (2009).
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Over the years, hurricane track forecasts and storm surge models, as well the digital terrain and bathymetry data they depend on, have improved significantly. Strides have also been made in the knowledge of the detailed variation of the surface wind field driving the surge. The area of least improvement has been in obtaining data on the temporal/spatial evolution of the mound of water that the hurricane wind and waves push against the shore to evaluate the performance of the numerical models. Tide gauges in the vicinity of the landfall are frequently destroyed by the surge. Survey crews dispatched after the event provide no temporal information and only indirect indications of the maximum water level over land. The landfall of Hurricane Bonnie on 26 August 1998, with a surge less than 2 m, provided an excellent opportunity to demonstrate the potential benefits of direct airborne measurement of the temporal/spatial evolution of the water level over a large area. Despite a 160-m variation in aircraft altitude, an 11.5-m variation in the elevation of the mean sea surface relative to the ellipsoid over the flight track, and the tidal variation over the 5-h data acquisition interval, a survey-quality global positioning system (GPS) aircraft trajectory allowed the NASA scanning radar altimeter carried by a NOAA hurricane research aircraft to demonstrate that an airborne wide-swath radar altimeter could produce targeted measurements of storm surge that would provide an absolute standard for assessing the accuracy of numerical storm surge models.
Wu, C.-C., J.-H. Chen, S.J. Majumdar, M.S. Peng, C.A. Reynolds, S.D. Aberson, R. Buizza, M. Yamaguchi, S.-G. Chen, T. Nakazawa, and K.-H. Chou. Inter-comparison of targeted observation guidance for tropical cyclones in the northwestern Pacific. Monthly Weather Review, 137(8):2471-2492 (2009).
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This study compares six different guidance products for targeted observations over the northwest Pacific Ocean for 84 cases of 2-day forecasts in 2006 and highlights the unique dynamical features affecting the tropical cyclone (TC) tracks in this basin. The six products include three types of guidance based on total-energy singular vectors (TESVs) from different global models, the ensemble transform Kalman filter (ETKF) based on a multimodel ensemble, the deep-layer mean (DLM) wind variance, and the adjoint-derived sensitivity steering vector (ADSSV). The similarities among the six products are evaluated using two objective statistical techniques to show the diversity of the sensitivity regions in large, synoptic-scale domains and in smaller domains local to the TC. It is shown that the three TESVs are relatively similar to one another in both the large and the small domains while the comparisons of the DLM wind variance with other methods show rather low similarities. The ETKF and the ADSSV usually show high similarity because their optimal sensitivity usually lies close to the TC. The ADSSV, relative to the ETKF, reveals more similar sensitivity patterns to those associated with TESVs. Three special cases are also selected to highlight the similarities and differences among the six guidance products and to interpret the dynamical systems affecting the TC motion in the northwestern Pacific. Among the three storms studied, Typhoon Chanchu was associated with the subtropical high, Typhoon Shanshan was associated with the midlatitude trough, and Typhoon Durian was associated with the subtropical jet. The adjoint methods are found to be more capable of capturing the signal of the dynamic system that may affect the TC movement or evolution than are the ensemble methods.
Xu, Y., J. Li, and S. Dong. Ocean circulation from altimetry: Progress and challenges. In Ocean Circulation and El Niño: New Research, J.A. Long and D.S. Wells (ed.). Nova Science Publishers, New York, 71-97 (2009).
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The paper provides a review of recent progresses in physical oceanography, such as results on studying ocean circulation and mesoscale ocean dynamics derived from satellite altimetry. Since 1992, satellite altimetry has provided an unprecedented 16 years monitoring of sea level and ocean circulation variations. Continuous measurements from satellites like TOPEX/Poseidon and Jason-1 help us understand and foresee the effects of the change in ocean circulation on climate and on catastrophic climate events such as El Niño and La Niña. Altimeter measurements have improved our understanding of both the dynamics and thermodynamics of western boundary currents by providing a synoptic view of the current systems and their interannual variations, and allowed scientists to quantify eddy-induced salt and heat transport and seasonal and interannual variations in eddy kinetic energy. Altimeter measurements have also been used to map eddies, quantify their amplitudes and diameters, track their trajectories, and examine eddy dynamics and their roles in the ocean processes and climate variability. Recent advances in satellite altimetry, in synergy with other remote sensing techniques, constrain the uncertainty of mechanic energy driving meridional overturning circulation which regulates climate change. Moreover, altimetry has discovered a surprising sea level anomaly propagation speed which challenges the existing linear Rossby wave theory, and revealed the presence of elusive zonal fronts and jets in the ocean. However, challenges still exist in monitoring the ocean variability from satellite altimetry. Satellite altimeters are not able to measure the time-mean geostrophic currents due to the large uncertainty in geoid. This poses challenges for deriving the absolute geostrophic flow in regions where bottom velocities are non-zero since hydrographic estimates of absolute dynamic topography are unable to capture the effects of the bottom. The uncertainties of satellite altimetry measurements have a high geographic variability. The existence of high frequency energetic barotropic motions in the ocean can lead to a large aliasing error in satellite altimetric observations. New evidences show that the combined aliasing from several neighboring and crossing tracks could produce unreal mesoscale signals in altimeter mapped product. Although satellites altimetry has improved our understanding of the climate system dramatically, it is important to keep in mind that problems still remain and new challenges will arise.
Zeng, H., J.Q. Chambers, R.I. Negron-Juarez, G.C. Hurtt, D.B. Baker, and M.D. Powell. Impacts of tropical cyclones on U.S. forest tree mortality and carbon flux from 1851 to 2000. Proceedings of the National Academy of Sciences, 106(19):7888-7892 (2009).
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Tropical cyclones cause extensive tree mortality and damage to forested ecosystems. A number of patterns in tropical cyclone frequency and intensity have been identified. There exist, however, few studies on the dynamic impacts of historical tropical cyclones at a continental scale. Here, we synthesized field measurements, satellite image analyses, and empirical models to evaluate forest and carbon cycle impacts for historical tropical cyclones from 1851 to 2000 over the continental U.S. Results demonstrated an average of 97 million trees affected each year over the entire United States, with a 53-Tg annual biomass loss, and an average carbon release of 25 Tg y-1. Over the period 1980-1990, released CO2 potentially offset the carbon sink in forest trees by 9-18% over the entire United States. U.S. forests also experienced twice the impact before 1900 than after 1900 because of more active tropical cyclones and a larger extent of forested areas. Forest impacts were primarily located in Gulf Coast areas, particularly southern Texas and Louisiana and south Florida, while significant impacts also occurred in eastern North Carolina. Results serve as an important baseline for evaluating how potential future changes in hurricane frequency and intensity will impact forest tree mortality and carbon balance.
Zhang, H.-M., R.W. Reynolds, R. Lumpkin, R. Molinari, K. Arzayus, M. Johnson, and T.M. Smith. An integrated global observing system for sea surface temperature using satellites and in-situ data: Research to operations. Bulletin of the American Meteorological Society, 90(1):31-38 (2009).
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This paper describes the optimal design and its research-to-operation transition of an integrated global observing system of satellites and in situ observations. The integrated observing system is used for climate assessment using sea surface temperature (SST). Satellite observations provide superior samplings while in situ observations provide the ground truth. Observing System Simulation Experiments (OSSEs) were used to objectively design an efficient in situ system to reduce satellite biases to a required accuracy. The system design was peer reviewed and was then transitioned into operations as a U.S. contribution to the international Global Climate Observing System (GCOS). A system performance measure was also formulated and operationally tracked under the Government Performance Results Act (GPRA). Additional OSSEs assisted the planning, programming, budgeting, and execution system at the National Oceanic and Atmospheric Administration (NOAA) to maximize design efficiency. This process of research to operation and decision making enables NOAA to strategically target its observing system investments. The principles of this specific example may have potential applicability to the other components of GCOS.
Zhang, J.A., W.M. Drennan, P.G. Black, and J.R. French. Turbulence structure of the hurricane boundary layer between the outer rain bands. Journal of the Atmospheric Sciences, 66(8):2455-2467 (2009).
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As part of the Coupled Boundary Layers Air-Sea Transfer (CBLAST)-Hurricane program, flights were conducted to directly measure turbulent fluxes and turbulence properties in the high-wind boundary layer of hurricanes between the outer rainbands. For the first time, vertical profiles of normalized momentum fluxes, sensible heat and humidity fluxes, and variances of three-dimensional wind velocities and specific humidity are presented for the hurricane boundary layer with surface wind speeds ranging from 20 to 30 m s-1. The turbulent kinetic energy budget is estimated, indicating that the shear production and dissipation are the major source and sink terms, respectively. The imbalance in the turbulent kinetic energy budget indicates that the unmeasured terms, such as horizontal advection, may be important in hurricane boundary layer structure and dynamics. Finally, the thermodynamic boundary layer height, estimated based on the virtual potential temperature profiles, is roughly half of the boundary layer height estimated from the momentum flux profiles. The latter height where momentum and humidity fluxes tend to vanish is close to that of the inflow layer and also of the maximum in the tangential velocity profiles.
Zhang, J.-Z., C.R. Kelble, C.J. Fischer, and L.D. Moore. Hurricane Katrina induced nutrient runoff from an agricultural area to coastal waters in Biscayne Bay, Florida. Estuarine, Coastal, and Shelf Science, 84(2):209-218 (2009).
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Water quality surveys conducted in Biscayne Bay, Florida, indicated enhanced nutrient input coupled with increased runoff as a result of precipitation associated with Hurricane Katrina. Nutrient concentrations before Katrina ranged from 0.06-24.2 mM (mean 3.3 mM) for nitrate and 0.01-0.18 mM (mean 0.1 mM) for soluble reactive phosphate. Five days after Katrina, nitrate concentrations ranged from 0.87-80.0 mM (mean 17.0 mM), with a bay-wide mean increase of 5.2-fold over pre-hurricane levels. Soluble reactive phosphate concentrations ranged from 0.07-0.62 mM (mean 0.2 mM), with a bay-wide mean increase of 2-fold over pre-hurricane levels. The maximum concentrations for both nitrate and soluble reactive phosphate were found at a water quality monitoring station near the mouth of Mowry Canal, which drains an agricultural area in the southern Biscayne Bay watershed near Homestead, Florida. At this station, nitrate and soluble reactive phosphate concentrations increased 7- and 10-fold, respectively. Storm-induced fertilizer runoff from this agricultural area caused a bay-wide increase in nutrient concentrations after Hurricane Katrina. Nutrient concentrations in the bay returned to pre-hurricane levels within three months after Hurricane Katrina, showing the resiliency of the Biscayne Bay ecosystem.
Zipser, E.J., C.H. Twohy, S.-C. Tsay, K.L. Thornhill, S. Tanelli, R. Ross, T.N. Krishnamurti, Q. Ji, G. Jenkins, S. Ismail, N.C. Hsu, R. Hood, G.M. Heymsfield, A. Heymsfield, J. Halverson, H.M. Goodman, R. Ferrare, J.P. Dunion, M. Douglas, R. Cifelli, G. Chen, E.V. Browell, and B. Anderson. The Saharan air layer and the fate of African easterly waves: NASA's AMMA field study of tropical cyclogenesis. Bulletin of the American Meteorological Society, 90(8):1137-1156 (2009).
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In 2006, NASA led a field campaign to investigate the factors that control the fate of African easterly waves (AEWs) moving westward into the tropical Atlantic Ocean. Aircraft and surface-based equipment were based on Cape Verdes islands, helping to fill some of the data void between Africa and the Caribbean. Taking advantage of the international African Monsoon Multidisciplinary Analysis (AMMA) program over the continent, the NASA-AMMA (NAMMA) program used enhanced upstream data, whereas NOAA aircraft farther west in the Atlantic studied several of the storms downstream. Seven AEWs were studied during AMMA, with at least two becoming tropical cyclones. Some of the waves that did not develop while being sampled near Cape Verde likely intensified in the central Atlantic instead. NAMMA observations were able to distinguish between the large-scale wave structure and the smaller-scale vorticity maxima that often form within the waves. A special complication of the east Atlantic environment is the Saharan air layer (SAL), which frequently accompanies the AEWs and may introduce dry air and heavy aerosol loading into the convective storm systems in the AEWs. One of the main achievements of NAMMA was the acquisition of a database of remote sensing and in-situ observations of the properties of the SAL, enabling dynamic models and satellite retrieval algorithms to be evaluated against high-quality real data. Ongoing research with this database will help determine how the SAL influences cloud micro-physics and perhaps also tropical cyclogenesis, as well as the more general question of recognizing the properties of small-scale vorticity maxima within tropical waves that are more likely to become tropical cyclones.
**2008**
Aberson, S.D. An alternative tropical cyclone intensity forecast verification technique. Weather and Forecasting, 23(6):1304-1310 (2008).
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The National Hurricane Center (NHC) does not verify official or model forecasts if those forecasts call for a tropical cyclone to dissipate or if the real tropical cyclone dissipates. A new technique in which these forecasts are included in a contingency table with all other forecasts is presented. Skill scores and probabilities are calculated. Forecast verifications with the currently used technique have shown a slight improvement in intensity forecasts. The new technique, taking into account all forecasts, suggests that the probability of a forecast having a large (>30 kt) error is decreasing, and the likelihood of the error being less than about 10 kt is increasing in time, at all forecast lead times except 12 h when the forecasts are already quite good.
Aberson, S.D. Large forecast degradations due to synoptic surveillance during the 2004 and 2005 hurricane seasons. Monthly Weather Review, 136(8):3138-3150 (2008).
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Though operational tropical cyclone synoptic surveillance generally leads to smaller track forecast errors in the National Oceanic and Atmospheric Administration Global Forecasting System (GFS) than would occur otherwise, not every case is improved. Very large GFS forecast degradations due to surveillance are investigated. Small perturbations to model initial conditions may have a large impact locally or downstream in a short time. In these cases, the perturbations are due either to erroneous data assimilated into the models or to issues with the complex data assimilation system itself, and may have caused the forecast degradations. Investigation of forecast and observing system failures can lead to procedural changes that may eliminate some causes of future large forecast errors.
Amornthammarong, N., and J.-Z. Zhang. Shipboard fluorometric flow analyzer for high-resolution underway measurement of ammonium in seawater. Analytical Chemistry, 80(4):1019-1026 (2008).
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A shipboard fluorometric flow analyzer has been developed for near-real-time, high-resolution underway measurement of ammonium in seawater. The fluorometric method is based on the reaction of ammonium with o-phthaldialdehyde (OPA) and sulfite. The reagents used in this method have been modified to suit seawater analysis. This method shows no refractive index and salinity effect from seawater samples. The potential interferences in seawater have been studied, and their effects have been reduced. The instrument response is linear over a wide range of ammonium concentration. The limit of detection of 1.1 nM was estimated in laboratory using ammonium standards prepared in distilled water. It should be noted that application of this method to low-level ammonium measurement requires a correction of interference species, such as amino acids. The sample throughput is 3600 h-1. The system can be used for both freshwater and seawater samples and has been used to monitor the distribution of ammonium in Florida coastal waters around an oceanic wastewater outfall.
Aoyoma, M., J. Barwell-Clarke, S. Becker, M. Blum, E.S. Braga, S.C. Coverly, E. Czobik, I. Dahllf, M. Dai, G.O. Donnell, C. Engelke, G.-C. Gong, G.-H. Hong, D.J. Hydes, M.-M. Jin, H. Kasai, R. Kerouel, Y. Kiyomono, M. Knockaert, N. Kress, K.A. Krogslund, M. Kumagai, S. Leterme, Y. Li, S. Masuda, T. Miyao, T. Moutin, A. Murata, N. Nagai, G. Nausch, M.K. Ngirchechol, A. Nybakk, H. Ogawa, J. van Ooijen, H. Ota, J.M. Pan, C. Payne, O. Pierre-Duplessix, M. Pujo-Pay, T. Raabe, K. Saito, K. Sato, C. Schmidt, M. Schuett, T.M. Shammon, J. Sun, T. Tanhua, L. White, E.M.S. Woodward, P. Worsfold, P. Yeats, T. Yoshimura, A. Younou, and J.-Z. Zhang. 2006 inter-laboratory comparison study of a reference material for nutrients in seawater. Technical Report No 58, Meteorological Research Institute, Tsukuba, Japan, 104 pp. (2008).
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Autoclaved natural seawater collected in the North Pacific Ocean was used as a reference material for analyzing nutrient concentrations in seawater during an inter-laboratory comparison study conducted in 2006; this study was a follow-up to a similar but smaller study conducted in 2003. Homogeneity of sample #2 was confirmed by the repeatability of the nutrient concentration measurements and those in terms of one sigma of standand deviation are 0.2%, 0.3%, and 0.2% for nitrate, phosphate, and silicate, respectively. Sets of six samples with concentration ranges of 0.1-42.4 µmol kg-1 for nitrate, 0.0-0.6 µmol kg-1 for nitrite, 0.0-3.0 µmol kg-1 for phosphate, and 1.7-156.1 µmol kg-1 for silicate were analyzed. A set of samples was distributed to each of 55 laboratories around the globe (20 countries), and results were returned by 52 of those laboratories (19 countries). Analytical precisions reported by the participating laboratories for all deteminands were generally lower, by at least 50%, than the consensus standard deviations of the reported concentrations. The consensus standard deviations for sample #2 for all determinands were 5 to 10 times as large as the homogeneities of sample #2 for all determinands. In some laboratories, the non-linearity of the calibration curve was not treated effectively. Our results indicate that variability in the in-house standards of the participating laboratories and the handling of the non-linearity of the calibration curve of the participating laboratories were the primary sources of inter-laboratory discrepancies. The results confirm that a certified reference material for nutrients in seawater and a common method for measuring nutrient concentrations are essential for the improvement of the global comparability of nutrient data in the worlds oceans.
Atlas, R., and G.D. Emmitt. Review of observing system simulation experiments to evaluate the potential impact of lidar winds on numerical weather prediction. ILRC24, Vol. 2 (ISBN 978-0-615-21489-4), 726-729 (2008).
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Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. OSSEs conducted at NASA/GSFC and NOAA/AOML in collaboration with Simpson Weather Associates have indicated significant potential for space-based lidar winds to improve numerical weather prediction. In this paper, we summarize OSSE methodology and earlier OSSE results, and present methodology and results from a "QuickOSSE" designed to assess the potential impact of lidar winds on the predicted track of a specific hurricane.
Atlas, R., and L.P. Riishojgaard. Application of OSSEs to observing system design. In Remote Sensing System Engineering, P.E. Ardanuy and J.J. Puschell (eds.). Proceedings, SPIE, 7087:708707, doi:10.1117/12.795344, 9 pp. (2008).
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Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. Extensive OSSEs have been conducted at NASA/GSFC and NOAA/AOML in collaboration with Simpson Weather Associates and operational data assimilation centers over the last 23 years. These OSSEs determined correctly the quantitative potential for several proposed satellite observing systems to improve weather analysis and prediction prior to their launch, evaluated trade-offs in orbits, coverage and accuracy for space-based wind lidars, and were used in the development of the methodology that led to the first beneficial impacts of satellite surface winds on numerical weather prediction. In this paper, we summarize OSSE methodology and earlier OSSE results, and present methodology and results from recent OSSEs.
Atlas, R., J. Ardizzone, and R.N. Hoffman. Application of satellite surface wind data to ocean wind analysis. In Remote Sensing System Engineering, P.E. Ardanuy and J.J. Puschell (eds.). Proceedings, SPIE, 7087:708707, doi:10.1117/12.795371, 7 pp. (2008).
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A new set of cross-calibrated, multi-satellite ocean surface wind data is described. The principal data set covers the global ocean for the period beginning in 1987 with six-hour and 25-km resolution, and is produced by combining all ocean surface wind speed observations from SSM/I, AMSR-E, and TMI, and all ocean surface wind vector observations from QuikSCAT and SeaWinds. An enhanced variational analysis method (VAM) performs quality control and combines these data with available conventional ship and buoy data and ECMWF analyses. The VAM analyses fit the data used very closely and contain small-scale structures not present in operational analyses. Comparisons with withheld WindSat observations are also shown to be very good. These data sets should be extremely useful to atmospheric and oceanic research, and to air-sea interaction studies.
Atlas, R., R.N. Hoffman, J. Ardizzone, M. Leidner, and J.C. Jusem. A new cross-calibrated, multi-satellite ocean surface wind product. Proceedings, International Geoscience and Remote Sensing Symposium, Boston, MA, July 7-11, 2008. IEEE Geoscience and Remote Sensing Society, CD-ROM, 4 pp. (2008).
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A new set of cross-calibrated, multi-satellite ocean surface wind data sets is introduced. The principal data set covers the global ocean for the period beginning in 1987 with six-hour, 25-km resolution and is produced by combining all ocean surface wind speed observations from SSM/I, AMSR-E, and TMI, and all ocean surface wind vector observations from QuikSCAT and SeaWinds. An enhanced variational analysis method quality controls and combines these data as well as available conventional ship and buoy data with ECMWF analyses. The analysis fits the data used very closely. Comparisons with withheld WindSat observations are also very good.
Baringer, M.O., and C.S. Meinen. The meridional overturning circulation. In State of the Climate in 2007, D.H. Levinson and J.H. Lawrimore (eds.). Bulletin of the American Meteorological Society, 88(7):S49-S51 (2008).
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No abstract.
Bell, M.M., and M.T. Montgomery. Observed structure, evolution, and potential intensity of category 5 Hurricane Isabel (2003) from 12-14 September. Monthly Weather Review, 136(6):2023-2046 (2008).
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Unprecedented observations of Hurricane Isabel (2003) at category 5 intensity were collected from 12 to 14 September. This study presents a detailed analysis of the inner-core structure, atmospheric boundary layer, sea surface temperature, and outflow layer of a superintense tropical cyclone using high-resolution in situ flight-level, NCAR GPS dropwindsonde, Doppler radar, and satellite measurements. The analysis of the dropwindsonde and in situ data includes a comprehensive discussion of the uncertainties associated with this observational dataset and provides an estimate of the storm-relative axisymmetric inner-core structure using Barnes objective analysis. An assessment of gradient and thermal wind balance in the inner core is also presented. The axisymmetric data composites presented in this study suggest that Isabel built a reservoir of high moist entropy air by sea-to-air latent heat flux inside the low-level eye that was utilized as an additional energy source to nearly maintain its extreme intensity even after crossing the cool wake of Hurricane Fabian. It is argued here that the combined mean and asymmetric eddy flux of high moist entropy air from the low-level eye into the eyewall represents an additional power source or "turbo boost" to the hurricane heat engine. Recent estimates of the ratio of sea-to-air enthalpy and momentum exchange at high wind speeds are used to suggest that Isabel utilized this extra power to exceed the previously assumed intensity upper bound for the given environmental conditions on all three days. This discrepancy between a priori potential intensity theory and observations may be as high as 35 m s-1 on 13 September.
Bell, G.D., E. Blake, C.W. Landsea, S.B. Goldenberg, R. Pasch, and T. Kimberlain. Atlantic basin. In State of the Climate in 2007, D.H. Levinson and J.H. Lawrimore (eds.). Bulletin of the American Meteorological Society, 88(7):S68-S71 (2008).
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No abstract.
Beron-Vera, F.J., M.J. Olascoaga, and G.J. Goni. Oceanic mesoscale eddies as revealed by Lagrangian coherent structures. Geophysical Research Letters, 35(8):L12603, doi:10.1029/2008GL033957 (2008).
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We demonstrate the feasibility of using dynamical systems tools to unambiguously identify mesoscale oceanic eddies from surface ocean currents derived using climatological hydrography and altimetry. Specifically, our analysis is based on extracting Lagrangian coherent structures (LCSs) from finite-time Lyapunov exponent (FTLE) fields. The FTLE fields reveal with unprecedented detail an intricate tangle of LCSs, which are hidden in ocean surface topography maps but sometimes are apparent in ocean color images. These LCSs delineate fluid domains with very different advective properties, and thus their detection provides an objective (i.e., frame-independent) means of identifying eddy boundaries. The importance of considering LCSs in quantifying transport by eddies is highlighted. Such a quantification does not rely on the common assumption-which is shown to be generally not valid-that transport is largely effected by the trapping and subsequent translation of water slugs inside eddies defined as the regions enclosed by sea height (streamfunction) contours within which rotation dominates over strain. LCSs are calculated for the whole globe and compared with satellite-tracked drogue drifter trajectories within a selected region of the South Atlantic.
Bourles, B., R. Lumpkin, M.J. McPhaden, F. Hernandez, P. Nobre, E. Campos, L. Yu, S. Planton, A. Busalacchi, A.D. Moura, J. Servain, and J. Trotte. The PIRATA program: History, accomplishments, and future directions. Bulletin of the American Meteorological Society, 89(8):1111-1125 (2008).
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The Pilot Research Moored Array in the tropical Atlantic (PIRATA) was developed as a multinational observation network to improve our knowledge and understanding of ocean-atmosphere variability in the tropical Atlantic. PIRATA was motivated by fundamental scientific issues and by societal needs for improved prediction of climate variability and its impact on the economies of West Africa, northeastern Brazil, the West Indies, and the United States. In this paper the implementation of this network is described, noteworthy accomplishments are highlighted, and the future of PIRATA in the framework of a sustainable tropical Atlantic observing system is discussed. We demonstrate that PIRATA has advanced beyond a Pilot program and, as such, we have redefined the PIRATA acronym to be Prediction and Research Moored Array in the Tropical Atlantic.
Collier, C., R. Ruzicka, K. Banks, L. Barbieri, J. Beal, D. Bingham, J. Bohnsack, S. Brooke, N. Craig, R. Dodge, L. Fisher, N. Gadbois, D. Gilliam, L. Gregg, T. Kellison, V. Kosmynin, B. Lapointe, E. McDevitt, J. Phipps, N. Poulos, J. Proni, P. Quinn, B. Riegl, R.Spieler, J. Walczak, B. Walker, and D. Warrick. The state of coral reef ecosystems of southeast Florida, pp. 131-159. In The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008, J.E. Waddell and A.M. Clarke (eds.). NOAA Technical Memorandum, NOAA NCCOS-73, 569 pp. (2008).
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No abstract.
DeMaria, M., J.D. Hawkins, J.P. Dunion, and D.K. Smith. Tropical intensity forecasting using a satellite-based total precipitable water product. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 5 pp. (2008).
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No abstract.
Dong, S., J. Sprintall, S.T. Gille, and L. Talley. Southern Ocean mixed-layer depth from Argo float profiles. Journal of Geophysical Research, 113(C6):C06013, doi:10.1029/2006JC004051 (2008).
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Argo float profiles of temperature, salinity, and pressure are used to derive the mixed-layer depth (MLD) in the Southern Ocean. MLD is determined from individual profiles using both potential density and potential temperature criteria, and a monthly climatology is derived from individual MLDs using an objective mapping method. Quantitative data are available in the auxiliary material. The spatial structures of MLDs are similar in each month, with deep mixed layers within and just north of the Antarctic Circumpolar Current (ACC) in the Pacific and Indian oceans. The deepest mixed layers are found from June to October and are located just north of the ACC where Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are formed. Examination of individual MLDs indicates that deep mixed layers (MLD > 400 m) from both the density and temperature criteria are concentrated in a narrow surface density band which is within the density range of SAMW. The surface salinity for these deep mixed layers associated with the SAMW formation are slightly fresher compared to historical estimates. Differences in air-sea heat exchanges, wind stress, and wind stress curl in the Pacific and Indian oceans suggest that the mode water formation in each ocean basin may be preconditioned by different processes. Wind mixing and Ekman transport of cold water from the south may assist the SAMW formation in the Indian Ocean. In the eastern Pacific, the formation of mode water is potentially preconditioned by the relative strong cooling and weak stratification from upwelling.
Dunion, J.P., and C.S. Marron. A reexamination of the Jordan mean tropical sounding based on awareness of the Saharan air layer: Results from 2002. Journal of Climate, 21(20):5242-5253 (2008).
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The Jordan mean tropical sounding has provided a benchmark for representing the climatology of the tropical North Atlantic and Caribbean Sea since 1958. However, recent studies of the Saharan air layer (SAL) have suggested that the tropical atmosphere in these oceanic regions may contain two distinct soundings (SAL and non-SAL) with differing thermodynamic and kinematic structures and that a single mean sounding like Jordans does not effectively represent these differences. This work addresses this possibility by examining over 750 rawinsondes from the tropical North Atlantic Ocean and Caribbean Sea during the 2002 hurricane season. It was found that a two-peak bimodal moisture distribution (dry SAL and moist non-SAL) exists in this region and that the Jordan sounding does not represent either distribution particularly well. Additionally, SAL soundings exhibited higher values of geopotential height, unique temperature profiles, and stronger winds (with an enhanced easterly component) compared to the moist tropical non-SAL soundings. The results of this work suggest that the Jordan mean tropical sounding may need to be updated to provide a more robust depiction of the thermodynamics and kinematics that exist in the tropical North Atlantic Ocean and Caribbean Sea during the hurricane season.
Dunkerton, T.J., M.T. Montgomery, and Z. Wang. Tropical cyclogenesis in a tropical wave critical layer: Easterly waves. Atmospheric Chemistry and Physics Discussions, 8(3):11149-11292 (2008).
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The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a surface low along the wave as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, resembles the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development within the critical layer is given by the intersection of the waves critical latitude and trough axis, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally this marsupial paradigm one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. This translation requires an appropriate gauge that renders translating streamlines and isopleths of translating stream function approximately equivalent to flow trajectories. In the translating frame, the closed circulation is stationary, and a dividing streamline effectively separates air within the critical layer from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because it provides (i) a region of cyclonic vorticity and weak deformation by the resolved flow, (ii) containment of moisture entrained by the gyre and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. These ideas are formulated in three new hypotheses describing the flow kinematics and dynamics, moist thermodynamics and wave/vortex interactions comprising the marsupial paradigm. A survey of 55 named tropical storms in 1998-2001 reveals that actual critical layers sometimes resemble the ideal east-west train of cats eyes, but are usually less regular, with one or more recirculation regions in the translating frame. It is shown that a wave gauge given by the translation speed of the parent wave is the appropriate choice, as well, for isolated proto-vortices carried by the wave. Some implications for entrainment/containment of vorticity and moisture in the cat's eye are discussed from this perspective, based on the observational survey.
Elipot, S., and R. Lumpkin. Spectral description of oceanic near-surface variability. Geophysical Research Letters, 35(2):L05606, doi:10.1029/2007GL032874 (2008).
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This paper provides a spectral description of near-surface oceanic velocity variability on a global scale. Rotary spectra of drifter velocities are estimated in zonal bands of the Indian, Pacific and Atlantic Oceans. The partition of energy between cyclonic and anticyclonic frequencies clearly identifies inertial oscillations at all latitudes. The meridional distribution of near-inertial energy is described in detail. The polarization of super-inertial energy is consistent with internal waves dynamics. Thus, the distribution of super-inertial energy may be a manifestation of freely propagating near-inertial waves on the beta-plane.
Fiechter, J., B.K. Haus, N. Melo, and C.N.K. Mooers. Physical processes impacting passive particle dispersal in the upper Florida Keys. Continental Shelf Research, 28(10-11):1261-1272 (2008).
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Physical processes affecting the dispersion of passive particles (e.g., coral larvae, pollutants) in the upper Florida Keys are investigated through in situ observations (acoustic Doppler current profilers and surface drifters) and numerical ocean circulation modeling (horizontal resolution: 800 m, vertical resolution: 0.1-1 m). During the study period in August 2006 (set to coincide with an annual coral spawning event), Lagrangian trajectories in the vicinity of the reef tract indicated that alongshelf advection was mainly poleward and due to the subtidal flow of the Florida Current, while cross-shelf advection was mainly onshore and due to wind-driven currents. Tidal currents resulted in predominantly alongshelf displacements, but did not contribute significantly to net passive particle transport on a weekly timescale. Typical advection distances were of the order of 10 to 50 km for pelagic durations of 1 week, with significant variability linked to geographical location. In contrast, the direction of transport from the offshore reefs remained essentially constant (i.e., potential dispersion pathways were limited). In addition, Lagrangian trajectories and progressive vector diagrams in the vicinity of the reef tract indicate that alongshelf variations in the cross-shelf velocity gradient associated with the FC are relatively weak on an alongshore scale of ca. 50 km. For August 2006, the highest particle concentrations typically occur inshore of the reef tract, thereby suggesting that onshore transport associated with wind-driven currents contributes significantly to the local retention of passive organisms (and other tracers) in the upper Florida Keys. Overall, the results illustrate the necessity of conducting targeted in situ observations and numerical model predictions to quantify the physical processes affecting reef-scale advection, especially in an effort to understand local retention and dispersion mechanisms for larval marine organisms.
Gentry, B., M. McGill, G. Schwemmer, M. Hardesty, A. Brewer, T. Wilkerson, R. Atlas, M. Sirota, S. Lindemann, and F. Hovis. New technologies for direct detection of Doppler lidar: Status of the TWiLiTE airborne molecular Doppler lidar project. ILRC24, Vol. 1 (ISBN 978-0-615-21489-4), 239-243 (2008).
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The Tropospheric Wind Lidar Technology Experiment (TWiLiTE) is a three-year program to advance the technology readiness level of the key technologies and subsystems of a molecular direct detection wind lidar system by validating them, at the system level, in an integrated airborne lidar system. The TWiLiTE Doppler lidar system is designed for autonomous operation on NASA high altitude research aircraft such as the WB57 or ER-2. These aircraft are capable of flying well above the mid-latitude tropopause so the downward-looking lidar will measure complete profiles of the horizontal wind field through the lower stratosphere and the entire troposphere. The completed system will profile winds in clear air from the aircraft altitude of 18 km to the surface with 250 m vertical resolution and a velocity precision of < 3 m/s. In this paper, we will describe the new technologies developed as part of the TWiLiTE program and present an update on the status of the airborne lidar system development.
Giammanco, I.M., J.L. Schroeder, M.D. Powell, and D.A. Smith. GPS dropwindsonde observations of tropical cyclone low-level wind maxima. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 8 pp. (2008).
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No abstract.
Gledhill, D.K., R. Wanninkhof, F.J. Millero, and M. Eakin. Ocean acidification of the greater Caribbean region, 1996-2006. Journal of Geophysical Research, 113(C10):C10031, doi:10.1029/2007JC004629 (2008).
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The global oceans serve as the largest sustained natural sink for increasing atmospheric carbon dioxide (CO2) concentrations. As this CO2 is absorbed by seawater, it not only reacts causing a reduction in seawater pH (or acidification) but also decreases the carbonate mineral saturation state (OMEGA), which plays an important role in calcification for many marine organisms. Ocean acidification could affect some of the most fundamental biological and geochemical processes of the sea in coming decades. Observations obtained in situ from Volunteer Observing Ships and multiple geochemical surveys have been extended using satellite remote sensing and modeled environmental parameters to derive estimates of sea-surface alkalinity (AT) and carbon dioxide partial pressure (pCO2,sw). Pairing estimates of AT and pCO2,sw have permitted characterization of the changes in sea-surface OMEGA, which have transpired over the past decade throughout the Greater Caribbean Region as a consequence of ocean acidification. The results reveal considerable spatial and temporal variability throughout the region. Despite this variability, we observed a strong secular decrease in aragonite saturation state (OMEGAarg) at a rate of approximately -0.012 0.001 OMEGAarg yr-1 (r2 = 0.97, P < 0.001).
Godin, O.E., and D.R. Palmer (eds.). History of Russian Underwater Acoustics. World Scientific Publishing Company, 1211 pp. (2008).
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No abstract.
Goni, G.J. Tropical cyclone heat potential. In State of the Climate in 2007, D.H. Levinson and J.H. Lawrimore (eds.). Bulletin of the American Meteorological Society, 88(7):S43-S45 (2008).
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No abstract.
Goodwin, K.D., and R.W. Litaker. Emerging technologies for monitoring recreational waters for bacteria and viruses. In Oceans and Human Health: Risk and Remedies from the Seas, P.J. Walsh, S.L. Smith, W.H. Gerwick, H. Solo-Gabriele, and L.E. Fleming (eds.). Elsevier Science Publishers, New York, 381-404 (2008).
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Water quality assessment involves the specific, sensitive, and rapid detection of bacterial indicators and pathogens in water samples, including viable but nonculturable (VBNC) cells. This work evaluates the specificity and sensitivity of a new method which combines a fluorescent in situ hybridization (FISH) approach with a physiological assay (direct viable count DVC) for the direct enumeration, at the single-cell level, of highly diluted viable cells of members of the family Enterobacteriaceae in freshwater and drinking water after membrane filtration. The approach (DVC-FISH) uses a new direct detection device, the laser scanning cytometer (Scan RDI). Combining the DVC-FISH method on a membrane with Scan RDI detection makes it possible to detect as few as one targeted cell in approximately 108 nontargeted cells spread over the membrane. The ability of this new approach to detect and enumerate VBNC enterobacterial cells in freshwater and drinking water distribution systems was investigated and is discussed.
Goodwin, K.D., L. Matragrano, and M.J. LaGier. The possibility of false negative results hampers the ability to elucidate the relationship between fecal indicator bacteria and human pathogens and source tracking markers in beach water and sand. In Marine Pollution: New Research, T.N. Hofer (ed.). Nova Science Publishers, Inc., New York, 255-277 (2008).
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Coastal waters can become contaminated with feces through sewage spills, septic tank leaks, animal droppings, and runoff. Beach closures are regulated by testing water samples for fecal-indicating bacteria (FIB), but recent data showing persistence or regrowth of indicators in sand has raised concerns that beach sand may also harbor dangerous bacteria and viruses. Conversely, there is the possibility that regrowth of indicator bacteria in sand and resuspension to the water column may actually produce false positive results. In such a scenario, concentrations of indicator bacteria would not be correlated with human fecal pollution. In this preliminary study, beach sand (wet and dry), water (marine and river), and raw sewage samples were PCR screened for several pathogenic microbes and markers of human fecal pollution. The PCR screen consisted of human specific Bacteroides (HF8 marker), human-specific enterococci (esp gene), Campylobacter jejuni, Escherichia coli 0157:H7, Salmonella spp., Staphylococcus aureus, and adenovirus. The results were compared to concentrations of enterococci, Escherichia coli, and Bacteroides species, as determined by membrane filtration methods. Molecular analysis yielded positive results only in samples of raw sewage, despite relatively high concentrations of FIB in many of the samples. However, estimates of the number of cells delivered to the PCR reaction suggested that few of the samples met the detection limit of the PCR reaction, despite exceedance of EPA single sample guidelines for recreational waters on many of the sample dates. A variety of factors could have contributed to the relatively poor delivery of cells to the PCR reaction, and the analysis indicated a need to improve nucleic acid processing in order to enable better delivery of DNA to downstream molecular methods.
Griffa, A., R. Lumpkin, and M. Veneziani. Cyclonic and anticyclonic motion in the upper ocean. Geophysical Research Letters, 35(1):L01608, doi:10.1029/2007GL032100 (2008).
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Upper ocean variability is highly energetic and contributes to key processes such as heat transport and water mass formation. Here, the distribution of ocean surface cyclonic and anticyclonic motion is computed from global drifter observations for scales from large eddies to submesoscale. Two zonal bands of small-scale motion are recovered: a known anticyclonic band at 30-40 latitude, mostly wind-induced, and an unexpected cyclonic band at 10-20 latitude. It is suggested that this is due to submesoscale processes related to salinity front instabilities. These results provide a first global view of the upper ocean including these motions.
Halliwell, G.R., L.K. Shay, S.D. Jacob, O.M. Smedstad, and E.W. Uhlhorn. Improving ocean model initialization for coupled tropical cyclone forecast models using GODAE nowcasts. Monthly Weather Review, 136(7):2576-2591 (2008).
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To simulate tropical cyclone (TC) intensification, coupled ocean-atmosphere prediction models must realistically reproduce the magnitude and pattern of storm-forced sea surface temperature (SST) cooling. The potential for the ocean to support intensification depends on the thermal energy available to the storm, which in turn depends on both the temperature and thickness of the upper-ocean warm layer. The ocean heat content (OHC) is used as an index of this potential. Large differences in available thermal energy associated with energetic boundary currents and ocean eddies require their accurate initialization in ocean models. Two generations of the experimental U.S. Navy ocean nowcast-forecast system based on the Hybrid Coordinate Ocean Model (HYCOM) are evaluated for this purpose in the northwest Caribbean Sea and Gulf of Mexico prior to Hurricanes Isidore and Lili (2002), Ivan (2004), and Katrina (2005). Evaluations are conducted by comparison to in situ measurements, the Navy's three-dimensional Modular Ocean Data Assimilation System (MODAS) temperature and salinity analyses, microwave satellite SST, and fields of OHC and 26C isotherm depth derived from satellite altimetry. Both nowcast-forecast systems represent the position of important oceanographic features with reasonable accuracy. Initial fields provided by the first-generation product had a large upper-ocean cold bias because the nowcast was initialized from a biased older-model run. SST response in a free-running Isidore simulation is improved by using initial and boundary fields with reduced cold bias generated from a HYCOM nowcast that relaxed model fields to MODAS analyses. A new climatological initialization procedure used for the second-generation nowcast system tended to reduce the cold bias, but the nowcast still could not adequately reproduce anomalously warm conditions present before all storms within the first few months following nowcast initialization. The initial cold biases in both nowcast products tended to decrease with time. A realistic free-running HYCOM simulation of the ocean response to Ivan illustrates the critical importance of correctly initializing both warm-core rings and cold-core eddies to correctly simulate the magnitude and pattern of SST cooling.
Hendee, J.C., L. Gramer, D.P. Manzello, and M. Jankulak. Integrating near real-time data for coral reef ecological forecasting. Proceedings of the Gulf and Caribbean Fisheries Institute, 59:525-528 (2008).
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The National Oceanic and Atmospheric Administration (NOAA) has committed to integrating ocean data from a variety of sources into an Integrated Ocean Observing System, and to work towards operational ecological forecasting as part of its Ecosystem Approach to Management. Consistent with this, NOAA's Coral Reef Conservation Program has committed to integrating coral data from a variety of sources for the specific benefit of coral reef researchers and Marine Protected Area (MPA) managers; and NOAA's Atlantic Oceanographic and Meteorological Laboratory, together with its NOAA and University of Miami partners, are contributing to this goal through their Integrated Coral Observing Network (ICON) project. ICON provides Web-based software to integrate satellite, monitoring station (in situ), and radar data sources in near real-time; and utilizes an inference engine (artificial intelligence software) to provide ecological forecasts using some or all of these data. The capabilities of ICON software are currently being focused upon one area in particular, Molasses Reef in the Florida Keys National Marine Sanctuary, to provide proof-of-concept, and to provide a "discovery prototype" for consideration by the MPA managers assembled at the GCFI conference. Feedback to ICON developers from MPA managers--based upon their own specific management requirements and priorities, and knowledge of the prototype capabilities--is essential to set priorities and enable additional ICON software engineering specifically tailored to MPA managers' needs. Featured in the prototype are several levels of user access: layperson, researcher, site maintainer, MPA manager, and software developer colleague. Depending upon user access, information products can include recent and historical single-source and integrated data output, custom graphics output, and ecological forecasts for coral bleaching, coral spawning, upwelling, pollution impacts and larval drift.
Hendee, J.C., L. Gramer, J.A. Kleypas, D.P. Manzello, M. Jankulak, and C. Langdon. The Integrated Coral Observing Network (ICON): Sensor solutions for sensitive sites. Proceedings, Third International Conference on Intelligent Sensors, Sensor Networks, and Information Processing, Melbourne, Australia, December 3-6, 2007. Institute of Electrical and Electronics Engineers (IEEE), 669-673 (2008).
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The National Oceanic and Atmospheric Administration's (NOAA) Integrated Coral Observing Network (ICON) has been operational since 2000 and works closely with most U.S. Government and many international environmental partners involved in coral reef research. The ICON program has pioneered the use of artificial intelligence techniques to assess near real-time data streams from environment sensor networks such as the SEAKEYS Network (Florida Keys), the Australia Institute of Marine Science Weather Network, NOAA's Coral Reef Ecosystem Division network in the Pacific, and its own Integrated Coral Observing Network (ICON) of stations in the Caribbean. Besides its innovative approach to coral monitoring station deployments, the ICON program recently pioneered techniques for the near real-time integration of satellite, in situ, and radar data sources for purposes of ecological forecasting of such events as coral bleaching, coral spawning, upwelling, and other marine behavioral or physical oceanographic events. The ICON program has also ushered in the use of Pulse-Amplitude-Modulating fluorometry to measure near real-time physiological recording of response to environmental stress during coral bleaching, thus providing even better ecological forecasting capabilities through artificial intelligence and data integrative techniques. Herewith, we describe these techniques, along with a report on new coral calcification instrumentation augmenting the ICON Network sensor array.
Hitchcock, G.L., W.S. Arnold, M. Frischer, C.R. Kelble, and R.K. Cowen. Short-term dispersal of an intentionally-released patch of larval Mercenaria Spp. In the Indian River Lagoon, Florida, USA. Bulletin of Marine Science, 82(1):41-57 (2008).
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In July 1998 approximately 2.5 x 108 of recently-spawned Mercenaria spp. larvae were intentionally released in the northernmost basin of the Indian River Lagoon, Florida, to characterize the initial dispersion from a point source at time scales of hours to days. Larval densities measured with a quantitative molecular method indicated ambient concentrations were enhanced by 10 larvae L-1 near surface drifters released with the larvae. Surface distributions from samples collected near the drifters indicate that larval patches developed during the first day. diffusive processes evaluated from dye releases yield apparent diffusivity coefficients that suggest diffusive processes could spread larvae over several km2 within 2 d. Our observations suggest that high-resolution methods for mapping larvae are essential to better resolve spatial distribution evolution at time scales of hours to days, and spatial scales of tens to hundreds of meters. This capability could better define the temporal evolution of larval distributions following a mass spawning event.
Huang, X.-L., and J.-Z. Zhang. Kinetic spectrophotometric determination of submicromolar orthophosphate by molybdate reduction. Microchemical Journal, 89(1):58-71 (2008).
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A kinetic spectrophotometric procedure was developed for determination of submicromolar orthophosphate based on the reaction in which orthophosphate serves as a catalyst in the reduction of molybdenum, and the initial rate of molybdenum-blue formation (Lambdamax = 780 nm) is proportional to the concentration of orthophosphate in the samples. The detection limit (3 x standard deviation of blank, n = 8) was 6 nM and the linear calibration ranged from 10 to 100 nM (r2 = 0.997). The precisions of this method were 3.3% at 10 nM and 5.4% at 50 nM (n = 8), respectively. Similar to other molybdate based methods, silica and arsenate in the samples can interfere with phosphate determination. The responses of silicate and arsenate were about 25% and 7% of that of orthophosphate, respectively, and their interferences were enhanced in the presence of phosphate in the samples due to the synergistic effect of phosphate with arsenate or silicate on the molybdate reagent.
Huang, X.-L., and J.-Z. Zhang. Rate of phosphoantimonylmolybdenum blue complex formation in acidic persulfate digested sample matrix for total dissolved phosphorus determination: Importance of post-digestion pH adjustment. Talanta, 77(1):340-345 (2008).
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Acidic persulfate oxidation is one of the most common procedures used to digest dissolved organic phosphorus compounds in water samples for total dissolved phosphorus determination. It has been reported that the rates of phosphoantimonyl-molybdenum blue complex formation were significantly reduced in the digested sample matrix. This study revealed that the intermediate products of persulfate oxidation, not the slight change in pH, cause the slowdown of color formation. This effect can be remedied by adjusting digested samples pH to a near neural to decompose the intermediate products. No disturbing effects of chlorine on the phosphoantimonylmolybdenum blue formation in seawater were observed. It is noted that the modification of mixed reagent recipe cannot provide near neutral pH for the decomposition of the intermediate products of persulfate oxidation. This study provides experimental evidence not only to support the recommendation made in APHA standard methods that the pH of the digested sample must be adjusted to within a narrow range of sample, but also to improve the understanding of role of residue from persulfate decomposition on the subsequent phosphoantimonylmolybdenum blue formation.
Huang, X.-L., Y. Chen, and M. Shenker. Chemical fractionation of phosphorus in stabilized biosolids. Journal of Environmental Quality, 37(5):1949-1958 (2008).
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Three chemicals--ferrous sulfate (FeSul), calcium oxide (CaO), and aluminum sulfate (alum)--were applied at different rates to stabilize P in fresh, anaerobically digested biosolids (FBS) obtained from an activated sewage treatment plant. A modified Hedley fractionation procedure was used to assess P forms in these sludge-borne materials and in a biosolids compost (BSC) prepared from the same FBS. Each biosolids material exhibited a unique pattern of P distribution among fractions. The most available P forms, namely: (i) water-soluble P (WSP); (ii) membrane-P; and (iii) NaHCO3-P, were stabilized by small rates of each of the chemicals; but the P transformation into more stable forms depended on the type of chemical added. The stabilized P forms were enhanced by high rates of CaO and FeSul, but were reduced by high rates of alum. The organic P (Po) in the first three fractions of the FeSul- and alum-stabilized biosolids was enhanced by the chemical addition, and Po transformation from NaOH-Po into NaHCO3-Po was found in calcium-stabilized biosolids. A positive relationship was found between NaHCO3-Po and the NaHCO3-extracted organic C in all chemically stabilized biosolids. One-step extraction by NaHCO3 or NaOH underestimated P extraction compared to the stepwise extraction. The reported results are consistent with solid-state P speciation reported earlier and contribute important information for optimizing biosolids stabilization to reduce P loss after incorporation in soils and for maximizing soil capacity to safely store pre-stabilized biosolids.
Jiang, L.-Q., W.-J. Cai, R. Wanninkhof, Y. Wang, and H. Lueger. Air-sea CO2 fluxes on the U.S. South Atlantic Bight: Spatial and seasonal variability. Journal of Geophysical Research, 113(C7):C07019, doi:10.1029/2007JC004366 (2008).
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The partial pressure of carbon dioxide (pCO2) in surface seawater on the South Atlantic Bight (SAB) of the United States was measured during six cruises from January 2005 to May 2006. The high-resolution pCO2 data allow us to create the first maps of the sea surface pCO2 over the SAB for all seasons. Contrary to an earlier study that was based on limited spatial and seasonal coverage, this study shows that the SAB is a net sink of atmospheric CO2 on an annual basis (-0.48 0.21 mol m-2 a-1). The inner shelf is a source of +1.20 0.24 mol m-2 a-1, while the middle and outer shelves are sinks of -1.23 0.19 and -1.37 0.21 mol m-2 a-1, respectively. Seasonally, the SAB shifts from a sink for atmospheric CO2 in winter to a source in summer. The annual cycle of sea surface temperature plays a dominant role in controlling the seasonal variation of the pCO2. Wind speeds are seasonally anti-correlated with the air-sea pCO2 differences, and this is an important factor in contributing to the net annual air-sea CO2 exchange. Factors related to the estimates of CO2 fluxes in the coastal ocean, such as the choice of wind speeds, the correction of gas transfer equations with nonlinearity coefficients, the effect of diel variations of pCO2, the spatial extrapolation of the pCO2 to the nearshore area, and the seasonal interpolation, are also discussed.
Johns, W.E., L.M. Beal, M.O. Baringer, J.R. Molina, S.A. Cunningham, T. Kanzow, and D. Rayner. Variability of shallow and deep western boundary currents off the Bahamas during 2004-2005: Results from the 26N RAPID-MOC array. Journal of Physical Oceanography, 38(3):605-623 (2008).
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Data from an array of six moorings deployed east of Abaco, Bahamas, along 26.5N during March 2004-May 2005 are analyzed. These moorings formed the western boundary array of a transbasin observing system designed to continuously monitor the meridional overturning circulation and meridional heat flux in the subtropical North Atlantic, under the framework of the joint U.K.-U.S. Rapid Climate Change (RAPID)-Meridional Overturning Circulation (MOC) Program. Important features of the western boundary circulation include the southward-flowing deep western boundary current (DWBC) below 1000 m and the northward-flowing "Antilles" Current in the upper 1000 m. Transports in the western boundary layer are estimated from direct current meter observations and from dynamic height moorings that measure the spatially integrated geostrophic flow between moorings. The results of these methods are combined to estimate the time-varying transports in the upper and deep ocean over the width of the western boundary layer to a distance of 500 km offshore of the Bahamas escarpment. The net southward transport of the DWBC across this region, inclusive of northward deep recirculation, is -26.5 Sv (Sv = 106 m3 s-1), which is divided nearly equally between upper (-13.9 Sv) and lower (-12.6 Sv) North Atlantic Deep Water (NADW). In the top 1000 m, 6.0 Sv flows northward in a thermocline-intensified jet near the western boundary. These transports are found to agree well with historical current meter data in the region collected between 1986 and 1997. Variability in both shallow and deep components of the circulation is large, with transports above 1000 m varying between -15 and +25 Sv and deep transports varying between -60 and +3 Sv. Much of this transport variability, associated with barotropic fluctuations, occurs on relatively short time scales of several days to a few weeks. Upon removal of the barotropic fluctuations, slower baroclinic transport variations are revealed, including a temporary stoppage of the lower NADW transport in the DWBC during November 2004.
Jones, L., P.G. Black, S.S. Chen, R.E. Hood, J.W. Johnson, C.S. Ruf, A. Mims, and C.C. Hennon. Next generation airborne Hurricane Imaging Radiometer (HIRAD): Improved forecast skill with wide field imagery. Tropical Meteorology Special Symposium, New Orleans, LA, January 20-24, 2008. American Meteorological Society, Boston, 8 pp. (2008).
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No abstract.
Kanzow, T., J. J.-M. Hirschi, C.S. Meinen, D. Rayner, S.A. Cunningham, J. Marotzke, W.E. Johns, H.L. Bryden, L.M. Beal, and M.O. Baringer. A prototype system of observing the Atlantic meridional overturning circulation: Scientific basis, measurement and risk mitigation strategies, and first results. Journal of Operational Oceanography, 1(1):19-28 (2008).
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The Atlantic Meridional Overturning Circulation (MOC) carries up to one quarter of the global northward heat transport in the Subtropical North Atlantic. A system monitoring the strength of the MOC volume transport has been operating since April 2004. The core of this system is an array of moored sensors measuring density, bottom pressure and ocean currents. A strategy to mitigate risks of possible partial failures of the array is presented, relying on backup and complementary measurements. The MOC is decomposed into five components, making use of the continuous moored observations, and of cable measurements across the Straits of Florida, and wind stress data. The components compensate for each other, indicating that the system is working reliably. The year-long average strength of the MOC is 18.7 5.6 Sv, with wind-driven and density-inferred transports contributing equally to the variability. Numerical simulations suggest that the surprisingly fast density changes at the western boundary are partially linked to westward propagating planetary waves.
Kelble, C.R., and J.N. Boyer. Southern estuaries hypothesis cluster: Water quality. Comprehensive Everglades Restoration Plan Assessment Team (eds.). Final 2007 System Status Report, 7-5-7.34 (2007).
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South Floridas bays and the plants and animals that they support reflect the volume, distribution, and quality of fresh water flowing into these aquatic systems. Past changes to the quality, quantity, timing, and distribution of freshwater flow have degraded water quality and compromised estuarine community structure and function in some areas of the southern estuaries. Current water quality monitoring programs provide adequate spatial and temporal coverage throughout the southern estuaries with the possible exception of the southwest Florida shelf where the temporal variability may not be adequately captured. Chlorophyll a was selected as an indicator of water quality because its biomass is an integrator of many of the water quality factors which may be altered by CERP. There is concern that increased freshwater flow due to CERP activities may result in more frequent, intense, and persistent phytoplankton blooms in the southern estuaries. The baseline conditions indicate that most of the southern estuaries is oligotrophic with median chlorophyll a concentrations of less than or approximately 1 ppb. This baseline data was used as the reference condition to assess the 2006 southern estuaries data, and only the Barnes, Manatee, and Blackwater Sound sub-region was found to have chlorophyll a biomass significantly higher than the baseline. This algal bloom was the result of an increase in total P in this subregion from the combined effects of highway construction and hurricane impacts, including the pre-hurricane freshwater release. This phytoplankton bloom illustrates the sensitivity of the southern estuaries to small increases in nutrient loading, because it took only a small increase in TP (> 10 ppb) to trigger this large phytoplankton bloom, which continues to persist. The ability of our methodologies to adequately detect this decline in water quality due to altered environmental conditions indicates the applicability of this technique to detect changes in water quality as a result of CERP activities. Understanding how CERP affects water quality in the southern estuaries will facilitate adaptively managing and guiding restoration efforts.
Landsea, C.W., D.A. Glenn, W. Bredemeyer, M. Chenoweth, R. Ellis, J.F. Gamache, L. Hufstetler, C.J. Mock, R. Perez, R. Prieto, J. Sanchez-Sesma, D. Thomas, and L. Woolcock. A reanalysis of the 1911-1920 Atlantic hurricane database. Journal of Climate, 21(10):2138-2168 (2008).
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A reanalysis of the Atlantic basin tropical storm and hurricane database ("best track") for the period of 1911-20 has been completed. This reassessment of the main archive for tropical cyclones of the North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico was necessary to correct systematic biases and random errors in the data as well as to search for previously unrecognized systems. A methodology for the reanalysis process for revising the track and intensity of tropical cyclone data is provided in detail. The dataset now includes several new tropical cyclones, excludes one system previously considered a tropical storm, makes generally large alterations in the intensity estimates of most tropical cyclones (both toward stronger and weaker intensities), and typically adjusts existing tracks with minor corrections. Average errors in intensity and track values are estimated for both open ocean conditions as well as for landfalling systems. Finally, highlights are given for changes to the more significant hurricanes to impact the United States, Central America, and the Caribbean for this decade.
Lavelle, J.W., and W.C. Thacker. A pretty good sponge: Dealing with open boundaries in limited area ocean models. Ocean Modelling, 20(3):270-292 (2008).
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The problem of computing within a limited domain surrounded by open boundaries is discussed within the context of the shallow-water wave equations by comparing three different treatments, all of which surround the domain by absorbing zones intended to prevent reflections of outgoing waves. The first, which has attracted a lot of attention for use in electromagnetic and aeroacoustic applications, is intended to prevent all reflections. However, it has not yet been developed to handle the second important requirement of open boundaries, namely the ability to pass information about external conditions into the domain of interest. The other two treatments, which absorb differences from a specified external solution, allow information to pass through the open boundary in both directions. One, based on the flow relaxation scheme of [Martinsen, E.A., Engedahl, H., 1987. Implementation and testing of a lateral boundary scheme as an open-boundary condition in a barotropic ocean model. Coastal Eng. 11, 603-627] and termed here the "simple sponge," relaxes all fields toward their external counterparts. The other, a simplification and generalization of the perfectly matched layer, referred to here as the "pretty good sponge," avoids absorbing the component of momentum parallel to the open boundary. Comparisons for a case that is dominated by outgoing waves shows the pretty good sponge to perform essentially as well as the perfectly matched layer and better than the simple sponge. In comparisons for a geostrophically balanced eddy passing through open boundaries, the pretty good sponge out-performed the simple sponge when the only external information available was about the advecting flow, but when information about the nature of the eddy in the sponge zones was also available, the simple sponge performed better. For the case of an equatorial soliton passing through the boundary and no information provided about its nature outside the open domain, again the pretty good sponge performed better. Proving useful for situations governed by nonlinear equations forced by external conditions and being easy to implement, the pretty good sponge should be considered for use with existing limited-area ocean models.
Lee, S.-K., and C. Wang. Tropical Atlantic decadal oscillation and its potential impact on the equatorial atmosphere-ocean dynamics: A simple model study. Journal of Physical Oceanography, 38(1):193-212 (2008).
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Simple coupled atmosphere-ocean models are used to study the potential influence of the tropical Atlantic Ocean decadal oscillation on the equatorial Atlantic atmosphere-ocean dynamics. Perturbing the model tropical Atlantic at the extratropics (25-30) with a decadal frequency, interhemispheric SST dipole mode emerges due to the wind-evaporation-SST feedback. Near the equator, a cross-equatorial oceanic gyre develops owing to the dipole-induced wind stress curl. Once formed, this oceanic gyre transports surface water across the equator from the cold to the warm hemisphere in the western boundary region and from the warm to the cold hemisphere in the Sverdrup interior. Interestingly, this occurs during both the positive and negative phases of the dipole oscillation, thus producing a persistent positive zonal SST gradient along the equator. Bjerknes-type feedback later kicks in to further strengthen the equatorial SST anomaly. Eventually, this feature grows to a quasi-stationary stage sustaining the equatorial westerly wind anomalies, thus also causing the depression (uplift) of the equatorial thermocline in the east (west), a condition similar to the Atlantic Nio. The dynamic relationship between the dipole SST oscillation and the equatorial thermocline suggests that a strengthening (weakening) of the dipole mode corresponds to a weakening (strengthening) of the equatorial thermocline slope.
Lee, S.-K., D.B. Enfield, and C. Wang. Why do some El Nios have no impact on tropical North Atlantic SST? Geophysical Research Letters, 35(13):L16705, doi:10.1029/2008GL034734 (2008).
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Warming of the Tropical North Atlantic (TNA) in boreal spring and early summer (April-June) following El Nio peaks in boreal winter is a well-known phenomenon that involves formation of the so-called atmospheric bridge (or teleconnection) from the Pacific. However, the existence of an El Nio in boreal winter does not guarantee a warm TNA in the following April-June (AMJ): for sixteen observed El Nio events that occurred during 1950-2005, the TNA (AMJ) remained neutral in six of them. A careful examination of the sixteen El Nio events leads to a hypothesis that if an El Nio ends before April, the TNA remains neutral. Here, we test this working hypothesis by performing multiple sets of ensemble model experiments using the NCAR atmospheric general circulation model coupled to a slab mixed layer ocean model. Analysis of the model experiments indicates that January-March (JFM) are the crucial months for the El Nio-induced warming of TNA. Therefore, if an El Nio does not continue throughout JFM, the atmospheric bridge connecting the tropical Pacific to the TNA is not persistent enough to force the TNA, thus the TNA remains neutral. Finally, our model experiments indicate even if an El Nio continues beyond JFM, the El Nio-induced warming of TNA in AMJ can be greatly reduced by Atlantic internal variability, and vice versa.
Lee, T.N., N. Melo, E. Johns, C. Kelble, R.H. Smith, and P.B. Ortner. On water renewal and salinity variability in the northeast subregion of Florida Bay. Bulletin of Marine Science, 82(1):83-105 (2008).
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The northeast subregion of Florida Bay receives approximately 75% of the direct freshwater runoff to the bay, most of which is retained within the subregion and has little impact on the dilution of hypersalinity development in adjacent subregions. Using direct measurements of the volume transports through connecting channels and indirectly estimating the total transport to the subregion from mean sea level variability, we show that interior basin water exchanges are weak and controlled by local wind forcing. East-west winds produced seasonally averaged throughflows of 33 and 78 m3 s-1 during the El Nio-influenced wet and dry seasons of 2002 and 2003, respectively, and resulted in a one year residence time for the northeast sub-region. The long residence time of the interior waters is due to the confining nature of the shallow banks and mangrove borders that surround the northeast subregion, as well as the lack of significant tidal exchange. Weak interbasin exchange results in the trapping of freshwater discharge from the Everglades within the northeast subregion. Development of hypersalinity within the north-central subregion of the bay has been associated with seagrass die-off and algal blooms that can cause water quality reduction in south Florida's coastal waters, including the Florida Keys reef tract. To reduce the development of hypersalinity within this region of the bay it will be necessary to divert a portion of the Everglades flow away from the northeast basin and into Whipray Basin during the dry season. Seasonal water balance estimates made for the northeast subregion and previous estimates from the north-central region indicate that groundwater inflows to Florida Bay are negligible and probably not a factor in water quality considerations.
Leidner, S.M., J. Ardizzone, J. Terry, E. Brin, and R. Atlas. Impact of satellite-derived ocean winds on hurricane forecasting at global and regional scales. 12th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS), New Orleans, LA, January 20-24, 2008. American Meteorological Society, Boston, 5 pp. (2008).
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No abstract.
Levine, N.M., S.C. Doney, R. Wanninkhof, K. Lindsay, and I.Y. Fung. Impact of ocean carbon system variability on the detection of temporal increases in anthropogenic CO2.Journal of Geophysical Research, 113(C3):C03019, doi:10.1029/2007JC004153 (2008).
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Estimates of temporal trends in oceanic anthropogenic carbon dioxide (CO2) rely on the ability of empirical methods to remove the large natural variability of the ocean carbon system. A coupled carbon-climate model is used to evaluate these empirical methods. Both the DELTA-C* and multiple linear regression (MLR) techniques reproduce the predicted increase in dissolved inorganic carbon for the majority of the ocean and have similar average percent errors for decadal differences (24.1% and 25.5%, respectively). However, this study identifies several regions where these methods may introduce errors. Of particular note are mode and deep water formation regions, where changes in air-sea disequilibrium and structure in the MLR residuals introduce errors. These results have significant implications for decadal repeat hydrography programs, indicating the need for subannual sampling in certain regions of the oceans in order to better constrain the natural variability in the system and to robustly estimate the intrusion of anthropogenic CO2.
Li, Q.P., D.A. Hansell, and J.-Z. Zhang. Underway monitoring of nanomolar nitrate plus nitrite and phosphate in oligotrophic seawater. Limnology and Oceanography: Methods, 6:319-326 (2008).
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To study nutrient dynamics and cycling in oligotrophic open ocean environments, continuous measurements of nanomolar nitrate, nitrite, and phosphate are valuable. However, such studies are usually impeded by the detection limits of conventional nutrient-sensors and analyzers. Here, we developed a shipboard deployable underway system for simultaneously monitoring nitrate plus nitrite and phosphate at nanomolar concentrations by the coupling of an optimized flow injection analytical system with two long-path liquid waveguide capillary cells (LWCC). The detection limits are ~2 nM for nitrate plus nitrite and ~1.5 nM for phosphate, respectively. Results from realtime surveys of waters over the west Florida continental shelf and the oligotrophic Sargasso Sea are presented. This system has also been successfully used to analyze more than 1000 discrete seawater samples manually during two cruises in the North Atlantic.
Lorsolo, S., J.L. Schroeder, P.P. Dodge, and F.D. Marks. An observational study of hurricane boundary layer small-scale coherent structures. Monthly Weather Review, 136(8):2871-2893 (2008).
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Data with high temporal and spatial resolution from Hurricanes Isabel (2003) and Frances (2004) were analyzed to provide a detailed study of near-surface linear structures with subkilometer wavelengths of the hurricane boundary layer (HBL). The analysis showed that the features were omnipresent throughout the data collection, displayed a horizontal and vertical coherency, and maintained an average orientation of 7 left of the low-level wind. A unique objective wavelength analysis was conducted, where wavelength was defined as the distance between two wind maxima or minima perpendicular to the features' long axis, and revealed that although wavelengths as large as 1400 m were observed, the majority of the features had wavelengths between 200 and 650 m. The assessed wavelengths differ from those documented in a recent observational study. To evaluate the correlation between the features and the underlying near-surface wind field, time and spectral analyses were completed and ground-relative frequency distributions of the features were retrieved. High-energy regions of the power spectral density (PSD) determined from near-surface data were collocated with the features' ground-relative frequency, illustrating that the features have an influence on the near-surface wind field. The additional energy found in the low-frequency range of the PSDs was previously identified as characteristic of the hurricane surface flow, suggesting that the features are an integral component of the HBL flow.
Lorsolo, S., J. Gamache, F. Marks, P. Dodge, and J.A. Zhang. Characterization of hurricane turbulence using airborne Doppler measurements. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 4 pp. (2008).
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No abstract.
Lowag, A., M.L. Black, and M.D. Eastin. External and internal influences on structural and intensity changes of Hurricane Bret (1999), Part I: Atmospheric and oceanic influences. Monthly Weather Review, 136(11):4320-4333 (2008).
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Hurricane Bret underwent a rapid intensification (RI) and subsequent weakening between 1200 UTC 21 August and 1200 UTC 22 August 1999 before it made landfall on the Texas coast 12 h later. Its minimum sea level pressure fell 35 hPa from 979 to 944 hPa within 24 h. During this period, aircraft of the National Oceanic and Atmospheric Administration (NOAA) flew several research missions that sampled the environment and inner core of the storm. These datasets are combined with gridded data from the National Centers for Environmental Prediction (NCEP) Global Model and the NCEP-National Center for Atmospheric Research (NCAR) reanalyses to document Brets atmospheric and oceanic environment as well as their relation to the observed structural and intensity changes. Brets RI was linked to movement over a warm ocean eddy and high sea surface temperatures (SSTs) in the Gulf of Mexico coupled with a concurrent decrease in vertical wind shear. SSTs at the beginning of the storms RI were approximately 29C and steadily increased to 30C as it moved to the north. The vertical wind shear relaxed to less than 10 kt during this time. Mean values of oceanic heat content (OHC) beneath the storm were about 20% higher at the beginning of the RI period than 6 h prior. The subsequent weakening was linked to the cooling of near-coastal shelf waters (to between 25 and 26C) by prestorm mixing combined with an increase in vertical wind shear. The available observations suggest no intrusion of dry air into the circulation core contributed to the intensity evolution. Sensitivity studies with the Statistical Hurricane Intensity Prediction Scheme (SHIPS) model were conducted to quantitatively describe the influence of environmental conditions on the intensity forecast. Four different cases with modified vertical wind shear and/or SSTs were studied. Differences between the four cases were relatively small because of the model design, but the greatest intensity changes resulted for much cooler prescribed SSTs. The results of this study underscore the importance of OHC and vertical wind shear as significant factors during RIs; however, internal dynamical processes appear to play a more critical role when a favorable environment is present.
Lozier, S., M.O. Baringer, J. Carton, P. Chang, T. Delworth, S.Hakkinen, W. Johns, K. Kelly, T. Lee, T. Liu, J. Toole, and J. Willis (U.S. CLIVAR AMOC Science Team). Progress report for a JSOST near-term priority assessing meridional overturning circulation variability: Implications for rapid climate change. U.S. CLIVAR Report 2008-1, U.S. CLIVAR Office, Washington, DC, 22 pp. (2008).
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No abstract.
Lueger, H., R. Wanninkhof, A. Olsen, J. Trinanes, T. Johannessen, D.W.R. Wallace, and A. Kortzinger. The sea-air CO2 flux in the North Atlantic estimated from satellite and Argo profiling float data. NOAA Technical Memorandum, OAR AOML-96, 28 pp. (2008).
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To improve the spatial and temporal resolution of sea-air carbon dioxide (CO2) flux estimates in the mid-latitude North Atlantic Ocean (30°N-63°N), empirical relationships were derived between the measured fugacity of CO2 in surface water (fCO2 sw), sea surface temperature (SST), and the mixed layer depth (MLD). Satellite chlorophyll was unsuccessful as a predictive parameter. The algorithms for fCO2 sw predictions were developed using Advanced Very High Resolution Radiometer (AVHRR) satellite SST and MLD data obtained from Argo floats. The root mean square (RMS) difference between the algorithms and fCO2 sw data was 9-10 µatm with a precision, determined from independent data, of 9-11 µatm. This precision is close to that necessary to constrain the sea-air flux in the mid-latitude North Atlantic Ocean to 0.1 Pg C yr-1. The algorithms were applied on high-resolution SST and MLD data to yield fCO2 sw proxy data for the entire region. The proxy data served to produce seasonal CO2 flux maps. In 2002, the mid-latitude North Atlantic was a year-round sink and took up 1.9 mol m-2 yr-1.
Lumpkin, R., and G.J. Goni. Surface current observations. In D.H. Levinson and J.H. Lawrimore (eds.). Bulletin of the American Meteorological Society, 88(7):S47-S49 (2008).
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No abstract.
Lumpkin, R., K. Speer, and K.P. Koltermann. Transport across 48N in the North Atlantic Ocean. Journal of Physical Oceanography, 38(4):733-752 (2008).
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Transports across 48N in the Atlantic Ocean are estimated from five repeat World Ocean Circulation Experiment (WOCE) hydrographic lines collected in this region in 1993-2000, from time-varying air-sea heat and freshwater fluxes north of 48N, and from a synthesis of these two data sources using inverse box model methods. Results from hydrography and air-sea fluxes treated separately are analogous to recently published transport variation studies and demonstrate the sensitivity of the results to either the choice of reference level and reference velocities for thermal wind calculations or the specific flux dataset chosen. In addition, flux-based calculations do not include the effects of subsurface mixing on overturning and transports of specific water masses. The inverse model approach was used to find unknown depth-independent velocities, interior diapycnal fluxes, and adjustments to air-sea fluxes subject to various constraints on the system. Various model choices were made to focus on annually averaged results, as opposed to instantaneous values during the occupation of the hydrographic lines. The results reflect the constraints and choices made in the construction of the model. The inverse model solutions show only marginal, not significantly different temporal changes in the net overturning cell strength and heat transport across 48N. These small changes are similar to seasonally or annually averaged numerical model simulations of overturning. Significant variability is found for deep transports and air-sea flux quantities in density layers. Put another way, if one ignores the details of layer exchanges, the model can be constrained to produce the same net overturning for each repeat line; however, constraining individual layers to have the same transport for each line fails. Diapycnal fluxes are found to be important in the mean but are relatively constant from one repeat line to the next. Mean air-sea fluxes are modified slightly but are still essentially consistent with either the NCEP data or the National Oceanography Centre, Southampton (NOC) Comprehensive Ocean-Atmosphere Data Set (COADS) within error. Modest reductions in air-sea flux uncertainties would give these constraints a much greater impact. Direct transport estimates over broader regions than the western boundary North Atlantic Current are needed to help resolve circulation structure that is important for variability in net overturning.
Mainelli, M., M. DeMaria, L.K. Shay, and G.J. Goni. Application of oceanic heat content estimation to operational forecasting of recent Atlantic category 5 hurricanes. Weather and Forecasting, 23(1):3-16 (2008).
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Research investigating the importance of the subsurface ocean structure on tropical cyclone intensity change has been ongoing for several decades. While the emergence of altimetry-derived sea height observations from satellites dates back to the 1980s, it was difficult and uncertain as to how to utilize these measurements in operations as a result of the limited coverage. As the in situ measurement coverage expanded, it became possible to estimate the upper oceanic heat content (OHC) over most ocean regions. Beginning in 2002, daily OHC analyses have been generated at the National Hurricane Center (NHC). These analyses are used qualitatively for the official NHC intensity forecast, and quantitatively to adjust the Statistical Hurricane Intensity Prediction Scheme (SHIPS) forecasts. The primary purpose of this paper is to describe how upper-ocean structure information was transitioned from research to operations, and how it is being used to generate NHC's hurricane intensity forecasts. Examples of the utility of this information for recent category 5 hurricanes (Isabel, Ivan, Emily, Katrina, Rita, and Wilma from the 2003-2005 hurricane seasons) are also presented. Results show that for a large sample of Atlantic storms, the OHC variations have a small but positive impact on the intensity forecasts. However, for intense storms, the effect of the OHC is much more significant, suggestive of its importance on rapid intensification. The OHC input improved the average intensity errors of the SHIPS forecasts by up to 5% for all cases from the category 5 storms, and up to 20% for individual storms, with the maximum improvement for the 72-96-h forecasts. The qualitative use of the OHC information on the NHC intensity forecasts is also described. These results show that knowledge of the upper-ocean thermal structure is fundamental to accurately forecasting intensity changes of tropical cyclones, and that this knowledge is making its way into operations. The statistical results obtained here indicate that the OHC only becomes important when it has values much larger than that required to support a tropical cyclone. This result suggests that the OHC is providing a measure of the upper ocean's influence on the storm and improving the forecast.
Manzello, D.P. Short and long-term ramifications of climate change upon coral reef ecosystems: Case studies across two oceans. Ph.D. thesis, University of Miami, Rosenstiel School of Marine and Atmospheric Science, 82 pp. (2008).
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World-wide coral reefs are in a state of decline as a result of many local and regional factors. Recent, global mass mortalities of reef corals due to record warm sea temperatures have led researchers to consider global warming as one of the most significant threats to the persistence of coral reef ecosystems over the next 100 years. It is well established that elevated sea temperatures cause widespread coral bleaching, yet confusion lingers as to what facet of extreme temperatures is most important. Utilizing long-term in situ datasets, nine thermal stress indices were calculated and their effectiveness at segregating bleaching years a posteriori for multiple reefs on the Florida Reef Tract was tested. Simple bleaching thresholds based on deviations above the climatological maximum monthly sea temperature were just as effective at identifying bleaching years as complex thermal stress indices. Near real-time bleaching alerts issued by NOAA's Integrated Coral Observing Network (ICON) are now based upon a running 30-day average SST, such that alerts are only issued when the running 30-day average SST exceeds the estimated bleaching threshold for a particular site. In addition to three widespread, mass-coral bleaching events, the Florida Reef Tract was impacted by three tropical storms and 12 hurricanes from 1997-2005. Sea surface cooling associated with the high frequency of hurricanes that impacted Florida in 2005 likely acted to ameliorate the severity and duration of bleaching. Nonetheless, hurricane-associated cooling is not expected to nullify the proposed effects of climate change on coral reefs. The role of thermal stress in coral bleaching has been extensively studied for eastern tropical Pacific (ETP) coral reefs. However, the ETP presents a unique opportunity as this region has sub-optimal conditions for coral reef development because of upwelling of carbon dioxide-enriched water along the shallow thermocline. This upwelling results in a depressed aragonite saturation state, which is likely an additional factor in the poor reef development throughout the ETP. The highest aragonite saturation states documented in this study occur in the Gulf of Chiriqu, which corresponds with the greatest reef development of the entire ETP. Seasonal upwelling had a significant effect on the carbonate chemistry of surface waters in Pacific Panama. This regionally-depressed aragonite saturation of the ETP appears to result in corals with a less dense skeleton. Density values of poritid corals from the Galapagos, where aragonite saturation was the lowest documented in this study, were significantly less dense relative to those from Panama and the Great Barrier Reef. The density of non-living pocilloporid framework components were no different across the ETP carbonate saturation gradients. This could be a result of the activity of boring sponges removing the primary carbonate material within the dead coral skeleton, thus lowering density, albeit physical-chemical dissolution cannot be ruled out. These studies provide real-world examples of the ramifications of global climate change upon coral reef ecosystems.
Manzello, D.P., J.A. Kleypas, D.A. Budd, C.M. Eakin, P.W. Glynn, and C. Langdon. Poorly cemented coral reefs of the eastern tropical Pacific: Possible insights into reef development in a high-CO2 world. Proceeding of the National Academy of Sciences, 105(30):10,450-10,455 (2008).
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Ocean acidification describes the progressive, global reduction in seawater pH that is currently underway because of the accelerating oceanic uptake of atmospheric CO2. Acidification is expected to reduce coral reef calcification and increase reef dissolution. Inorganic cementation in reefs describes the precipitation of CaCO3 that acts to bind framework components and occlude porosity. Little is known about the effects of ocean acidification on reef cementation and whether changes in cementation rates will affect reef resistance to erosion. Coral reefs of the eastern tropical Pacific (ETP) are poorly developed and subject to rapid bioerosion. Upwelling processes mix cool, subthermocline waters with elevated pCO2 (the partial pressure of CO2) and nutrients into the surface layers throughout the ETP. Concerns about ocean acidification have led to the suggestion that this region of naturally low pH waters may serve as a model of coral reef development in a high-CO2 world. We analyzed seawater chemistry and reef framework samples from multiple reef sites in the ETP and found that a low carbonate saturation state (Omega) and trace abundances of cement are characteristic of these reefs. These low cement abundances may be a factor in the high bioerosion rates previously reported for ETP reefs, although elevated nutrients in upwelled waters may also be limiting cementation and/or stimulating bioerosion. ETP reefs represent a real-world example of coral reef growth in low-Omega waters that provide insights into how the biological-geological interface of coral reef ecosystems will change in a high-CO2 world.
Marks, F.D., P.G. Black, M.T. Montgomery, and R.W. Burpee. Structure of the eye and eyewall of Hurricane Hugo (1989). Monthly Weather Review, 136(4):1237-1259 (2008).
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On 15 September 1989, one of NOAA's WP-3D research aircraft, N42RF [lower aircraft (LA)], penetrated the eyewall of Hurricane Hugo. The aircraft had an engine fail in severe turbulence while passing the radius of maximum wind and before entering the eye at 450-m altitude. After the aircraft returned to controlled flight within the 7-km radius eye, it gained altitude gradually as it orbited in the eye. Observations taken during this period provide an updated model of the inner-core structure of an intense hurricane and suggest that LA penetrated an intense cyclonic vorticity maximum adjacent to the strongest convection in the eyewall [eyewall vorticity maximum (EVM)]. This EVM was distinct from the vortex-scale cyclonic circulation observed to orbit within the eye three times during the 1 h that LA circled in the eye. At the time, Hugo had been deepening rapidly for 12 h. The maximum flight-level tangential wind was 89 m s-1 at a radius of 12.5 km; however, the primary vortex peak tangential wind, derived from a 100-s filter of the flight-level data, was estimated to be 70 m s-1, also at 12.5-km radius. The primary vortex tangential wind was in approximate gradient wind balance, was characterized by a peak in angular velocity just inside the radius of maximum wind, and had an annular vorticity structure slightly interior to the angular velocity maximum. The EVM along the aircraft's track was roughly 1 km in diameter with a peak cyclonic vorticity of 1.25 x 10-1 s-1. The larger circulation center, with a diameter >15 km, was observed within the eye and exhibited an average orbital period of 19 min. This period is about the same as that of the angular velocity maximum of the axisymmetric mean vortex and is in reasonable agreement with recent theoretical and model predictions of a persistent trochoidal "wobble" of circulation centers in mature hurricane-like vortices. This study is the first with in situ documentation of these vortical entities, which were recently hypothesized to be elements of a lower-tropospheric eye/eyewall mixing mechanism that supports strong storms.
Meinen, C.S. Accuracy in mooring motion temperature corrections. Journal of Atmospheric and Oceanic Technology, 25(12):2293-2303 (2008).
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Moored temperature sensors, whether fixed or profiling, routinely need to be corrected to remove the signals associated with the vertical motion of the sensors when the moorings blow over in strong flow events (for profiling sensors the problems occur only at the upper end of the profiling range). Hydrographic data are used to estimate the accuracy with which moored temperature sensors in the Gulf Stream can be corrected for mooring motion aliasing using standard correction techniques, and the implications for other ocean regions are discussed. Comparison with hydrographic data and coincident inverted echo sounder (IES) data from the Synoptic Ocean Prediction Experiment (SYNOP) shows that the errors inherent in mooring motion corrected temperatures during significant pressure deflections are potentially 2-3 times as large as previous estimates based on a smaller dataset of observations in the Kuroshio at approximately the same latitude in the Pacific. For sensors with a nominal level of 400 dbar and a typical root-mean-square pressure deflection of 150 dbar, accuracy limits of up to 0.7C on the corrected temperatures are applicable. Deeper sensors typically have smaller accuracy bounds. There is a suggestion that the presence of a mode water layer near the nominal depth of the shallowest sensor can result in much higher errors in mooring motion corrected temperature data. The accuracy estimates derived herein should apply not only to moorings deployed in the Gulf Stream but also to all currents that exhibit similar velocity amplitudes and thermal gradients such as the Agulhas or Kuroshio.
Meinen, C.S., and M.O. Baringer. Atlantic meridional overturning circulation shows significant changes in early data from international monitoring systems at 26.5N. U.S. CLIVAR Variations, 6(1):1-3 (2008).
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No abstract.
Miller, T.L., R.M. Atlas, P.G. Black, J.L. Case, S.S. Chen, R.E. Hood, J.W. Johnson, J. Jones, C.S. Ruf, and E.W. Uhlhorn. Simulation of the impact of new aircraft and satellite-based ocean surface wind measurements on H*Wind analyses. 12th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS), New Orleans, LA, January 20-24, 2008. American Meteorological Society, Boston, 6 pp. (2008).
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No abstract.
Miller, T.L., R. Atlas, P.G. Black, C.C. Hennon, S.S. Chen, R.E. Hood, J.W. Johnson, L. Jones, C.S. Ruf, and E.W. Uhlhorn. Simulation of the impact of new ocean surface wind measurements on H*Wind analyses. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 7 pp. (2008).
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No abstract.
Molinari, R.L., Z. Garraffo, and D. Snowden. Differences between observed and coupled simulation of North Atlantic sea surface currents and temperature. Journal of Geophysical Research, 113(C9):C09011, doi:10.1029/2008JC004848 (2008).
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North Atlantic sea surface temperature (SST) distributions derived from observations and a coupled model from NOAAs Geophysical Fluid Dynamics Laboratory, CM2.1, are compared to evaluate the models ability to simulate recent (1900 to the present) oceanic surface characteristics. The North Atlantic focus will limit our analyses to spatial scales less than gyre, scales usually not addressed in previous model-observation comparisons. Identifying model differences from observations at these scales will assist modelers in identifying problems to be considered and remedies to be applied. The properties compared are the mean annual SST, standard deviation, amplitude of the annual and semiannual harmonic, decadal meridional movements of the axis of the Gulf Stream, propagation of SST anomalies along the axis of the Gulf Stream, and 100-year trends in SST records. Because of the dependence of SST on surface currents, observed flow from surface drifters and simulated flow from 15 m fields are also compared. The model simulates the large-scale properties of all the variables compared. However, there are areas of differences in some variables that can be related to inadequacies in the simulated current fields. For example, the model Gulf Stream (GS) axis after separation from the western boundary is located some 100 km north of the observed axis, which contributes to an area of warmer simulated SSTs. The absence of a slope current in the same region that advects colder water from the Labrador Sea in the observations also contributes to this area of higher model SSTs. The model North Atlantic Current (NAC) is located to the east of the observed NAC contributing to a large area of SST discrepancy. The patterns of the amplitude of the annual harmonic are similar with maximum amplitude off the east coast of northern North America. The semiannual harmonic exhibits relatively large amplitudes (>1C) north of about 55N, a signal not found in the observations. In both the model and observations, a region of increased standard deviations encompasses the GS and NAC. The model simulates north-south migrations of the GS core but at a longer period (20 years) than observed. The model does not simulate the SST anomalies that propagate along the observed GS and NAC. The model captures both the spatial and temporal characteristics of the Atlantic Multidecadal Oscillation. Both model and observations exhibit a dipole in trends, with positive trends in the subtropical Atlantic and negative trends in the subpolar gyre. The modeled region of negative trends is limited to the western subpolar Atlantic. The observed trends extend farther to the east.
Moore, R.W., M.T. Montgomery, and H.C. Davies. The integral role of a diabatic Rossby vortex in a heavy snowfall event. Monthly Weather Review, 136(6):1878-1897 (2008).
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On 24-25 February 2005, a significant east coast cyclone deposited from 4 to nearly 12 in. (~10-30 cm) of snow on parts of the northeastern United States. The heaviest snowfall and most rapid deepening of the cyclone coincided with the favorable positioning of an upper-level, short-wave trough immediately upstream of a preexisting surface cyclone. The surface cyclone in question formed approximately 15 h before the heaviest snowfall along a coastal front in a region of frontogenesis and heavy precipitation. The incipient surface cyclone subsequently intensified as it moved to the northeast, consistently generating the strongest convection to the east-northeast of the low-level circulation center. The use of potential vorticity (PV) inversion techniques and a suite of mesoscale model simulations illustrates that the early intensification of the incipient surface cyclone was primarily driven by diabatic effects and was not critically dependent on the upper-level wave. These facts, taken in conjunction with the observed structure, energetics, and Lagrangian evolution of the incipient surface disturbance, identify it as a diabatic Rossby vortex (DRV). The antecedent surface vorticity spinup associated with the DRV phase of development is found to be integral to the subsequent rapid growth. The qualitative similarity with a number of observed cases of explosive cyclogenesis leaves open the possibility that a DRV-like feature comprises the preexisting positive low-level PV anomaly in a number of cyclogenetic events that exhibit a two-stage evolution.
Munoz, E., and R. Czujko. AMS membership survey results: Profile of AMS membership residing outside the United States of America. Bulletin of the American Meteorological Society, 89(6):900-904 (2008).
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No abstract.
Munoz, E., A.J. Busalacchi, S. Nigam, and A. Ruiz-Barradas. Winter and summer structure of the Caribbean low-level jet. Journal of Climate, 21(6):1260-1276 (2008).
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The Caribbean region shows maxima in easterly winds greater than 12 m s-1 at 925 hPa in July and February, herein referred to as the summer and winter Caribbean low-level jet (LLJ), respectively. It is important to understand the controls and influences of the Caribbean LLJ because other LLJs have been observed to be related to precipitation variability. The purpose of this study is to identify the mechanisms of the Caribbean LLJ formation and variability and their association to the regional hydroclimate. Climatological fields are calculated from the North American Regional Reanalysis and the 40-yr ECMWF Re-Analysis from 1979 to 2001. It is observed that the low-level (925 hPa) zonal wind over the Caribbean basin has a semiannual cycle and an interannual variability, with greater standard deviation during boreal summer. The semiannual cycle has peaks in February and July, which are regional amplifications of the large-scale circulation. High mountains to the south of the Caribbean Sea influence the air temperature meridional gradient, providing a baroclinic structure that favors a stronger easterly wind. The boreal summer strengthening of the Caribbean LLJ is associated with subsidence over the subtropical North Atlantic from the May-to-July shift of the ITCZ and the evolution of the Central American monsoon. Additionally, the midsummer minimum of Caribbean precipitation is related to the Caribbean LLJ through greater moisture flux divergence. From May to September the moisture carried by the Caribbean LLJ into the Gulf of Mexico is strongest. The summer interannual variability of the Caribbean LLJ is due to the variability of the meridional pressure gradient across the Caribbean basin, influenced by tropical Pacific variability during summer.
Murillo, S.T. Determination of the circulation center and inner core evolution of Hurricane Danny (1997) using the GBVTD-simplex algorithm. M.S. thesis, University of Hawaii at Manoa, 57 pp. (2008).
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The evolution and structure of Hurricane Danny (1997) is examined via a single-Doppler radar tropical cyclone (TC) wind retrieval technique, the ground-based velocity track display (GBVTD) algorithm. The GBVTD technique is applied to 5-hours of data gathered simultaneously by two WSR-88D radars in Mobile, AL (KMOB) and Slidell, LA (KLIX) at ~6 minute intervals. The circulation centers and the primary circulations of Danny derived from these two independent radar observations (~60 volumes from each radar) are used to evaluate the accuracy of the GBVTD algorithm and the GBVTD-simplex center finding algorithm. Other observations, such as dual-Doppler analysis, dropwindsonde, and in-situ measurements from the NOAA WP-3D and the U.S. Air Force Reserve Command WC-130 (AFRC), aircraft provide independent assessments of the TC center and structure. It is found that the GBVTD-simplex derived centers, which used only the maximum mean tangential wind as the sole criterion, were unsatisfactory and unstable. An improved algorithm is proposed to seek time continuity in RMW, maximum mean tangential wind, and the center position in order to reduce the large fluctuations experienced in this study and the results are used to quantify the accuracy of the derived circulation centers. The quality of the GBVTD-derived circulation from these new centers is assessed. Danny's kinematic structure retrieved from KLIX and KMOB data using the improved sets of centers are consistent with the structures retrieved from the dual-Doppler analyses. Danny evolved from a mostly axisymmetric TC into a wave number one asymmetric TC then returned to an axisymmetric TC during this five-hour period.
Murillo, S.T., W.-C. Lee, G.M. Barnes, M.M. Bell, and F.D. Marks. Determination of the circulation center and inner core evolution of Hurricane Danny (1997) using the GBVTD-simplex algorithm. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, 5 pp. (2008).
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No abstract.
Murillo, S.T., R.E. Pandya, R.Y. Chu, J.A. Winkler, R. Czujko, and E.M.C. Cutrim. AMS membership survey results: An overview and longitudinal analysis of the demographics of the American Meteorological Society. Bulletin of the American Meteorological Society, 89(5):727-733 (2008).
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The 2005 membership survey is the fifth in a series of surveys that has monitored the composition of the AMS since 1975. The responses of the 2005 survey reveal several interesting changes in the educational level, employment characteristics, and personal status of Society members. The proportion of members with Ph.D. degrees has increased with time to 46% of the regular (nonstudent) and retired members in 2005. Universities/colleges, the federal government, and radio/TV remain the three most important employers of AMS members, although their relative importance has changed with time, with universities/colleges now employing more members than the federal government. Most AMS members continue to report that they became interested in the atmospheric sciences in either elementary school or as undergraduates, although the importance of early (K-6) experiences has increased with time. The age distribution of AMS members in 2005 suggests that the gradual aging of the AMS membership reported earlier (based on the responses to the 1993 and 1999 surveys) is no longer evident. The 2005 survey results also suggest that the percentage of women in the AMS, although still small, has nearly doubled since 1999. However, there has not been comparable progress in increasing the ethnic diversity of the AMS membership. This paper is the first of a series, each focusing on a particular aspect of the survey results.
Musgrave, K.D., C.A. Davis, and M.T. Montgomery. Numerical simulations of the formation of Hurricane Gabrielle (2001). Monthly Weather Review, 136(8):3151-3167 (2008).
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This study examines the formation of Hurricane Gabrielle (2001), focusing on whether an initial disturbance and vertical wind shear were favorable for development. This examination is performed by running numerical experiments using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5). Gabrielle is chosen as an interesting case to study since it formed in the subtropics only a few days before making landfall in Florida. Three simulations are run: a control run and two sensitivity experiments. The control run is compared with observations to establish the closeness of the model output to Gabrielle's observed formation. The two sensitivity experiments are designed to test the response of the developing tropical cyclone to alterations in the initial conditions. The first sensitivity experiment removes the initial (or precursor) disturbance, a midtropospheric vortex located over Florida. The second sensitivity experiment reduces the vertical wind shear over the area of formation. The control run produces a system comparable to Gabrielle. The convection in the control run is consistently located downshear of the center of circulation. In the first sensitivity experiment, with the removal of the initial disturbance, no organized system develops. This indicates the importance of the midtropospheric vortex in Gabrielle's formation. The second sensitivity experiment, which reduces the vertical wind shear over the area of Gabrielle's formation, produces a system that can be identified as Gabrielle. This system, however, is weaker than both the control run and the observations of Gabrielle. This study provides direct evidence of a favorable influence of modest vertical wind shear on the formation of a tropical cyclone in this case.
Nguyen, V.S., N., R.K. Smith, and M.T. Montgomery. Tropical cyclone intensification and predictability in three dimensions. Quarterly Journal of the Royal Meteorological Society, 134(632):563-582 (2008).
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We present numerical-model experiments to investigate the dynamics of tropical-cyclone amplification and its predictability in three dimensions. For the prototype amplification problem beginning with a weak-tropical-storm-strength vortex, the emergent flow becomes highly asymmetric and dominated by deep convective vortex structures, even though the problem as posed is essentially axisymmetric. The asymmetries that develop are highly sensitive to the boundary-layer moisture distribution. When a small random moisture perturbation is added in the boundary layer at the initial time, the pattern of evolution of the flow asymmetries is changed dramatically, and a non-negligible spread in the local and azimuthally-averaged intensity results. We conclude, first, that the flow on the convective scales exhibits a degree of randomness, and only those asymmetric features that survive in an ensemble average of many realizations can be regarded as robust; and secondly, that there is an intrinsic uncertainty in the prediction of maximum intensity using either maximum-wind or minimum-surface-pressure metrics. There are clear implications for the possibility of deterministic forecasts of the mesoscale structure of tropical cyclones, which may have a major impact on the intensity and on rapid intensity changes. Some other aspects of vortex structure are addressed also, including vortex-size parameters, and sensitivity to the inclusion of different physical processes or higher spatial resolution. We investigate also the analogous problem on a beta-plane, a prototype problem for tropical-cyclone motion. A new perspective on the putative role of the wind--evaporation feedback process for tropical-cyclone intensification is offered also. The results provide new insight into the fluid dynamics of the intensification process in three dimensions, and at the same time suggest limitations of deterministic prediction for the mesoscale structure. Larger-scale characteristics, such as the radius of gale-force winds and beta-gyres, are found to be less variable than their mesoscale counterparts.
Palmer, C.J., T.D. Bonilla, J.A. Bonilla, S. Elmir, K.D. Goodwin, H.M. Solo-Gabriele, and A. Abdelzaher. The future for monitoring. In Oceans and Human Health: Risk and Remedies from the Seas, P.J. Walsh, S.L. Smith, W.H. Gerwick, H. Solo-Gabriele, and L.E. Fleming (eds.). Elsevier Science Publishers, New York, 405-429 (2008).
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No abstract.
Park, G.-H., K. Lee, R. Wanninkhof, J.-Z. Zhang, D.A. Hansell, and R.A. Feely. Large, non-Redfieldian drawdown of nutrients and carbon in the extratropical North Atlantic Ocean (46N): Evidence for dinitrogen fixation? Limnology and Oceanography, 53(5):1697-1704 (2008).
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Considerable drawdown of total dissolved inorganic carbon (CT) and oversaturation of oxygen (O2) within a cold (15C) oligotrophic eddy in the extratropical North Atlantic Ocean (46N, 20.5W) indicate that, despite the absence of nitrate (NO3), the eddy was highly productive. Estimates of net community production using the mass balances of CT and O2 were two to five times greater than those obtained using the mass balance of NO3. The remineralization rates obtained using the integrated rates of CT and NO3 accumulation and O2 utilization for the upper thermocline waters (35-300-m depth) were in agreement with CT- and O2-based net community production over the same period; however, all the estimates exceeded the NO3 -based net community production by a factor of two to five, pointing to a considerable accumulation of NO3 in the upper thermocline in excess of changes in the mixed-layer NO3 inventory. The amount of this excess NO3 suggests that a considerable fraction of the net community production was not supported by the mixed-layer NO3 inventory and that an external source of NO3 must be present. Of the various mechanisms that might explain the inequity between NO3 drawdown in the surface layer and NO3 accumulation in the upper thermocline, N2 fixation is the most viable yet surprising mechanism for producing such excess NO3 in this oligotrophic eddy. A significant fraction of net community production in oligotrophic extratropical waters could be supported by processes that are not fully explored or to date have been considered to be insignificant.
Persing, J., and M.T. Montgomery. Isolating surface flux influences on simulated hurricane intensity. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 3 pp. (2008).
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No abstract.
Powell, M.D., and T.A. Reinhold. Reply. Bulletin of the American Meteorological Society, 89(2):221-223 (2008).
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No abstract.
Powell, M.D., and T.A. Reinhold. Reply to Hsu and Blanchards comments on "Tropical cyclone destructive potential by integrated kinetic energy." Bulletin of the American Meteorological Society, 89(10):1577 (2008).
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No abstract.
Proni, J.R., S.J. Stamates, T.P. Carsey, J.-Z. Zhang, C.D. Sinigalliano, and K.F. Sullivan. Acoustic methods for water mass delineation in coastal marine ecosystems. Proceedings, Ninth European Conference on Underwater Acoustics (ECUA 2008), Paris, France, June 29-July 4, 2008. European Acoustics Association, Volume 1, 237-242 (2008).
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Acoustical methods play an important role in identifying sources of nutrient to coral reef ecosystems in the South Florida coastal waters. Nutrient fluxes into the coastal ocean are associated with distinct water masses such as inlet discharge plumes, wastewater outfall discharge plumes, and up-welling of deep oceanic water. Various nutrient-bearing water masses can be identified by water column acoustic backscatter profiles, obtained via either ship-borne instrumentation or in-situ instrumentation. Such multidimensional images of water masses can be used to optimize the design of chemical and biological sampling efforts. Examples of water mass imaging will be presented as well as the use of such images in the design of water quality sampling programs.
Pu, Z., X. Li, C.S. Velden, S.D. Aberson, and W.T. Liu. The impact of aircraft dropsonde and satellite wind data on numerical simulations of two landfalling tropical storms during Tropical Cloud Systems and Processes Experiment. Weather and Forecasting, 23(1):62-79 (2008).
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Dropwindsonde, Geostationary Operational Environmental Satellite-11 (GOES-11) rapid-scan atmospheric motion vectors, and NASA Quick Scatterometer (QuikSCAT) near-surface wind data collected during NASA's Tropical Cloud Systems and Processes (TCSP) field experiment in July 2005 were assimilated into an advanced research version of the Weather Research and Forecasting (WRF) model using its three-dimensional variational data assimilation (3DVAR) system. The impacts of the mesoscale data assimilation on WRF numerical simulation of Tropical Storms Cindy and Gert (2005) near landfall are examined. Sensitivity of the forecasts to the assimilation of each single data type is investigated. Specifically, different 3DVAR strategies with different analysis update cycles and resolutions are compared in order to identify the better methodology for assimilating the data from research aircraft and satellite for tropical cyclone study. The results presented herein indicate the following. (1) Assimilation of dropwindsonde and satellite wind data into the WRF model improves the forecasts of the two tropical storms up to the landfall time. The QuikSCAT wind information is very important for improving the storm track forecast, whereas the dropwindsonde and GOES-11 wind data are also necessary for improved forecasts of intensity and precipitation. (2) Data assimilation also improves the quantitative precipitation forecasts (QPFs) near landfall of the tropical storms. (3) A 1-h rapid-update analysis cycle at high resolution (9 km) provides more accurate tropical cyclone forecasts than a regular 6-h analysis cycle at coarse (27 km) resolution. The high-resolution rapidly updated 3DVAR analysis cycle might be a practical way to assimilate the data collected from tropical cyclone field experiments.
Rogers, R.F., and E.W. Uhlhorn. Observations of the structure and evolution of surface and flight-level wind asymmetries in Hurricane Rita (2005). Geophysical Research Letters, 35(21):L22811, doi:10.1029/2008GL034774 (2008).
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Knowledge of the magnitude and distribution of surface winds, including the structure of azimuthal asymmetries in the wind field, are important factors for tropical cyclone forecasting. With its ability to remotely measure surface wind speeds, the stepped frequency microwave radiometer (SFMR) has assumed a prominent role for the operational tropical cyclone forecasting community. An example of this instruments utility is presented here, where concurrent measurements of aircraft flight-level and SFMR surface winds are used to document the wind field evolution over three days in Hurricane Rita (2005). The amplitude and azimuthal location (phase) of the wavenumber-1 asymmetry in the storm-relative winds varied at both levels over time. The peak was found to the right of storm track at both levels on the first day. By the third day, the peak in flight-level storm-relative winds remained to the right of storm track, but it shifted to left of storm track at the surface, resulting in a 60-degree shift between the surface and flight-level and azimuthal variations in the ratio of surface to flight-level winds. The asymmetric differences between the surface and flight-level maximum wind radii also varied, indicating a vortex whose tilt was increasing.
Rule, E. Unmanned aircraft systems for hurricane research. Earth System Monitor, 17(2):7 (2008).
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No abstract.
Sabine, C.L., R.A. Feely, R. Wanninkhof, and T. Takahashi. The global ocean carbon cycle. In State of the Climate in 2007, D.H. Levinson and J.H. Lawrimore (eds.). Bulletin of the American Meteorological Society, 88(7):S52-S56 (2008).
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No abstract.
Sallee, J.-B., K. Speer, R. Morrow, and R. Lumpkin. An estimate of Lagrangian eddy statistics and diffusion in the mixed layer of the Southern Ocean. Journal of Marine Research, 66(4):441-463 (2008).
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A statistical analysis of surface drifter observations is used to compute eddy length and time scales and eddy diffusion in the Southern Ocean. Eddy diffusion values of the order of 104 m2 s-1 are found in the energetic western boundary currents north of the Antarctic Circumpolar Current (ACC) and secondary peaks occur where the ACC negotiates topography. The diffusivity shows an increase from the Antarctic continent to the core of the ACC, then a slight decrease or a stable plateau within the ACC. North of the ACC, diffusivity generally decreases into the interior of ocean basins, except in the western boundary regions where values are maximum. Diffusivity is also calculated from simulated trajectories based on altimetric geostrophic velocities, with and without mean flow, as well as with simulated trajectories based on Ekman currents. Ekman currents at the drogue depth (15 m) have only a small impact, and the geostrophic currents dominate the eddy diffusivity. Complementary statistical analyses confirm these results. The surface drifter cross-stream eddy diffusion is used to test a simple parameterization based on satellite altimetric observations of eddy kinetic energy (EKE). For EKE 0.015 m2 s-2, kappa = 1.35EKE Ld m2 s-1, where Ld is the first baroclinic Rossby radius. This parameterization holds in the energetic ACC, consistent with an eddy field in the frozen field regime. Over the broader areas of weaker eddy fields, mixing is fairly uniform and stable at about kappa = 1800 1000 m2 s-1.
Sellwood, K.J., S. Majumdar, I. Szunyogh, and B. Mapes. Predicting the influence of observations on medium-range forecasts of atmospheric flow. Quarterly Journal of the Royal Meteorological Society, 134(637):2011-2027 (2008).
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In recent years, the Ensemble Transform Kalman Filter (ETKF) has been demonstrated to be useful for identifying a priori dynamically important locations for the placement of supplementary dropwindsonde observations aimed at improving short-range (1-3 day) forecasts of high-impact winter weather. In this paper, the ability of this strategy to predict the influence (or signal) of assimilating observations into the NCEP Global Forecast System for forecasts of 200 hPa wind up to 6 days is evaluated. Using a 50-member ECMWF ensemble, the ETKF was found to exhibit significantly higher skill than a seasonal climatology of the important locations in predicting both (1) the spatial structure of signals within the storm track on a case-by-case basis; and (2) the variance of these signals over a 2-month period, within objectively chosen verification regions on synoptic scales. The verification region was selected by extracting the zonal envelope of the Rossby wave packet associated with the propagating ETKF signal variance. It is recommended that larger verification regions be used for longer lead times, due to the eastward expansion of the wave packet. The capability of the ETKF to predict signal variance out to 6 days was found to be dependent on the flow regime. The ETKF was most capable when the background flow was predominantly zonal, and least capable in instances where the observations were placed upstream of a blocking high over the north-eastern Pacific. Therefore, the ETKF is sometimes (but not always) able to predict when there exists significant potential for a particular group of observations to improve medium-range forecasts.
Serafy, J.E., C.R. Keble, T.R. Capo, S.A. Luthy and P.B. Ortner. Vertical movement rates of captive larval billfishes (Istiophoridae) collected from the Straits of Florida. Florida Scientist, 71(1):23-30 (2008).
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Challenges associated with species identification, live collection and laboratory maintenance of billfish larvae have hindered research on their physiology and behavior. In the present study, short-duration neuston net tows in the Straits of Florida yielded 19 live istiophorid billfish larvae, which were immediately placed in a shipboard vertical swimming chamber to measure their vertical movement rates. After swimming trials, larvae were transferred to the laboratory where they were identified to species, classified as to flexion stage and measured for length. Mean vertical swimming speeds of captive larval sailfish (Istiophorus platypterus) and blue marlin (Makaira nigricans) ranged from 1.0 to 7.0 cm s-1 or 1.6 to 5.6 body lengths s-1. These rates exceed most larval fish sinking rates reported for other species and are comparable to mean larval "cruising" speeds reported for several temperate freshwater and marine fishes; however, they appear far lower than most swimming speed estimates for reef fish larvae.
Shay, L.K., and E.W. Uhlhorn. Loop Current response to Hurricanes Isidore and Lili. Monthly Weather Review, 136(9):3248-3274 (2008).
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Recent hurricane activity over the Gulf of Mexico basin has underscored the importance of the Loop Current (LC) and its deep, warm thermal structure on hurricane intensity. During Hurricanes Isidore and Lili in 2002, research flights were conducted from both National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft to observe pre-, in- and poststorm ocean conditions using airborne expendable ocean profilers to measure temperature, salinity, and current structure. Atmospheric thermodynamic and wind profiles and remotely sensed surface winds were concurrently acquired as each storm moved over the LC. Observed upper-ocean cooling was about 1C as Isidore moved across the Yucatan Straits at a speed of 4 m s-1. Given prestorm ocean heat content (OHC) levels exceeding 100 kJ cm-2 in the LC (current velocities >1 m s-1), significant cooling and deepening of the ocean mixed layer (OML) did not occur in the straits. Estimated surface enthalpy flux at Isidores eyewall was 1.8 kW m-2, where the maximum observed wind was 49 m s-1. Spatially integrating these surface enthalpy fluxes suggested a maximum surface heat loss of 9.5 kJ cm-2 at the eyewall. Over the Yucatan Shelf, observed ocean cooling of 4.5C was caused by upwelling processes induced by wind stress and an offshore wind-driven transport. During Hurricane Lili, ocean cooling in the LC was ~1C but more than 2C in the Gulf Common Water, where the maximum estimated surface enthalpy flux was 1.4 kW m-2, associated with peak surface winds of 51 m s-1. Because of Lili's asymmetric structure and rapid translational speed of 7 m s-1, the maximum surface heat loss resulting from the surface enthalpy flux was less than 5 kJ cm-2. In both hurricanes, the weak ocean thermal response in the LC was primarily due to the lack of energetic near-inertial current shears that develop across the thin OML observed in quiescent regimes. Bulk Richardson numbers remained well above criticality because of the strength of the upper-ocean horizontal pressure gradient that forces northward current and thermal advection of warm water distributed over deep layers. As these oceanic regimes are resistive to shear-induced mixing, hurricanes experience a more sustained surface enthalpy flux compared to storms moving over shallow quiescent mixed layers. Because ocean cooling levels induced by hurricane force winds depend on the underlying oceanic regimes, features must be accurately initialized in coupled forecast models.
Smith, R.K., and M.T. Montgomery. Balanced boundary layers used in hurricane models. Quarterly Journal of the Royal Meteorological Society, 134(635):1385-1395 (2008).
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We examine the formulation and accuracy of various approximations made in representing the boundary layer in simple axisymmetric hurricane models, especially those that assume strict gradient wind balance in the radial direction. Approximate solutions for a steady axisymmetric slab boundary-layer model are compared with a full model solution. It is shown that the approximate solutions are generally poor in the inner core region of the vortex, where the radial advection term in the radial momentum equation is important and cannot be neglected. These results affirm some prior work and have implications for a range of theoretical studies of vhurricane dynamics, including theories of potential intensity, that employ balanced boundary-layer formulations.
Smith, R.K., M.T. Montgomery, and S. Vogl. A critique of Emanuel's hurricane model and potential intensity theory. Quarterly Journal of the Royal Meteorological Society, 134(632):551-561 (2008).
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We present a critique of Emanuel's steady-state hurricane model, which is a precursor to his theory for hurricane potential intensity (PI). We show that a major deficiency of the theory is the tacit assumption of gradient wind balance in the boundary layer, a layer that owes its existence to gradient wind imbalance in the radial momentum equation. If a more complete boundary-layer formulation is included using the gradient wind profiles obtained from Emanuel's theory, the tangential wind speed in the boundary layer becomes supergradient, invalidating the assumption of gradient wind balance. We show that the degree to which the tangential wind is supergradient depends on the assumed boundary-layer depth. The full boundary-layer solutions require a knowledge of the tangential wind profile above the boundary layer in the outer region where there is subsidence into the layer and they depend on the breadth of this profile. This effect is not considered in Emanuel's theory. We argue that a more complete theory for the steady-state hurricane would require the radial pressure gradient above the boundary layer to be prescribed or determined independently of the boundary layer. The issues raised herein highlight a fundamental problem with Emanuel's theory for PI, since that theory makes the same assumptions as in the steady-state hurricane model. Our current findings together with recent studies examining intense hurricanes suggest a way forward towards a more consistent theory for hurricane PI.
Stern, D.P., D.S. Nolan, and S.D. Aberson. Simulations and observations of extreme low-level updrafts in Hurricane Isabel. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 6 pp. (2008).
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No abstract.
Stewart, J.R., R.J. Gast, R.S. Fujioka, H.M. Solo-Gabriele, J.S. Meschke, L.A. Amaral-Zettler, E. Del Castillo, M.F. Polz, T.K. Collier, M.S. Strom, C.D. Sinigalliano, P.D.R. Moeller, and A.F. Holland. The coastal environment and human health: Microbial indicators, pathogens, sentinels and reservoirs. Environmental Health, 7(Suppl. 2):S3, doi:10.1186/1476-069X-7-S2-S3 (2008).
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Innovative research relating oceans and human health is advancing our understanding of disease-causing organisms in coastal ecosystems. Novel techniques are elucidating the loading, transport and fate of pathogens in coastal ecosystems, and identifying sources of contamination. This research is facilitating improved risk assessments for seafood consumers and those who use the oceans for recreation. A number of challenges still remain and define future directions of research and public policy. Sample processing and molecular detection techniques need to be advanced to allow rapid and specific identification of microbes of public health concern from complex environmental samples. Water quality standards need to be updated to more accurately reflect health risks and to provide managers with improved tools for decision-making. Greater discrimination of virulent versus harmless microbes is needed to identify environmental reservoirs of pathogens and factors leading to human infections. Investigations must include examination of microbial community dynamics that may be important from a human health perspective. Further research is needed to evaluate the ecology of non-enteric water-transmitted diseases. Sentinels should also be established and monitored, providing early warning of dangers to ecosystem health. Taken together, this effort will provide more reliable information about public health risks associated with beaches and seafood consumption, and how human activities can affect their exposure to disease-causing organisms from the oceans.
Swart, S., S. Speich, I.J. Ansorge, G.J. Goni, S. Gladyshev, and J.R.E. Lutjeharms. Transport and variability of the Antarctic Circumpolar Current south of Africa. Journal of Geophysical Research, 113(C9):C09014, doi:10.1029/2007JC004223 (2008).
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Data from five CTD and 18 XBT sections are used to estimate the baroclinic transport (referenced to 2500 dbar) of the ACC south of Africa. Surface dynamic height is derived from XBT data by establishing an empirical relationship between vertically integrated temperature and surface dynamic height calculated from CTD data. This temperature-derived dynamic height data compare closely with dynamic heights calculated from CTD data (average RMS difference = 0.05 dyn m). A second empirical relationship between surface dynamic height and cumulative baroclinic transport is defined, allowing us to study a more extensive time series of baroclinic transport derived from upper ocean temperature sections. From 18 XBT transects of the ACC, the average baroclinic transport, relative to 2500 dbar, is estimated at 90 2.4 Sv. This estimate is comparable to baroclinic transport values calculated from CTD data. We then extend the baroclinic transport time-series by applying an empirical relationship between dynamic height and cumulative baroclinic transport to weekly maps of absolute dynamic topography derived from satellite altimetry, between 14 October 1992 and 23 May 2007. The estimated mean baroclinic transport of the ACC, obtained this way, is 84.7 3.0 Sv. These transports agree well with simultaneous in-situ estimates (RMS difference in net transport = 5.2 Sv). This suggests that sea level anomalies largely reflect baroclinic transport changes above 2500 dbar.
Tao, W.-K., D. Anderson, R. Atlas, J. Chern, P. Houser, A. Hou, S. Lang, W. Lau, C. Peters-Lidard, R. Kakar, S. Kumar, W. Lapenta, X. Li, T. Matsui, M. Rienecker, B.-W. Shen, J.J. Shi, J. Simpson, and X. Zeng. A Goddard multi-scale modeling system with unified physics. GEWEX News, 18(1):6-8 (2008).
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No abstract.
Terwey, W.D., and M.T. Montgomery. Secondary eyewall formation in two idealized, full-physics modeled hurricanes. Journal of Geophysical Research, 113(D12):D12112, doi:10.1029/2007JD0088979 (2008).
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Prevailing hypotheses for secondary eyewall formation are examined using data sets from two high-resolution mesoscale numerical model simulations of the long-time evolution of an idealized hurricane vortex in a quiescent tropical environment with constant background rotation. The modeled hurricanes each undergo a secondary eyewall cycle, casting doubt on a number of other authors' hypotheses for secondary eyewall formation due to idealizations present in the simulation formulations. A new hypothesis for secondary eyewall formation is proposed here and is shown to be supported by these high-resolution numerical simulations. The hypothesis requires the existence of a region with moderate horizontal strain deformation and a sufficient low-level radial potential vorticity gradient associated with the primary swirling flow, moist convective potential, and a wind-moisture feedback process at the air-sea interface to form the secondary eyewall. The crux of the formation process is the generation of a finite-amplitude lower-tropospheric cyclonic jet outside the primary eyewall with a jet width on the order of a local effective beta scale determined by the mean low-level radial potential vorticity gradient and the root-mean square eddy velocity. This jet is hypothesized to be generated by the anisotropic upscale cascade and axisymmetrization of convectively generated vorticity anomalies through horizontal shear turbulence and sheared vortex Rossby waves as well as by the convergence of system-scale cyclonic vorticity by the low-level radial inflow associated with the increased convection. Possible application to the problem of forecasting secondary eyewall events is briefly considered.
Thacker, W.C. Estimating salinity between 25S and 45S in the Atlantic Ocean using local regression. Journal of Atmospheric and Oceanic Technology, 25(1):114-130 (2008).
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The empirical relationship between salinity and temperature in the South Atlantic is quantified with the aid of local regression. To capture the spatial character of the TS relationship, models are fitted to data for each point on a three-dimensional grid with spacing of 1 in latitude, 2 in longitude, and 25 dbar in the vertical. To ensure sufficient data for statistical reliability each fit is to data from a region extending over several grid points weighted so that more remote data exert less influence than those closer to the target grid point. Both temperature and its square are used as regressors to capture the curvature seen in TS plots, and latitude and longitude are used to capture systematic spatial variations over the fitting regions. In addition to using statistics of residuals to characterize how well the models fit the data, errors for data not used in fitting are examined to verify the models' abilities to simulate independent data. The best model overall for the entire region at all depths is quadratic in temperature and linear in longitude and latitude.
Thomas, H., A.E.F. Prowe, I.D. Lima, S.C. Doney, R. Wanninkhof, R.J. Greatbatch, U. Schuster, and A. Corbiere. Changes in the North Atlantic Oscillation influence CO2 uptake in the North Atlantic over the past two decades. Global Biogeochemical Cycles, 22(4):GB4027, doi:10.1029/2007GB003167 (2008).
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Observational studies report a rapid decline of ocean CO2 uptake in the temperate North Atlantic during the last decade. We analyze these findings using ocean physical-biological numerical simulations forced with interannually varying atmospheric conditions for the period 1979-2004. In the simulations, surface ocean water mass properties and CO2 system variables exhibit substantial multiannual variability on sub-basin scales in response to wind-driven reorganization in ocean circulation and surface warming/cooling. The simulated temporal evolution of the ocean CO2 system is broadly consistent with reported observational trends and is influenced substantially by the phase of the North Atlantic Oscillation (NAO). Many of the observational estimates cover a period after 1995 of mostly negative or weakly positive NAO conditions, which are characterized in the simulations by reduced North Atlantic Current transport of subtropical waters into the eastern basin and by a decline in CO2 uptake. We suggest therefore that air-sea CO2 uptake may rebound in the eastern temperate North Atlantic during future periods of more positive NAO, similar to the patterns found in our model for the sustained positive NAO period in the early 1990s. Thus, our analysis indicates that the recent rapid shifts in CO2 flux reflect decadal perturbations superimposed on more gradual secular trends. The simulations highlight the need for long-term ocean carbon observations and modeling to fully resolve multiannual variability, which can obscure detection of the long-term changes associated with anthropogenic CO2 uptake and climate change.
Tory, K.J., and M.T. Montgomery. Tropical cyclone formation: A synopsis of the system-scale development. Extended Abstracts, 28th Conference on Hurricanes and Tropical Meteorology, Orlando, Florida, April 28-May 2, 2008. American Meteorological Society, Boston, 6 pp. (2008).
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No abstract.
Uhlhorn, E.W. Gulf of Mexico Loop Current mechanical energy and vorticity response to a tropical cyclone. Ph.D. thesis, University of Miami, Rosenstiel School of Marine and Atmospheric Science, 148 pp. (2008).
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The ocean mixed layer response to a tropical cyclone within, and immediately adjacent to, the Gulf of Mexico Loop Current is examined using a combination of ocean profiles and a numerical model. A comprehensive set of temperature, salinity, and current profiles acquired from aircraft-deployed expendable probes is utilized to analyze the three-dimensional oceanic energy and circulation evolution in response to Hurricane Lili's (2002) passage. Mixed-layer temperature analyses show that the Loop Current cooled <1°C in response to the storm, in contrast to typically observed larger decreases of 3-5°C. Correspondingly, vertical current shears, which are partly responsible for entrainment mixing, were found to be up to 50% weaker, on average, than observed in previous studies within the directly-forced region. The Loop Current, which separates the warmer, lighter Caribbean Subtropical water from the cooler, heavier Gulf Common water, was found to decrease in intensity by -0.18 ± 0.25 m s-1 over an approximately 10-day period within the mixed layer. Contrary to previous tropical cyclone ocean response studies which have assumed an approximately horizontally homogeneous ocean structure prior to storm passage, a kinetic energy loss of 5.8 ± 6.3 k Jm-2, or approximately 1 wind stress-scaled energy unit, was observed. Using near-surface currents derived from satellite altimetry data, the Loop Current is found to vary similarly in magnitude, suggesting storm-generated energy is rapidly removed by the pre-existing Loop Current. Further examination of the energy response using an idealized numerical model reveals that due to: (1) favorable coupling between the wind stress and pre-existing current vectors; and (2) wind-driven currents flowing across the large horizontal pressure gradient; wind energy transfer to mixed-layer kinetic energy can be more efficient in these regimes as compared to the case of an initially horizontally homogeneous ocean. However, nearly all of this energy is removed by advection by 2 local inertial periods after storm passage, and little evidence of the storms impact remains. Mixed-layer vorticity within the idealized current also shows a strong direct response, but little evidence of a near-inertial wave wake results.
Voss, D., H. Maring, and K.D. Goodwin. Production of salt aerosol and bioaerosol from a sea-salt aerosol generator. In Marine Pollution: New Research, T.N. Hofer (ed.). Nova Science Publishers, Inc., New York, 398-429 (2008).
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No abstract.
Wang, C., and S.-K. Lee. Global warming and United States landfalling hurricanes. Geophysical Research Letters, 35(2):L02708, doi:10.1029/2007GL032396 (2008).
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A secular warming of sea surface temperature occurs almost everywhere over the global ocean. Here we use observational data to show that global warming of the sea surface is associated with a secular increase of tropospheric vertical wind shear in the main development region (MDR) for Atlantic hurricanes. The increased wind shear coincides with a weak but robust downward trend in U.S. landfalling hurricanes, a reliable measure of hurricanes over the long term. Warmings over the tropical oceans compete with one another, with the tropical Pacific and Indian Oceans increasing wind shear and the tropical North Atlantic decreasing wind shear. Warmings in the tropical Pacific and Indian Oceans win the competition and produce increased wind shear which reduces U.S. landfalling hurricanes. Whether future global warming increases the vertical wind shear in the MDR for Atlantic hurricanes will depend on the relative role induced by secular warmings over the tropical oceans.
Wang, C., S.-K. Lee, and D.B. Enfield. Atlantic warm pool acting as a link between Atlantic multidecadal oscillation and Atlantic tropical cyclone activity. Geochemistry Geophysics Geosystems, 9:Q05V03, doi:10.1029/2007GC001809 (2008).
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Multidecadal variability of Atlantic tropical cyclone activity is observed to relate to the Atlantic Multidecadal Oscillation (AMO), a mode manifesting primarily in sea surface temperature (SST) in the high latitudes of the North Atlantic. In the low latitudes of the North Atlantic, a large body of warm water called the Atlantic Warm Pool (AWP) comprises the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic. AWP variability occurs on both interannual and multidecadal timescales as well as with a secular variation. The AWP multidecadal variability coincides with the signal of the AMO; that is, the warm (cool) phases of the AMO are characterized by repeated large (small) AWPs. Since the climate response to the North Atlantic SST anomalies is primarily forced at the low latitudes and the AWP is in the path of or a birthplace for Atlantic tropical cyclones, the influence of the AMO on Atlantic tropical cyclone activity may operate through the mechanism of the AWP-induced atmospheric changes. The AWP-induced changes related to tropical cyclones that we emphasize here include a dynamical parameter of tropospheric vertical wind shear and a thermodynamical parameter of convective instability. More specifically, an anomalously large (small) AWP reduces (enhances) the vertical wind shear in the hurricane main development region and increases (decreases) the moist static instability of the troposphere, both of which favor (disfavor) Atlantic tropical cyclone activity. This is the most plausible way in which the AMO relationship with Atlantic tropical cyclones can be understood.
Wang, C., S.-K. Lee, and D.B. Enfield. Climate response to anomalously large and small Atlantic warm pools during the summer. Journal of Climate, 21(11):2437-2450 (2008).
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This paper uses the NCAR Community Atmospheric Model to show the influence of Atlantic warm pool (AWP) variability on the summer climate and Atlantic hurricane activity. The model runs show that the climate response to the AWP's heating extends beyond the AWP region to other regions such as the eastern North Pacific. Both the sea level pressure and precipitation display a significant response of low (high) pressure and increased (decreased) rainfall to an anomalously large (small) AWP, in areas with two centers located in the western tropical North Atlantic and in the eastern North Pacific. The rainfall response suggests that an anomalously large (small) AWP suppresses (enhances) the midsummer drought, a phenomenon with a diminution in rainfall during July and August in the region around Central America. In response to the pressure changes, the easterly Caribbean low-level jet is weakened (strengthened), as is its westward moisture transport. An anomalously large (small) AWP weakens (strengthens) the southerly Great Plains low-level jet, which results in reduced (enhanced) northward moisture transport from the Gulf of Mexico to the United States east of the Rocky Mountains and thus decreases (increases) the summer rainfall over the central United States, in agreement with observations. An anomalously large (small) AWP also reduces (enhances) the tropospheric vertical wind shear in the main hurricane development region and increases (decreases) the moist static instability of the troposphere, both of which favor (disfavor) the intensification of tropical storms into major hurricanes. Since the climate response to the North Atlantic SST anomalies is primarily forced at low latitudes, this study implies that reduced (enhanced) rainfall over North America and increased (decreased) hurricane activity due to the warm (cool) phase of the Atlantic multidecadal oscillation may be partly due to the AWP-induced changes of the northward moisture transport and the vertical wind shear and moist static instability associated with more frequent large (small) summer warm pools.
Westerink, J.J., R.A. Luettich, J.C. Feyen, J.H. Atkinson, C. Dawson, H.J. Roberts, M.D. Powell, J.P. Dunion, E.J. Kubatko, and H. Pourtaheri. A basin- to channel-scale unstructured grid hurricane storm surge model applied to southern Louisiana. Monthly Weather Review, 136(3):833-864 (2008).
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Southern Louisiana is characterized by low-lying topography and an extensive network of sounds, bays, marshes, lakes, rivers, and inlets that permit widespread inundation during hurricanes. A basin- to channel-scale implementation of the Advanced Circulation (ADCIRC) unstructured grid hydrodynamic model has been developed that accurately simulates hurricane storm surge, tides, and river flow in this complex region. This is accomplished by defining a domain and computational resolution appropriate for the relevant processes, specifying realistic boundary conditions, and implementing accurate, robust, and highly parallel unstructured grid numerical algorithms. The model domain incorporates the western North Atlantic, the Gulf of Mexico, and the Caribbean Sea so that interactions between basins and the shelf are explicitly modeled and the boundary condition specification of tidal and hurricane processes can be readily defined at the deep water open boundary. The unstructured grid enables highly refined resolution of the complex overland region for modeling localized scales of flow while minimizing computational cost. Kinematic data assimilative or validated dynamic-modeled wind fields provide the hurricane wind and pressure field forcing. Wind fields are modified to incorporate directional boundary layer changes due to overland increases in surface roughness, reduction in effective land roughness due to inundation, and sheltering due to forested canopies. Validation of the model is achieved through hindcasts of Hurricanes Betsy and Andrew. A model skill assessment indicates that the computed peak storm surge height has a mean absolute error of 0.30 m.
Zhang, J.A., P.G. Black, J.R. French, and W.M. Drennan. First direct measurements of enthalpy flux in the hurricane boundary layer: The CBLAST results. Geophysical Research Letters, 35(11):L14813, doi:10.1029/2008GL034374 (2008).
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Hurricanes extract energy from the warm ocean through enthalpy fluxes. As part of the Coupled Boundary Layer Air-Sea Transfer (CBLAST) experiment, flights were conducted to measure turbulent fluxes in the high-wind boundary layer of hurricanes. Here we present the first field observations of sensible heat and enthalpy flux for 10m wind speeds to 30 m s-1. The analyses indicate no statistically significant dependence of these bulk exchange coefficients on wind speed. As a measure of hurricane development potential, we compute the mean ratio of the exchange coefficient for enthalpy to that for momentum and find it to be significantly below the lowest threshold estimated by previous investigators. This suggests that the enthalpy flux required for hurricane development may come from sources other than turbulent fluxes, such as lateral fluxes from the vortex warm core, or sea spray. Alternatively, it demands a re-evaluation of the theoretical models used to derive the threshold.
Zhang, J.A., K.B. Katsaros, P.G. Black, S. Lehner, J.R. French, and W.M. Drennan. Effects of roll vortices on turbulent fluxes in the hurricane boundary layer. Boundary-Layer Meteorology, 128(2):173-189 (2008).
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Boundary-layer secondary circulations or "roll vortices" can have a significant influence on the turbulent exchange of momentum, sensible heat and moisture throughout the hurricane boundary layer. In this study, analyses of data from a WP-3D aircraft of the National Oceanic and Atmospheric Administration (NOAA) are presented. As part of the Coupled Boundary Layer Air-Sea Transfer (CBLAST)-hurricane experiment sponsored through the Office of Naval Research and NOAA's annual hurricane research program, flights were conducted to investigate energy exchange across the air-sea interface. We present the first in-situ aircraft-based observations of rolls in the hurricane boundary layer and investigate their influence on energy and momentum exchange. The rolls detected in Hurricane Isidore (year 2002) have a characteristic wavelength of about 900 m, in good agreement with analyses of data from a synthetic aperture radar image captured by the Canadian Space Agency's RADARSAT satellite in the same storm. Our analyses of the airborne data suggest that roll vortices may be a significant factor modulating the air-sea momentum exchange.
**2007**
Atlas, R., S.-J. Lin, B.-W. Shen, O. Reale, and K.-S. Yeh. Improving hurricane prediction through innovative global modeling. In Extending the Horizons: Advances in Computing, Optimization, and Decision Technologies, E.K. Baker, A. Joseph, A. Mehrotra, and M.A. Trick (eds.). Springer, 1-14 (2007).
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Current global and regional models incorporating both in situ and remotely sensed observations have achieved a high degree of skill in forecasting the movement of hurricanes. Nevertheless, significant improvements in the prediction of hurricane landfall and intensification are still needed. To meet these needs, research on new observing systems, data assimilation techniques, and better models is being performed. These include the Hurricane Weather Research and Forecasting regional model development by NOAA, as well as the development of an advanced "seamless" global weather and climate model, as a collaborative project involving both NOAA and NASA. This latter model, when completed, will be used to improve short and extended range forecasts of hurricanes, as well as to determine the relationship between global climate change and long-term variations in hurricane frequency and intensity, more accurately than is possible today. As a starting point for the seamless global weather and climate model, the horizontal resolution of the previously developed finite volume General Circulation Model has been increased to 1/12° (approximately 9 km) in a series of success steps. This was made possible by advances in both computing and optimization technologies.
Atlas, R., O. Reale, J. Ardizzone, J. Terry, J.-C. Jusem, E. Brin, D. Bungato, and J.F. Le Marshall. Evaluation of WINDSAT surface wind data and its impact on ocean surface wind analyses and numerical weather prediction. Preprints, 11th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS), San Antonio, TX, January 14-18, 2007. American Meteorological Society, Boston, CD-ROM, 6 pp. (2007).
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A detailed evaluation of the latest version of WINDSAT surface wind data has recently been performed to determine the quality of these data and their usefulness for ocean surface wind analysis and numerical weather prediction. The first component of this evaluation consisted of both subjective and objective comparisons of WINDSAT wind vectors to other sources of ocean surface winds (e.g., ship and buoy observations, QuikSCAT satellite winds, or model derived wind analyses). This was followed by data impact experiments using a variational surface wind analysis, as well as an operational four-dimensional data assimilation system. The results of this evaluation demonstrate the usefulness of WINDSAT data, but also show deficiencies relative to current scatterometer measurements.
Baringer, M.O., and S.L. Garzoli. Meridional heat transport determined with expendable bathythermographs, Part I: Error estimates from model and hydrographic data. Deep-Sea Research, Part I, 54(8):1390-1401 (2007).
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Heat transports estimated from CTD data collected during the World Ocean Circulation Experiment (WOCE) along the January 1993 30S hydrographic transect (A10) and the output from a numerical model show a mean heat transport of 0.40 and 0.550.24 PW (standard deviation), respectively. The model shows a large annual cycle in heat transport (more than 30% of the variance) with a maximum (minimum) heat transport in July (February) of 0.68 (0.41) PW. Using these data, a method is proposed and evaluated to calculate the heat transport from temperature data obtained from a trans-basin section of expendable bathythermographs (XBTs) profiles. In this method, salinity is estimated from Argo profiles and CTD casts for each XBT temperature observation using statistical relationships between temperature, latitude, longitude, and salinity computed along constant-depth surfaces. Full-depth temperature/salinity profiles are obtained by extending the profiles to the bottom of the ocean using deep climatological data. The meridional transport is then determined by using the standard geostrophic method, applying NCEP-derived Ekman transports, and requiring that the salt flux through the Bering Straits be conserved. The results indicate that the methods described here can provide heat transport estimates with a maximum uncertainty of 0.18 PW (1 PW=1015 W). Most of this uncertainty is due to the climatology used to estimate the deep structure and issues related to not knowing the absolute velocity field and most especially characterizing barotropic motions. Nevertheless, when the methodology is applied to temperatures collected along 30S (A10) and direct model integrations, the results are very promising. Results from the numerical model suggest that ageostrophic non-Ekman motions can contribute less than 0.05 PW to heat transport estimates in the South Atlantic.
Baringer, M.O., and C.S. Meinen. Global oceans: The meridional overturning circulation and oceanic heat transport. In State of the Climate in 2006, A. Arguez, A.M. Waple, and A.M. Sanchez-Lugo (eds.). Bulletin of the American Meteorological Society, 88(6):S38-S39 (2007).
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No abstract.
Baums, I.B., K.D. Goodwin, T.L. Kiesling, D. Wanless, M.R. Diaz, and J.W. Fell. Luminex detection of fecal indicators in river samples, marine recreational water, and beach sand. Marine Pollution Bulletin, 54(5):521-536 (2007).
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Research to understand and remediate coastal pollution is moving toward a multitiered approach in which traditional enumeration of fecal indicators is accompanied by molecular analysis of a variety of targets. Technology that rapidly detects multiple microbial contaminants would benefit from such an approach. The Luminex 100 system is a suspension array that assays multiple analytes rapidly in a single well of a microtiter plate. The ability of the system to simultaneously detect multiple fecal indicating bacteria in environmental samples was tested. Primer/probe sets were designed to simultaneously detect the following fecal indicators: the Bacteroides fragilis group, Enterococcus spp., Escherichia coli and Shigella spp., Bacteroides distasonis, and Ent. faecalis. Specificity and sensitivity of the Luminex probes was tested against laboratory cultures. In addition, sequencing, culture plate testing, and specificity testing with environmental isolates were steps taken to validate the function of the assay with environmental samples. Luminex response to cultures and to environmental samples was consistent with sequencing results, suggesting that the technology has the potential to simultaneously detect multiple targets for coastal water quality applications, particularly as progress is made to efficiently extract DNA from water and sediment matrices.
Bell, G.D., E. Blake, C.W. Landsea, M. Chelliah, R. Pasch, K.C. Mo, and S.B. Goldenberg. The tropics: Tropical cyclones-Atlantic basin. In State of the Climate in 2006, A. Arguez, A.M. Waple, and A.M. Sanchez-Lugo (eds.). Bulletin of the American Meteorological Society, 88(6):S48-S51 (2007).
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No abstract.
Black, P.G., E.A. D'Asaro, W.M. Drennan, J.R. French, P.P. Niiler, T.B. Sanford, E.J. Terrill, E.J. Walsh, and J.A. Zhang. Air-sea exchange in hurricanes: Synthesis of observations from the Coupled Boundary Layer Air-Sea Transfer Experiment. Bulletin of the American Meteorological Society, 88(3):357-374 (2007).
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The Coupled Boundary Layer Air-Sea Transfer (CBLAST) field program, conducted from 2002 to 2004, has provided a wealth of new air-sea interaction observations in hurricanes. The wind speed range for which turbulent momentum and moisture exchange coefficients have been derived based upon direct flux measurements has been extended by 30% and 60%, respectively, from airborne observations in Hurricanes Fabian and Isabel in 2003. The drag coefficient (CD) values derived from CBLAST momentum flux measurements show CD becoming invariant with wind speed near a 23 m s-1 threshold rather than a hurricane-force threshold near 33 m s-1. Values above 23 m s-1 are lower than previous open-ocean measurements. The Dalton number estimates (CE) derived from CBLAST moisture flux measurements are shown to be invariant with wind speeds up to 30 m s-1, which is in approximate agreement with previous measurements at lower winds. These observations imply a CE/CD ratio of approximately 0.7, suggesting that additional energy sources are necessary for hurricanes to achieve their maximum potential intensity. One such additional mechanism for augmented moisture flux in the boundary layer might be "roll vortex" or linear coherent features, observed by CBLAST 2002 measurements to have wavelengths of 0.9-1.2 km. Linear features of the same wavelength range were observed in nearly concurrent RADARSAT Synthetic Aperture Radar (SAR) imagery. As a complement to the aircraft measurement program, arrays of drifting buoys and subsurface floats were successfully deployed ahead of Hurricanes Fabian (2003) and Frances (2004) [16 (6) and 38 (14) drifters (floats), respectively, in the two storms]. An unprecedented set of observations was obtained, providing a four-dimensional view of the ocean response to a hurricane for the first time ever. Two types of surface drifters and three types of floats provided observations of surface and sub-surface oceanic currents, temperature, salinity, gas exchange, bubble concentrations, and surface wave spectra to a depth of 200 m on a continuous basis before, during, and after storm passage, as well as surface atmospheric observations of wind speed (via acoustic hydrophone) and direction, rain rate, and pressure. Float observations in Frances (2004) indicated a deepening of the mixed layer from 40 to 120 m in approximately 8 h, with a corresponding decrease in SST in the right-rear quadrant of 3.2C in 11 h, roughly one-third of an inertial period. Strong inertial currents with a peak amplitude of 1.5 m s-1 were observed. Vertical structure showed that the critical Richardson number was reached sporadically during the mixed-layer deepening event, suggesting shear-induced mixing as a prominent mechanism during storm passage. Peak significant waves of 11 m were observed from the floats to complement the aircraft-measured directional wave spectra.
Borges, A.V., and R. Wanninkhof. Preface: 37th International Liege Colloquium on Ocean Dynamics, Liege, Belgium, May 2-6, 2005, 5th International Symposium on Gas Transfer at Water Surfaces. Journal of Marine Systems, 66(1-4):1-3 (2007).
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No abstract.
Bourles, B., P. Brandt, G. Caniaux, M. Dengler, Y. Gouriou, E. Key, R. Lumpkin, F. Marin, R.L. Molinari, and C. Schmid. African Monsoon Multidisciplinary Analysis (AMMA): Special measurements in the tropical Atlantic. CLIVAR Exchanges, 12(2):7-9 (2007).
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No abstract.
Broecker, W.S., and R. Wanninkhof. Mono Lake radiocarbon: The mystery deepens. EOS, Transactions, American Geophysical Union, 88(12):141-142 (2007).
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The ratio of carbon-14 (14C) to carbon in the dissolved inorganic carbon (SIGMA-CO2) of California's Mono Lake has continued to rise at a rate far faster than expected from the invasion of bomb-test 14C-labeled atmospheric CO2. Two explanations can be given. One is that the invasion rate of carbon dioxide from the atmosphere is 5 or so times higher than that for chemically inert gases. The second is that Mono Lake has been used as a site for clandestine disposal of radiocarbon.
Carrasco, H.N. Data mining assisted automated quality control of tropical cyclone wind data. M.S. thesis, University of Miami, Rosenstiel School of Marine and Atmospheric Science, 82 pp. (2007).
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Meteorological observations are collected around the world in real-time to help meteorologists understand severe weather events, such as tropical cyclones. Tropical cyclones affect life on much of the world's coastlines. Data from meteorological observations are utilized by many models and analysis systems to help predict tropical cyclones and increase meteorologists' understanding of them. Data mining techniques such as clustering are useful tools that help find patterns within data. Particularly, a key aspect of most spatial clustering algorithms is their ability to detect noise. In the area of tropical cyclone quality control, this noise is the data that needs to be removed before scheduling an analysis. DBSCAN is an existing clustering algorithm that can locate patterns based on the density of observations to find complex shapes and eliminate noise, and thus is adopted in this study. In this thesis, the H*Wind-DBSCAN framework was designed and implemented to create a data mining tool that assists automated quality control within H*Wind for the various observations collected in and around tropical cyclones. H*Wind is a tool used to monitor and analyze tropical cyclone data around the globe. Combining many platforms of different observing systems, H*Wind allows meteorologists to interact with observation data. However, the quality control process is a slow and difficult task performed manually. Depending on the number of available observations the process can take from only a few minutes to sometimes over half an hour. Therefore, the H*Wind-DBSCAN framework was designed and developed using knowledge about the structure of a tropical cyclone in an attempt to efficiently and effectively cluster observations using DBSCAN. The H*Wind-DBSCAN framework flags those observations considered noise by DBSCAN and prevents them from being used in the analysis process. Typical spatial clustering routines cluster data points using the distance between two data points on a single coordinate plane. The proposed H*Wind-DBSCAN framework integrates the Cartesian Coordinate System and Cylindrical Coordinate System based on the circulation found within tropical cyclones in order to more accurately construct clusters. Several case studies were conducted, and the results demonstrate that the proposed H*Wind-DBSCAN framework improves the overall automated quality control performance as compared to using either coordinate system alone. Using the framework, the resulting flagged observations are helpful to determine areas of interest for a closer examination and to construct a decent quality controlled data set for the tropical cyclone wind analysis system.
Cerveny, R.S., J. Lawrimore, R. Edwards, and C.W. Landsea. Extreme weather records: Compilation, adjudication, and publication. Bulletin of the American Meteorological Society, 88(6):853-860 (2007).
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No abstract.
Chavez, F.P., T. Takahashi, W.-J. Cai, G. Friederich, B. Hales, R. Wanninkhof, and R.A. Feely. Coastal oceans, pp. 157-166. In The First State of the Carbon Cycle Report (SOCCR): The North American Carbon Budget and Implications for the Global Carbon Cycle. Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research, A.W. King, L. Dilling, G.P. Zimmerman, D.M. Fairman, R.A. Houghton, G. Marland, A.Z. Rose, and T.J. Wilbanks (eds.). National Oceanic and Atmospheric Administration, National Climatic Data Center, Asheville, NC, USA, 264 pp. (2007).
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No abstract.
Conzemius, R.J., R.W. Moore, M.T. Montgomery, and C.A. Davis. Mesoscale convective vortex formation in a weakly sheared moist neutral environment. Journal of the Atmospheric Sciences, 64(5):1443-1466 (2007).
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Idealized simulations of a diabatic Rossby vortex (DRV) in an initially moist neutral baroclinic environment are performed using the fifth-generation National Center for Atmospheric Research-Pennsylvania State University (NCAR-PSU) Mesoscale Model (MM5). The primary objective is to test the hypothesis that the formation and maintenance of midlatitude warm-season mesoscale convective vortices (MCVs) are largely influenced by balanced flow dynamics associated with a vortex that interacts with weak vertical shear. As a part of this objective, the simulated DRV is placed within the context of the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX) field campaign by comparing its tangential velocity, radius of maximum winds, CAPE, and shear with the MCVs observed in BAMEX. The simulations reveal two distinct scales of development. At the larger scale, the most rapidly growing moist baroclinic mode is excited, and exponential growth of this mode occurs during the simulation. Embedded within the large-scale baroclinic wave is a convective system exhibiting the characteristic DRV development, with a positive potential vorticity (PV) anomaly in the lower troposphere and a negative PV anomaly in the upper troposphere, and the positive/negative PV doublet tilted downshear with height. The DRV warm-air advection mechanism is active, and the resulting deep convection helps to reinforce the DRV against the deleterious effects of environmental shear, causing an eastward motion of the convective system as a whole. The initial comparisons between the simulated DRVs and the BAMEX MCVs show that the simulated DRVs grew within background conditions of CAPE and shear similar to those observed for BAMEX MCVs and suggest that the same dynamical mechanisms are active. Because the BAMEX field campaign sampled MCVs in different backgrounds of CAPE and shear, the comparison also demonstrates the need to perform additional simulations to explore these different CAPE and shear regimes and to understand their impacts on the intensity and longevity of MCVs. Such a study has the additional benefit of placing MCV dynamics in an appropriate context for exploring their relevance to tropical cyclone formation.
Cram, T.A., J. Persing, M.T. Montgomery, and S.A. Braun. A Lagrangian trajectory view on transport and mixing processes between the eye, eyewall, and environment using a high-resolution simulation of Hurricane Bonnie (1998). Journal of the Atmospheric Sciences, 64(6):1835-1856 (2007).
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The transport and mixing characteristics of a large sample of air parcels within a mature and vertically sheared hurricane vortex are examined. Data from a high-resolution (2-km horizontal grid spacing) numerical simulation of real-case Hurricane Bonnie (1998) are used to calculate Lagrangian trajectories of air parcels in various subdomains of the hurricane (namely, the eye, eyewall, and near environment) to study the degree of interaction (transport and mixing) between these subdomains. It is found that: (1) there is transport and mixing from the low-level eye to the eyewall that carries air possessing relatively high values of equivalent potential temperature (thetae), which can enhance the efficiency of the hurricane heat engine; (2) a portion of the low-level inflow of the hurricane bypasses the eyewall to enter the eye, and this air both replaces the mass of the low-level eye and lingers for a sufficient time (order 1 h) to acquire enhanced entropy characteristics through interaction with the ocean beneath the eye; (3) air in the mid- to upper-level eye is exchanged with the eyewall such that more than half the air of the eye is exchanged in 5 h in this case of a sheared hurricane; and (4) that one-fifth of the mass in the eyewall at a height of 5 km has an origin in the mid- to upper-level environment where thetae is much less than in the eyewall, which ventilates the ensemble average eyewall thetae by about 1 K. Implications of these findings for the problem of hurricane intensity forecasting are briefly discussed.
Cunningham, S.A., T. Kanzow, D. Rayner, M.O. Baringer, W.E. Johns, J. Marotzke, H.R. Longworth, E.M. Grant, J.J-M. Hirschi, L.M. Beal, C.S. Meinen, and L.H. Bryden. Temporal variability of the Atlantic meridional overturning circulation at 26.5N. Science, 317(5840):935-938 (2007).
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The vigor of Atlantic meridional overturning circulation (MOC) is thought to be vulnerable to global warming, but its short-term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain. We combine continuous measurements of the MOC (beginning in 2004) using the purposefully designed transatlantic Rapid Climate Change array of moored instruments deployed along 26.5N, with time series of Gulf Stream transport and surface-layer Ekman transport to quantify its intra-annual variability. The year-long average overturning is 18.7 5.6 sverdrups (Sv) (range: 4.0 to 34.9 Sv, where 1 Sv = a flow of ocean water of 106 cubic meters per second). Interannual changes in the overturning can be monitored with a resolution of 1.5 Sv.
Dong, S., S.T. Gille, and J. Sprintall. An assessment of the Southern Ocean mixed layer heat budget. Journal of Climate, 20(17):4425-4442 (2007).
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The mixed layer heat balance in the Southern Ocean is examined by combining remotely sensed measurements and in situ observations from 1 June 2002 to 31 May 2006, coinciding with the period during which Advanced Microwave Scanning Radiometer-Earth Observing System (EOS) (AMSR-E) sea surface temperature measurements are available. Temperature/salinity profiles from Argo floats are used to derive the mixed layer depth. All terms in the heat budget are estimated directly from available data. The domain-averaged terms of oceanic heat advection, entrainment, diffusion, and air-sea flux are largely consistent with the evolution of the mixed layer temperature. The mixed layer temperature undergoes a strong seasonal cycle, which is largely attributed to the air-sea heat fluxes. Entrainment plays a secondary role. Oceanic advection also experiences a seasonal cycle, although it is relatively weak. Most of the seasonal variations in the advection term come from the Ekman advection, in contrast with western boundary current regions where geostrophic advection controls the total advection. Substantial imbalances exist in the regional heat budgets, especially near the northern boundary of the Antarctic Circumpolar Current. The biggest contributor to the surface heat budget error is thought to be the air-sea heat fluxes, because only limited Southern Hemisphere data are available for the reanalysis products and, hence, these fluxes have large uncertainties. In particular, the lack of in situ measurements during winter is of fundamental concern. Sensitivity tests suggest that a proper representation of the mixed layer depth is important to close the budget. Salinity influences the stratification in the Southern Ocean; temperature alone provides an imperfect estimate of mixed layer depth and, because of this, also an imperfect estimate of the temperature of water entrained into the mixed layer from below.
Dong, S., S.L. Hautala, and K.A. Kelly. Interannual variations in upper-ocean heat content and heat transport convergence in the western North Atlantic. Journal of Physical Oceanography, 37(11):2682-2697 (2007).
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Subsurface temperature data in the western North Atlantic Ocean are analyzed to study the variations in the heat content above a fixed isotherm and contributions from surface heat fluxes and oceanic processes. The study region is chosen based on the data density; its northern boundary shifts with the Gulf Stream position, and its southern boundary shifts to contain constant volume. The temperature profiles are objectively mapped to a uniform grid (0.5 latitude and longitude, 10 m in depth, and 3 months in time). The interannual variations in upper-ocean heat content show good agreement with the changes in the sea surface height from the Ocean Topography Experiment (TOPEX)/Poseidon altimeter; both indicate positive anomalies in 1994 and 1998-99 and negative anomalies in 1996-97. The interannual variations in surface heat fluxes cannot explain the changes in upper-ocean heat storage rate. On the contrary, a positive anomaly in heat released to the atmosphere corresponds to a positive upper-ocean heat content anomaly. The oceanic heat transport, mainly owing to the geostrophic advection, controls the interannual variations in heat storage rate, which suggests that geostrophic advection plays an important role in the air-sea heat exchange. The 18C isotherm depth and layer thickness also show good correspondence to the upper-ocean heat content; a deep and thin 18C layer corresponds to a positive heat content anomaly. The oceanic transport in each isotherm layer shows an annual cycle, converging heat in winter, and diverging in summer in a warm layer; it also shows interannual variations with the largest heat convergence occurring in even warmer layers during the period of large ocean-to-atmosphere flux.
Dorst, N.M. The National Hurricane Research Project: 50 years of research, rough rides, and name changes. Bulletin of the American Meteorological Society, 88(10):1566-1588 (2007).
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After the disastrous Atlantic hurricane season of 1954, the Weather Bureau created the National Hurricane Research Project (NHRP) to advance tropical cyclone science and improve forecasts. In the late 1950s, NHRP pioneered quantitative observations with instrumented aircraft and shaped the modern understanding of tropical cyclones. By the early 1960s, it was intimately involved in Project STORMFURY, the U.S. Government's hurricane modification program. During this time, it was collocated with the Miami, Florida, hurricane forecast office, and became a permanent laboratory. Its scientists became involved in international experiments and collaborated with researchers from around the world. In the 1970s, its theoretical and computer modeling work advanced, supporting STORMFURY. The project required the acquisition of new aircraft. Ironically, the improved instrumentation led to the dissolution of STORMFURY in 1983. Researchers found new avenues of investigation, including hurricane climatology, synoptic flow interaction, tropical cyclone dynamics, and improving intensity forecasts.
Dorst, N.M., and E. Rule. Fifty years of NOAA hurricane research. Mariners Weather Log, 51(1):10-13 (2007).
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For over 50 years, NOAA scientists have applied theoretical studies and computer models and have flown aircraft into hurricanes, all to better understand what makes these storms tick. This research has resulted in a much deeper scientific understanding of hurricanes and improved NOAA hurricane forecasts.
Drennen, W.M., J.A. Zhang, J.F. French, C. McCormick, and P.G. Black. Turbulent fluxes in the hurricane boundary layer, Part II: Latent heat flux. Journal of the Atmospheric Sciences, 64(4):1103-1115 (2007).
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As part of the recent ONR-sponsored Coupled Boundary Layer Air-Sea Transfer (CBLAST) Departmental Research Initiative, an aircraft was instrumented to carry out direct turbulent flux measurements in the high wind boundary layer of a hurricane. During the 2003 field season flux measurements were made during Hurricanes Fabian and Isabel. Here the first direct measurements of latent heat fluxes measured in the hurricane boundary layer are reported. The previous wind speed range for humidity fluxes and Dalton numbers has been extended by over 50%. Up to 30 m s-1, the highest 10-m winds measured, the Dalton number is not significantly different from the Humidity Exchange over the Sea (HEXOS) result, with no evidence of an increase with wind speed.
Dye, J.E., M.G. Bateman, H.J. Christian, E. Defer, C.A. Grainger, W.D. Hall, E.P. Krider, S.A. Lewis, D.M. Mach, F.J. Merceret, J.C. Willett, and P.T. Willis. Electric fields, cloud microphysics, and reflectivity in anvils of Florida thunderstorms. Journal of Geophysical Research, 112(D11):D11215, doi:10.1029/2006JD007550 (2007).
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A coordinated aircraft-radar project that investigated the electric fields, cloud microphysics, and radar reflectivity of thunderstorm anvils near Kennedy Space Center is described. Measurements from two cases illustrate the extensive nature of the microphysics and electric field observations. As the aircraft flew from the edges of anvils into the interior, electric fields very frequently increased abruptly from ~1 to >10 kV m1 even though the particle concentrations and radar reflectivity increased smoothly. The abrupt increase in field usually occurred when the aircraft entered regions with a reflectivity of 10-15 dBZ. We suggest that the abrupt increase in electric field was because the charge advection from the convective core did not occur across the entire breadth of the anvil and because the advection of charge was not constant in time. Also, some long-lived anvils showed enhancement of electric field and reflectivity far downwind of the convective core. Screening layers were not detected near the edges of the anvils. Comparisons of electric field magnitude with particle concentration or reflectivity for a combined data set that included all anvil measurements showed a threshold behavior. When the average reflectivity, such as in a 3-km cube, was less than approximately 5 dBZ, the electric field magnitude was <3 kV m1. Based on these findings, the Volume Averaged Height Integrated Radar Reflectivity (VAHIRR) is now being used by the NASA, the Air Force, the and Federal Aviation Administration in new Lightning Launch Commit Criteria as a diagnostic for high electric fields in anvils.
French, J.F., W.M. Drennan, J.A. Zhang, and P.G. Black. Turbulent fluxes in the hurricane boundary layer, Part I: Momentum flux. Journal of the Atmospheric Sciences, 64(4):1089-1102 (2007).
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An important outcome from the ONR-sponsored Coupled Boundary Layer Air-Sea Transfer (CBLAST) Hurricane Program is the first-ever direct measurements of momentum flux from within hurricane boundary layers. In 2003, a specially instrumented NOAA P3 aircraft obtained measurements suitable for computing surface wind stress and ultimately estimating drag coefficients in regions with surface wind between 18 and 30 m s-1. Analyses of data are presented from 48 flux legs flown within 400 m of the surface in two storms. Results suggest a roll-off in the drag coefficient at higher wind speeds, in qualitative agreement with laboratory and modeling studies and inferences of drag coefficients using a log-profile method. However, the amount of roll-off and the wind speed at which the roll-off occurs remains uncertain, underscoring the need for additional measurements.
Garzoli, S.L., and M.O. Baringer. Meridional heat transport determined with expendable bathythermographs, Part II: South Atlantic transport. Deep-Sea Research, Part I, 54(8):1402-1420 (2007).
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Fourteen temperature sections collected between July 2002 and May 2006 are analyzed to obtain estimates of the meridional heat transport variability of the South Atlantic Ocean. The methodology proposed in Part I is used to calculate the heat transport from temperature data obtained from high-density XBT profiles taken along transects from Cape Town, South Africa to Buenos Aires, Argentina. Salinity is estimated from Argo profiles and CTD casts for each XBT temperature observation using statistical relationships between temperature, latitude, longitude, and salinity computed along constant-depth surfaces. Full-depth temperature/salinity profiles are obtained by extending the profiles to the bottom of the ocean using deep climatological data. The meridional transport is then determined by using the standard geostrophic method, applying NCEP-derived Ekman transports, and requiring that salt flux through the Bering Straits be conserved. The results from the analysis indicate a mean meridional heat transport of 0.54 PW (PW=1015 Watts) with a standard deviation of 0.11 PW. The geostrophic component of the heat flux has a marked annual cycle following the variability of the Brazil Malvinas Confluence Front, and the geostrophic annual cycle is 180° out of phase with the annual cycle observed in the Ekman fluxes. As a result, the total heat flux shows significant interannual variability with only a small annual cycle. Uncertainties due to different wind products and locations of the sections are independent of the methodology used.
Halverson, J., M.L. Black, S. Braun, D. Cecil, M. Goodman, A. Heymsfield, G. Heymsfield, R. Hood, T. Krishnamurti, G. McFarquhar, M.J. Mahoney, J. Molinari, R.F. Rogers, J. Turk, C. Velden, D.-L. Zhang, E. Zipser, and R. Kakar. NASA's Tropical Cloud Systems and Processes (TCSP) Experiment: Investigating tropical cyclogenesis and hurricane intensity change. Bulletin of the American Meteorological Society, 88(6):867-882 (2007).
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In July 2005, the National Aeronautics and Space Administration investigated tropical cyclogenesis, hurricane structure, and intensity change in the eastern North Pacific and western Atlantic using its ER-2 high-altitude research aircraft. The campaign, called the Tropical Cloud Systems and Processes (TCSP) experiment, was conducted in conjunction with the National Oceanic and Atmospheric Administration/ Hurricane Research Division's Intensity Forecasting Experiment. A number of in situ and remote sensor datasets were collected inside and above four tropical cyclones representing a broad spectrum of tropical cyclone intensity and development in diverse environments. While the TCSP datasets directly address several key hypotheses governing tropical cyclone formation, including the role of vertical wind shear, dynamics of convective bursts, and upscale growth of the initial vortex, two of the storms sampled were also unusually strong, early season storms. Highlights from the genesis missions are described in this article, along with some of the unexpected results from the campaign. Interesting observations include an extremely intense, highly electrified convective tower in the eyewall of Hurricane Emily and a broad region of mesoscale subsidence detected in the lower stratosphere over landfalling Tropical Storm Gert.
Hendee, J.C. The integrated coral observing network. Earth System Monitor, 15(4):10 (2007).
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No abstract.
Huang, X.-L., Y. Chen, and M. Shenker. Solid phosphorus phases in aluminum- and iron-treated biosolids. Journal of Environmental Quality, 36(2):549-556 (2007).
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Stabilization of phosphorus (P) in sewage sludge (biosolids) to reduce water-soluble P concentrations is essential for minimizing P loss from amended soils and maximizing the capacity of the soil to safely serve as an outlet for this waste material. The chemical form at which P is retained in biosolids stabilized by Al2(SO4)318H2O (alum) or FeSO47H2O (FeSul) was investigated by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray elemental spectrometry (EDXS) and by X-ray diffraction (XRD). Both treatments resulted in the formation of a Ca-P phase, probably brushite. Phosphorus was further retained in the alum-treated biosolids by precipitation of an Al-P phase with an Al/P molar ratio of about 1:1, while in the FeSul-treated biosolids, P was retained by both precipitation with Fe/P molar ratios of 1:1 or 1.5:1, and by adsorption onto newly formed Fe hydroxides exhibiting an Fe/P molar ratio of up to 11:1. All of these mechanisms efficiently reduced P solubility and are crucial in biosolids environmentally safe agronomic beneficial use for this waste product; however, each P phase formed may react differently in the amended soil, depending on soil properties. Thus, the proper P stabilization method would depend on the target soil.
Joiner, J., E. Brin, R. Treadon, J. Derber, P. Van Delst, A. Da Silva, J. Le Marshall, P. Poli, R. Atlas, D. Bungato, and C. Cruz. Effects of data selection and error specification on the assimilation of AIRS data. Quarterly Journal of the Royal Meteorological Society, 133(622):181-196 (2007).
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The Atmospheric InfraRed Sounder (AIRS), flying aboard NASA's Aqua satellite with the Advanced Microwave Sounding Unit-A (AMSU-A) and four other instruments, has been providing data for use in numerical weather prediction and data assimilation systems for over three years. The full AIRS data set is currently not transmitted in near-real time to the prediction/assimilation centres. Instead, data sets with reduced spatial and spectral information are produced and made available within three hours of the observation time. In this paper, we evaluate the use of different channel selections and error specifications. We achieve significant positive impact from the Aqua AIRS/AMSU-A combination during our experimental time period of January 2003. The best results are obtained using a set of 156 channels that do not include any in the H2O band between 1080 and 2100 cm-1. The H2O band channels have a large influence on both temperature and humidity analyses. If observation and background errors are not properly specified, the partitioning of temperature and humidity information from these channels will not be correct, and this can lead to a degradation in forecast skill. Therefore, we suggest that it is important to focus on background error specification in order to maximize the impact from AIRS and similar instruments. In addition, we find that changing the specified channel errors has a significant effect on the amount of data that enters the analysis as a result of quality control thresholds that are related to the errors. However, moderate changes to the channel errors do not significantly impact forecast skill with the 156 channel set. We also examine the effects of different types of spatial data reduction on assimilated data sets and NWP forecast skill. Whether we pick the centre or the warmest AIRS pixel in a 3×3 array affects the amount of data ingested by the analysis but does not have a statistically significant impact on the forecast skill.
Jones, TA., D.J. Cecil, and J.P. Dunion. The environmental and inner-core conditions governing the intensity of Hurricane Erin (2001). Weather and Forecasting, 22(4):708-725 (2007).
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The evolution of Hurricane Erin (2001) is presented from the perspective of its environmental and inner-core conditions, particularly as they are characterized in the Statistical Hurricane Intensity Prediction Scheme with Microwave Imagery (SHIPS-MI). Erin can be described as having two very distinct periods. The first, which occurred between 1 and 6 September 2001, was characterized by a struggling tropical storm failing to intensify as the result of unfavorable environmental and inner-core conditions. The surrounding environment during this period was dominated by moderate shear and mid- to upper-level dry air, both caused in some part by the presence of a Saharan air layer (SAL). Further intensification was inhibited by the lack of sustained deep convection and latent heating near the low-level center. The authors attribute this in part to negative effects from the SAL. The thermodynamic conditions associated with the SAL were not well sampled by the SHIPS parameters, resulting in substantial overforecasting by both SHIPS and SHIPS-MI. Instead, the hostile conditions surrounding Erin caused its dissipation on 6 September. The second period began on 7 September when Erin re-formed north of the original center. Erin began to pull away from the SAL and moved over 29C sea surface temperatures, beginning a rapid intensification phase and reaching 105 kt by 1800 UTC 9 September. SHIPS-MI forecasts called for substantial intensification as in the previous period, but this time the model underestimated the rate of intensification. The addition of inner-core characteristics from passive microwave data improved the skill somewhat compared to SHIPS, but still left much room for improvement. For this period, it appears that the increasingly favorable atmospheric conditions caused by Erin moving away from the SAL were not well sampled by SHIPS or SHIPS-MI. As a result, the intensity change forecasts were not able to take into account the more favorable environment.
Jurado, J.L., G.L. Hitchcock, and P.B. Ortner. Seasonal variability of nutrient and phytoplankton distributions on the southwest Florida inner shelf. Bulletin of Marine Science, 80(1):21-43 (2007).
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Surface nutrient concentrations and phytoplankton biomass were monitored on the southwest Florida inner shelf during two years of contrasting rainfall (1999-2000) to assess potential linkages between freshwater discharge and surface phytoplankton communities. A diatom bloom began between April and June each year near Cape Sable during the period of peak freshwater discharge and maximum annual nutrient flux from the Shark River watershed. The bloom began as netplankton biomass (>5 µm size-fraction Chl a) and increased following an increase in discharge from the Shark River. Maximum phytoplankton biomass occurred in October when Rhizolosenia spp. dominated the netplankton community, and the annual maximum occurred in biogenic silica (BSiO2) concentrations, at 10 and 20 µmol L-1 in 1999 and 2000, respectively. Results suggest riverine discharge onto the southwest Florida inner shelf is an important nutrient source that influences the timing and distribution of annual diatom blooms. Although particulate matter composition suggests nitrogen potentially limits phytoplankton biomass during most of the year, the diatom community may be limited by silicon availability at bloom termination.
Kanzow, T., S.A. Cunningham, D. Rayner, J.J.-M. Hirschi, W.E. Johns, M.O. Baringer, H.L. Bryden, L.M. Beal, C.S. Meinen, and J. Marotzke. Observed flow compensation associated with the MOC at 26.5N in the Atlantic. Science, 317(5840):938-941 (2007).
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The Atlantic meridional overturning circulation (MOC), which provides one-quarter of the global meridional heat transport, is composed of a number of separate flow components. How changes in the strength of each of those components may affect that of the others has been unclear because of a lack of adequate data. We continuously observed the MOC at 26.5N for 1 year using end-point measurements of density, bottom pressure, and ocean currents; cable measurements across the Straits of Florida; and wind stress. The different transport components largely compensate for each other, thus confirming the validity of our monitoring approach. The MOC varied over the period of observation by 5.7 x 106 cubic meters per second, with density-inferred and wind-driven transports contributing equally to it. We find evidence for depth-independent compensation for the wind-driven surface flow.
Kelble, C.R., E.M. Johns, W.K. Nuttle, T.N. Lee, R.H. Smith, and P.B. Ortner. Salinity patterns of Florida Bay. Estuarine, Coastal, and Shelf Science, 71(1-2):318-334 (2007).
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The salinity of Florida Bay has undergone dramatic changes over the past century. Salinity values reached their most extreme, up to 70, in the late 1980s, concurrent with ecological changes in Florida Bay including a mass seagrass die-off. In this study, surface salinity was measured at approximately monthly intervals between 1998 and 2004. The 7-year data set was analyzed to quantify the effects of precipitation, runoff, evaporation, and climatic variability on salinity in Florida Bay. Overall mean Bay-wide salinity varied from a low of 24.2 just after the passing of Hurricane Irene in October 1999 to a high of 41.8 near the end of a drought period in July 2001. Bay-wide mean salinity exhibited dramatic decreases, up to -0.5 per day, whereas increases were slower, with a maximum rate of 0.1 per day. The freshwater budget for Florida Bay was slightly negative on an annual basis with significant positive monthly values observed during the peak of the rainy season (August through October) and significant negative monthly values observed during the peak of the dry season (March through May). This resulted in a minimum mean monthly Bay-wide salinity in January and a maximum monthly mean in July. Mean salinity for the overall Bay and for each of its four sub-regions could be predicted with reasonable accuracy utilizing a mass balance box model. There was no monotonic trend in salinity over this 7-year study; however, meteorological phenomena, such as tropical cyclones and El Nio-Southern Oscillation, dramatically altered the salinity patterns of Florida Bay on interannual time scales.
LaGier, M.J., J.W. Fell, and K.D. Goodwin. Electrochemical detection of harmful algae and other microbial contaminants in coastal waters using hand-held biosensors. Marine Pollution Bulletin, 54(6):757-770 (2007).
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Standard methods to identify microbial contaminants in the environment are slow, laborious, and can require specialized expertise. This study investigated electrochemical detection of microbial contaminants using commercially available, hand-held instruments. Electrochemical assays were developed for a red tide dinoflagellate (Karenia brevis), fecal-indicating bacteria (Enterococcus spp.), markers indicative of human sources of fecal pollution (human cluster Bacteroides and the esp gene of Enterococcus faecium), bacterial pathogens (Escherichia coli 0157:H7, Salmonella spp., Campylobacter jejuni, Staphylococcus aureus), and a viral pathogen (adenovirus). For K. brevis, two assay formats (Rapid PCR-Detect and Hybrid PCR-Detect) were tested and both provided detection limits of 10 genome equivalents for DNA isolated from K. brevis culture and amplified by PCR. Sensitivity with coastal water samples was sufficient to detect K. brevis that was "present" (< 1000 cells/l) without yielding false positive results and the electrochemical signal was significantly different than for samples containing cells at "medium" concentrations (100,000 to <106 cells/l). Detection of K. brevis RNA was also shown. Multi-target capability was demonstrated with an 8-plex assay for bacterial and viral targets using isolated DNA, natural beach water spiked with human feces, and water and sediments collected from New Orleans, Louisiana following Hurricane Katrina. Furthermore, direct detection of dinoflagellate and bacterial DNA was achieved using lysed cells rather than extracted nucleic acids, allowing streamlining of the process. The methods presented can be used to rapidly (3-5 h) screen environmental water samples for the presence of microbial contaminants and have the potential to be integrated into semi-automated detection platforms.
Lee, S.-K., D.B. Enfield, and C. Wang. What drives the seasonal onset and decay of the western hemisphere warm pool? Journal of Climate, 20(10):2133-2146 (2007).
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The annual heat budget of the Western Hemisphere warm pool (WHWP) is explored using the output of an ocean general circulation model (OGCM) simulation. According to the analysis, the WHWP cannot be considered as a monolithic whole with a single set of dominating processes that explain its behavior. The three regions considered, namely the eastern north Pacific (ENP), the Gulf of Mexico (GoM), and the Caribbean Sea (CBN), are each unique in terms of the atmospheric and oceanic processes that dominate the corresponding heat budgets. In the ENP region, clear-sky shortwave radiation flux is responsible for the growth of the warm pool in boreal spring, while increased cloud cover in boreal summer and associated reduction in solar radiation play a crucial role for the ENP warm pool's demise. Ocean upwelling in the Costa Rica Dome connected to surrounding areas by horizontal advection offers a persistent yearlong cooling mechanism. Over the Atlantic, the clear-sky radiation flux that increases monotonically from December to May and decreases later is largely responsible for the onset and decay of the Atlantic-side warm pool in boreal summer and fall. The CBN region is affected by upwelling and horizontal advective cooling within and away from the coastal upwelling zone off northern South America during the onset and peak phases, thus slowing down the warm pool's development, but no evidence was found that advective heat flux divergence is important in the GoM region. Turbulent mixing is also an important cooling mechanism in the annual cycle of the WHWP, and the vertical shear at the warm pool base helps to sustain the turbulent mixing. Common to all three WHWP regions is the reduction of wind speed at the peak phase, suggestive of a convection-evaporation feedback known to be important in the Indo-Pacific warm pool dynamics.
Lee, T.N., E. Johns, and P.B. Ortner. Physical processes, pp. 30-54. In Florida Bay Science Program: A Synthesis of Research on Florida Bay, J. Hunt and W. Nuttle (eds.). Fish and Wildlife Research Institute, FWRI Technical Report, TR-11, 148 pp. (2007).
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No abstract.
Li, T., C.-Y. She, H.-L. Liu, and M.T. Montgomery. Evidence of a gravity wave breaking event and the estimation of the wave characteristics from sodium lidar observation over Fort Collins, Colorado (41N, 105W). Geophysical Research Letters, 34(5):L05815, doi:10.1029/2006GL028988 (2007).
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On the night of December 3rd, 2004 (UT day 338), we observed a significant acceleration of horizontal wind near 100 km between 0900 and 0915 UT accompanied by a temperature cooling at the same altitude and warming below it. The Lomb spectrum analysis of the raw dataset revealed that a gravity wave with 1.5 hr period was significant between 0500 and 0900 UT, but blurred after 0900 UT, suggesting the transfer of wave energy and momentum from wave field to mean flow. Most likely, this observed phenomenon is due to the breaking of an upward propagating gravity wave with an apparent period of ~1.5 hr. Using linear saturation theory and assuming a monochromatic wave packet, we estimated the characteristics of breaking gravity wave, eddy diffusion coefficient, and a simple relation between Prandtl number and turbulence localization measure when the wave is breaking, from the experimentally determined heating rate, horizontal wind acceleration, and background temperature and winds.
Lillibridge, J., N. Shay, M. DeMaria, G. Goni, M. Mainelli, R. Scharroo, and L. Russell. Hurricane intensity forecasting at NOAA using ENVISAT altimetry. Proceeding, Envisat Symposium 2007, Montreaux, Switzerland, April 23-27, 2007. European Space Agency, SP-636 (CD-ROM), 7 pp. (2007).
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NOAA's National Hurricane Center (NHC) has a number of skillful track guidance models, but only a limited number of intensity prediction schemes. The relatively low skill of intensity forecasts is due to the complexity of the problem, which involves a very wide range of scales, and interaction with the underlying ocean. The empirical Statistical Hurricane Intensity Prediction Scheme (SHIPS) provides intensity predictions with accuracy comparable to those from the coupled three-dimensional GFDL hurricane model. SHIPS was implemented at NHC in 1996, and upgraded in 2004 to include upper ocean heat content (OHC) estimated from satellite altimetry. It is believed that hurricane intensification can occur over regions where OHC values exceed 50 kJ/cm2, not just in regions of high sea surface temperature. The OHC analysis presently incorporates sea surface height from Jason-1 and Geosat Follow-On. Envisat altimetry is expected to be included in the OHC analysis for the 2007 hurricane season. Efforts are underway to reduce the latency of Envisat data by including the Fast-Delivery Marine Abridged Record (FDMAR) products.
Lonfat, M., R.F. Rogers, T. Marchok, and F.D. Marks. A parametric model for predicting hurricane landfall. Monthly Weather Review, 135(9):3086-3097 (2007).
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This study documents a new parametric hurricane rainfall prediction scheme, based on the rainfall climatology and persistence model (R-CLIPER) used operationally in the Atlantic Ocean basin to forecast rainfall accumulations. Although R-CLIPER has shown skill at estimating the mean amplitude of rainfall across the storm track, one underlying limitation is that it assumes that hurricanes produce rain fields that are azimuthally symmetric. The new implementations described here take into account the effect of shear and topography on the rainfall distribution through the use of parametric representations of these processes. Shear affects the hurricane rainfall by introducing spatial asymmetries, which can be reasonably well modeled to first order using a Fourier decomposition. The effect of topography is modeled by evaluating changes in elevation of flow parcels within the storm circulation between time steps and correcting the rainfall field in proportion to those changes. Effects modeled in R-CLIPER and those from shear and topography are combined in a new model called the Parametric Hurricane Rainfall Model (PHRaM). Comparisons of rainfall accumulations predicted from the operational R-CLIPER model, PHRaM, and radar-derived observations show some improvement in the spatial distribution and amplitude of rainfall when shear is accounted for and significant improvements when both shear and topography are modeled.
Lumpkin, R. Water movement and circulation. In Hidden Depths: Atlas of the Oceans, A.E. Theberge (ed.). Collins Publishers (ISBN: 9780061345142), 50-63 (2007).
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No abstract.
Lumpkin, R., and G.J. Goni. Global oceans: Surface current observations. In State of the Climate in 2006, A. Arguez, A.M. Waple, and A.M. Sanchez-Lugo (eds.). Bulletin of the American Meteorological Society, 88(6):S36-S37 (2007).
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No abstract.
Lumpkin, R., and M.C. Pazos. Measuring surface currents with Surface Velocity Program drifters: The instrument, its data, and some recent results. In Lagrangian Analysis and Prediction of Coastal and Ocean Dynamics, A. Griffa, A.D. Kirwan, A.J. Mariano, T. Ozgokmen, and H.T. Rossby (eds.). Cambridge University Press, 39-67 (2007).
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No abstract.
Lumpkin, R., and K. Speer. Global ocean meridional overturning. Journal of Physical Oceanography, 37(10):2550-2562 (2007).
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A decade-mean global ocean circulation is estimated using inverse techniques, incorporating air-sea fluxes of heat and freshwater, recent hydrographic sections, and direct current measurements. This information is used to determine mass, heat, freshwater, and other chemical transports, and to constrain boundary currents and dense overflows. The 18 boxes defined by these sections are divided into 45 isopycnal (neutral density) layers. Diapycnal transfers within the boxes are allowed, representing advective fluxes and mixing processes. Air-sea fluxes at the surface produce transfers between outcropping layers. The model obtains a global overturning circulation consistent with the various observations, revealing two global-scale meridional circulation cells: an upper cell, with sinking in the Arctic and subarctic regions and upwelling in the Southern Ocean, and a lower cell, with sinking around the Antarctic continent and abyssal upwelling mainly below the crests of the major bathymetric ridges.
Manzello, D.P., R. Berkelmans, and J.C. Hendee. Coral bleaching indices and thresholds for the Florida Reef Tract, Bahamas, and St. Croix, U.S. Virgin Islands. Marine Pollution Bulletin, 54(12):1923-1931 (2007).
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It is well established that elevated sea temperatures cause widespread coral bleaching, yet confusion lingers as to what facet of extreme temperatures is most important. Utilizing long-term in situ datasets, we calculated nine thermal stress indices and tested their effectiveness at segregating bleaching years a posteriori for multiple reefs on the Florida Reef Tract. The indices examined represent three aspects of thermal stress: (1) short-term, acute temperature stress; (2) cumulative temperature stress; and (3) temperature variability. Maximum monthly sea surface temperature (SST) and the number of days >30.5C were the most significant; indicating that cumulative exposure to temperature extremes characterized bleaching years. Bleaching thresholds were warmer for Florida than the Bahamas and St. Croix, U.S. Virgin Islands reflecting differences in seasonal maximum SST. Hindcasts showed that monthly mean SST above a local threshold explained all bleaching years in Florida, the Bahamas, and U.S. Virgin Islands.
Manzello, D.P., M. Brandt, T.B. Smith, D. Lirman, J.C. Hendee, and R.S. Nemeth. Hurricanes benefit bleached corals. Proceedings of the National Academy of Sciences, 104(29):12,035-12,039 (2007).
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Recent, global mass-mortalities of reef corals due to record warm sea temperatures have led researchers to consider global warming as one of the most significant threats to the persistence of coral reef ecosystems. The passage of a hurricane can alleviate thermal stress on coral reefs, highlighting the potential for hurricane associated cooling to mitigate climate change impacts. We provide evidence that hurricane-induced cooling was responsible for the documented differences in the extent and recovery time of coral bleaching between the Florida Reef Tract and the U.S. Virgin Islands during the Caribbean-wide 2005 bleaching event. These results are the only known scenario where the effects of a hurricane can benefit a stressed marine community.
Marchok, T.P., R.F. Rogers, and R.E. Tuleya. Validation schemes for tropical cyclone quantitative precipitation forecasts: Evaluation of operational models for U.S. landfalling cases. Weather and Forecasting, 22(4):726-746 (2007).
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A scheme for validating quantitative precipitation forecasts (QPFs) for landfalling tropical cyclones is developed and presented here. This scheme takes advantage of the unique characteristics of tropical cyclone rainfall by evaluating the skill of rainfall forecasts in three attributes: the ability to match observed rainfall patterns, the ability to match the mean value and volume of observed rainfall, and the ability to produce the extreme amounts often observed in tropical cyclones. For some of these characteristics, track-relative analyses are employed that help to reduce the impact of model track forecast error on QPF skill. These characteristics are evaluated for storm-total rainfall forecasts of all U.S. landfalling tropical cyclones from 1998 to 2004 by the NCEP operational models, that is, the Global Forecast System (GFS), the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model, and the North American Mesoscale (NAM) model, as well as the benchmark Rainfall Climatology and Persistence (R-CLIPER) model. Compared to R-CLIPER, all of the numerical models showed comparable or greater skill for all of the attributes. The GFS performed the best of all of the models for each of the categories. The GFDL had a bias of predicting too much heavy rain, especially in the core of the tropical cyclones, while the NAM predicted too little of the heavy rain. The R-CLIPER performed well near the track of the core, but it predicted much too little rain at large distances from the track. Whereas a primary determinant of tropical cyclone QPF errors is track forecast error, possible physical causes of track-relative differences lie with the physical parameterizations and initialization schemes for each of the models. This validation scheme can be used to identify model limitations and biases and guide future efforts toward model development and improvement.
Marks, F.D. Recent results from NOAA's hurricane Intensity Forecast Experiment (IFEX). Preprints, 11th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS), San Antonio, TX, January 14-18, 2007. American Meteorological Society, Boston, CD-ROM, 6 pp. (2007).
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No abstract.
McGillis, W.R., J.H. Dacey, J.D. Ware, D.T. Ho, J.T. Bent, W.E. Asher, C.J. Zappa, P.A. Raymond, R. Wanninkhof, and S. Komori. Air-water reconciliation between the atmospheric CO2 profile and mass balance techniques. In Transport at the Air-Sea Interface: Measurements, Models, and Parameterizations, C.S. Garbe, R.A. Handler, and B. Jahne (eds.). Springer-Verlag, Berlin, 181-192 (2007).
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Studies deploying atmospheric flux-profile techniques in laboratory wind-wave tanks have been performed to demonstrate and verify the use of air-side turbulent transport models and micrometeorological approaches to accurately determine air-water gas transfer velocities. Air-water gas transfer velocities have been estimated using the CO2 atmospheric flux-profile technique in laboratory wind-wave tanks both at the NASA Wallops Flight Facility, USA and Kyoto University, Japan. Gas fluxes using the flux-profile and the waterside mass balance techniques have been reconciled. Air-water fluxes of H2O and momentum were also measured simultaneously in a linear wind-wave tank. The waterside mass balances used the evasion of SF6. The CO2, H2O, and momentum fluxes were calculated using the atmospheric flux-profile technique over a wind speed range of 1 to 14 m s-1. The CO2 and H2O atmospheric profile model uses airside turbulent diffusivities derived from momentum fluxes. These studies demonstrate that the quantification of air-water CO2 fluxes using the atmospheric flux-profile technique can be implemented in the laboratory. The profile technique can be used to measure an air-water flux in much less time than a mass balance. Effects of surfactants, wind speed, and wind stress on air-water transfer are also explored using the flux-profile technique. Validation of the air-water CO2 gas exchange in laboratory wind-wave tanks provides evidence and support that this technique may be used in field studies.
Mestas-Nunez, A.M., D.B. Enfield, and C. Zhang. Water vapor fluxes over the Intra-Americas Sea: Seasonal and interannual variability and associations with rainfall. Journal of Climate, 20(9):1910-1922 (2007).
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The seasonal and interannual variability of moisture transports over the Intra-Americas Sea (including the Gulf of Mexico and the Caribbean Sea) is evaluated using the NCEP-NCAR global reanalysis. The seasonal variability of these moisture transports is consistent with previous studies and shows distinctive winter and summer regimes. Boreal winter moisture is mainly delivered to the central United States from the Pacific with some contribution from the Gulf of Mexico. It is during the boreal summer that the moisture flow over the Intra-Americas Sea is most effective in supplying the water vapor to the central United States via the northern branch of the Caribbean low-level jet. The increase of intensity of this jet during July is associated with an increase in evaporation over the Intra-Americas Sea, consistent with midsummer drought conditions over this region. During both summer and winter, the interannual variability of the inflow of moisture from the Intra-Americas Sea into central United States is associated with Caribbean low-level jet variability. The source of the varying moisture is mainly the Gulf of Mexico and the North Atlantic area just east of the Bahamas Islands and the sink is precipitation over east-central United States. The main teleconnection pattern for these interannual variations appears to be the Pacific-North American, although in boreal winter ENSO and possibly the North Atlantic Oscillation may also play a role. During boreal summer, associations with ENSO mainly involve the zonal moisture exchange between the Intra-Americas Sea/tropical Atlantic and the tropical Pacific.
Moyer, A.C., J.L. Evans, and M.D. Powell. Comparison of observed gale radius statistics. Meteorology and Atmospheric Physics, 97(1-4):41-55 (2007).
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Forecasts of tropical cyclone track and intensity have long been used to characterize the evolution and expected threat from a tropical storm. However, in recent years, recognition of the contributions of subtropical cyclogenesis to tropical storm formation and the process of extratropical transition to latter stages of the once-tropical storm's lifecycle have raised awareness about the importance of storm structure. Indeed, the structure of a cyclone determines the distribution and intensity of the significant weather associated with that storm. In this study, storm structure is characterized in terms of significant wind radii. The radii of tropical storm, damaging, and hurricane-force winds, as well as the radius of maximum winds are all analyzed. These wind radii are objectively derived from the H*Wind surface wind analysis system. Initially, six years of these data are examined for consistency with previous studies. Having ascertained that the H*Wind radii are realistic, detailed comparisons are performed between the H*Wind and NHC Best Track wind radii for two years (2004 and 2005) of North Atlantic tropical storm and hurricane cases. This intercomparison reveals an unexpected bias: the H*Wind radii are consistently larger than the NHC Best Track for all but the smallest and least intense storms. Further examination of the objectively-determined H*Wind tropical storm force wind radius data compared to subjectively-determined radii for the same storm times demonstrates that the objective wind radii are underestimating the extent of the tropical storm force wind area. Since the objective H*Wind radii are large compared to the NHC Best Track - and yet underestimate the area of tropical storm force winds - this argues for further examination of the methods used to ascertain these significant wind radii.
Nacapricha, D., N. Amornthammarong, K. Sereenonchai, P. Anujarawat, and P. Wilairat. Low cost telemetry with PC sound card for chemical analysis applications. Talanta, 71(2):605-609 (2007).
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This work describes the development of a telemetric system in conjunction with a computer sound card for recording of signals. For signal transmission, a transmission wireless microphone was utilized, making the telemeter compatible with the sound card normally equipped inside a personal computer. The developed telemeter is a low-cost apparatus capable of remote monitoring. With the sampling rate of 10 Hz, 100% accuracy was obtained up to a distance of 30 m. The precision was good (% RSD = 0.03-0.09), with relatively low noise. The effective signal range was from 0 to 2 V, with approximately 1100 working steps (greater than 10 bit A/D). The telemetric system was shown to be suitable for wireless recording of outputs from spectrophotometer and pH meter. Potential applications in chemical analysis were demonstrated.
Pandya, R.E., D.R. Smith, D.J. Charlevoix, G.M. Fisher, S.T. Murillo, K.A. Murphy, D.M. Stanitski, and T.M. Whittaker. The 15th AMS Education Symposium. Bulletin of the American Meteorological Society, 88(1):83-85 (2007).
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No abstract.
Powell, M.D., and T.A. Reinhold. Tropical cyclone destructive potential by integrated kinetic energy. Bulletin of the American Meteorological Society, 88(4):513-526 (2007).
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Tropical cyclone damage potential, as currently defined by the Saffir-Simpson scale and the maximum sustained surface wind speed in the storm, fails to consider the area impact of winds likely to force surge and waves or cause particular levels of damage. Integrated kinetic energy represents a framework that captures the physical process of ocean surface stress forcing waves and surge while also taking into account structural wind loading and the spatial coverage of the wind. Integrated kinetic energy was computed from gridded, objectively analyzed surface wind fields of 23 hurricanes representing large and small storms. A wind destructive potential rating was constructed by weighting wind speed threshold contributions to the integrated kinetic energy, based on observed damage in Hurricanes Andrew, Hugo, and Opal. A combined storm surge and wave destructive potential rating was assigned according to the integrated kinetic energy contributed by winds greater than tropical storm force. The ratings are based on the familiar 1-5 range, with continuous fits to allow for storms as weak as 0.1 or as strong as 5.99.
Powell, M.D., and T.A. Reinhold. Reply to comments on "Tropical cyclone destructive potential by integrated kinetic energy." Bulletin of the American Meteorological Society, 88(11):1800-1801 (2007).
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No abstract.
Reynolds, C.A., M.S. Peng, S.J. Majumdar, S.D. Aberson, C.H. Bishop, and R. Buizza. Interpretation of adaptive observing guidance for Atlantic tropical cyclones. Monthly Weather Review, 135(12):4006-4029 (2007).
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Adaptive observing guidance products for Atlantic tropical cyclones are compared using composite techniques that allow one to quantitatively examine differences in the spatial structures of the guidance maps and relate these differences to the constraints and approximations of the respective techniques. The guidance maps are produced using the ensemble transform Kalman filter (ETKF) based on ensembles from the National Centers for Environmental Prediction and the European Centre for Medium-Range Weather Forecasts (ECMWF), and total-energy singular vectors (TESVs) produced by ECMWF and the Naval Research Laboratory. Systematic structural differences in the guidance products are linked to the fact that TESVs consider the dynamics of perturbation growth only, while the ETKF combines information on perturbation evolution with error statistics from an ensemble-based data assimilation scheme. The impact of constraining the SVs using different estimates of analysis error variance instead of a total-energy norm, in effect bringing the two methods closer together, is also assessed. When the targets are close to the storm, the TESV products are a maximum in an annulus around the storm, whereas the ETKF products are a maximum at the storm location itself. When the targets are remote from the storm, the TESVs almost always indicate targets northwest of the storm, whereas the ETKF targets are more scattered relative to the storm location and often occur over the northern North Atlantic. The ETKF guidance often coincides with locations in which the ensemble-based analysis error variance is large. As the TESV method is not designed to consider spatial differences in the likely analysis errors, it will produce targets over well-observed regions, such as the continental United States. Constraining the SV calculation using analysis error variance values from an operational 3D variational data assimilation system (with stationary, quasi-isotropic background error statistics) results in a modest modulation of the target areas away from the well-observed regions, and a modest reduction of perturbation growth. Constraining the SVs using the ETKF estimate of analysis error variance produces SV targets similar to ETKF targets and results in a significant reduction in perturbation growth, due to the highly localized nature of the analysis error variance estimates. These results illustrate the strong sensitivity of SVs to the norm (and to the analysis error variance estimate used to define it) and confirm that discrepancies between target areas computed using different methods reflect the mathematical and physical differences between the methods themselves.
Rogers, R.F., M.L. Black, S.S. Chen, and R.A. Black. An evaluation of microphysics fields from mesoscale model simulations of tropical cyclones, Part I: Comparisons with observations. Journal of the Atmospheric Sciences, 64(6):1811-1834 (2007).
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This study presents a framework for comparing hydrometeor and vertical velocity fields from mesoscale model simulations of tropical cyclones with observations of these fields from a variety of platforms. The framework is based on the Yuter and Houze constant frequency by altitude diagram (CFAD) technique, along with a new hurricane partitioning technique, to compare the statistics of vertical motion and reflectivity fields and hydrometeor concentrations from two datasets: one consisting of airborne radar retrievals and microphysical probe measurements collected from tropical cyclone aircraft flights over many years, and another consisting of cloud-scale (1.67-km grid length) tropical cyclone simulations using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5). Such comparisons of the microphysics fields can identify biases in the simulations that may lead to an identification of deficiencies in the modeling system, such as the formulation of various physical parameterization schemes used in the model. Improvements in these schemes may potentially lead to better forecasts of tropical cyclone intensity and rainfall. In Part I of this study, the evaluation framework is demonstrated by comparing the radar retrievals and probe measurements to MM5 simulations of Hurricanes Bonnie (1998) and Floyd (1999). Comparisons of the statistics from the two datasets show that the model reproduces many of the gross features seen in the observations, though notable differences are evident. The general distribution of vertical motion is similar between the observations and simulations, with the strongest up- and downdrafts making up a small percentage of the overall population in both datasets, but the magnitudes of vertical motion are weaker in the simulations. The model-derived reflectivities are much higher than observed, and correlations between vertical motion and hydrometeor concentration and reflectivity show a much stronger relationship in the model than what is observed. Possible errors in the data processing are discussed as potential sources of differences between the observed and simulated datasets in Part I. In Part II, attention will be focused on using the evaluation framework to investigate the role that different model configurations (i.e., different resolutions and physical parameterizations) play in producing different microphysics fields in the simulation of Hurricane Bonnie. The microphysical and planetary boundary layer parameterization schemes, as well as higher horizontal and vertical resolutions, will be tested in the simulation to identify the extent to which changes in these schemes are reflected in improvements of the statistical comparisons with the observations.
Sabine, C.L., R.A. Feely, and R. Wanninkhof. Global oceans: Global ocean carbon cycle. In State of the Climate in 2006, A. Arguez, A.M. Waple, and A.M. Sanchez-Lugo (eds.). Bulletin of the American Meteorological Society, 88(6):S40-S43 (2007).
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No abstract.
Schecter, D.A., and M.T. Montgomery. Waves in a cloudy vortex. Journal of the Atmospheric Sciences, 64(2):314-337 (2007).
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This paper derives a system of equations that approximately govern small-amplitude perturbations in a nonprecipitating cloudy vortex. The cloud coverage can be partial or complete. The model is used to examine moist vortex Rossby wave dynamics analytically and computationally. One example shows that clouds can slow the growth of phase-locked counter-propagating vortex Rossby waves in the eyewall of a hurricane-like vortex. Another example shows that clouds can (indirectly) damp discrete vortex Rossby waves that would otherwise grow and excite spiral inertia-gravity wave radiation from a monotonic cyclone at high Rossby number.
Schmid, C., R.L. Molinari, R. Sabina, Y.-H. Daneshzadeh, X. Xia, E. Forteza, and H. Yang. The real-time data management system for Argo profiling float observations. Journal of Atmospheric and Oceanic Technology, 24(9):1608-1628 (2007).
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Argo is an internationally coordinated program directed at deploying and maintaining an array of 3000 temperature and salinity profiling floats on a global 3° latitude x 3° longitude grid. Argo floats are deployed from research vessels, merchant ships, and aircraft. After launch they sink to a prescribed pressure level (typically 1000-2000 dbar), where most floats remain for 10 days. The floats then return to the surface, collecting temperature and salinity profiles. At the surface they transmit the data to a satellite and sink again to repeat the cycle. As of 10 August 2006 there are 2489 floats reporting data. The International Argo Data Management Team oversees the development and implementation of the data management protocols of Argo. Two types of data systems are active: real time and delayed mode. The real-time system receives the transmissions from the Argo floats, extracts the data, checks their quality, and makes them available to the users. The objective of the real-time system is to provide Argo profiles to the operational and research community within 24 h of their measurement. This requirement makes it necessary to control the quality of the data automatically. The delayed-mode quality control is directed at a more detailed look at the profiles using statistical methods and scientific review of the data. In this paper, the real-time data processing and quality-control methodology is described in detail. Results of the application of these procedures to Argo profiles are described.
Sereenonchai, K., P. Saetear, N. Amornthammarong, K. Uraisin, P. Wilairat, S. Motomizu, and D. Nacapricha. Membraneless vaporization unit for direct analysis of solid sample. Analytica Chimica Acta, 597(1):157-162 (2007).
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A new apparatus, called "membraneless vaporization" (MBL-VP) unit was designed and developed for direct analysis of solid samples. Solid analyte was converted into a gaseous form which then reacts with an indicator reagent. Change in absorbance was used to quantitate the analyte. Stirring with a magnetic bar was employed to facilitate the evaporation of the gas. Unlike the pervaporation technique, hydrophobic membrane was not required for this MBL-VP technique. Application of the membraneless technique for direct determination of calcium carbonate in calcium supplements, has shown it to be very precise (RSD = 2.5% for 0.16 mmol CO32-), with detection limit of 0.5 mg CaCO3. Results by this method agreed well with flame atomic absorption spectrometric method. Sample throughput was 20 samples h-1.
Sinigalliano, C.D., M.B. Gidley, T. Shibata, D. Whitman, T.H. Dixon, E. Laws, A. Hou, D. Bachoon, L. Brand, L. Amaral-Zettler, R.J. Gast, G.F. Steward, O.D. Nigro, R. Fujioka, W.Q. Betancourt, G. Vithanage, J. Mathews, L.E. Fleming, and H.M. Solo-Gabriele. Impacts of Hurricanes Katrina and Rita on the microbial landscape of the New Orleans area. Proceedings of the National Academy of Sciences, 104(21):9029-9034 (2007).
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Floodwaters in New Orleans from Hurricanes Katrina and Rita were observed to contain high levels of fecal indicator bacteria and microbial pathogens, generating concern about long-term impacts of these floodwaters on the sediment and water quality of the New Orleans area and Lake Pontchartrain. We show here that fecal indicator microbe concentrations in offshore waters from Lake Pontchartrain returned to prehurricane concentrations within two months of the flooding induced by these hurricanes. Vibrio and Legionella species within the lake were more abundant in samples collected shortly after the floodwaters had receded compared with samples taken within the subsequent three months; no evidence of a long-term hurricane-induced algal bloom was observed. Giardia and Cryptosporidium were detected in canal waters. Elevated levels of fecal indicator bacteria observed in sediment could not be solely attributed to impacts from floodwaters, as both flooded and nonflooded areas exhibited elevated levels of fecal indicator bacteria. Evidence from measurements of Bifidobacterium and bacterial diversity analysis suggest that the fecal indicator bacteria observed in the sediment were from human fecal sources. Epidemiologic studies are highly recommended to evaluate the human health effects of the sediments deposited by the floodwaters.
Sweeney, C., E. Gloor, A.R. Jacobson, R.M. Key, G. McKinley, J.L. Sarmiento, and R. Wanninkhof. Constraining global air-sea gas exchange for CO2 with recent bomb 14C measurements. Global Biogeochemical Cycles, 21(2):GB2015, doi:10.1029/2006GB002784 (2007).
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The 14CO2 released into the stratosphere during bomb testing in the early 1960s provides a global constraint on air-sea gas exchange of soluble atmospheric gases like CO2. Using the most complete database of dissolved inorganic radiocarbon, DI14C, available to date and a suite of ocean general circulation models in an inverse mode we recalculate the ocean inventory of bomb-produced DI14C in the global ocean and confirm that there is a 25% decrease from previous estimates using older DI14C data sets. Additionally, we find a 33% lower globally averaged gas transfer velocity for CO2 compared to previous estimates (Wanninkhof, 1992) using the NCEP/NCAR Reanalysis 1 1954-2000 where the global mean winds are 6.9 m s-1. Unlike some earlier ocean radiocarbon studies, the implied gas transfer velocity finally closes the gap between small-scale deliberate tracer studies and global-scale estimates. Additionally, the total inventory of bomb-produced radiocarbon in the ocean is now in agreement with global budgets based on radiocarbon measurements made in the stratosphere and troposphere. Using the implied relationship between wind speed and gas transfer velocity ks = 0.27 u102 (Sc/660)-0.5 and standard partial pressure difference climatology of CO2 we obtain an net air-sea flux estimate of 1.3 0.5 PgCyr-1 for 1995. After accounting for the carbon transferred from rivers to the deep ocean, our estimate of oceanic uptake (1.8 0.5 PgCyr-1) compares well with estimates based on ocean inventories, ocean transport inversions using ocean concentration data, and model simulations.
Thacker, W.C. Data assimilation with inequality constraints. Ocean Modelling, 16(3-4):264-276 (2007).
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If values of variables in a numerical model are limited to specified ranges, these restrictions should be enforced when data are assimilated. The simplest option is to assimilate without regard for constraints and then to correct any violations without worrying about additional corrections implied by correlated errors. This paper addresses the incorporation of inequality constraints into the standard variational framework of optimal interpolation with emphasis on our limited knowledge of the underlying probability distributions. Simple examples involving only two or three variables are used to illustrate graphically how active constraints can be treated as error-free data when background errors obey a truncated multi-normal distribution. Using Lagrange multipliers, the formalism is expanded to encompass the active constraints. Two algorithms are presented, both relying on a solution ignoring the inequality constraints to discover violations to be enforced. While explicitly enforcing a subset can, via correlations, correct the others, pragmatism based on our poor knowledge of the underlying probability distributions suggests the expedient of enforcing them all explicitly to avoid the computationally expensive task of determining the minimum active set. If additional violations are encountered with these solutions, the process can be repeated. Simple examples are used to illustrate the algorithms and to examine the nature of the corrections implied by correlated errors.
Thacker, W.C. Estimating salinity to complement observed temperature, Part 1: Gulf of Mexico. Journal of Marine Systems, 65(1-4):224-248 (2007).
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This paper and its companion [Thacker, W.C., Sindlinger, L., 2006-this issue. Estimating salinity to complement observed temperature: 2. Northwestern Atlantic. Journal of Marine Systems, doi:10.1016/j.jmarsys.2005.06.007.] document initial efforts in a project with the goal of developing capability for estimating salinity on a region-by-region basis for the world oceans. The primary motivation for this project is to provide information for correcting salinity, and thus density, when assimilating expendable-bathythermograph (XBT) data into numerical simulations of oceanic circulation, while a secondary motivation is to provide information for calibrating salinity from autonomous profiling floats. Empirical relationships between salinity and temperature, which can be identified from archived conductivity-temperature-depth (CTD) data, provide the basis for the salinity estimates. The Gulf of Mexico was chosen as the first region to explore for several reasons: (1) It's geographical separation from the Caribbean Sea and the North Atlantic Ocean makes it a "small ocean" characterized by a deep central basin surrounded by a substantial continental shelf. (2) The archives contain a relatively large number of CTD data that can be used to establish empirical relationships. (3) The sharp fronts associated with the Loop Current and its rings, which separate water with different thermal and haline characteristics, pose a challenge for estimating salinity. In spite of the shelf and the fronts, the relationship between salinity and temperature was found to be sufficiently regular that a single empirical model could be used to estimate salinity on each pressure surface for the entire Gulf for all seasons. In and below the thermocline, root-mean-square estimation errors are small, less than 0.02 psu for pressures greater than 400 dbar, corresponding to potential density errors of less than 0.015 kg/m3. Errors for estimates nearer to the surface can be an order of magnitude larger.
Thacker, W.C., and L.R. Sindlinger. Estimating salinity to complement observed temperature, Part 2: Northwestern Atlantic. Journal of Marine Systems, 65(1-4):249-267 (2007).
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This paper addresses the problem of estimating salinity for a large region in the Atlantic Ocean containing the Gulf Stream and its recirculation. Together with Part 1 [Thacker, W.C., 2006-this issue. Estimating salinity to complement observed temperature: 1. Gulf of Mexico. Journal of Marine Systems, doi:10.1016/j.jmarsys.2005.06.008.] dealing with the Gulf of Mexico, this reports on the first efforts of a project for developing world-wide capability for estimating salinity to complement expendable-bathythermograph (XBT) data. Such estimates are particularly important for this region, where the strong frontal contrasts render the task of assimilating XBT data into numerical models more sensitive to the treatment of salinity. Differences in salinity's co-variability with temperature and with longitude, latitude, and day-of-year from the northwestern part of the region with the Gulf Stream to the southeastern part more characteristic of the Sargasso Sea suggested that the region be partitioned to achieve more accurate salinity estimates. In general, accuracies were better in the southeastern sub-region than in the more highly variable northwestern sub-region with root-mean-square estimation errors of 0.15 psu at 25 dbar and 0.02 psu at 300 dbar as compared with 0.35 psu and 0.50 psu, respectively, but in the southeast there was an unexpected error maximum around 1000 dbar where estimates were slightly less accurate than in the northwest. For pressures greater than 1400 dbar root-mean-square errors in both sub-regions were less than 0.02 psu.
Tory, K.J., N.E. Davidson, and M.T. Montgomery. Prediction and diagnosis of tropical cyclone formation in an NWP system, Part III: Diagnosis of developing and nondeveloping storms. Journal of the Atmospheric Sciences, 64(9):3195-3213 (2007).
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This is the third of a three-part investigation into tropical cyclone (TC) genesis in the Australian Bureau of Meteorology's Tropical Cyclone Limited Area Prediction System (TC-LAPS), an operational numerical weather prediction (NWP) forecast model. In Parts I and II, a primary and two secondary vortex enhancement mechanisms were illustrated, and shown to be responsible for TC genesis in a simulation of TC Chris. In this paper, five more TC-LAPS simulations are investigated: three developing and two nondeveloping. In each developing simulation the pathway to genesis was essentially the same as that reported in Part II. Potential vorticity (PV) cores developed through low- to middle-tropospheric vortex enhancement in model-resolved updraft cores (primary mechanism) and interacted to form larger cores through diabatic upscale vortex cascade (secondary mechanism). On the system scale, vortex intensification resulted from the large-scale mass redistribution forced by the upward mass flux, driven by diabatic heating, in the updraft cores (secondary mechanism). The nondeveloping cases illustrated that genesis can be hampered by (i) vertical wind shear, which may tilt and tear apart the PV cores as they develop, and (ii) an insufficient large-scale cyclonic environment, which may fail to sufficiently confine the warming and enhanced cyclonic winds, associated with the atmospheric adjustment to the convective updrafts. The exact detail of the vortex interactions was found to be unimportant for qualitative genesis forecast success. Instead the critical ingredients were found to be sufficient net deep convection in a sufficiently cyclonic environment in which vertical shear was less than some destructive limit. The often-observed TC genesis pattern of convection convergence, where the active convective regions converge into a 100-km-diameter center, prior to an intense convective burst and development to tropical storm intensity is evident in the developing TC-LAPS simulations. The simulations presented in this study and numerous other simulations not yet reported on have shown good qualitative forecast success. Assuming such success continues in a more rigorous study (currently under way) it could be argued that TC genesis is largely predictable provided the large-scale environment (vorticity, vertical shear, and convective forcing) is sufficiently resolved and initialized.
Uhlhorn, E.W., P.G. Black, J.L. Franklin, M. Goodberlet, J. Carswell, and A.S. Goldstein. Hurricane surface wind mesurements from an operational Stepped Frequency Microwave Radiometer. Monthly Weather Review, 135(9):3070-3085 (2007).
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For the first time, the NOAA/Aircraft Operations Center (AOC) flew stepped frequency microwave radiometers (SFMRs) on both WP-3D research aircraft for operational hurricane surface wind speed measurement in 2005. An unprecedented number of major hurricanes provided ample data to evaluate both instrument performance and surface wind speed retrieval quality up to 70 m s-1 (Saffir-Simpson category 5). To this end, a new microwave emissivity-wind speed model function based on estimates of near-surface winds in hurricanes by global positioning system (GPS) dropwindsondes is proposed. For practical purposes, utilizing this function removes a previously documented high bias in moderate SFMR-measured wind speeds (10-50 m s-1), and additionally corrects an extreme wind speed (>60 m s-1) underestimate. The AOC operational SFMRs yield retrievals that are precise to within ~2% at 30 m s-1, which is a factor of 2 improvement over the NOAA Hurricane Research Division's SFMR, and comparable to the precision found here for GPS dropwindsonde near-surface wind speeds. A small (1.6 m s-1), but statistically significant, overall high bias was found for independent SFMR measurements utilizing emissivity data not used for model function development. Across the range of measured wind speeds (10-70 m s-1), SFMR 10-s averaged wind speeds are within 4 m s-1 (rms) of the dropwindsonde near-surface estimate, or 5%-25% depending on speed. However, an analysis of eyewall peak wind speeds indicates an overall 2.6 m s-1 GPS low bias relative to the peak SFMR estimate on the same flight leg, suggesting a real increase in the maximum wind speed estimate due to SFMR's high-density sampling. Through a series of statistical tests, the SFMR is shown to reduce the overall bias in the peak surface wind speed estimate by ~50% over the current flight-level wind reduction method and is comparable at extreme wind speeds. The updated model function is demonstrated to behave differently below and above the hurricane wind speed threshold (~32 m s-1), which may have implications for air-sea momentum and kinetic energy exchange. The change in behavior is at least qualitatively consistent with recent laboratory and field results concerning the drag coefficient in high wind speed conditions, which show a fairly clear "leveling off" of the drag coefficient with increased wind speed above ~30 m s-1. Finally, a composite analysis of historical data indicates that the earth-relative SFMR peak wind speed is typically located in the hurricane's right-front quadrant, which is consistent with previous observational and theoretical studies of surface wind structure.
Walsh, K.J.E., M. Fiorino, C.W. Landsea, and K. McInnes. Objectively determined resolution-dependent threshold criteria for the detection of tropical cyclones in climate models and reanalyses. Journal of Climate, 20(10):2307-2314 (2007).
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Objectively derived resolution-dependent criteria are defined for the detection of tropical cyclones in model simulations and observationally based analyses. These criteria are derived from the wind profiles of observed tropical cyclones, averaged at various resolutions. Both an analytical wind profile model and two-dimensional observed wind analyses are used. The results show that the threshold wind speed of an observed tropical cyclone varies roughly linearly with resolution. The criteria derived here are compared to the numerous different criteria previously employed in climate model simulations. The resulting method provides a simple means of comparing climate model simulations and reanalyses.
Wang, C. Variability of the Caribbean low-level jet and its relations to climate. Climate Dynamics, 29(4):411-422 (2007).
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A maximum of easterly zonal wind at 925 hPa in the Caribbean region is called the Caribbean Low-Level Jet (CLLJ). Observations show that the easterly CLLJ varies semi-annually, with two maxima in the summer and winter and two minima in the fall and spring. Associated with the summertime strong CLLJ are a maximum of sea level pressure (SLP), a relative minimum of rainfall (the mid-summer drought), and a minimum of tropical cyclogenesis in July in the Caribbean Sea. It is found that both the meridional gradients of sea surface temperature (SST) and SLP show a semi-annual feature, consistent with the semi-annual variation of the CLLJ. The CLLJ anomalies vary with the Caribbean SLP anomalies that are connected to the variation of the North Atlantic Subtropical High (NASH). In association with the cold (warm) Caribbean SST anomalies, the atmosphere shows the high (low) SLP anomalies near the Caribbean region that are consistent with the anomalously strong (weak) easterly CLLJ. The CLLJ is also remotely related to the SST anomalies in the Pacific and Atlantic, reflecting that these SST variations affect the NASH. During the winter, warm (cold) SST anomalies in the tropical Pacific correspond to a weak (strong) easterly CLLJ. However, this relationship is reversed during the summer. This is because the effects of ENSO on the NASH are opposite during the winter and summer. The CLLJ varies in phase with the North Atlantic Oscillation (NAO) since a strong (weak) NASH is associated with a strengthening (weakening) of both the CLLJ and the NAO. The CLLJ is positively correlated with the 925-hPa meridional wind anomalies from the vocean to the United States via the Gulf of Mexico. Thus, the CLLJ and the meridional wind carry moisture from the ocean to the central United States, usually resulting in an opposite (or dipole) rainfall pattern in the tropical North Atlantic Ocean and Atlantic warm pool versus the central United States.
Wang, C., and S.-K. Lee. Atlantic warm pool, Caribbean low-level jet, and their potential impact on Atlantic hurricanes. Geophysical Research Letters, 34(2):L02703, doi:10.1029/2006GL028579 (2007).
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The Atlantic Warm Pool (AWP) is a large body of warm water (warmer than 28.5C) that appears in the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic during the summer and fall. Located to its northeastern side is the North Atlantic Subtropical High (NASH) that produces the easterly trade winds in the tropics. The trade winds carry moisture from the tropical North Atlantic into the Caribbean Sea where the flow intensifies, forming the Caribbean Low-Level Jet (CLLJ). This paper finds that the easterly CLLJ is maximized in the summer and winter, whereas it is minimized in the fall and spring. The semi-annual feature of the CLLJ results from the semi-annual variation of sea level pressure in the Caribbean region associated with the east-west excursion of the NASH. The AWP's impact is to weaken the summertime NASH, especially at its southwestern edge and thus weaken the easterly CLLJ. The weakening of the easterly CLLJ, in conjunction with the AWP-induced change of upper-level wind, reduces the tropospheric vertical wind shear that favors hurricane formation and intensification during August-October.
Wang, C., S.-K. Lee, and D.B. Enfield. Impact of the Atlantic warm pool on the summer climate of the western hemisphere. Journal of Climate, 20(20):5021-5040 (2007).
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The Atlantic warm pool (AWP) is a large body of warm water that comprises the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic. Located to its northeastern side is the North Atlantic subtropical high (NASH), which produces the tropical easterly trade winds. The easterly trade winds carry moisture from the tropical North Atlantic into the Caribbean Sea, where the flow intensifies, forming the Caribbean low-level jet (CLLJ). The CLLJ then splits into two branches: one turning northward and connecting with the Great Plains low-level jet (GPLLJ), and the other continuing westward across Central America into the eastern North Pacific. The easterly CLLJ and its westward moisture transport are maximized in the summer and winter, whereas they are minimized in the fall and spring. This semiannual feature results from the semiannual variation of sea level pressure in the Caribbean region owing to the westward extension and eastward retreat of the NASH. The NCAR Community Atmospheric Model and observational data are used to investigate the impact of the climatological annual mean AWP on the summer climate of the Western Hemisphere. Two groups of the model ensemble runs with and without the AWP are performed and compared. The model results show that the effect of the AWP is to weaken the summertime NASH, especially at its southwestern edge. The AWP also strengthens the summertime continental low over the North American monsoon region. In response to these pressure changes, the CLLJ and its moisture transport are weakened, but its semiannual feature does not disappear. The weakening of the easterly CLLJ increases (decreases) moisture convergence to its upstream (downstream) and thus enhances (suppresses) rainfall in the Caribbean Sea (in the far eastern Pacific west of Central America). Model runs show that the AWP's effect is to always weaken the southerly GPLLJ. However, the AWP strengthens the GPLLJ's northward moisture transport in the summer because the AWP-induced increase of specific humidity overcomes the weakening of southerly wind, and vice versa in the fall. Finally, the AWP reduces the tropospheric vertical wind shear in the main development region that favors hurricane formation and development during August-October.
Wang, Z.A., X. Liu, R.H. Byrne, R. Wanninkhof, R.E. Bernstein, E.A. Kaltenbacher, and J. Patten. Simultaneous spectrophotometric flow-through measurements of pH, carbon dioxide fugacity, and total inorganic carbon in seawater. Analytica Chimica Acta, 596(1):23-36 (2007).
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An autonomous multi-parameter flow-through CO2 system has been developed to simultaneously measure surface seawater pH, carbon dioxide fugacity (fCO2), and total dissolved inorganic carbon (DIC). All three measurements are based on spectrophotometric determinations of solution pH at multiple wavelengths using sulfonephthalein indicators. The pH optical cell is machined from a PEEK polymer rod bearing a bore-hole with an optical pathlength of ~15 cm. The fCO2 optical cell consists of Teflon AF 2400 (DuPont) capillary tubing sealed within the bore-hole of a PEEK rod. This Teflon AF tubing is filled with a standard indicator solution with a fixed total alkalinity, and forms a liquid core waveguide (LCW). The LCW functions as both a long pathlength (~15 cm) optical cell and a membrane that equilibrates the internal standard solution with external seawater. fCO2 is then determined by measuring the pH of the internal solution. DIC is measured by determining the pH of standard internal solutions in equilibrium with seawater that has been acidified to convert all forms of DIC to CO2. The system runs repetitive measurement cycles with a sampling frequency of ~7 samples (21 measurements) per hour. The system was used for underway measurements of sea surface pH, fCO2, and DIC during the CLIVAR/CO2 A16S cruise in the South Atlantic Ocean in 2005. The field precisions were evaluated to be 0.0008 units for pH, 0.9 µatm for fCO2, and 2.4 µmol kg-1 for DIC. These field precisions are close to those obtained in the laboratory. Direct comparison of our measurements and measurements obtained using established standard methods revealed that the system achieved field agreements of 0.0012 0.0042 units for pH, 1.0 2.5 µatm for fCO2, and 2.2 6.0 µmol kg-1 for DIC. This system integrates spectrophotometric measurements of multiple CO2 parameters into a single package suitable for observations of both seawater and freshwater.
Wanninkhof, R. The impact of different gas exchange formulations and wind speed products on global air-sea CO2 fluxes. In Transport at the Air-Sea Interface: Measurements, Models, and Parameterizations, C.S. Garbe, R.A. Handler, and B. Jahne (eds.). Springer-Verlag, 1-23 (2007).
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Significant advances have been made over the last decade in estimating air-sea CO2 fluxes over the ocean by the bulk formulation that expresses the flux as the product of the gas transfer velocity and the concentration difference of aqueous CO2 over the liquid boundary layer. This has resulted in a believable global monthly climatology of air-sea CO2 fluxes over the ocean on a 4 by 5 grid. It is shown here that the global air-sea CO2 fluxes are very sensitive to estimates of gas transfer velocity and the parameterization of gas transfer with wind. Wind speeds can now be resolved at sufficient temporal and spatial resolution that they should not limit the estimates, but the absolute magnitudes of winds for different wind products differ significantly. It is recommended to use satellite-derived wind products that have the appropriate resolution instead of assimilated products that often do not appropriately resolve variability on sub-daily and sub-25-km space scales. Parameterizations of gas exchange with wind differ in functional form and magnitude but the difference between the most-used quadratic relationships is about 15%. Based on current estimates of uncertainty of the air-water CO2 concentration differences, the winds, and the gas exchange-wind speed parameterization, each parameter contributes similarly to the overall uncertainty in the flux that is estimated at 25%.
Wanninkhof, R., A. Olsen, and J.A. Trinanes. Air-sea CO2 fluxes in the Caribbean Sea from 2002-2004. Journal of Marine Systems, 66(1-4):272-284 (2007).
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Air-sea fluxes in the Caribbean Sea are presented based on measurements of partial pressure of CO2 in surface seawater, pCO2sw, from an automated system onboard the cruise ship Explorer of the Seas for 2002 through 2004. The pCO2sw values are used to develop algorithms of pCO2sw based on sea surface temperature (SST) and position. The algorithms are applied to assimilated SST data and remotely sensed winds on a 1 by 1 grid to estimate the fluxes on weekly timescales in the region. The positive relationship between pCO2sw and SST is lower than the isochemical trend, suggesting counteracting effects from biological processes. The relationship varies systematically with location with a stronger dependence further south. Furthermore, the southern area shows significantly lower pCO2sw in the fall compared to the spring at the same SST, which is attributed to differences in salinity. The annual algorithms for the entire region show a slight trend between 2002 and 2004, suggesting an increase of pCO2sw over time. This is in accord with the increasing pCO2sw due to the invasion of anthropogenic CO2. The annual fluxes of CO2 yield a net invasion of CO2 to the ocean that ranges from -0.04 to -1.2 mol m-2 year-1 over the three years. There is a seasonal reversal in the direction of the flux with CO2 entering into the ocean during the winter and an evasion during the summer. Year-to-year differences in flux are primarily caused by temperature anomalies in the late winter and spring period resulting in changes in invasion during these seasons. An analysis of pCO2sw before and after Hurricane Frances (September 4-6, 2004), and wind records during the storm suggest a large local enhancement of the flux but minimal influence on annual fluxes in the region.
Willoughby, H.E., E.N. Rappaport, and F.D. Marks. Hurricane forecasting: The state of the art. Natural Hazards Review, 8(3):45-49 (2007).
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In this article, we summarize current forecasting practice, the performance of the forecasting enterprise, and the impacts of tropical cyclones from a meteorological perspective. In the past, a forecast was considered successful if it predicted the hurricane's position and intensity 12-72 h into the future. By the 1990s, forecast users came to expect more specific details such as spatial distributions of rainfall, winds, flooding, and high seas. In the early 21st century, forecasters extended their time horizons to 120 h. Meteorologists have maintained homogeneous statistics on forecast accuracy for more than 50 years. These verification statistics are reliable metrics of meteorological performance. In terms of outcomes, forecasting in the late 20th century prevented 66-90% of the hurricane-related deaths in the United States that would have resulted from techniques used in the 1950s, but it is difficult to demonstrate an effect on property damage. The economic and human consequences of the response to forecasts and warnings are also poorly known. A final key concern is how to frame forecasts to address users' needs and to elicit optimum responses.
Wu, C.-C., K.-H. Chou, P.-H. Lin, S.D. Aberson, M.S. Peng, and T. Nakazawa. The impact of dropsonde data on typhoon track forecasting in DOTSTAR. Weather and Forecasting, 22(6):1157-1176 (2007).
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Starting from 2003, a new typhoon surveillance program, Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR), was launched. During 2004, 10 missions for eight typhoons were conducted successfully with 155 dropwindsondes deployed. In this study, the impact of these dropwindsonde data on tropical cyclone track forecasts has been evaluated with five models (four operational and one research models). All models, except the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model, show the positive impact that the dropwindsonde data have on tropical cyclone track forecasts. During the first 72 h, the mean track error reductions in the National Centers for Environmental Predictions (NCEP) Global Forecast System (GFS), the Navy Operational Global Atmospheric Prediction System (NOGAPS) of the Fleet Numerical Meteorology and Oceanography Center (FNMOC), and the Japanese Meteorological Agency (JMA) Global Spectral Model (GSM) are 14%, 14%, and 19%, respectively. The track error reduction in the Weather Research and Forecasting (WRF) model, in which the initial conditions are directly interpolated from the operational GFS forecast, is 16%. However, the mean track improvement in the GFDL model is a statistically insignificant 3%. The 72-h-average track error reduction from the ensemble mean of the above three global models is 22%, which is consistent with the track forecast improvement in Atlantic tropical cyclones from surveillance missions. In all, despite the fact that the impact of the dropwindsonde data is not statistically significant due to the limited number of DOTSTAR cases in 2004, the overall added value of the dropwindsonde data in improving typhoon track forecasts over the western North Pacific is encouraging. Further progress in the targeted observations of the dropwindsonde surveillances and satellite data, and in the modeling and data assimilation system, is expected to lead to even greater improvement in tropical cyclone track forecasts.
Zhang, J.-Z., and X.-L. Huang. Relative importance of solid-phase phosphorus and iron on the sorption behavior of sediments. Environmental Science and Technology, 41(8):2789-2795 (2007).
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Of all the metal oxide particles, amorphous iron oxides have the greatest adsorption capacity for phosphate. Coastal sediments are often coated with terrigenous amorphous iron oxides, and those containing high iron are thought to have a high adsorption capacity. However, this conventional wisdom is based largely upon studies of phosphate adsorption on laboratory-synthesized minerals themselves containing no phosphorus. Using natural sediments that contain variable phosphorus and iron, our results demonstrate that the exchangeable phosphate rather than the iron oxides of sediments governs the overall sorption behavior. The iron oxide content becomes important only in sediments that are poor in phosphorus. A total of 40 sampling sites across the Florida Bay provide detailed spatial distributions both of the sediment's zero equilibrium phosphate concentration (EPC0) and of the distribution coefficient (Kd) that are consistent with the distribution of the exchangeable phosphate content of the sediment. This study provides the first quantitative relationships between sorption characteristics (EPC0 and Kd) and the exchangeable phosphate content of natural sediments.
**2006**
Aberson, S.D., and B.J. Etherton. Targeting and data assimilation studies during Hurricane Humberto (2001). Journal of the Atmospheric Sciences, 63(1):175-186 (2006).
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Two operational synoptic surveillance missions were conducted by the National Oceanic and Atmospheric Administration into Hurricane Humberto (2001). Forecasts from two leading dynamical hurricane track forecast models were improved substantially during the watch and warning period before a projected landfall by the assimilation of the additional dropwindsonde data. Feasibility tests with a barotropic model suggest that further improvements may be obtained by the use of the ensemble transform Kalman filter for assimilating these additional data into the model. This is the first effort to assimilate data into a hurricane model using the ensemble transform Kalman filter.
Aberson, S.D., and J.B. Halverson. Kelvin-Helmholtz billows in the eyewall of Hurricane Erin. Monthly Weather Review, 134(3):1036-1038 (2006).
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A photograph of vertically aligned KelvinHelmholtz billows in the eastern eyewall of Hurricane Erin on 10 September 2001 is presented. The vertical shear instability in the horizontal winds necessary to produce the billows is confirmed with a high-altitude dropwindsonde observation. This shear instability is not known to be common in tropical cyclone eyewalls and is likely only in cases with a very large eyewall tilt. However, research and reconnaissance aircraft pilots need to be aware of the possibility of their existence, along with other types of hazardous conditions, in such rare circumstances.
Aberson, S.D., and D.P. Stern. Extreme horizontal winds measured by dropwindsondes in hurricanes. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Aberson, S.D., J.P. Dunion, and F.D. Marks. A photograph of a wavenumber-2 asymmetry in the eye of Hurricane Erin. Journal of the Atmospheric Sciences, 63(1):387-391 (2006).
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A photograph of a wavenumber-2 asymmetry in the eye of Hurricane Erin taken during a NOAA WP-3D research flight during the Fourth Convection and Moisture Experiment (CAMEX-4) field program on 10 September 2001 is described. The photograph of the cloud structure within the eye is evaluated using airborne and satellite remote sensing observations, and a possible explanation for the asymmetry is presented.
Aberson, S.D., M.T. Montgomery, M.M. Bell, and M.L. Black. Hurricane Isabel (2003): New insights into the physics of intense storms, Part II: Extreme localized wind. Bulletin of the American Meteorological Society, 87(10):1349-1354 (2006).
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An unprecedented dataset of category-5 Hurricane Isabel was collected on 12-14 September 2003. This two-part series focuses on novel dynamical and thermodynamical aspects of Isabel's inner-core structure on 13 September. In Part I, using a composite of dropwindsonde and in situ aircraft data, the authors suggested that the axisymmetric structure of Isabel showed that the storm was superintense. Mesocyclones seen clearly in satellite imagery within the eye of Hurricane Isabel are hypothesized to mix high-entropy air at low levels in the eye into the eyewall, stimulating explosive convective development and a concomitant local horizontal wind acceleration. Part II focuses on a unique set of observations into an extraordinary small- (miso) scale cyclonic feature inside of the inner edge of the eyewall of Hurricane Isabel. A dropwindsonde released into this feature measured the strongest known horizontal wind in a tropical cyclone. This particular observation is discussed in the context of concurrent observations from airborne Doppler radar and other airborne instruments. These observations show wind even stronger than the system-scale superintense wind suggested in Part I. Speculation on the frequency of occurrence of these "little whirls" and their potentially catastrophic impacts are presented.
Aberson, S.D., M.L. Black, R.A. Black, R.W. Burpee, J.J. Cione, C.W. Landsea, and F.D. Marks. Thirty years of tropical cyclone research with the NOAA P-3 aircraft. Bulletin of the American Meteorological Society, 87(8):1039-1055 (2006).
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In 1976 and 1977, the National Oceanic and Atmospheric Administration purchased two customized WP-3D (P-3) aircraft to conduct tropical cyclone (TC) research. During their first 30 years, the P-3s have proved to be invaluable research platforms, obtaining data at the micro- to synoptic scale, with missions conducted in 134 TCs in the Atlantic and eastern Pacific Oceans and near Australia. Analyses of the observations led to many new insights about TC structure, dynamics, thermodynamics, and environmental interactions. The real-time use of the information by the National Hurricane and Environmental Modeling Centers of the National Centers for Environmental Prediction (NCEP), as well as later research, has helped to increase the accuracy of wind, flood, and storm surge forecasts and severe weather warnings and has resulted in significant improvements to operational numerical model guidance for TC-track forecasts. In commemoration of the first 30 years of research with these aircraft, this manuscript presents a brief overview of the instrumentation aboard the aircraft and the major research findings during this period.
Atlas, R., O. Reale, B.-W. Shen, and S.-J. Lin. The use of remotely sensed data and innovative modeling to improve hurricane prediction. In Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XII, S.S. Shen and P.E. Lewis (eds.). Proceedings, SPIE, 6233:62330U, doi:10.1117/12.673221, 8 pp. (2006).
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The assimilation of remotely sensed data from aircraft and satellites has contributed substantially to the current accuracy of operational hurricane forecasting. In the 1960s, satellite imagery revolutionized hurricane detection and forecasting. Since that time, quantitative remotely sensed data (e.g., atmospheric motion winds, passive infrared and microwave radiances or retrievals of temperature, moisture, surface wind and rain rate, active microwave measurements of surface wind and rain rate) and significant advances in modeling and data assimilation have increased the accuracy of hurricane track forecasts very significantly. The development of advanced next-generation models in combination with new types of remotely sensed observation (e.g., space-based lidar winds) should yield significant further improvements in the timing and location of landfall and in the predicted intensification of hurricanes.
Atlas, R., O. Reale, J. Ardizzone, J. Terry, J.-C. Jusem, E. Brin, D. Bungato, and P. Woiceshyn. Geophysical validation of WINDSAT surface wind data and its impact on numerical weather prediction. In Atmospheric and Environmental Remote Sensing Data Processing and Utilization II: Perspective on Calibration/Validation Initiatives and Strategies, A.H. Huang and H.J. Bloom (eds.). Proceedings, SPIE, 6301:63010C, doi:10.1117/12.680923, 7 pp. (2006).
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A detailed evaluation of the latest version of WINDSAT surface wind data has recently been performed to determine the quality of these data and their usefulness for ocean surface wind analysis and numerical weather prediction. The first component of this evaluation consisted of both subjective and objective comparisons of WINDSAT wind vectors to other sources of ocean surface winds (e.g., ship and buoy observations, QuikSCAT satellite winds, or model derived wind analyses). This was followed by data impact experiments using a variational surface wind analysis, as well as an operational four-dimensional data assimilation system. The results of this evaluation demonstrate the usefulness of WINDSAT data, but also show deficiencies relative to current scatterometer measurements.
Ayina, L.-H., A. Bentamy, A.M. Mestas-Nunez, and G. Madec. The impact of satellite winds and latent heat fluxes in a numerical simulation of the tropical Pacific Ocean. Journal of Climate, 19(22):5889-5902 (2006).
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Several oceanic operational programs use remotely sensed fluxes to complement atmospheric operational analyses from major national weather prediction centers. The main goal of this study is to evaluate the ability of the ocean model (ORCA) to correctly simulate the dynamic of the tropical Pacific Ocean in 1996-98 when forced by the satellite turbulent fluxes (wind stress and latent heat fluxes). The results are compared with the oceanic response resulting from forcing the model with the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. Three sensitivity simulations forced with satellite and atmospheric analysis fields are performed. The control experiment is forced with the ECMWF fluxes. The solutions of these simulations are compared with data from the Tropical Atmosphere-Ocean (TAO) buoys and from sea surface temperatures analysis by Reynolds and Smith in the equatorial Pacific Ocean. The analysis results indicate that the model reproduces well the major spatial and temporal oceanic structures including the main characteristics of the 1997-98 El Nio. More specifically, the comparisons with buoys indicate that the experiment forced by the winds and the satellite latent heat fluxes is closer to the observations. They provide weak rms difference and strong correlations along the whole 500-m depth column. Furthermore, the correlations with the SST analysis vary between 75% and 95% compared to 65% and 77% for the experiment forced by ECMWF fluxes. The currents in the first 350 m also show a strong sensitivity to satellite turbulent fluxes.
Baringer, M.O., and C.S. Meinen. Global oceans: Thermohaline circulation. In State of the Climate in 2005, K.A. Shein, A.M. Waple, H.J. Diamond, and J.M. Levy (eds.). Bulletin of the American Meteorological Society, 87(6):S27-S28 (2006).
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No abstract.
Baringer, M.O., G.J. Goni, and S.L. Garzoli. Atlantic high density XBT lines, pp. 181-182. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Baringer, M.O., C.S. Meinen, and S.L. Garzoli. The meridional overturning circulation and oceanic heat transport, pp. 68-73. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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Coupled ocean-atmosphere models have demonstrated a strong correlation between the meridional overturning circulation (MOC) and climate variability. NOAA has a 20+ year history of making observations of some of the North Atlantic MOC components, however the first basin-wide time-series observations are now being made and a long-term monitoring system is being designed. Results from 2005 indicate little change in the Florida Current compared to the long-term mean of the transport obtained from cable data, and in the ocean interior there is little evidence of meaningful differences from the long-term averages of the limited historical data that exists for comparison.
Baringer, M.O., C.S. Meinen, and S.L. Garzoli. Western boundary time series in the Atlantic Ocean, pp. 150-158. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp.(2006).
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No abstract.
Baringer, M.O., S.L. Garzoli, G.J. Goni, W.C. Thacker, and R. Lumpkin. Quarterly reports on the state of the ocean: Meridional heat transport variability in the Atlantic Ocean, pp. 265-267. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Bell, G.D., E. Blake, K.C. Mo, C.W. Landsea, R. Pasch, M. Chelliah, and S.B. Goldenberg. Tropical cyclones: Atlantic basin. In State of the Climate in 2005, K.A. Shein, A.M. Waple, H.J. Diamond, and J.M. Levy (eds.). Bulletin of the American Meteorological Society, 87(6):S33-S37 (2006).
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No abstract.
Bell, G.D., E. Blake, K.C. Mo, C.W. Landsea, R. Pasch, M. Chelliah, S.B. Goldenberg, and H.J. Diamond. The record breaking 2005 Atlantic hurricane season. In State of the Climate in 2005, K.A. Shein, A.M. Waple, H.J. Diamond, and J.M. Levy (eds.). Bulletin of the American Meteorological Society, 87(6):S44-S45 (2006).
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No abstract.
Black, P.G., E.A. D'Asaro, J.R. French, and W.M. Drennan. Synthesis of major results from the Coupled Boundary Layer Air-Sea Transfer Experiment (CBLAST) in hurricanes (2003-2004). Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 8 pp. (CD-ROM) (2006).
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No abstract.
Brandt, S., J.C. Hendee, P. Levin, J. Phinney, D. Scheurer, and F. Schwing. White Paper #5: Ecological forecasting, pp. 52-63. In Ecosystem Science Capabilities Required to Support NOAA's Mission in the Year 2020, S.A. Murawski and G.C. Matlock (eds.). NOAA Technical Memorandum, NMFS-F/SPO-74, 97 pp. (2006).
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No abstract.
Carter, G., P. Restrepo, J. Hameedi, P.B. Ortner, C. Sellinger, J. Stein, and T. Beechie. White Paper #3: Freshwater issues, pp. 29-39. In Ecosystem Science Capabilities Required to Support NOAA's Mission in the Year 2020, S.A. Murawski and G.C. Matlock (eds). NOAA Technical Memorandum, NMFS-F/SPO-74, 97 pp. (2006).
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No abstract.
Casal, T.G.D., L.M. Beal, and R. Lumpkin. A North Atlantic deep-water eddy in the Agulhas Current system. Deep-Sea Research, Part I, 53(10):1718-1728 (2006).
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One hundred and twelve stations of CTDO2 and LADCP were collected in the Agulhas Current system as part of the Agulhas Undercurrent experiment (AUCE) in March 2003. Along an offshore section, at approximately 35.6°S and 27.3°E to the northwest of the tip of the Agulhas Plateau, an unusual feature was revealed between 2200 and 3500 m depth, imbedded in the northward moving NADW layer. An anomalously high salinity of 34.83, 0.03 saltier than the surrounding water, was observed. Maximums in the potential temperature and oxygen were also found, with isotherms dropping by about 250 m over 50 km and a doming of the oxygen layers. From the convex lens structure of the neutral surfaces, we conclude that we sampled an anticyclonic eddy of NADW. Since the LADCP data reveal deep velocities up to 20 cm s-1, yet no anticyclonic circulation, whereas the geostrophic velocity referenced to the bottom shows a weak anticyclonic circulation, we inferred that we sampled the outer edge of the eddy and not its core. From an analysis of the water properties within the eddy and a comparison with known properties in the SE Atlantic Ocean and SW Indian Ocean, we conclude that the eddy was formed in the Agulhas Retroflection region. We speculate that the eddy was the result of an instability in the NADW slope current, which flows from the SE Atlantic around the Agulhas Bank. A deeply penetrating Agulhas Ring spun up the deep waters, pinching off an eddy, which later detached from the slope current and was carried southward. Once offshore, it coupled with the surface Agulhas Return Current, whose meandering path advected the eddy northeastward and ejected it over the Agulhas Plateau.
Chahine, M.T., T.S. Pagano, H.H. Aumann, R. Atlas, C. Barnet, J. Blaisdell, L. Chen, M. Divakarla, E.J. Fetzer, M. Goldberg, C. Gautier, S. Granger, S. Hannon, F.W. Irion, R. Kakar, E. Kalnay, B.H. Lambrigtsen, S.-Y. Lee, J. LeMarshall, W.W. McMillan, L. McMillin, E.T. Olsen, H. Revercomb, P. Rosenkranz,W.L. Smith, D. Staelin, L.L. Strow, J. Susskind, D. Tobin, W. Wolf, and L. Zhou. AIRS: Improving weather forecasting and providing new data on greenhouse gases. Bulletin of the American Meteorological Society, 87(7):911-926 (2006).
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The Atmospheric Infrared Sounder (AIRS) and its two companion microwave sounders, AMSU and HSB, were launched into polar orbit onboard the NASA Aqua Satellite in May 2002. NASA required the sounding system to provide high-quality research data for climate studies and to meet NOAA's requirements for improving operational weather forecasting. The NOAA requirement translated into global retrieval of temperature and humidity profiles with accuracies approaching those of radiosondes. AIRS also provides new measurements of several greenhouse gases, such as CO2, CO, CH4, O3, SO2, and aerosols. The assimilation of AIRS data into operational weather forecasting has already demonstrated significant improvements in global forecast skill. At NOAA/NCEP, the improvement in the forecast skill achieved at 6 days is equivalent to gaining an extension of forecast capability of six hours. This improvement is quite significant when compared to other forecast improvements over the last decade. In addition to NCEP, ECMWF and the Met Office have also reported positive forecast impacts due AIRS. AIRS is a hyperspectral sounder with 2,378 infrared channels between 3.7 and 15.4 µm. NOAA/NESDIS routinely distributes AIRS data within 3 hours to NWP centers around the world. The AIRS design represents a breakthrough in infrared space instrumentation with measurement stability and accuracies far surpassing any current research or operational sounder. The results we describe in this paper are "work in progress," and although significant accomplishments have already been made much more work remains in order to realize the full potential of this suite of instruments.
Chen, S.S., J.A. Knaff, and F.D. Marks. Effects of vertical wind shear and storm motion on tropical cyclone rainfall asymmetries deduced from TRMM. Monthly Weather Review, 134(11):3190-3208 (2006).
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Vertical wind shear and storm motion are two of the most important factors contributing to rainfall asymmetries in tropical cyclones (TCs). Global TC rainfall structure, in terms of azimuthal distribution and asymmetries relative to storm motion, has been previously described using the Tropical Rainfall Measuring Mission Microwave Imager rainfall estimates. The mean TC rainfall distribution and the wavenumber-1 asymmetry vary with storm intensity and geographical location among the six oceanic basins. This study uses a similar approach to investigate the relationship between the structure of TC rainfall and the environmental flow by computing the rainfall asymmetry relative to the vertical wind shear. The environmental vertical wind shear is defined as the difference between the mean wind vectors of the 200- and 850-hPa levels over an outer region extending from the radius of 200-800 km around the storm center. The wavenumber-1 maximum rainfall asymmetry is downshear left (right) in the Northern (Southern) Hemisphere. The rainfall asymmetry decreases (increases) with storm intensity (shear strength). The rainfall asymmetry maximum is predominantly downshear left for shear values > 7.5 m s-1. Large asymmetries are usually observed away from the TC centers. As TC intensity increases, the asymmetry maximum shifts upwind to the left. The analysis is further extended to examine the storm motion and the vertical wind shear and their collective effects on TC rainfall asymmetries. It is found that the vertical wind shear is a dominant factor for the rainfall asymmetry when shear is >5 m s-1. The storm motion-relative rainfall asymmetry in the outer rainband region is comparable to that of shear relative when the shear is <5 m s-1, suggesting that TC translation speed becomes an important factor in the low shear environment. The overall TC rainfall asymmetry depends on the juxtaposition and relative magnitude of the storm motion and environmental shear vectors in all oceanic basins.
Chou, K.-H., C.-C. Wu, P.-H. Lin, S.D. Aberson, M. Peng, and T. Nakazawa. The impact of dropsonde data from DOTSTAR on tropical cyclone track forecasting. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 12 pp. (CD-ROM) (2006).
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No abstract.
Contreras, R.F., D. Esteban Fernandez, P.S. Chang, and P.G. Black. High resolution airborne radar measurements of Hurricane Isabel. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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The Imaging Wind and Rain Airborne Profiler (IWRAP) is a dual-frequency, conically-scanning Doppler radar that measures high resolution profiles of rain's effective reflectivity Ze and Doppler velocity, as well as surface wind vectors via scatterometry. IWRAP was flown aboard a NOAA WP-3D aircraft during the 2002, 2003, 2004, and 2005 hurricane seasons as part of the ONR's Coupled Boundary Layers Air-Sea Transfer (CBLAST) experiment, NASA's Ocean Vector Winds research, and the NOAA/NESDIS Ocean Winds and Rain experiments. We will start with a description of IWRAP and its capabilities. Following this we will introduce a new dataset available to the CBLAST community. We will finish with high resolution radar observations of Hurricane Isabel with an emphasis on the 3-D structure of the storm, especially in the atmospheric boundary layer (ABL).
Corbosiero, K.L., J. Molinari, A.R. Aiyyer, and M.L. Black. The structure and evolution of Hurricane Elena (1985), Part II: Convective asymmetries and evidence for vortex Rossby waves. Monthly Weather Review, 134(11):3073-3091 (2006).
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A portable data recorder attached to the Weather Surveillance Radar-1957 (WSR-57) in Apalachicola, Florida, collected 313 radar scans of the reflectivity structure within 150 km of the center of Hurricane Elena (in 1985) between 1310 and 2130 UTC 1 September. This high temporal and spatial (750 m) resolution dataset was used to examine the evolution of the symmetric and asymmetric precipitation structure in Elena as the storm rapidly strengthened and attained maximum intensity. Fourier decomposition of the reflectivity data into azimuthal wavenumbers revealed that the power in the symmetric (wavenumber 0) component dominated the reflectivity pattern at all times and all radii by at least a factor of 2. The wavenumber 1 asymmetry accounted for less than 20% of the power in the reflectivity field on average and was found to be forced by the environmental vertical wind shear. The small-amplitude wavenumber 2 asymmetry in the core was associated with the appearance and rotation of an elliptical eyewall. This structure was visible for nearly 2 h and was noted to rotate cyclonically at a speed equal to half of the local tangential wind. Outside of the eyewall, individual peaks in the power in wavenumber 2 were associated with repeated instances of cyclonically rotating, outward-propagating inner spiral rainbands. Four separate convective bands were identified with an average azimuthal velocity of 25 m s-1, or ~68% of the local tangential wind speed, and an outward radial velocity of 5.2 m s-1. The azimuthal propagation speeds of the elliptical eyewall and inner spiral rainbands were consistent with vortex Rossby wave theory. The elliptical eyewall and inner spiral rainbands were seen only in the 6-h period prior to peak intensity, when rapid spinup of the vortex had produced an annular vorticity profile, similar to those that have been shown to support barotropic instability. The appearance of an elliptical eyewall was consistent with the breakdown of eyewall vorticity into mesovortices, asymmetric mixing between the eye and eyewall, and a slowing of the intensification rate. The inner spiral rainbands might have arisen from high eyewall vorticity ejected from the core during the mixing process. Alternatively, because the bands were noted to emanate from the vertical shear-forced deep convection in the northern eyewall, they could have formed through the axisymmetrization of the asymmetric diabatically generated eyewall vorticity.
DeMaria, M., J.A. Knaff, and J. Kaplan. On the decay of tropical cyclone winds crossing narrow landmasses. Journal of Applied Meteorology and Climatology, 45(3):491-499 (2006).
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A method is developed to adjust the Kaplan and DeMaria tropical cyclone inland wind decay model for storms that move over narrow landmasses. The basic assumption that the wind speed decay rate after landfall is proportional to the wind speed is modified to include a factor equal to the fraction of the storm circulation that is over land. The storm circulation is defined as a circular area with a fixed radius. Application of the modified model to Atlantic Ocean cases from 1967 to 2003 showed that a circulation radius of 110 km minimizes the bias in the total sample of landfalling cases and reduces the mean absolute error of the predicted maximum winds by about 12%. This radius is about 2 times the radius of maximum wind of a typical Atlantic tropical cyclone. The modified decay model was applied to the Statistical Hurricane Intensity Prediction Scheme (SHIPS), which uses the Kaplan and DeMaria decay model to adjust the intensity for the portion of the predicted track that is over land. The modified decay model reduced the intensity forecast errors by up to 8% relative to the original decay model for cases from 2001 to 2004 in which the storm was within 500 km from land.
DeMaster, D., M. Fogarty, D.M. Mason, G. Matlock, and A. Hollowed. White Paper #2: Management of living marine resources in an ecosystem context, pp. 15-28. In Ecosystem Science Capabilities Required to Support NOAA's Mission in the Year 2020, S.A. Murawski and G.C. Matlock (eds). NOAA Technical Memorandum, NMFS-F/SPO-74, 97 pp. (2006).
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No abstract.
Dunion, J.P., J.D. Hawkins, and C.S. Velden. Hunting for Saharan air with the NOAA G-IV jet. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Eastin, M.D., P.D. Reasor, D.S. Nolan, F.D. Marks, and J.F. Gamache. Evolution of low-wavenumber vorticity during rapid intensification: A dual-Doppler analysis. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 6 pp. (CD-ROM) (2006).
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No abstract.
Enfield, D.B., and L. Cid-Serrano. Projecting the risk of future climate shifts. International Journal of Climatology, 27(6):885-895 (2006).
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Recent research has shown that decadal-to-multidecadal (D2M) climate variability is associated with environmental changes that have important consequences for human activities, such as public health, water availability, frequency of hurricanes, and so forth. As scientists, how do we convert these relationships into decision support products useful to water managers, insurance actuaries, and others, whose principal interest lies in knowing when future climate regime shifts will likely occur that affect long-horizon decisions? Unfortunately, numerical models are far from being able to make deterministic predictions for future D2M climate shifts. However, the recent development of paleoclimate reconstructions of the Atlantic multidecadal oscillation (AMO) (Gray et al., 2004) and Pacific decadal oscillation (PDO) (MacDonald and Case, 2005) give us a viable alternative: to estimate probability distribution functions from long climate index series that allow us to calculate the probability of future D2M regime shifts. In this paper, we show how probabilistic projections can be developed for a specific climate mode--the AMO as represented by the Gray et al. (2004) tree ring reconstruction. The methods are robust and can be applied to any D2M climate mode for which a sufficiently long index series exists, as well as to the growing body of paleo-proxy reconstructions that have become available. The target index need not be a paleo-proxy calibrated against a climate index; it may profitably be calibrated against a specific resource of interest, such as stream flow or lake levels.
Enfield, D.B., S.-K. Lee, and C. Wang. How are large western hemisphere warm pools formed? Progress in Oceanography, 70(2-4):346-365 (2006).
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During the boreal summer, the Western Hemisphere warm pool (WHWP) stretches from the eastern North Pacific to the tropical North Atlantic and is a key feature of the climate of the Americas and Africa. In the summers following nine El Nio events during 1950-2000, there have been five instances of extraordinarily large warm pools averaging about twice the climatological annual size. These large warm pools have induced a strengthened divergent circulation aloft and have been associated with rainfall anomalies throughout the western hemisphere tropics and subtropics and with more frequent hurricanes. However, following four other El Nio events large warm pools did not develop, such that the mere existence of El Nio during the boreal winter does not provide the basis for predicting an anomalously large warm pool the following summer. In this paper, we find consistency with the hypothesis that large warm pools result from an anomalous divergent circulation forced by sea surface temperature (SST) anomalies in the Pacific, the so-called atmospheric bridge. We also find significant explanations for why large warm pools do not always develop. If the El Nio event ends early in the eastern Pacific, the Pacific warm anomaly lacks the persistence needed to force the atmospheric bridge and the Atlantic portion of the warm pool remains normal. If SST anomalies in the eastern Pacific do not last much beyond February of the following year, then the eastern North Pacific portion of the warm pool remains normal. The overall strength of the Pacific El Nio does not appear to be a critical factor. We also find that when conditions favor a developing atmospheric bridge and the winter atmosphere over the North Atlantic conforms to a negative North Atlantic Oscillation (NAO) pattern (as in 1957-58 and 1968-69), the forcing is reinforced and the warm pool is stronger. On the other hand, if a positive NAO pattern develops the warm pool may remain normal even if other circumstances favor the atmospheric bridge, as in 1991-92. Finally, we could find little evidence that interactions internal to the tropical Atlantic are likely to mitigate for or against the formation of the largest warm pools, although they may affect smaller warm pool fluctuations or the warm pool persistence.
Esteban-Fernandez, D., J.R. Carswell, S. Frasier, P.S. Chang, P.G. Black, and F.D. Marks. Dual-polarized C- and Ku-band ocean backscatter response to hurricane-force winds. Journal of Geophysical Research, 111(C8):C08013, doi:10.1029/2005JC003048 (2006).
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Airborne ocean backscatter measurements at C- and Ku-band wavelengths and H and V polarizations at multiple incidence angles obtained in moderate to very high wind speed conditions (25-65 m s-1) during missions through several tropical cyclones are presented. These measurements clearly show that the normalized radar cross sections (NRCS) response stops increasing at hurricane-force winds for both frequency bands and polarizations except for high incidence angles at C-band and H polarization. The results also show the mean NRCS departing from a power law behavior for all the presented frequency bands, polarizations, and incidence angles, suggesting a reduction in the drag coefficient. The overall flattening of the azimuthal response of the NRCS is also very apparent in all cases. A new set of geophysical model functions (GMFs) at C- and Ku-band are developed from these direct ocean backscatter observations for ocean surface winds ranging from 25 to 65 m s-1. The developed GMFs provide a much more accurate characterization of the NRCS versus wind speed and direction, and their implementation in operational retrieval algorithms from satellite-based scatterometer observations would result in better wind fields. The differences between these measurements and other currently available GMFs, such as QuikSCAT, NSCAT2, CMOD4, and CMOD5, are reported. The implementation of these GMFs in retrieval algorithms will result in better wind fields from satellite-based scatterometers measurements.
Etherton, B.J., C.-C. Wu, S.J. Majumdar, and S.D. Aberson. A comparison of targeting techniques for 2005 Atlantic tropical cyclones. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Evan, A.T., J.P. Dunion, J.A. Foley, A.K. Heidinger, and C.S. Velden. New evidence for a relationship between Atlantic tropical cyclone activity and African dust outbreaks. Geophysical Research Letters, 33(19):L19813, doi:10.1029/ 2006GL026408 (2006).
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It is well known that Atlantic tropical cyclone activity varies strongly over time, and that summertime dust transport over the North Atlantic also varies from year to year, but any connection between tropical cyclone activity and atmospheric dust has been limited to a few case studies. Here we report new results that demonstrate a strong relationship between interannual variations in North Atlantic tropical cyclone activity and atmospheric dust cover as measured by satellite, for the years 1982-2005. While we cannot conclusively demonstrate a direct causal relationship, there appears to be robust link between tropical cyclone activity and dust transport over the Tropical Atlantic.
Feely, R.A., T. Takahashi, R.H. Wanninkhof, M.J. McPhaden, C.E. Cosca, S.C. Sutherland, and M.-E. Carr. Decadal variability of the air-sea CO2 fluxes in the equatorial Pacific Ocean. Journal of Geophysical Research, 111(C8):C08S90, doi:10.1029/2005JC003129 (2006).
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In order to determine the interannual and decadal changes in the air-sea carbon fluxes of the equatorial Pacific, we developed seasonal and interannual relationships between the fugacity of CO2 (fCO2) and sea surface temperature (SST) from shipboard data that were applied to high-resolution temperature fields deduced from satellite data to obtain high-resolution large-scale estimates of the regional fluxes. The data were gathered on board research ships from November 1981 through June 2004 between 95W and 165E. The distribution of fCO2sw during five El Nio periods and four La Nia periods were documented. Observations made during the warm boreal winter-spring season and during the cooler boreal summer-fall season of each year enabled us to examine the interannual and seasonal variability of the fCO2sw-SST relationships. A linear fit through all of the data sets yields an inverse correlation between SST and fCO2sw, with both interannual and seasonal differences in slope. On average, the surface water fCO2 in the equatorial region has been increasing at a rate similar to the atmospheric CO2 increase. In addition, there appears to be a slight increase (~27%) in the outgassing flux of CO2 after the 1997-1998 Pacific Decadal Oscillation (PDO) regime shift. Most of this flux increase is due to increase in wind speeds after the spring of 1998, although increases in fCO2sw after 1998 are also important. These increases are coincident with the recent rebound of the shallow water meridional overturning circulation in the tropical and subtropical Pacific after the regime shift.
Feely, R.A., R. Wanninkhof, C.L. Sabine, G.C. Johnson, M.O. Baringer, J. Bullister, C.W. Mordy, and J.-Z. Zhang. Global repeat hydrographic/CO2/tracer surveys in support of CLIVAR and global carbon cycle objectives: Carbon inventories and fluxes, pp. 196-205. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
French, J.R., W.M. Drennan, J.A. Zhang, and P.G. Black. Direct airborne measurements of momentum flux in hurricanes. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 6 pp. (CD-ROM) (2006).
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No abstract.
Garzoli, S.L., R.L. Molinari, and R. Lumpkin. Surface drifter program, pp. 124-127. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Graber, H.C., V.J. Cardone, R.E. Jensen, D.N. Slinn, S.C. Hagen, A.T. Cox, M.D. Powell, and C. Grassl. Coastal forecasts and storm surge predictions for tropical cyclones: A timely partnership program. Oceanography, 19(1):130-141 (2006).
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As more people and associated infrastructure concentrate along coastal areas, the United States is becoming more vulnerable to the impact of tropical cyclones. It is not surprising, especially after the past two hurricane seasons, that hurricanes are the costliest natural disasters because of the migration of the population towards the coast and the resulting changes in the national wealth density or revenue. A better understanding of both hurricane frequencies and intensities as they vary from year to year and their relation to changes in damages is of great interest to scientists, public and private-decision makers, and the general public. The estimation of tropical-cyclone-generated waves and surge in coastal waters and the nearshore zone is of critical importance to the timely evacuation of coastal residents, and the assessment of damage to coastal property in the event that a storm makes landfall. The model predictions of waves and storm surge in coastal waters are functionally related and both depend on the reliability of the atmospheric forcing. Hurricane Georges (1998), Ivan (2004), and Katrina and Wilma (2005) are excellent examples of intense tropical cyclones with numerous landfalls and unexpected changes in intensity and movement. Although there are no perfect predictions of the time and location of landfall and the intensity and size of the storm, we are able to forecast wind strength, storm-wave height, and surge levels that are expected along the official track from the National Hurricane Center (NHC) as well as from an ensemble of about a dozen track forecasts that would bracket the results from the least to worst conditions. The variability of these parameters, if known for different forecast tracks, could positively impact the advisories. To be effective and useful, a critical component of any forecast system is its timeliness.
Graves, L.P., J.C. McWilliams, and M.T. Montgomery. Vortex evolution due to straining: A mechanism for dominance of strong, interior anticyclones. Geophysical and Astrophysical Fluid Dynamics, 100(3):151-183 (2006).
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In this article we address two questions: Why do freely evolving vortices weaken on average, even when the viscosity is very small? Why, in the fluid's interior, away from vertical boundaries and under the influence of Earth's rotation and stable density stratification, do anticyclonic vortices become dominant over cyclonic ones when the Rossby number and deformation radius are finite? The context for answering these questions is a rotating, conservative, Shallow-water model with Asymmetric and Gradient-wind Balance approximations. The controlling mechanisms are vortex weakening under straining deformation (with a weakening that is substantially greater for strong cyclones than strong anticyclones) followed by a partially compensating vortex strengthening during a relaxation phase dominated by Vortex Rossby Waves (VRWs) and their eddy-mean interaction with the vortex. The outcome is a net, strain-induced vortex weakening that is greater for cyclones than anticyclones when the deformation radius is not large compared to the vortex radius and the Rossby number is not small. Furthermore, when the exterior strain flow is sustained, the vortex changes also are sustained: for small Rossby number (i.e., the quasigeostrophic limit, QG), vortices continue to weaken at a relatively modest rate, but for larger Rossby number, cyclones weaken strongly and anticyclones actually strengthen systematically when the deformation radius is comparable to the vortex radius. The sustained vortex changes are associated with strain-induced VRWs on the periphery of the mean vortex. It therefore seems likely that, in a complex flow with many vortices, anticyclonic dominance develops over a sequence of transient mutual straining events due to the greater robustness of anticyclones (and occasionally their net strengthening).
Halliwell, G.R., L.K. Shay, E.W. Uhlhorn, S.D. Jacob, and O.M. Smedstad. Improving ocean state initialization in coupled tropical cyclone forecast models. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Hausman, S.A., K.V. Ooyama, and W.H. Schubert. Potential vorticity structure of simulated hurricanes. Journal of the Atmospheric Sciences, 63(1):87-108 (2006).
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To better understand the processes involved in tropical cyclone development, the authors simulate an axisymmetric tropical-cyclone-like vortex using a two-dimensional model based on nonhydrostatic dynamics, equilibrium thermodynamics, and bulk microphysics. Sensitivity experiments reveal that the simulated cyclones are sensitive to the effects of ice, primarily through the reduced fall velocity of precipitation above the freezing level rather than through the latent heat of fusion, and to the effects of vertical entropy transport by precipitation.
Hendee, J.C., E.R. Stabenau, L. Florit, D. Manzello, and C. Jeffris. Infrastructure and capabilities of a near real-time meteorological and oceanographic in situ instrumented array and its role in marine environmental decision support. In Remote Sensing of Aquatic Coastal Ecosystem Processes, L.L. Richardson and E.F. LeDrew (eds.). Springer Verlag, Volume 9, 135-156 (2006).
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No abstract.
Hendricks, E.A., and M.T. Montgomery. Rapid scan views of convectively generated mesovortices in sheared Tropical Cyclone Gustav. Weather and Forecasting, 21(6):1041-1050 (2006).
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On 9-10 September 2002, multiple mesovortices were captured in great detail by rapid scan visible satellite imagery in subtropical, then later, Tropical Storm Gustav. These mesovortices were observed as low-level cloud swirls while the low-level structure of the storm was exposed due to vertical shearing. They are shown to form most plausibly via vortex tube stretching associated with deep convection; they become decoupled from the convective towers by vertical shear; they are advected with the low-level circulation; finally they initiate new hot towers on their boundaries. Partial evidence of an axisymmetrizing mesovortex and its hypothesized role in the parent vortex spinup is presented. Observations from the mesoscale and synoptic scale are synthesized to provide a multiscale perspective of the intensification of Gustav that occurred on 10 September. The most important large-scale factors were the concurrent relaxation of the 850-200 hPa-deep layer vertical wind shear from 10-15 to 5-10 m s-1 and movement over pockets of very warm sea surface temperatures (approximately 29.5°-30.5°C). The mesoscale observations are not sufficient alone to determine the precise role of the deep convection and mesovortices in the intensification. However, qualitative comparisons are made between the mesoscale processes observed in Gustav and recent full-physics and idealized numerical simulations to obtain additional insight.
Hood, R.E., E. Zipser, G.M. Heymsfield, R. Kakar, J. Halverson, R.F. Rogers, and M.L. Black. Overview of the field phase of the NASA Tropical Cloud Systems and Processes (TCSP) Experiment. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 3 pp. (CD-ROM) (2006).
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No abstract.
Hood, R.E., R.J. Blakeslee, M. Goodman, D.J. Cecil, D.M. Mach, F.J. LaFontaine, G.M. Heymsfield, F.D. Marks, and E.J. Zipser. Classification of tropical oceanic precipitation using high altitude aircraft microwave and electric field measurements. Journal of the Atmospheric Sciences, 63(1):218-233 (2006).
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During the 1998 and 2001 hurricane seasons of the western Atlantic Ocean and Gulf of Mexico, the Advanced Microwave Precipitation Radiometer (AMPR), the ER-2 Doppler (EDOP) radar, and the Lightning Instrument Package (LIP) were flown aboard the NASA ER-2 high-altitude aircraft as part of the Third Convection and Moisture Experiment (CAMEX-3) and the Fourth Convection and Moisture Experiment (CAMEX-4). Several hurricanes, tropical storms, and other precipitation systems were sampled during these experiments. An oceanic rainfall screening technique has been developed using AMPR passive microwave observations of these systems collected at frequencies of 10.7, 19.35, 37.1, and 85.5 GHz. This technique combines the information content of the four AMPR frequencies regarding the gross vertical structure of hydrometeors into an intuitive and easily executable precipitation mapping format. The results have been verified using vertical profiles of EDOP reflectivity and lower-altitude horizontal reflectivity scans collected by the NOAA WP-3D Orion radar. Matching the rainfall classification results with coincident electric field information collected by the LIP readily identifies convective rain regions within the precipitation fields. This technique shows promise as a real-time research and analysis tool for monitoring vertical updraft strength and convective intensity from airborne platforms such as remotely operated or uninhabited aerial vehicles. The technique is analyzed and discussed for a wide variety of precipitation types using the 26 August 1998 observations of Hurricane Bonnie near landfall.
Houze, R.A., S.S. Chen, W.-C. Lee, R.F. Rogers, J.A. Moore, G.J. Stossmeister, M.M. Bell, J.L. Cetrone, W. Zhao, and S.R. Brodzik. The Hurricane Rainband and Intensity Experiment: Observations and modeling of Hurricanes Katrina, Ophelia, and Rita (2005). Bulletin of the American Meteorological Society, 87(11):1503-1521 (2006).
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The Hurricane Rainband and Intensity Change Experiment (RAINEX) used three P3 aircraft aided by high-resolution numerical modeling and satellite communications to investigate the 2005 Hurricanes Katrina, Ophelia, and Rita. The aim was to increase the understanding of tropical cyclone intensity change by interactions between a tropical cyclone's inner core and rainbands. All three aircraft had dual-Doppler radars, with the Electra Doppler Radar (ELDORA) on board the Naval Research Laboratory's P3 aircraft, providing particularly detailed Doppler radar data. Numerical model forecasts helped plan the aircraft missions, and innovative communications and data transfer in real time allowed the flights to be coordinated from a ground-based operations center. The P3 aircraft released approximately 600 dropsondes in locations targeted for optimal coordination with the Doppler radar data, as guided by the operations center. The storms were observed in all stages of development, from tropical depression to category 5 hurricane. The data from RAINEX are readily available through an online Field Catalog and RAINEX Data Archive. The RAINEX data-set is illustrated in this article by a preliminary analysis of Hurricane Rita, which was documented by multiaircraft flights on five days (1) while a tropical storm, (2) while rapidly intensifying to a category 5 hurricane, (3) during an eye-wall replacement, (4) when the hurricane became asymmetric upon encountering environmental shear, and (5) just prior to landfall.
Huang, X.-L., and J.-Z. Zhang. Surfactant-sensitized malachite green method for trace determination of orthophosphate in aqueous solution. Analytica Chimica Acta, 580(1):55-67 (2006).
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A surfactant-sensitized spectrophotometric method for determination of trace orthophosphate has been developed using anion surfactant (Ultrawet 60 L) with molybdate and malachite green in low acidic medium (pHT 1.0). The method detection limit (3x standard deviation of blank, n = 10) was 8 nM, and the calibration curve was linear over a range of 10-400 nM (r2 = 0.997). The molar absorptivity was 1.26 x 105 L mol-1 cm-1 at 600 nm with the background correction at 530 nm. The precision of method was 3.4% at 50 nM and 2.4% at 100 nM orthophosphate (n = 10). The hydrolysis of eight organic phosphorus and polyphosphate compounds was less than 2% of the total phosphorus present (5-10 µM). This method showed less arsenate interference than previous methods, with only 3% even in the presence of orthophosphate in the samples. No interference of silicate up to 40 µM was observed. Background anions (in an order of SO42- > NO3- > Cl-) have greater effects than cations (Ca2+ > Mg2+ > Na+) on the reagent blank and the molar absorptivity of the color product.
Jaimes, B., L.K. Shay, E.W. Uhlhorn, T.M. Cook, J. Brewster, G.R. Halliwell, and P.G. Black. Influence of Loop Current ocean heat content on Hurricanes Katrina, Rita, and Wilma. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Jiang, H., P.G. Black, E.J. Zipser, F.D. Marks, and E.W. Uhlhorn. Validation of rain-rate estimation in hurricanes from the Stepped Frequency Microwave Radiometer: Algorithm correction and error analysis. Journal of the Atmospheric Sciences, 63(1):252-267 (2006).
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Simultaneous observations by the lower fuselage (LF) radar, the tail (TA) radar, and the Stepped Frequency Microwave Radiometer (SFMR) on board the NOAA WP-3D aircraft are used to validate the rainfall rate estimates from microwave emission measurements of SFMR in tropical cyclones. Data collected in Hurricane Bonnie (1998) and Hurricane Humberto (2001) with a total of 820 paired samples are used in the comparisons. The SFMR 10-s path-integrated rain rates are found to have an overestimate in light rain and an underestimate in heavy rain relative to radar rainfall estimates. Examination of the existing SFMR algorithm shows that the coefficient should be changed in the attenuation-rain-rate relationship used in the inversion algorithm. After this correction, a linear regression result with a correlation coefficient of 0.8 and a slope close to 1 is obtained. But an overall high bias of 5 mm h-1 of the SFMR rainfall estimate relative to radar is also found. The error analysis shows that the bias is nearly independent of rain type, a result confirming Jorgensen and Willis' conclusion that the drop size distributions between convective and stratiform rain in hurricanes are similar. It is also shown that the bias is a weak function of wind speed, as well as a weak inverse function of radial distance to the hurricane center. Temperature dependence has been ruled out as the main explanation. After doing sensitivity tests, the authors conclude that the bias results from a combination of two factors: an underestimate of the freezing-level height and a downward increase of radar reflectivity in the high wind regions. If the true downward increase is 1-2 dBZ km-1, a 0.5-km underestimate of the freezing-level height could account for up to a 3-5 mm h-1 bias.
Johnson, G.C., S. Levitus, J.M. Lyman, C. Schmid, and J.K. Willis. Ocean heat content variability, pp. 74-84. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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Upper ocean heat content is important in understanding and predicting climate phenomena such hurricanes, El Niño, and global warming. This quantity is estimated globally from in situ and satellite data for 2005. The results are compared against estimates from 2004, the past decade, and the past 50 years. The widespread deployment of Argo Project floats starting in 2003 greatly reduces uncertainties in global yearly averages of upper ocean heat content. Interannual variability of the seasonal cycle in mixed layer thickness and temperature (thus mixed layer heat content) is discussed in the tropical Atlantic.
Kakar, R., F.D. Marks, G. McFarquhar, and R. Hood. Preface. Journal of the Atmospheric Sciences, 63(1):3-4 (2006).
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No abstract.
Kaplan, J., and M. DeMaria. Estimating the likelihood of rapid intensification in the Atlantic and east Pacific basins using SHIPS model data. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Katsaros, K.B., R.T. Pinker, A. Bentamy, J.A. Carton, W.M. Drennan, and A.M. Mestas-Nunez. Net air-sea flux estimates for the tropical and subtropical Atlantic Ocean based on satellite data. Proceedings, 3rd MSG RAO Workshop, Helsinki, Finland, June 12-16, 2006. European Space Agency, ESA SP-619, 77-82 (2006).
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The objective of our work is to estimate the net heat exchange across the air-sea interface in the tropical and subtropical Atlantic Ocean using mainly satellite data. The net flux and the various terms will be used to study the processes in the upper ocean related to changes in sea surface temperature (SST). This variable influences atmospheric circulations and is indicative of upper ocean circulations in this area. We employ data from METEOSAT-7 and 8 and from the Special Sensor Microwave/Imager (SSM/I) for the shortwave and long-wave radiative fluxes and for estimates of SST. For turbulent flux calculations, we use the bulk aerodynamic method with satellite estimates for wind speed and atmospheric humidity and temperature. We expect our work to shed light on rainfall regimes in Africa and South America and on the changes and slope of the tropical thermocline structure in the Atlantic Ocean.
Kourafalou, V.H., R.S. Balotro, G. Peng, T.N. Lee, E. Johns, P.B. Ortner, A. Wallcraft, and T. Townsend. Seasonal variability of circulation and salinity around Florida Bay and the Florida Keys: SoFLA-HYCOM results and comparison to in-situ data. University of Miami Technical Report, RSMAS 2006-04, 102 pp. (2006).
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No abstract.
Lavin, M.F., P.C. Fiedler, J.A. Amador, L.T. Ballance, J. Farber-Lorda, and A.M. Mestas-Nunez. A review of eastern tropical Pacific oceanography: Summary. Progress in Oceanography, 69(2-4):391-398 (2006).
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The collection of articles in this volume reviewing eastern tropical Pacific oceanography is briefly summarized, and updated references are given. The region is an unusual biological environment as a consequence of physical characteristics and patterns of forcing, including a strong and shallow thermocline, the ITCZ and coastal wind jets, equatorial upwelling, the Costa Rica Dome, eastern boundary and equatorial current systems, low iron input, inadequate ventilation of subthermocline waters, and dominance of ENSO-scale temporal variability. Remaining unanswered questions are presented.
Lee, K., L.T. Tong, F.J. Millero, C.L. Sabine, A.G. Dickson, C. Goyet, G.-H. Park, R. Wanninkhof, R.A. Feely, and R.M. Key. Global relationships of total alkalinity with salinity and temperature in surface waters of the world's oceans. Geophysical Research Letters, 33(19):L19605, doi:10.1029/2006GL027207 (2006).
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A simple function of sea surface salinity (SSS) and temperature (SST) in the form AT = a + b (SSS - 35) + c (SSS - 35)2 + d (SST - 20) + e (SST - 20)2 fits surface total alkalinity (AT) data for each of five oceanographic regimes within an area-weighted uncertainty of ±8.1 µmol kg-1 (1 sigma). Globally coherent surface AT data (n = 5,692) used to derive regional correlations of AT with SSS and SST were collected during the global carbon survey in the 1990s. Such region-specific AT algorithms presented herein enable the estimation of the global distribution of surface AT when observations of SSS and SST are available.
Lee, T.N., E. Johns, N. Melo, R.H. Smith, P.B. Ortner, and N. Smith. On Florida Bay hypersalinity and water exchange. Bulletin of Marine Science, 79(2):301-327 (2006).
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Florida Bay is made up of a collection of shallow basins separated by mud banks and mangrove islands situated between the Florida mainland and the Florida Keys. The bay is located downstream of the Everglades discharge that has been altered over the past century due to South Florida land use practices, leading to reduced water delivery to Florida Bay and elevated salinities. The reduced freshwater flow has had the strongest impacts in the north-central region of the bay, in the vicinity of Whipray basin (WB), where extreme hypersalinity can develop along with degradation of water quality and seagrass die-off. We use direct measurement of water exchange between Whipray and surrounding regions for dry and wet seasons of 2001 together with detailed salinity surveys, sea level measurements, and freshwater flux estimates to evaluate water and salt balances, and to estimate basin water renewal rates and residence times. Water renewal of WB is strongly regulated by local wind forcing. Winds toward the east from the passage of cold fronts during the winter/spring dry season resulted in a mean eastward flow through Whipray of 11 m3 s-1, with inflows over the wide western mud banks, and outflows through the eastern and southern channels. Conversely, winds toward the southwest and west typical of the summer/fall wet season produced a mean throughflow of 3 m3 s-1, with inflows through the eastern channels and outflows over the western banks. The time required for complete renewal of WB waters is estimated at 6-12 mo. Water balances are used to estimate a weak seasonal average groundwater input to Whipray of 1.7 m3 s-1 during the dry season and a negative groundwater flow or downwelling of -4.7 m3 s-1 for the wet season. Hypersalinity development was found to be caused by the combination of reduced freshwater inputs during the dry season combined with weak basin water renewal rates. Hypersalinity development could be greatly reduced by diversion of freshwater to WB via McCormick Creek during dry seasons.
Lentini, C., G.J. Goni, and D.B. Olson. Investigation of Brazil Current rings in the confluence region. Journal of Geophysical Research, 111(C6):C06013, doi:10.1029/2005JC002988 (2006).
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TOPEX/Poseidon-derived along track SHA, climatological temperature, and salinity fields were used within a two-layer scheme to estimate the depth of the 8°C isotherm in the southwestern Atlantic. These fields were used to monitor the formation and characteristics of the Brazil Current warm-core anticyclonic rings shed by the first meander trough after poleward excursions of the Brazil Current (BC). Results reveal that 40 warm-core rings were shed by the BC between January 1993 and October 1998. The observed lifetime ranges between 1 and 4 months, with a mean value of approximately 2 months. At any given time, two to three anticyclonic rings coexisted in the Brazil-Malvinas confluence region. Most of the rings drifted southward without coalescing with their parent current. Only four rings were identified as being reabsorbed by the BC front after they were shed. No evidence of propagation or absorption of these anticyclones into the eastern limb of the subtropical gyre was observed. These rings have a mean horizontal length scale of 55 km, mean upper-layer thickness of 260 m, and mean translation speed of 10 km d-1. Volume anomaly and available potential energy computations showed a mean value of 3.6 x 1012 m3 and 2.5 x 1015 J, respectively. The upper layer transport of the BC was also computed, and a relationship between variations in the southward transport and ring shedding activity was examined. Computation of the heat flux anomaly of the BC rings is estimated to be approximately 0.045 PW per annum. Compilation of these results indicates that warm-core rings created by meandering boundary current extensions in different regions are generally similar.
Li, Y.-H., L. Menviel, and T.-H. Peng. Nitrate deficits by nitrification and denitrification processes in the Indian Ocean. Deep-Sea Research, Part I, 53(1):94-110 (2006).
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The three-end-member mixing model of Li and Peng [Latitudinal change of remineralization ratios in the oceans and its implication for nutrient cycles, Global Biogeochemical Cycles, 16:1130-1145] was applied to the World Ocean Circulation Experiment (WOCE) data from Indian Ocean to obtain additional estimates on the remineralization ratios (P\N\Corg\-O2) of organic matter in the oxygenated regions. The results show systematic changes of the remineralization ratios with latitude and depth in the Indian Ocean. The average remineralization ratios for Indian warm water masses (potential temperature theta > ~10°C) are P\N\Corg\-O2 = 1\(15.6±0.7)\(110±9)\(159±8). These are comparable to the traditional Redfield ratios (P\N\Corg\-O2 = 1\16\106\138), and are in good agreement with Anderson's [On the hydrogen and oxygen content of marine phytoplankton, Deep-Sea Research, Part I, 42:1675-1680] values of P\N\Corg\-O2 = 1\16\106\150 within the given uncertainties. Separation of nitrate deficits resulting from aerobic partial nitrification (dN) and anaerobic denitrification (dN") processes using empirical equations is shown to be useful and consistent with other observations. The dN maximum coincides with the phosphate and nitrate maximums, lies within the oxycline below the oxygen minimum zone, and is in contact with the continental slope sediments. The dN maximum lies within the oxygen minimum zone with O2 < ~2 µmol/kg, is in contact with shelf or upper slope sediments, and is always associated with a secondary nitrite maximum in the water column. The spatial extent of dN is much larger than that of dN". The low N/P remineralization ratio (<15) for deep waters (theta < ~10°C) and the dN maximum in the lower oxycline can be best explained by the partial conversion of organic nitrogen into N2, N2O, and NO by yet unidentified bacteria during oxidation of organic matter. These bacteria may have evolved in a low oxygen and high nitrate environment to utilize both oxygen and nitrate as terminal electron acceptors during oxidation of organic matter (i.e., the partial nitrification hypothesis). Direct proof is urgently needed.
Lindberg, W.J., T.K. Frazer, K.M. Portier, F. Vose, J. Loftin, D.J. Murie, D.M. MasonN, B. Nagy, and M.K. Hart. Density-dependent habitat selection and performance by a large mobile reef fish. Ecological Applications, 16(2):731-746 (2006).
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Many exploited reef fish are vulnerable to over-fishing because they concentrate over hard-bottom patchy habitats. How mobile reef fish use patchy habitat, and the potential consequences on demographic parameters, must be known for spatially explicit population dynamics modeling, for discriminating Essential Fish Habitat (EFH) and for effectively planning conservation measures (e.g., marine protected areas, stock enhancement and artificial reefs). Gag, Mycteroperca microlepis, is an ecologically and economically important warm-temperate grouper in the southeastern USA, with behavioral and life history traits conducive to large-scale field experiments. The Suwannee Regional Reef System (SRRS) was built of standard habitat units (SHUs) in 1991-1993 to manipulate and control habitat patchiness and intrinsic habitat quality, and thereby test predictions from habitat selection theory. Colonization of the SRRS by gag over the first 6 years showed significant interactions of SHU size, spacing and reef age; with trajectories modeled using a quadratic function for closely spaced SHUs (25 m) and a linear model for widely spaced SHUs (225 m), with larger SHUs (16 standardized cubes) accumulating significantly more gag faster than smaller 4-cube SHUs (mean = 72.5 gag/16-cube SHU at 225-m spacing by year 6, compared to 24.2 gag/4-cube SHU for same spacing and reef age). Residency times (mean = 9.8 mos.), indicative of choice and measured by ultrasonic telemetry (1995-1998), showed significant interaction of SHU size and spacing consistent with colonization trajectories. Average relative weight (Wr) and incremental growth were greater on smaller than larger SHUs (mean Wr = 104.2 versus 97.7; incremental growth differed by 15%), contrary to patterns of abundance and residency. Experimental manipulation of shelter on a subset of SRRS sites (2000-2001) confirmed our hypothesis that shelter limits local densities of gag, which, in turn, regulates their growth and condition. Density-dependent habitat selection (DDHS) for shelter and individual growth dynamics were therefore interdependent ecological processes that help to explain how patchy reef habitat sustains gag production. Moreover, gag selected shelter at the expense of maximizing their growth. Thus, mobile reef fishes could experience density-dependent effects on growth, survival, and/or reproduction (i.e., demographic parameters) despite reduced stock sizes as a consequence of fishing.
Liu, Q., M. Surgi, S. Lord, W.-S. Wu, D. Parrish, S. Gopalakrishnan, J. Waldrop, and J.F. Gamache. Hurricane initialization in HWRF model. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 2 pp. (CD-ROM) (2006).
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No abstract.
Lonfat, M., R.F. Rogers, F.D. Marks, T. Marchok, and A. Boissonnade. The effect of shear and topography on rainfall forecasting with R-CLIPER. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 2 pp. (CD-ROM) (2006).
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No abstract.
Lueger, H., R.H. Wanninkhof, D.W.R. Wallace, and A. Kortzinger. CO2 fluxes in the subtropical and subarctic North Atlantic based on measurements from a volunteer observing ship. Journal of Geophysical Research, 111(6):C06024, doi:10.1029/2005JC003101 (2006).
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Surface seawater pCO2 and related parameters were measured at high frequency onboard the volunteer observing ship M/V Falstaff in the North Atlantic Ocean between 36° and 52°N. Over 90,000 data points were used to produce monthly CO2 fluxes for 2002/2003. The air-sea CO2 fluxes calculated by two different averaging schemes were compared. The first approach used gas transfer velocity determined from wind speed retrieved at the location of the ship and called colocated winds, while for the second approach a monthly averaged gas transfer velocity was calculated from the wind for each grid pixel including the variability in wind. The colocated wind speeds determined during the time of passage do not capture the monthly wind speed variability of the grid resulting in fluxes that were 47% lower than fluxes using the monthly averaged wind products. The Falstaff CO2 fluxes were in good agreement with a climatology using averaged winds. Over the entire region they differed by 2-5%, depending on the time-dependent correction scheme to account for the atmospheric in increase in pCO2. However, locally the flux differences between the ship measurements and the climatology were greater, especially in regions north of 45°N, like the eastern sector. A comparison of two wind speed products showed that the annual CO2 sink is 4% less when using 6 hourly NCEP/NCAR wind speeds compared to the QuikSCAT wind speed data.
Lumpkin, R., and G.J. Goni. Evaluating the ocean observing system: Performance measurement for heat storage, pp. 263-264. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Lumpkin, R., and G.J. Goni. Global oceans: Surface currents. In State of the Climate in 2005, K.A. Shein, A.M. Waple, H.J. Diamond, and J.M. Levy (eds.). Bulletin of the American Meteorological Society, 87(6):S25-S26 (2006).
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No abstract.
Lumpkin, R., and G.J. Goni. Surface currents, pp. 61-67. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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Surface currents are measured in-situ by an array of 14 primarily tropical moored buoys and a global array of approximately 1250 drifters. Current variations can also be estimated from satellite altimetry. In 2005, westward current anomalies of nearly 20 cm/s were observed in the equatorial Pacific between 120°W and the dateline, with strong monthly anomalies in the western Pacific associated with equatorial wave passage. In the Atlantic Ocean, the Florida Current and Gulf Stream were close to their long-term climatological strengths.
Majumdar, S.J., S.D. Aberson, C.H. Bishop, R. Buizza, M.S. Peng, and C.A. Reynolds. A comparison of adaptive observing guidance for Atlantic tropical cyclones. Monthly Weather Review, 134(9):2354-2372 (2006).
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Airborne adaptive observations have been collected for more than two decades in the neighborhood of tropical cyclones, to attempt to improve short-range forecasts of cyclone track. However, only simple subjective strategies for adaptive observations have been used, and the utility of objective strategies to improve tropical cyclone forecasts remains unexplored. Two objective techniques that have been used extensively for midlatitude adaptive observing programs, and the current strategy based on the ensemble deep-layer mean (DLM) wind variance, are compared quantitatively using two metrics. The ensemble transform Kalman filter (ETKF) uses ensembles from NCEP and the ECMWF. Total-energy singular vectors (TESVs) are computed by the ECMWF and the Naval Research Laboratory, using their respective global models. Comparisons of 78 guidance products for 2-day forecasts during the 2004 Atlantic hurricane season are made, on both continental and localized scales relevant to synoptic surveillance missions. The ECMWF and NRL TESV guidance identifies similar large-scale target regions in 90% of the cases, but are less similar to each other in the local tropical cyclone environment (56% of the cases) with a more stringent criterion for similarity. For major hurricanes, all techniques usually indicate targets close to the storm center. For weaker tropical cyclones, the TESV guidance selects similar targets to those from the ETKF (DLM wind variance) in only 30% (20%) of the cases. ETKF guidance using the ECMWF ensemble is more like that provided by the NCEP ensemble (and DLM wind variance) for major hurricanes than for weaker tropical cyclones. Minor differences in these results occur when a different metric based on the ranking of fixed storm-relative regions is used.
Manzello, D., J.C. Hendee, D. Ward, and Z. Hillis-Starr. An evaluation of environmental parameters coincident with the partial bleaching event in St. Croix, U.S. Virgin Islands (2003). Proceedings, 10th International Coral Reef Symposium, Okinawa, Japan, June 28-July 2, 2004. International Society for Coral Reef Studies, 709-717 (2006).
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A partial bleaching event was reported in September and October 2003 in St. Croix, yet no bleaching alert was produced by the expert system software dubbed the Coral Reef Early Warning System (CREWS). This presents an opportunity for refining the modeling and predictive success of the CREWS software specifically for the St. Croix site by examination of the pertinent environmental parameters (sea temperature, wind speeds, irradiance) associated with the 2003 bleaching event. Elevated sea temperatures were likely the primary catalyst of bleaching and were coincident with dampened wind speeds. The least attenuation (greatest penetration) of UVB occurred during October when bleaching was most severe, but was variable. A nearly parallel trend with wind speed and UVB penetration was found and supports the hypothesis that the attenuation of UVB into the water column is controlled by CDOM concentrations, which are elevated due to wind-driven mixing.
Marchok, T., R.F. Rogers, and R. Tuleya. New methods for evaluating rainfall forecasts from operational models for landfalling tropical cyclones. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 5 pp. (CD-ROM) (2006).
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No abstract.
McArthur,C.J., S.J. Stamates, and J.R. Proni. Review of the real-time current monitoring requirement for the Miami Ocean Dredged Material Disposal Site. NOAA Technical Memorandum, OAR AOML-95, 13 pp. (2006).
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The Environmental Protection Agency manages an Ocean Dredged Material Disposal Site (ODMDS) offshore Miami, Florida. To protect coral reefs west of the ODMDS, use of the disposal site is restricted during periods of reef-directed currents. In 1995, the National Oceanic and Atmospheric Administration developed a real-time current monitoring program for the Corps of Engineers for disposal of material from the Phase I Deepening Project at the Port of Miami. The program consists of a system for measuring and reporting currents at the ODMDS in real-time and a set of evaluation criteria for determining when disposal can occur. The initial system deployments resulted in three years of data from 1995 through 2000. This data is reviewed and analyzed to assess the impacts on dredging operations and the potential or disposal plume interaction with the nearby coral reefs.
McFarquhar, G.M., H. Zhang, G.M. Heymsfield, J.B. Halverson, R.E. Hood, J. Dudhia, and F.D. Marks. Factors affecting the evolution of Hurricane Erin (2001) and the distributions of hydrometeors: Role of microphysical processes. Journal of the Atmospheric Sciences, 63(1):127-150 (2006).
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Fine-resolution simulations of Hurricane Erin are conducted using the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5) to investigate roles of thermodynamic, boundary layer, and microphysical processes on Erin's structure and evolution. Choice of boundary layer scheme has the biggest impact on simulations, with the minimum surface pressure (Pmin) averaged over the last 18 h (when Erin is relatively mature) varying by over 20 hPa. Over the same period, coefficients used to describe graupel fall speeds (Vg) affect Pmin by up to 7 hPa, almost equivalent to the maximum 9-hPa difference between microphysical parameterization schemes; faster Vg and schemes with more hydrometeor categories generally give lower Pmin. Compared to radar reflectivity factor (Z) observed by the NOAA P-3 lower fuselage radar and the NASA ER-2 Doppler radar (EDOP) in Erin, all simulations overpredict the normalized frequency of occurrence of Z larger than 40 dBZ and underpredict that between 20 and 40 dBZ near the surface; simulations overpredict Z larger than 25 to 30 dBZ and underpredict that between 15 and 25 or 30 dBZ near the melting layer, the upper limit depending on altitude. Brightness temperatures (Tb) computed from modeled fields at 37.1- and 85.5-GHz channels that respond to scattering by graupel-size ice show enhanced scattering, mainly due to graupel, compared to observations. Simulated graupel mixing ratios are about 10 times larger than values observed in other hurricanes. For the control run at 6.5 km averaged over the last 18 simulated hours, Doppler velocities computed from modeled fields (Vdop) greater than 5 m s-1 make up 12% of Erin's simulated area for the base simulation but less than 2% of the observed area. In the eyewall, 5% of model updrafts above 9 km are stronger than 10 m s-1, whereas statistics from other hurricanes show that 5% of updrafts are stronger than only 5 m s-1. Variations in distributions of Z, vertical motion, and graupel mixing ratios between schemes are not sufficient to explain systematic offsets between observations and models. A new iterative condensation scheme, used with the Reisner mixed-phase microphysics scheme, limits unphysical increases of equivalent potential temperature associated with many condensation schemes and reduces the frequency of Z larger than 50 dBZ, but has minimal effect on Z below 50 dBZ, which represent 95% of the modeled hurricane rain area. However, the new scheme changes the Erin simulations in that 95% of the updrafts are weaker than 5 m s-1 and Pmin is up to 12 hPa higher over the last 18 simulated hours.
McGillis, W.R., and R.H. Wanninkhof. Aqueous CO2 gradients for air-sea flux estimates. Marine Chemistry, 98(1):100-108 (2006).
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The concentration of gaseous carbon dioxide (CO2) in surface seawater is a fundamental control on the CO2 flux between the ocean and atmosphere. However, the concentration gradient in the aqueous mass boundary layer determines the magnitude and direction of the flux. The gradients of CO2 in the aqueous mass boundary layer cannot be measured directly and are usually inferred from partial pressures or fugacities of CO2 (fCO2) in the air and water. In addition to the fCO2, the temperatures at the top and bottom of the aqueous mass boundary layer must be known to determine the thermodynamic driving force of CO2 gas transfer. Expressing the gradient in terms of the aqueous CO2 concentration, [CO2aq], also avoids some conceptual ambiguities. In particular, expressing the CO2 as a fugacity, which is defined relative to the gas phase, when the gas exchange rate is controlled in the aqueous mass boundary layer often leads to errors in interpretation with respect to changes in boundary layer temperature. As a result, the enhanced CO2 flux caused by the cool skin effect appears to be overestimated. Apart from the difficulties estimating the temperature at the top and bottom of the aqueous mass boundary layer, the temperature dependence of solubility and fugacity of CO2 is uncertain to the degree that it can bias air-sea CO2 flux estimates. The CO2aq at the surface, [CO2aq0], is at equilibrium with the atmospheric CO2 level. As [CO2aq0] is strongly temperature dependent, it will be significantly higher at high latitude compared to low latitude, while atmospheric CO2 levels show much less of a gradient.
Meinen, C.S., M.O. Baringer, and S.L. Garzoli. Variability in Deep Western Boundary Current transports: Preliminary results from 26.5N in the Atlantic. Geophysical Research Letters, 33(17):L17610, doi:10.1029/2006GL026965 (2006).
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Transport fluctuations of the deep limb of the Meridional Overturning Circulation (MOC) near the western boundary are presented from a line of inverted echo sounders, bottom pressure sensors, and a deep current meter east of Abaco Island, Bahamas, at 26.5°N from September 2004 through September 2005. The mean southward flow between 800 dbar and 4800 dbar was 39 x 106 m3 s-1, with a northward recirculation of 28 x 106 m3 s-1, leaving a net southward flow of 11 x 106 m3 s-1 as the through-flow of the Deep Western Boundary Current (DWBC). The mean southward DWBC flow essentially equals previous values that were measured at the same location by arrays of current meters deployed from 1986 to 1992. DWBC transport spectra indicate that barotropic and baroclinic changes have very similar energy levels at most periods less than 10 days and that barotropic changes dominate at periods of 10-80 days.
Mestas-Nunez, A.M., and A.J. Miller. Interdecadal variability and climate change in the eastern tropical Pacific: A review. Progress in Oceanography, 69(2-4):267-284 (2006).
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In this paper, we review interdecadal climatic variability in the eastern tropical Pacific Ocean. This variability dominates the climatic fluctuations in the North Pacific on scales between ENSO and the centennial trend and is commonly referred to as the Pacific Decadal Oscillation or PDO. We include a historical overview and a summary of observational work that describes the surface, tropospheric and subsurface signatures of this variability. Descriptions of interdecadal variability are incomplete at best, mostly due to limitations in the observational record. We emphasize that the well-known "ENSO-like" sea surface temperature (SST) pattern describing the PDO may not be an accurate representation. In the eastern tropical Pacific, the SST maxima are displaced north and south of the equator with larger amplitudes in the northern branch near the coast of North America, which has significant implications for the troposphere-driven circulations. Several mechanisms have been proposed to explain the PDO. We review these mechanisms and models, which capture our present level of understanding of the problem. We conclude by reporting there is little evidence of both multidecadal variability and the centennial trend in the eastern tropical Pacific. This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific.
Mestas-Nunez, A.M., A. Bentamy, and K.B. Katsaros. Seasonal and El Nio variability in weekly satellite evaporation over the global ocean during 1996-1998. Journal of Climate, 19(10):2025-2035 (2006).
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The seasonal and anomaly variability of satellite-derived weekly latent heat fluxes occurring over the global oceans during a three-year period (January 1996-December 1998) is investigated using EOF and harmonic analyses. The seasonal cycle of latent heat flux is estimated by least squares fitting the first three (annual, semiannual, and four month) harmonics to the data. The spatial patterns of amplitudes of these harmonics agree well with the corresponding patterns for wind speed. The annual harmonic captures an oscillation that reflects high evaporation in late fall/early winter and low evaporation in late spring/early summer in both hemispheres, with larger amplitudes in the Northern Hemisphere over the western side of the oceans and significant phase differences within each hemisphere. The main feature of the semiannual harmonic is its large amplitude in the Asian monsoon region (e.g., in the Arabian Sea its amplitude is about 1.5 larger than the annual) and the out-of-phase relationship of this region with the high latitudes of the North Pacific, consistent with other studies. The third harmonic shows three main regions with relatively large amplitudes, one in the Arabian Sea and two out-of-phase regions in the central midlatitude North and South Pacific. After removing this estimate of the seasonal cycle from the data, the leading EOF of the anomalies isolates the 1997-1998 El Nio signal, with enhanced evaporation in the eastern tropical Pacific, around the Maritime Continent, in the midlatitude North and South Pacific, and the equatorial Indian Ocean, and reduced evaporation elsewhere around the global ocean during April 1997-April 1998. This pattern is consistent with known patterns of ENSO variability and with the "atmospheric bridge" teleconnection concept. The current study illustrates the usefulness of satellite-derived latent heat fluxes for climatic applications.
Molinari, J., P.P. Dodge, D. Vollaro, K.L. Corbosiero, and F.D. Marks. Mesoscale aspects of the downshear reformation of a tropical cyclone. Journal of the Atmospheric Sciences, 63(1):341-354 (2006).
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The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance flights. Initially the storm was a marginal tropical storm in an environment with strong 850-200-hPa vertical wind shear of 12-13 m s-1 and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of, rather than within, a strong downshear-left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972-hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just 3 h earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intensify. Despite the subsequent weakening of the reformed center, it reached land with greater intensity than the original center. It is argued that this intensification process was set into motion by the vertical wind shear in the presence of an environment with upward motion forced by the upper tropospheric trough. In addition, the new center formed much closer to the coast and made landfall much earlier than predicted. Such vertical-shear-induced intensity and track fluctuations are important to understand, especially in storms approaching the coast.
Molinari, R.L. NOAA's XBT network, pp. 179-180. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Molinari, R.L., R. Lumpkin, C. Schmid, and M. McPhaden. NOAA's PIRATA northeast extension, pp. 136-137. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Montgomery, M.T., M.M. Bell, S.D. Aberson, and M.L. Black. Hurricane Isabel (2003): New insights into the physics of intense storms, Part I: Mean vortex structure and maximum intensity estimates. Bulletin of the American Meteorological Society, 87(10):1335-1347 (2006).
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This study is an observational analysis of the inner-core structure, sea surface temperature, outflow layer, and atmospheric boundary layer of an intense tropical cyclone whose intensity and structure is consistent with recent numerical and theoretical predictions of superintense storms. The findings suggest new scientific challenges for the current understanding of hurricanes. Unprecedented observations of the category-5 Hurricane Isabel (2003) were collected during 12-14 September. This two-part article reports novel dynamic and thermodynamic aspects of the inner-core structure of Isabel on 13 September that was made possible by analysis of these data. Here, a composite of the axisymmetric structure of the inner core and environment of Isabel is estimated using global positioning system dropwindsondes and in situ aircraft data. In Part II, an extreme wind speed observation on the same day is discussed in the context of this work. The axisymmetric data composite suggests a reservoir of high-entropy air inside the low-level eye and significant penetration of inflowing near-surface air from outside. The analysis suggests that the low-level air penetrating the eye is enhanced thermodynamically by acquiring additional entropy through interaction with the ocean and replaces air mixed out of the eye. The results support the hypothesis that this high-entropy eye air "turboboosts" the hurricane engine upon its injection into the eyewall clouds. Recent estimates of the ratio of sea-to-air enthalpy and momentum exchange at high wind speeds are used to suggest that Isabel utilized this extra power to exceed the previously assumed intensity upper bound by 10-35 m s-1 for the given environmental conditions. Additional study with other datasets is encouraged to further test the superintensity hypothesis.
Mooers, C.N.K., H.-S. Kang, I. Bang, and D.P. Snowden. Some lessons learned from comparisons of numerical simulations and observations of the JES circulation. Oceanography, 19(3):86-95 (2006).
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No abstract.
Morris, V., P. Clemente-Colon, N.R. Nalli, E. Joseph, R.A. Armstrong, Y. Detres, M.D. Goldberg, P.J. Minnett, and R. Lumpkin. Measuring trans-Atlantic aerosol transport from Africa. EOS, Transactions, American Geophysical Union, 87(50):565, 571 (2006).
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An estimated three billion metric tons of mineral aerosols are injected into the troposphere annually from the Saharan desert [Prospero et al., 1996]. Additionally, smoke from biomass burning sites in the savanna grasslands in sub-Saharan Africa contribute significant quantities of smaller-sized aerosols [e.g., Hobbs, 2000]. These windswept aerosols from the African continent are responsible for a variety of climate, health, and environmental impacts on both global and regional scales that span the Western Hemisphere. Unfortunately, in situ measurements of aerosol evolution and transport across the Atlantic are difficult to obtain, and satellite remote sensing of aerosols can be challenging.
Park, G.-H., K. Lee, R.H. Wanninkhof, and R.A. Feely. Empirical temperature-based estimates of variability in the oceanic uptake of CO2 over the past two decades. Journal of Geophysical Research, 111(C7):C07S07, doi:10.1029/2005JC003090 (2006).
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We infer the year-to-year variability of net global air-sea CO2 fluxes from observed interannual changes in wind speed and estimated differences in CO2 partial pressure between surface seawater (pCO2SW) and the overlying atmosphere. Changes in pCO2SW are estimated from changes in sea surface temperature via seasonal algorithms that relate pCO2SW to sea surface temperature. Our diagnostic model yields an interannual variability of ±0.18 petagrams (1-sigma, Pg = 1015 grams) of carbon per year for the period 1982-2001. El Niño Southern Oscillation-induced changes in the equatorial efflux contribute approximately 70% of the diagnostic modeled global variability. Regional flux anomalies for areas outside the equatorial Pacific are found to neither systematically reinforce nor counteract each other during times of transition from El Niño years to normal years. The interannual variability of ±0.18 Pg C yr-1 obtained in the present work is at the low end of previous estimates that falls in the range of ±0.2 to ±0.5 Pg C yr-1. Of the previous estimates, lower values are generally estimated from global ocean circulation-biogeochemical models, while higher values are derived from atmospheric inversion models constrained by atmospheric CO2 observations. Comparisons of our modeled results with two time series data sets and equatorial Pacific data suggest that our diagnostic model is not able to capture the full range of pCO2SW variations; this is probably due to the inability of the empirical model to fully account for changes in surface pCO2SW related to ocean biological and physical processes. The small interannual variability in our modeled fluxes suggests that observed year-to-year variations in the rate of atmospheric CO2 increase are primarily caused by changes in the rate of CO2 uptake by the land biosphere.
Pelegri, J.L., J.H. Churchill, A.D. Kirwan, S.-K. Lee, R.E. Munn, and N.R. Pettigrew. Gabriel T. Csanady: Understanding the physics of the ocean. Progress in Oceanography, 70(2-4):91-112 (2006).
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Gabriel T. Csanady turned 80 in December 2005, and we celebrate it with this special Progress in Oceanography issue. It comprises 20 papers covering some of the many areas that Gabe contributed significantly throughout his professional career. In this introductory paper, we briefly review Gabe's career as an engineer, meteorologist and oceanographer, and highlight some of his major contributions to oceanography, both as a scientist as well as an educator. But we also use this opportunity to remember and thank Gabe, and his wife Joyce, for being such good friends and mentors to several generations of oceanographers. The authors of the collection of papers in this volume deserve special thanks for their efforts. We also are pleased to acknowledge the support of Progress in Oceanography's editor, Detlef Quadfasel, and the many anonymous reviewers who generously contributed their time and expertise.
Piekle, R.A., C.W. Landsea, M. Mayfield, J. Laver, and R. Pasch. Reply to "Hurricanes and global warming potential linkages and consequences." Bulletin of the American Meteorological Society, 87(5):628-631 (2006).
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No abstract.
Plattner, S., D.M. Mason, G.A. Leshkevich, D.J. Schwab, and E.S. Rutherford. Classifying and forecasting coastal upwellings in Lake Michigan using satellite-derived temperature images and buoy data. Journal of Great Lakes Research, 32(1):63-76 (2006).
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Coastal upwellings are common in the Great Lakes but have lacked enumeration and systematic classification of spatial extent, frequency, duration, and magnitude. Near real-time sea surface temperature (SST) images derived from the Advanced Very High Resolution Radiometer (AVHRR) provide indices of upwelling events, but visual inspection of daily images can be tedious. Moreover, the definition of what constitutes an upwelling from AVHRR data is subjective. We developed a semi-automated method to classify upwellings during the period of thermal stratification using daily, cloud-free surface temperature charts from AVHRR SST data. Then we statistically evaluated the location, frequency, magnitude, extent, and duration of upwelling events in Lake Michigan from 1992-2000. Further, we analyzed meteorological data from the National Data Buoy Center buoys in an attempt to improve the reliability of the classification and to provide a means for future forecast of coastal upwelling. Although variable, upwelling events along the western shoreline were preceded by four days of southerly and west-to-northwesterly winds, while upwelling events occurring along the eastern shore were preceded by four days of northerly winds. Probability of an upwelling event occurring was a function of the direction-weighted wind speed, reaching a 100% probability at direction weighted wind speeds of 11 m s-1 for the western shore. Probability of an upwelling occurrence along the east coast reached 73% at 11 m s-1 and 100% at 13 m s-1. Continuous measurements of wind data with a sufficient temporal resolution are required during the entire upwelling season to improve the predictability of upwellings.
Reynolds, C.A., M.S. Peng, S.J. Majumdar, S.D. Aberson, C.H. Bishop, and R. Buizza. Interpretation of tropical cyclone targeting guidance. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 10 pp. (CD-ROM) (2006).
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No abstract.
Riishojgaard, L.P., R. Atlas, and G.D. Emmitt. Reply to "The impact of Doppler lidar wind observations on a single-level meteorological analysis." Journal of Applied Meteorology and Climatology, 45(6):887-888 (2006).
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No abstract.
Roemmich, D.H., R.E. Davis, S.C. Riser, W.B. Owens, R.L. Molinari, S.L. Garzoli, and G.C. Johnson. The ARGO Project: Global ocean observations for understanding and prediction of climate variability, pp. 187-191. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Rogers, R.F., M.L. Black, F.D. Marks, K.M. Valde, and S.S. Chen. A comparison of tropical cyclone hydrometeor profiles from TRMM, airborne radar, and high-resolution simulations. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 3 pp. (CD-ROM) (2006).
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No abstract.
Rogers, R.F., M.L. Black, R. Hood, J. Halverson, E. Zipser, and G. Heymsfield. The Intensity Forecasting Experiment (IFEX): A NOAA multi-year field program for improving tropical cyclone intensity forecasting. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 5 pp. (CD-ROM) (2006).
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No abstract.
Rogers, R.F., M.L. Black, P.T. Willis, R.A. Black, A. Heymsfield, A. Bansemer, and G. Heymsfield. An evaluation of the microphysics fields of Hurricane Dennis (2005) at different stages of its lifecycle. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Rogers, R.F., S.D. Aberson, M.L. Black, P.G. Black, J.J. Cione, P.P. Dodge, J.P. Dunion, J.F. Gamache, J. Kaplan, M.D. Powell, L.N. Shay, N. Surgi, and E.W. Uhlhorn. The Intensity Forecasting Experiment: A NOAA multi-year field program for improving tropical cyclone intensity forecasts. Bulletin of the American Meteorological Society, 87(11):1523-1537 (2006).
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In 2005, NOAA's Hurricane Research Division (HRD), part of the Atlantic Oceanographic and Meteorological Laboratory, began a multi-year experiment called the Intensity Forecasting Experiment (IFEX). By emphasizing a partnership among NOAA's HRD, Environmental Modeling Center (EMC), National Hurricane Center (NHC), Aircraft Operations Center (AOC), and National Environmental Satellite Data Information Service (NESDIS), IFEX represents a new approach for conducting hurricane field program operations. IFEX is intended to improve the prediction of tropical cyclone (TC) intensity change by: (1) collecting observations that span the TC life cycle in a variety of environments; (2) developing and refining measurement technologies that provide improved real-time monitoring of TC intensity, structure, and environment; and (3) improving the understanding of the physical processes important in intensity change for a TC at all stages of its life cycle. This paper presents a summary of the accomplishments of IFEX during the 2005 hurricane season. New and refined technologies for measuring such fields as surface and three-dimensional wind fields, and the use of unmanned aerial vehicles, were achieved in a variety of field experiments that spanned the life cycle of several tropical cyclones, from formation and early organization to peak intensity and subsequent landfall or extratropical transition. Partnerships with other experiments during 2005 also expanded the spatial and temporal coverage of the data collected in 2005. A brief discussion of the plans for IFEX in 2006 is also provided.
Russell, J.L., C. Sweeney, A. Gnanadesikan, R.A. Feely, and R. Wanninkhof. Optimal network design to detect spatial patterns and variability of ocean carbon sources and sinks from underway surface pCO2 measurements, pp. 229-231. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Sabine, C.L., R.A. Feely, and R.H. Wanninkhof. Global oceans: Ocean carbon. In State of the Climate in 2005, K.A. Shein, A.M. Waple, H.J. Diamond, and J.M. Levy. Bulletin of the American Meteorological Society, 87(6):S29-S30 (2006).
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No abstract.
Sabine, C.L., R.A. Feely, and R. Wanninkhof. The global ocean carbon cycle: Inventories, sources, and sinks, pp. 97-104. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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The ocean plays a major role in the global carbon cycle. Long-term (decadal) changes in ocean carbon inventory are examined by repeating measurements that are made along specific cruise tracks at intervals of 5-15 years. Recent cruises have suggested that the relative role of the Pacific versus the Atlantic storage of CO2 has changed over the last decade. Shorter-term (daily to inter-annual) changes in ocean carbon uptake are examined with sea-air CO2 flux estimates from instruments deployed on ships and moorings. The growing surface CO2 data set also indicates that there is significant interannual variability in the sea-air CO2 flux.
Schmid, C., and G.J. Goni. Evaluating the ocean observing system: Performance measurement for heat storage, pp. 261-262. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Serafy, J.E., T.R. Capo, and C.R. Kelble. Live capture of larval billfishes: Design and field testing of the continuous access Neuston observation net (CANON). Bulletin of Marine Science, 79(3):853-857 (2006).
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Basic research on larval billfish biology and ecology has been hampered by difficulties with species identification, the capture of live specimens, and their survival after capture (Richards, 1974; Post et al., 1997; Serafy et al., 2003). Whereas, genetic techniques are helping to resolve the identification problems (McDowell and Graves, 2002; Hyde et al., 2005; Luthy et al., 2005), obtaining live, uninjured billfish larvae for scientific study remains a serious obstacle (Idrisi et al., 2003; Serafy et al., 2003). To date, the most successful effort to collect live istiophorid larvae, and to subsequently maintain them in captivity, was conducted by Post et al. (1997). They sampled over a 2-yr period off Miami, Florida with a circular, 1 m diameter plankton net with 1 mm mesh. By limiting their Neuston tow duration to 2 min or less, overall larval istiophorid survival immediately after collection was 30%. Building on the Post et al. (1997) work, we addressed the problem of live billfish collection by developing a new Neuston gear in which tow duration can span, uninterrupted, whatever time period desired, and while underway, its cod-end contents are both viewable and immediately collectable. The rationale behind the "continuous access Neuston observation net" (CANON) design is that the key to minimizing larval injury (due to net abrasion, turbulence, and interactions with other organisms in the cod-end) lies in reducing the time larvae spend in the collection gear. Here, we describe the components, configuration, and operation of the CANON as well as provide results of its performance relative to conventional Neuston net sampling. Possible future applications for this new gear are also described.
Shay, L.K., and E.W. Uhlhorn. Loop Current interactions during Hurricanes Isidore and Lili. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 4 pp. (CD-ROM) (2006).
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No abstract.
Shen, B.-W., R. Atlas, J.-D. Chern, O. Reale, S.-J. Lin, T. Lee, and J. Chang. The 0.125 degree finite-volume general circulation model on the NASA Columbia supercomputer: Preliminary simulations of mesoscale vortices. Geophysical Research Letters, 33(5):L05801, doi:10.1029/2005GL024594 (2006).
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The NASA Columbia supercomputer was ranked second on the TOP500 List in November 2004. Such a quantum jump in computing power provides unprecedented opportunities to conduct ultra-high resolution simulations with the finite-volume General Circulation Model (fvGCM). During 2004, the model was run in real time experimentally at 0.25 degree resolution producing remarkable hurricane forecasts (Atlas et al., 2005). In 2005, the horizontal resolution was further doubled, which makes the fvGCM comparable to the first mesoscale resolving General Circulation Model at the Earth Simulator Center (Ohfuchi et al., 2004). Nine 5-day 0.125 degree simulations of three hurricanes in 2004 are presented first for model validation. Then it is shown how the model can simulate the formation of the Catalina eddies and Hawaiian lee vortices, which are generated by the interaction of the synoptic-scale flow with surface forcing, and have never been reproduced in a GCM before.
Shen, B.-W., R. Atlas, O. Reale, S.-J. Lin, J.-D. Chern, J. Chang, C. Henze, and J.-L. Li. Hurricane forecasts with a global mesoscale-resolving model: Preliminary results with Hurricane Katrina (2005). Geophysical Research Letters, 33(13):L13813, doi:10.1029/2006GL026143 (2006).
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It is known that General Circulation Models (GCMs) have insufficient resolution to accurately simulate hurricane near-eye structure and intensity. The increasing capabilities of high-end computers have changed this. The mesoscale-resolving finite-volume GCM (fvGCM) has been experimentally deployed on the NASA Columbia supercomputer, and its performance is evaluated in this study by choosing Hurricane Katrina as an example. In late August 2005, Katrina underwent two stages of rapid intensification, and became the sixth most intense hurricane in the Atlantic. Six 5-day simulations of Katrina at both 0.25° and 0.125° show comparable track forecasts but the 0.125° runs provide much better intensity forecasts, producing the center pressure with errors of only 12 hPa. In the runs examined in this study, the 0.125° simulates better near-eye wind distributions and a more realistic average intensification rate. To contribute to the ongoing research on the effects of disabling convection parameterization (CP), we present promising results by comparing 0.125° runs with disabled CPs against runs with enabled CPs.
Stabenau, E.R., J.C. Hendee, and L. Florit. Techniques for the automated assessment of intense light and high sea temperature on coral response. Proceedings, 10th International Coral Reef Symposium, Okinawa, Japan, June 28-July 2, 2004. International Society for Coral Reef Studies, 702-708 (2006).
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Field observations of temperature and the intensity of light were used in concert with data from a continuously monitoring pulse amplitude modulating (PAM) fluorometer to create an expert system decision table of in hospit zooxanthellae response to high sea temperature and intense light. A diffuse attenuation based spectral slope coefficient (SKd) is developed to provide real-time enhancement of optical data from discrete detector bands to estimate the full spectra and intensity of light at a coral's surface. During studies with a PAM fluorometer, seawater temperature was increased by less than 1°C (starting temperature 29.4°C) over four days, and resulted in subtle decreases in fluorescent yield in two Montastrea faveolata ust before the onset of coral bleaching. Following this increase, cloudy conditions reduced insolation levels which lead to fluroescent yield recovery from a low night-time value of 0.56 back to an initial value of 0.61.
Stern, D., and S.D. Aberson. Extreme vertical winds measured by dropsondes in hurricanes. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 5 pp. (CD-ROM) (2006).
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No abstract.
Sun, W., M. Cetin, W.C. Thacker, T.M. Chin, and A.S. Willsky. Variational approaches on discontinuity localization and field estimation in sea surface temperature and soil moisture. IEEE Transactions on Geoscience and Remote Sensing, 44(2):336-350 (2006).
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Some applications in remote sensing require estimating a field containing a discontinuity whose exact location is a priori unknown. Such fields of interest include sea surface temperature in oceanography and soil moisture in hydrology. For the former, oceanic fronts form a temperature discontinuity, while in the latter sharp changes exist across the interface between soil types. To complicate the estimation process, remotely sensed measurements often exhibit regions of missing observations due to occlusions such as cloud cover. Similarly, water surface and ground-based sensors usually provide only an incomplete set of measurements. Traditional methods of interpolation and smoothing for estimating the fields from such potentially sparse measurements often blur across the discontinuities in the field.
Takahashi, T., S.C. Sutherland, R.A. Feely, and R.H. Wanninkhof. Decadal change of the surface water pCO2 in the North Pacific: A synthesis of 35 years of observations. Journal of Geophysical Research, 111(C7):C07S05, doi:10.1029/2005JC003074 (2006).
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Surface water pCO2 data observed over the three decades between 1970 and 2004 are analyzed for space and time (mean decadal) variability in 32 10° x 10° box areas over the North Pacific Ocean north of 10°N. During this period, the pCO2 values at SST increased at a mean decadal rate of 12.0 4.8 µatm decade-1 in all but four areas located in the vicinity of the Bering and Okhotsk Seas, where they decreased at a mean rate of -11.1 5.7 µatm decade-1. The mean rate of increase for the open ocean areas is indistinguishable from the mean atmospheric CO2 increase rate of 15 µatm decade-1 (or 1.5 ppm yr-1) suggesting that the North Pacific surface waters as a whole have been following the atmospheric CO2 increase. However, the rate of increase varies geographically, reflecting differences in local oceanographic processes including lateral mixing of waters from marginal seas, upwelling of subsurface waters and biological activities. The decrease observed in the southern Bering Sea and the peripheries of the Okhotsk Sea may be accounted for by the combined effects of intensified biological production and changes in lateral and vertical mixing in these areas. The natural logarithm of wintertime pCO2 values normalized to a constant temperature and salinity of 14.3°C and 34.0 (the basin mean values, respectively) is correlated with winter SST. Using this relationship, the wintertime TCO2 in mixed layer can be expressed as a function of winter SST with a standard error of 5 µmol kg-1.
Takahashi, T., F. Millero, R. Key, D. Chipman, E. Peltola, S. Rubin, C. Sweeney, and S. Sutherland. Determination of carbon dioxide, hydrographic, and chemical parameters during the R/V Nathaniel B. Palmer cruise in the southern Indian Ocean (WOCE section SO4I, 3 May-4 July 1996). Oak Ridge National Laboratory/Carbon Dioxide Information Analysis Center, ORNL/CDIAC-150, NDP-086, 50 pp. (2006).
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This report discusses the procedures and methods used to measure total carbon dioxide (TCO2), total alkalinity (TALK), and partial pressure of CO2 (pCO2) at hydrographic stations during the cruise of research vessel (R/V) Nathaniel B. Palmer in the Southern Indian Ocean on the S04I section as a part of the Joint Global Ocean Flux Study (JGOFS)/World Ocean Circulation Experiment (WOCE). The carbon-related measurements were sponsored by the U.S. Department of Energy (DOE). The expedition started in Cape Town, South Africa, on May 3, 1996, and ended in Hobart, Australia, on July 4, 1996. Instructions for accessing the data are provided. The TCO2 was measured in discrete water samples using the Lamont-Doherty Earth Observatory (LDEO) coulomteric system with an overall precision of 1.7 µmol/kg. TALK was determined by potentiometric titration with an overall precision of 1.7 µmol/kg. During the S04I cruise pCO2 was also measured using the LDEO equilibrator-gas chromatograph system with a precision of 0.5% (including the station-to-station reproducibility) at a constant temperature of 4.0°C. The R/V Nathaniel B. Palmer S04I data set is available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center. The NDP consists of the oceanographic data files and this printed documentation, which describes the contents and format of all files as well as the procedures and methods used to obtain the data.
Tory, K.J., M.T. Montgomery, and N.E. Davidson. Prediction and diagnosis of tropical cyclone formation in an NWP system, Part I: The critical role of vortex enhancement in deep convection. Journal of the Atmospheric Sciences, 63(12):3077-3090 (2006).
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This is the first of a three-part investigation into tropical cyclone (TC) genesis in the Australian Bureau of Meteorology's Tropical Cyclone Limited Area Prediction System (TC-LAPS), an operational numerical weather prediction (NWP) forecast model. The primary TC-LAPS vortex enhancement mechanism is presented in Part I, the entire genesis process is illustrated in Part II using a single TC-LAPS simulation, and in Part III a number of simulations are presented exploring the sensitivity and variability of genesis forecasts in TC-LAPS. The primary vortex enhancement mechanism in TC-LAPS is found to be convergence/stretching and vertical advection of absolute vorticity in deep intense updrafts, which result in deep vortex cores of 60-100 km in diameter (the minimum resolvable scale is limited by the 0.15 horizontal grid spacing). On the basis of the results presented, it is hypothesized that updrafts of this scale adequately represent mean vertical motions in real TC genesis convective regions, and perhaps that explicitly resolving the individual convective processes may not be necessary for qualitative TC genesis forecasts. Although observations of sufficient spatial and temporal resolution do not currently exist to support or refute this proposition, relatively large-scale (30 km and greater), lower- to midlevel tropospheric convergent regions have been observed in tropical oceanic environments during the Global Atmospheric Research Programme (GARP) Atlantic Tropical Experiment (GATE), the Equatorial Mesoscale Experiment (EMEX), and the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE), and regions of extreme convection of the order of 50 km are often (remotely) observed in TC genesis environments. These vortex cores are fundamental for genesis in TC-LAPS. They interact to form larger cores, and provide net heating that drives the system-scale secondary circulation, which enhances vorticity on the system scale akin to the classical Eliassen problem of a balanced vortex driven by heat sources. These secondary vortex enhancement mechanisms are documented in Part II. In some recent TC genesis theories featured in the literature, vortex enhancement in deep convective regions of mesoscale convective systems (MCSs) has largely been ignored. Instead, they focus on the stratiform regions. While it is recognized that vortex enhancement through midlevel convergence into the stratiform precipitation deck can greatly enhance midtropospheric cyclonic vorticity, it is suggested here that this mechanism only increases the potential for genesis, whereas vortex enhancement through low- to midlevel convergence into deep convective regions is necessary for genesis.
Tory, K.J., M.T. Montgomery, N.E. Davidson, and J.D. Kepert. Prediction and diagnosis of tropical cyclone formation in an NWP system, Part II: A diagnosis of Tropical Cyclone Chris formation. Journal of the Atmospheric Sciences, 63(12):3091-3113 (2006).
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This is the second of a three-part investigation into tropical cyclone (TC) genesis in the Australian Bureau of Meteorology's Tropical Cyclone Limited Area Prediction System (TC-LAPS). The primary TC-LAPS vortex enhancement mechanism (convergence/stretching and vertical advection of absolute vorticity in convective updraft regions) was presented in Part I. In this paper (Part II) results from a numerical simulation of TC Chris (western Australia, February 2002) are used to illustrate the primary and two secondary vortex enhancement mechanisms that led to TC genesis. In Part III a number of simulations are presented exploring the sensitivity and variability of genesis forecasts in TC-LAPS. During the first 18 h of the simulation, a mature vortex of TC intensity developed in a monsoon low from a relatively benign initial state. Deep upright vortex cores developed from convergence/stretching and vertical advection of absolute vorticity within the updrafts of intense bursts of cumulus convection. Individual convective bursts lasted for 6-12 h, with a new burst developing as the previous one weakened. The modeled bursts appear as single updrafts, and represent the mean vertical motion in convective regions because the 0.15 grid spacing imposes a minimum updraft scale of about 60 km. This relatively large scale may be unrealistic in the earlier genesis period when multiple smaller-scale, shorter-lived convective regions are often observed, but observational evidence suggests that such scales can be expected later in the process. The large scale may limit the convection to only one or two active bursts at a time, and may have contributed to a more rapid model intensification than that observed. The monsoon low was tilted to the northwest, with convection initiating about 100-200 km west of the low-level center. The convective bursts and associated upright potential vorticity (PV) anomalies were advected cyclonically around the low, weakening as they passed to the north of the circulation center, leaving remnant cyclonic PV anomalies. Strong convergence into the updrafts led to rapid ingestion of nearby cyclonic PV anomalies, including remnant PV cores from decaying convective bursts. Thus convective intensity, rather than the initial vortex size and intensity, determined dominance in vortex interactions. This scavenging of PV by the active convective region, termed diabatic upscale vortex cascade, ensured that PV cores grew successively and contributed to the construction of an upright central monolithic PV core. The system-scale intensification (SSI) process active on the broader scale (300-500-km radius) also contributed. Latent heating slightly dominated adiabatic cooling within the bursts, which enhanced the system-scale secondary circulation. Convergence of low- to midlevel tropospheric absolute vorticity by this enhanced circulation intensified the system-scale vortex. The diabatic upscale vortex cascade and SSI are secondary processes dependent on the locally enhanced vorticity and heat respectively, generated by the primary mechanism.
Tracey, K.L., D.R. Watts, C.S. Meinen, and D.S. Luther. Synoptic maps of temperature and velocity within the Subantarctic Front south of Australia. Journal of Geophysical Research, 111(C10):C10016, doi:1029/2005JC002905 (2006).
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From April 1995 to March 1997 a 450-km array of inverted echo sounders, horizontal electric field recorders, and current meters measured the horizontal and vertical structure of the current, temperature, and salinity fields associated with the Subantarctic Front (SAF) south of Australia. Synoptic maps of the temperature and velocity fields often show the SAF divided into two zonally separated jets, which are also found in the mean. These jets were in close proximity yet directed toward different azimuths. The daily maps also show that the SAF often flowed as a single strong jet, during which times it underwent vigorous meandering, with crest-to-trough meridional distances ~250 km. These meanders stalled within the array and contorted to form "S"-shaped paths. In one case a cold-core ring was formed. Propagating meanders have periods of 20-70 days, wavelengths of 240-420 km, and phase speeds of 12-6 km d-1. Deep currents reveal strong cyclones and anticyclones propagating primarily eastward through the array beneath the meandering jet. Thus, at times the deep flow is aligned with the upper flow, whereas at other times, significant barotropic flows cross the upper front. Occasionally, the northern Polar Front was also found within the array. The observed variability illustrates how the interaction of a meandering current with transient features such as meanders and eddies makes the identification of a front difficult when a single isotherm or isopycnal is utilized as the definition.
Uhlhorn, E.W., and L.K. Shay. Mechanical energy and vorticity balances within the ocean mixed layer under tropical cyclones. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 3 pp. (CD-ROM) (2006).
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No abstract.
Walsh, K.J.E., M. Fiorina, C.W. Landsea, and K. McInnes. Objective detection of tropical cyclones in climate models. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 2 pp. (CD-ROM) (2006).
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No abstract.
Wang, C. An overlooked feature of tropical climate: Inter-Pacific Atlantic variability. Geophysical Research Letters, 33(12):LI2702, doi:10.1029/2006GL026324 (2006).
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Both the tropical Pacific and Atlantic host an equatorial mode of interannual variability called the Pacific El Nio and the Atlantic Nio, respectively. Although the Pacific El Nio does not correlate with the Atlantic Nio, anomalous warming or cooling of the two equatorial oceans can form an inter-Pacific-Atlantic sea surface temperature (SST) gradient variability that induces surface zonal wind anomalies over equatorial South America and over some regions of both ocean basins. The zonal wind anomalies act to bridge the interaction of the two ocean basins, reinforcing the inter-Pacific-Atlantic SST gradient through atmospheric Walker circulations and oceanic dynamics. Thus, a positive feedback seems to exist for climate variability of the tropical Pacific-Atlantic Oceans and atmosphere system, in which the inter-basin SST gradient is coupled to the overlying atmospheric wind. Rainfall responds to the inter-Pacific-Atlantic SST gradient by showing an anti-symmetric configuration between the two equatorial oceans, suggesting that rainfall is sensitive to the equatorial inter-basin SST gradient, regardless of which ocean is anomalously warm or cold.
Wang, C., and P.C. Fiedler. ENSO variability in the eastern tropical Pacific: A review. Progress in Oceanography, 69(2-4):239-266 (2006).
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El Nio-Southern Oscillation (ENSO) encompasses variability in both the eastern and western tropical Pacific. During the warm phase of ENSO, the eastern tropical Pacific is characterized by equatorial positive sea surface temperature (SST) and negative sea level pressure (SLP) anomalies, while the western tropical Pacific is marked by off-equatorial negative SST and positive SLP anomalies. Corresponding to this distribution are equatorial westerly wind anomalies in the central Pacific and equatorial easterly wind anomalies in the far western Pacific. Occurrence of ENSO has been explained as either a self-sustained, naturally oscillatory mode of the coupled ocean-atmosphere system or a stable mode triggered by stochastic forcing. Whatever the case, ENSO involves the positive ocean-atmosphere feedback hypothesized by Bjerknes. After an El Nio reaches its mature phase, negative feedbacks are required to terminate growth of the mature El Nio anomalies in the central and eastern Pacific. Four requisite negative feedbacks have been proposed: reflected Kelvin wave at the ocean western boundary, discharge process due to Sverdrup transport, western Pacific wind-forced Kelvin wave, and anomalous zonal advection. These negative feedbacks may work together for terminating El Nio, with their relative importance being time-dependent. ENSO variability is most pronounced along the equator and the coast of Ecuador and Peru. However, the eastern tropical Pacific also includes a warm pool north of the equator where important variability occurs. Seasonally, ocean advection seems to play an important role for SST variations of the eastern Pacific warm pool. Interannual variability in the eastern Pacific warm pool may be largely due to a direct oceanic connection with the ENSO variability at the equator. Variations in temperature, stratification, insolation, and productivity associated with ENSO have implications for phytoplankton productivity and for fish, birds, and other organisms in the region. Long-term changes in ENSO variability may be occurring and are briefly discussed. This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific.
Wang, W., and C. Wang. Formation and decay of the spring warm pool in the South China Sea. Geophysical Research Letters, 33(2):L02615, doi:10.1029/2005GL025097 (2006).
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As part of the southeast Asian monsoon system, the South China Sea (SCS) is characterized by monsoon wind transition from northeasterly to southwesterly in the boreal spring. Correspondingly, a spring warm pool (SWP) with mixed layer temperature warmer than 29°C is formed and peaked in May over the central SCS and then decays in June. Calculations of the heat budget showed that the surface heat flux and ocean dynamics have different roles in the formation and decay of the SWP. The surface heat flux is found to play a dominant role for the formation of the SWP in May. The onset of the southwest monsoon corresponds to an increase in cloudiness and rainfall and a strong wind speed in the SCS that decrease the surface heat flux in June. Moreover, the onset of the southwest monsoon also changes oceanic circulation pattern that advects cold water from the northwest to the southeast and pumps cold water into the upper mixed layer. These cooling effects overcome the warming effect of the surface heat flux, resulting in the decay of the SWP in June.
Wang, C., D.B. Enfield, S.-K. Lee, and C.W. Landsea. Influences of the Atlantic warm pool on western hemisphere summer rainfall and Atlantic hurricanes. Journal of Climate, 19(12):3011-3028 (2006).
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The Atlantic warm pool (AWP) of water warmer than 28.5°C comprises the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic (TNA). The AWP reaches its maximum size around September, with large AWPs being almost three times larger than small ones. Although ENSO teleconnections are influential on the AWP, about two-thirds of the large and small AWP variability appears unrelated to ENSO. The AWP is usually geographically different from the TNA; however, the AWP size is correlated with the TNA SST anomalies. During August to October, large AWPs and warm TNA are associated with increased rainfall over the Caribbean, Mexico, the eastern subtropical Atlantic, and the southeast Pacific, and decreased rainfall in the northwest United States, Great Plains, and eastern South America. In particular, rainfall in the Caribbean, Central America, and eastern South America from August to October is mainly related to the size of the AWP. Large (small) AWPs and warm (cold) TNA correspond to a weakening (strengthening) of the northward surface winds from the AWP to the Great Plains that disfavors (favors) moisture transport for rainfall over the Great Plains. On the other hand, large (small) AWPs and warm (cold) TNA strengthen (weaken) the summer regional Atlantic Hadley circulation that emanates from the warm pool region into the southeast Pacific, changing the subsidence over the southeast Pacific and thus the stratus cloud and drizzle there. The large AWP, associated with a decrease in sea level pressure and an increase in atmospheric convection and cloudiness, corresponds to a weak tropospheric vertical wind shear and a deep warm upper ocean, and thus increases Atlantic hurricane activity.
Wang, C., W. Wang, D. Wang, and Q. Wang. Interannual variability of the South China Sea associated with El Nio. Journal of Geophysical Research, 111(C3):C03023, doi:10.1029/2005JC003333 (2006).
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Interannual sea surface temperature (SST) anomalies in the South China Sea (SCS) are largely influenced by El Nio through El Nio-driven atmospheric and oceanic changes. This paper discovers a new observed feature of the SCS SST anomalies: a double-peak evolution following an El Nio event. The first and second peaks occur around February and August, respectively, in the subsequent year of the El Nio year (denoted by February [+1] and August [+1]). During and after the mature phase of El Nio, a change of atmospheric circulation alters the local SCS near-surface air temperature, humidity, cloudiness, and monsoon wind. These factors influence surface heat fluxes and oceanic flows over the SCS that can either warm or cool the SCS depending upon stages of SST anomaly evolution. The shortwave radiation and latent heat flux anomalies are major contributions to the first peak of the SCS SST anomalies, although the geostrophic heat advections warm the western boundary region of the SCS. After the first peak of February [+1], both the Ekman and geostrophic heat advections, assisted with a reduction of the net heat flux anomalies, cool the SCS SST anomalies. In August [+1], the mean meridional geostrophic heat advection makes the SCS SST anomalies peak again. Then, the latent heat flux anomalies (mainly attributed to anomalous air-sea difference in specific humidity) and the mean zonal geostrophic heat advection take over for the cooling of the SCS after the second peak.
Wanninkhof, R., R.A. Feely, N.R. Bates, F.J. Millero, T. Takahashi, and S. Cook. Document ocean carbon sources and sinks: Surface water pCO2 measurements from ships, pp. 207-215. In Annual Report on the State of the Ocean and the Ocean Observing System for Climate (FY-2005), J.M. Levy, D.M. Stanitski, and P. Arkin (eds.). NOAA Office of Climate Observation, Silver Spring, MD, 337 pp. (2006).
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No abstract.
Willoughby, H.E., R.W. Darling, and M.E. Rahn. Parametric representation of the primary hurricane vortex, Part II: A new family of sectionally continuous profiles. Monthly Weather Review, 134(4):1102-1120 (2006).
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For applications such as windstorm underwriting or storm-surge forecasting, hurricane wind profiles are often approximated by continuous functions that are zero at the vortex center, increase to a maximum in the eyewall, and then decrease asymptotically to zero far from the center. Comparisons between the most commonly used functions and aircraft observations reveal systematic errors. Although winds near the peak are too strong, they decrease too rapidly with distance away from the peak. Pressure-wind relations for these profiles typically overestimate maximum winds. A promising alternative is a family of sectionally continuous profiles in which the wind increases as a power of radius inside the eye and decays exponentially outside the eye after a smooth polynomial transition across the eyewall. Based upon a sample of 493 observed profiles, the mean exponent for the power law is 0.79 and the mean decay length is 243 km. The database actually contains 606 aircraft sorties, but 113 of these failed quality-control screening. Hurricanes stronger than Saffir-Simpson category 2 often require two exponentials to match the observed rapid decrease of wind with radius just outside the eye and slower decrease farther away. Experimentation showed that a fixed value of 25 km was satisfactory for the faster decay length. The mean value of the slower decay length was 295 km. The mean contribution of the faster exponential to the outer profile was 0.10, but for the most intense hurricanes it sometimes exceeded 0.5. The power-law exponent and proportion of the faster decay length increased with maximum wind speed and decreased with latitude, whereas the slower decay length decreased with intensity and increased with latitude, consistent with the qualitative observation that more intense hurricanes in lower latitudes usually have more sharply peaked wind profiles.
Yablonsky, R.M., I.Ginis, E.W. Uhlhorn, and A. Falkovich. Using AXBTs to improve the performance of coupled hurricane-ocean models. Preprints, 27th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, April 24-28, 2006. American Meteorological Society, Boston, 7 pp. (CD-ROM) (2006).
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No abstract.
Zhang, J.-Z. Enhanced sensitivity in flow injection analysis using a long pathlength liquid waveguide capillary flow cell for spectrophotometric detection. Analytical Sciences, 22(1):57-60 (2006).
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Incorporation of a liquid waveguide capillary flow cell into a flow injection instrument enhances the sensitivity of flow injection analysis with spectrophotometric detection by two orders of magnitude. Nitrite determination at nM levels has been used to demonstrate the feasibility of this novel technique for trace analysis. Combining the long pathlength spectrophotometry with flow injection analysis, this technique has advantages of low detection limit, good precision and high sample throughput.
Zhang, J.-Z., and C.J. Fischer. A simplified resorcinol method for direct spectrophotometric determination of nitrate in seawater. Marine Chemistry, 99(1-4):220-226 (2006).
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A direct, spectrophotometric method has been adapted for quantitative determination of nitrate concentrations in seawater. The method is based on nitration of resorcinol in acidified seawater, resulting in a color product. The absorption spectrum obtained for the reaction product shows a maximum absorption at 505 nm, with a molar absorptivity of 1.7 x 104 L mol-1 cm-1. This method has a detection limit of 0.5 µM and is linear up to 400 µM for nitrate. The advantage of this method is that all reagents are in aqueous solutions without involving cadmium granules as a heterogeneous reactant, as in conventional methods, and therefore is simple to implement. Application of the resorcinol to seawater analysis demonstrated that the results obtained are in good agreement with the conventional approach involving the reduction of nitrate by cadmium followed by diazotization.
**2005**
Ansorge, I., S. Speich, J. Lutjeharms, G.J. Goni, G. Rautenbach, P. Froneman, and S.L. Garzoli. Monitoring the oceanic flow between Africa and Antarctica: Report of the first Good Hope cruise. South Africa Journal of Science, 101(3-4):29-35 (2005).
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No abstract.
Arnold, W.S., G.L. Hitchcock, M.E. Frischer, R. Wanninkhof, and Y.P. Sheng. Dispersal of an introduced larval cohort in a coastal lagoon. Limnology and Oceanography, 50(2):587-597 (2005).
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Patterns of larval dispersal influence the structure of marine biological communities, but many aspects of larval dispersal remain poorly understood. For example, much of our present understanding of larval dispersal is based on models that integrate aspects of physical oceanography and larval biology, but the predictions of those models are generally not tested because we lack the methodology for real-time larval tracking. In the present study, we used both modeled and measured data to track an introduced larval cohort essentially from fertilization to presumed settlement. Larvae of the hard clam Mercenaria were released into a labeled water parcel in the Banana River Lagoon, Florida, within 8.5 hours of nursery production and then were tracked for the duration of their estimated 8-day pelagic life span. Comparisons of modeled versus measured larval distribution indicate that the fate of the larvae as predicted by a tracer model and by the concentration of coincidentally released sulfur hexafluoride (SF6) did not agree with the fate of the larvae as predicted by the path of subsurface drifters and by a particle trajectory model. Thus, modeled predictions of larval dispersal must be interpreted with care. Additionally, one component of larval dispersal that was observed in the study but that was not accounted for in the model was the spread of larvae along the path of advection. That trail of larvae may have important consequences for patterns of recruitment and resultant community structure, but it is not considered in most treatments of larval dispersal.
Atlas, R. Results of recent OSSEs to evaluate the potential impact of lidar winds. In Lidar Remote Sensing for Environmental Monitoring VI, U.N. Singh (ed.). Proceedings, SPIE, 5887:118-125 (2005).
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Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. OSSEs conducted at NASA GSFC and elsewhere have indicated significant potential for space-based lidar winds to improve numerical weather prediction. In this paper we summarize OSSE methodology and earlier OSSE results, and present methodology and new results from a Quick OSSE designed to assess the potential impact of lidar winds on the predicted track of a specific hurricane.
Atlas, R. The impact of AIRS on weather prediction. In Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XI, S.S. Shen and P.E. Lewis (eds.). Proceedings, SPIE, 5806:599-606 (2005).
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Observing system simulation experiments (OSSE) conducted prior to the launch of AIRS indicated significant potential for AIRS temperature soundings to improve numerical weather prediction (NWP), provided that cloud effects could be cleared effectively. Since the launch of AIRS aboard the AQUA satellite, a detailed geophysical validation of AIRS data has been performed. This included collocations of AIRS temperatures with in situ observations and model analyses, and observing system experiments (OSEs) to evaluate the actual impact of AIRS data on NWP. At the NASA Goddard Space Flight Center, we are evaluating AIRS data in several different forms, and are performing impact studies using multiple data assimilation systems. In general, the results of the OSE confirm the results of the earlier simulation experiments in that a meaningful positive impact of AIRS data is obtained and this impact depends strongly upon the assimilation of partially cloudy AIRS data.
Atlas, R. The impact of current and future polar-orbiting satellite data on numerical weather prediction at NASA/GSFC. In Applications with Weather Satellites, W.P. Menzel and T. Iwasaki (eds.). Proceedings, SPIE, 5658:132-143 (2005).
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Satellite observations are a critical component of the global atmospheric observing system and contribute substantially to the current accuracy of numerical weather forecasts. In this paper, two types of experiments related to the effectiveness of these and other observations are described. These are: Observing System Experiments (OSEs), which are conducted to evaluate the impact of an existing observing system; and Observing System Simulation Experiments (OSSEs) which are conducted to evaluate the potential for future observing systems to improve NWP, as well as to evaluate trade-offs in observing system design, and to develop and test improved methods for data assimilation. This paper summarizes the methodology for such experiments and presents selected results from OSEs to evaluate satellite data sets that have recently become available to the global observing system, such as AIRS and SeaWinds, and results from recent OSSEs to determine the potential impact of space-based lidar winds.
Atlas, R., A.Y. Hou, and R. Oreste. Application of SeaWinds scatterometer and TMI-SSM/I rain rates to hurricane analysis and forecasting. Journal of Photogrammetry and Remote Sensing, 59(4):233-243 (2005).
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Results provided by two different assimilation methodologies involving data from passive and active space-borne microwave instruments are presented. The impact of the precipitation estimates produced by the TRMM Microwave Imager (TMI) and Special Sensor Microwave/Imager (SSM/I) in a previously developed 1D variational continuous assimilation algorithm for assimilating tropical rainfall is shown on two hurricane cases. Results on the impact of the SeaWinds scatterometer on the intensity and track forecast of a mid-Atlantic hurricane are also presented. This work is the outcome of a collaborative effort between NASA and NOAA and indicates the substantial improvement in tropical cyclone forecasting that can result from the assimilation of space-based data in global atmospheric models.
Atlas, R., O. Reale, B.-W. Shen, S.-J. Lin, J.-D. Chern, W. Putman, T. Lee, K.-S. Yeh, M. Bosilovich, and J. Radakovich. Hurricane forecasting with the high-resolution NASA finite volume general circulation model. Geophysical Research Letters, 32(3):L03807, doi:10.1029/2004GL021513 (2005).
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A high-resolution finite volume general circulation model (fvGCM), resulting from a development effort of more than ten years, is now being run operationally at the NASA Goddard Space Flight Center and Ames Research Center. The model is based on a finite volume dynamical core with terrain-following Lagrangian control volume discretization and performs efficiently on massive parallel architectures. The computational efficiency allows simulations at a resolution of a quarter of a degree, which is double the resolution currently adopted by most global models in operational weather centers. Such fine global resolution brings us closer to overcoming a fundamental barrier in global atmospheric modeling for both weather and climate, because tropical cyclones can be more realistically represented. In this work, preliminary results are shown. Fifteen simulations of four Atlantic tropical cyclones in 2002 and 2004, chosen because of varied difficulties presented to numerical weather forecasting, are performed. The fvGCM produces very good forecasts of these tropical systems, adequately resolving problems like erratic track, abrupt recurvature, intense extratropical transition, multiple landfall and reintensification, and interaction among vortices.
Baringer, M.O., and S.L. Garzoli. Western boundary time series in the Atlantic Ocean, pp. 90-101. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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No abstract.
Baringer, M.O., G.J. Goni, and S.L. Garzoli. Atlantic high density XBT lines, pp. 84-89. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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No abstract.
Bateman, M., D. Mach, S. Lewis, J. Dye, E. Defer, C.A. Grainger, and P.T. Willis. Comparison of in-situ electric field and radar derived parameters for stratiform clouds in central Florida. Preprints, Conference on Meteorological Applications of Lightning Data, San Diego, CA, January 9-13, 2005. American Meteorological Society, Boston, 8 pp. (2005).
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No abstract.
Bell, G.D., S.B. Goldenberg, C.W. Landsea, E.S. Blake, R. Pasch, M. Chelliah, and K. Mo. Atlantic hurricane season. Bulletin of the American Meteorological Society, 86(6):S26-S29 (2005).
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No abstract.
Blake, E.S., E.N. Rappaport, J.D. Jarrell, and C.W. Landsea. The deadliest, costliest, and most intense United States tropical cyclones from 1851 to 2004 (and other frequently requested hurricane facts). NOAA Technical Memorandum, NWS TPC-4, 48 pp. (2005).
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This technical memorandum lists the deadliest and costliest tropical cyclones in the United States during 1851-2004. The compilation ranks damage, as expressed by monetary losses, in three ways: (1) contemporary estimates; (2) contemporary estimates adjusted by inflation to 2004 dollars; and (3) contemporary estimates adjusted for inflation and the growth of population and personal wealth (Pielke and Landsea, 1998) to 2004. In addition, the most intense (i.e., major) hurricanes to make landfall in the United States during the period are listed. Some additional statistics on United States hurricanes of this and previous centuries, and tropical cyclones in general, are also presented.
Browder, J.A., R. Alleman, S. Markeley, P.B. Ortner, and P.A. Pitts. Biscayne Bay conceptional ecological model. Wetlands, 25(4):854-869 (2005).
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Biscayne Bay is a naturally clear-water bay that spans the length of Miami-Dade County, Florida, USA. It is bordered on the east by barrier islands that include Miami Beach and is an almost completely urban bay in the north and a relatively natural bay in the south. Planned water management changes in the next few years may decrease freshwater flows to the bay from present sources, while offering reclaimed wastewater in return. In addition, a project is planned to restore the former diffuse freshwater flow to the Bay through many small creeks crossing coastal wetlands by redistributing the water that now flows into the Bay through several large canals. To guide a science-based, adaptive-management approach to water-management planning, a conceptual ecological model of Biscayne Bay was developed based upon a series of open workshops involving researchers familiar with Biscayne Bay. The CEM model relates ecological attributes of the Bay to outside forcing functions, identified as water management, watershed development, and sea-level rise. The model depicts the effects of these forcing functions on the ecological attributes of the Bay through four stressors. The hypothesized pathways of these effects include salinity patterns, water quality, sediment contaminant concentrations, and physical impacts. Major research questions were identified with regard to uncertainties explicit in the model. The issues addressed include, for example: (1) the quantitative relationship between upstream water management, rainfall, and flow into Biscayne Bay; (2) the salinity gradient required to restore the historical estuarine fish community; (3) the potential effect of freshwater inputs on benthic habitats; and (4) the effect of introduced nutrient and contaminant loads, including the effects of reclaimed wastewater.
Carsey, T.P., and H.E. Willoughby. Ozone measurements from eyewall transects of two Atlantic tropical cyclones. Monthly Weather Review, 133(1):166-174 (2005).
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Measurements of ozone (O3) concentrations obtained during aircraft eyewall crossings of tropical cyclone Floyd (September 1999) and Georges (September 1998) by NOAA P-3 hurricane research aircraft showed marked changes between the intensifying and weakening stages of the storms' life cycles. Renewed deepening appeared to be underway near landfall of both storms. During intensification, ozone levels indicated that air either descended from an altitude <1 km above flight level or was strongly diluted with low-O3 eyewall air. During weakening, ozone concentrations were low throughout the eye and eyewall, consistent with the eye's being filled with boundary layer air.
Carsey, T.P., R. Ferry, K.D. Goodwin, P.B. Ortner, J.R. Proni, P. Swart, and J.-Z. Zhang. Brevard County nearshore ocean nutrification analysis. NOAA Technical Report, OAR AOML-37 (PB2006-101563), 84 pp. (2005).
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In response to public concerns regarding the possibility of elevated nutrients in the Brevard County surf zone, Brevard County and Canaveral Port Authority officials contracted the National Oceanic and Atmospheric Administration (NOAA), Atlantic Oceanographic and Meteorological Laboratory (AOML) in Miami to assemble an expert panel of scientists to critically assess the issue. The panel included scientists from AOML, the Environmental Protection Agency, and the University of Miami's Rosenstiel School for Marine and Atmospheric Science. The expert panel was charged with reviewing scientific data and literature to answer a series of questions aimed at determining the existence of elevated nutrients along Brevard County Beaches and the various impacts of elevated nutrients to near shore ecology and human health. The panel was also tasked with evaluating methods for detecting nutrient sources and the impact of cruise and gaming vessels. Lastly, the panel was asked to make recommendations for future monitoring and research. The panel found that existing data did not support the claim that nutrient levels in the surf zone along Brevard County beaches were elevated. In fact, available data indicated that the Brevard County coast had comparatively less nutrients than other observed regions on Florida's east coast. The nutrient concentrations found in the surf zone should not pose a direct risk to human health. Furthermore, there was no evidence of elevated levels of sewage-indicating bacteria in numerous samples taken within the Brevard County surf zone. There was also no scientific evidence that red tide blooms, caused by the organism Karenia brevis, were related to near shore coastal nutrients off Brevard County beaches. Even if elevated nutrients had been found, the response of near shore ecology would depend on a complex set of factors, such as naturally-occurring biological, physical, meteorological, and geochemical forces, which would need to be considered in an integrated fashion. The panel concluded that although the nitrogen isotope method may be used to help identify sources of pollution, such measurements could not be used in isolation to determine the presence of sewage pollution. Based on information from numerous peer-reviewed sources, the panel concluded that one cannot simply assign a particular value to unambiguously indicate sewage contamination. To effectively utilize this method in Brevard County, a much greater understanding of the nitrogen cycle in this particular ecosystem would be needed, including analysis of isotopes in a variety of local sources and organisms. Additional data would be needed to verify the analysis of nutrient data conducted by the panel and to establish a baseline for any future monitoring efforts. Scientifically rigorous answers to the difficult questions posed to the panel would require a comprehensive interdisciplinary program that would include nutrient and microbiological water quality monitoring, techniques to determine nutrient sources (e.g., stable isotope studies of multiple elements, biochemical sewage markers, and deliberate tracers), circulation studies, and mass-balance and numeric modeling. The scope and expense of such a program implies it would be feasible only with the leveraging that can be obtained by close cooperation and coordination with ongoing and planned federal and state programs.
Cook, S.K., and R.L. Molinari. ENSO observing system, XBT component, task-1 operations, pp. 108-110. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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No abstract.
Corbosiero, K.L., J. Molinari, and M.L. Black. The structure and evolution of Hurricane Elena (1985), Part 1: Symmetric intensification. Monthly Weather Review, 133(10):2905-2921 (2005).
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One of the most complete aircraft reconnaissance and ground-based radar datasets of a single tropical cyclone was recorded in Hurricane Elena (1985) as it made a slow, three-day anticyclonic loop in the Gulf of Mexico. Eighty-eight radial legs and 47 vertical incidence scans were collected aboard NOAA WP-3D aircraft, and 1,142 ground-based radar scans were made of Elena's eyewall and inner rainbands as the storm intensified from a disorganized category 2 to an intense category 3 hurricane. This large amount of continuously collected data made it possible to examine changes that occurred in Elena's inner-core symmetric structure as the storm intensified. On the first day of study, Elena was under the influence of vertical wind shear from an upper-tropospheric trough to the west. The storm was disorganized, with no discernable eyewall and nearly steady values of tangential wind and relative vorticity. Early on the second day of study, a near superposition and constructive interference occurred between the trough and Elena, coincident with upward vertical velocities and the radial gradient of reflectivity becoming concentrated around the 30-km radius. Once an inner wind maximum and eyewall developed, the radius of maximum winds contracted and a sharp localized vorticity maximum emerged, with much lower values on either side. This potentially unstable vorticity profile was accompanied by a maximum in equivalent potential temperature in the eyewall, deeper and stronger inflow out to 24 km from the eyewall, and mean outflow toward the eyewall from the eye. Within 6-12 h, intensification came to an end and Elena began to slowly weaken. Vorticity and equivalent potential temperature at 850 hPa showed indications of prior mixing between the eye and eyewall. During the weakening stage, an outflow jet developed at the eyewall radius. A strong 850-hPa updraft accompanied the outflow jet, yet convection was less active aloft than before. This feature appeared to represent a shallow, outward-sloping updraft channel associated with the spindown of the storm.
DeMaria, M., M. Mainelli, L.K. Shay, J. Knaff, and J. Kaplan. Further improvements to the Statistical Hurricane Intensity Prediction Scheme (SHIPS). Weather and Forecasting, 20(4):531-543 (2005).
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Modifications to the Atlantic and east Pacific versions of the operational Statistical Hurricane Intensity Prediction Scheme (SHIPS) for each year from 1997 to 2003 are described. Major changes include the addition of a method to account for the storm decay over land in 2000, the extension of the forecasts from three to five days in 2001, and the use of an operational global model for the evaluation of the atmospheric predictors instead of a simple dry-adiabatic model beginning in 2001. A verification of the SHIPS operational intensity forecasts is presented. Results show that the 1997-2003 SHIPS forecasts had statistically significant skill (relative to climatology and persistence) out to 72 h in the Atlantic, and at 48 and 72 h in the east Pacific. The inclusion of the land effects reduced the intensity errors by up to 15% in the Atlantic, and up to 3% in the east Pacific, primarily for the shorter-range forecasts. The inclusion of land effects did not significantly degrade the forecasts at any time period. Results also showed that the four to five-day forecasts that began in 2001 did not have skill in the Atlantic, but had some skill in the east Pacific. An experimental version of SHIPS that included satellite observations was tested during the 2002 and 2003 seasons. New predictors included brightness temperature information from Geostationary Operational Environmental Satellite (GOES) channel 4 (10.7 µm) imagery, and oceanic heat content (OHC) estimates inferred from satellite altimetry observations. The OHC estimates were only available for the Atlantic basin. The GOES data significantly improved the east Pacific forecasts by up to 7% at 12-72 h. The combination of GOES and satellite altimetry improved the Atlantic forecasts by up to 3.5% through 72 h for those storms west of 50°W.
Eastin, M.D., W.M. Gray, and P.G. Black. Buoyancy of convective vertical motions in the inner core of intense hurricanes, Part I: General statistics. Monthly Weather Review, 133(1):188-208 (2005).
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The buoyancy of hurricane convective vertical motions is studied using aircraft data from 175 radial legs collected in 14 intense hurricanes at four altitudes ranging from 1.5 to 5.5 km. The data of each leg are initially filtered to separate convective-scale features from background mesoscale structure. Convective vertical motion events, called cores, are identified using the criteria that the convective-scale vertical velocity must exceed 1.0 m s-1 for at least 0.5 km. A total of 620 updraft cores and 570 downdraft cores are included in the dataset. Total buoyancy is calculated from convective-scale virtual potential temperature, pressure, and liquid water content using the mesoscale structure as the reference state. Core properties are summarized for the eyewall and rainband regions at each altitude. Characteristics of core average convective vertical velocity, maximum convective vertical velocity, and diameter are consistent with previous studies of hurricane convection. Most cores are superimposed upon relatively weak mesoscale ascent. The mean eyewall (rainband) updraft core exhibits small, but statistically significant, positive total buoyancy below 4 km (between 2 and 5 km) and a modest increase in vertical velocity with altitude. The mean downdraft core not superimposed upon stronger mesoscale ascent also exhibits positive total buoyancy and a slight decrease in downward vertical velocity with decreasing altitude. Buoyant updraft cores cover less than 5% of the total area in each region but accomplish ~40% of the total upward transport. A one-dimensional updraft model is used to elucidate the relative roles played by buoyancy, vertical perturbation pressure gradient forces, water loading, and entrainment in the vertical acceleration of ordinary updraft cores. Small positive total buoyancy values are found to be more than adequate to explain the vertical accelerations observed in updraft core strength, which implies that ordinary vertical perturbation pressure gradient forces are directed downward, opposing the positive buoyancy forces. Entrainment and water loading are also found to limit updraft magnitudes. The observations support some aspects of both the hot tower hypothesis and symmetric moist neutral ascent, but neither concept appears dominant. Buoyant convective updrafts, however, are integral components of the hurricane's transverse circulation.
Eastin, M.D., W.M. Gray, and P.G. Black. Buoyancy of convective vertical motions in the inner core of intense hurricanes, Part II: Case studies. Monthly Weather Review, 133(1):209-227 (2005).
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This is the second of two papers on the buoyancy of convective vertical motions in the inner core of intense hurricanes. This paper uses extensive airborne radar, dropwindsonde, and flight-level observations in Hurricanes Guillermo (1997) and Georges (1998) to illustrate typical azimuthal distribution of buoyant convection and demonstrate that the low-level eye can be an important source region for buoyant eyewall convection. In both hurricanes, eyewall vertical velocity and radar reflectivity are asymmetric and exhibit persistent relationships with the direction of the environmental vertical wind shear. Mesoscale vertical motions exhibit a wavenumber-1 structure with maximum ascent downshear and weak descent upshear. The mesoscale reflectivity maxima are located left-of-shear. Buoyant eyewall updraft cores and transient convective-scale reflectivity cells are predominantly downshear and left-of-shear. Most eyewall downdraft cores that transport significant mass downward are located upshear. Negative buoyancy was most common in left-of-shear downdrafts, with positive buoyancy dominant in upshear downdrafts. Inward-spiraling rainbands located outside the eyewall exhibit upband/downband asymmetries. Upband segments contain more convective reflectivity cells and buoyant updraft cores than the more stratiform downband segments. Equal numbers of downdraft cores are found upband and downband, but the majority exhibit negative buoyancy. Several buoyant updraft cores encountered in the midlevel eyewall exhibit equivalent potential temperatures (thetae) much higher than the thetae observed in the low-level eyewall, but equivalent to the thetae observed in the low-level eye. Asymmetric low-wavenumber circulations appear responsible for exporting the high-thetae eye air into the relatively low-thetae eyewall and generating the locally buoyant updraft cores. Implications of these results upon conceptual models of hurricane structure are discussed. Three mechanisms, whereby an ensemble of asymmetric buoyant convection could contribute to hurricane evolution, are also discussed.
Enfield, D.B., and S.-K. Lee. The heat balance of the western hemisphere warm pool. Journal of Climate, 18(4):2662-2681 (2005).
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The thermodynamic development of the western hemisphere warm pool and its four geographic subregions are analyzed. The subregional warm pools of the eastern North Pacific and equatorial Atlantic are best developed in the boreal spring, while in the Gulf of Mexico and Caribbean, the highest temperatures prevail during the early and late summer, respectively. For the defining isotherms chosen (27.5°, 28.0°, 28.5°C) the warm pool depths are similar to the mixed-layer depth (20-40 m) but are considerably less than the Indo-Pacific warm pool depth (50-60 m). The heat balance of the WHWP subregions is examined through two successive types of analysis: first by considering a changing volume ("bubble") bounded by constant temperature wherein advective fluxes disappear and diffusive fluxes can be estimated as a residual, and second by considering a slab layer of constant dimensions with the bubble diffusion estimates as an additional input and the advective heat flux divergence as a residual output. From this sequential procedure it is possible to disqualify as being physically inconsistent four of seven surface heat flux climatologies: the NCEP-NCAR reanalysis (NCEP1) and the ECMWF 15-yr global reanalysis (ERA-15) because they yield a nonphysical diffusion of heat into the warm pools from their cooler surroundings, and the unconstrained da Silva and Southampton datasets because their estimated diffusion rates are inconsistent with the smaller rates of the better understood Indo-Pacific warm pool when the bubble analysis is applied to both regions. The remaining surface flux datasets of da Silva and Southampton (constrained) and Oberhuber have a much narrower range of slab surface warming (+25 5 W m-2) associated with bubble residual estimates of total diffusion of -5 to -20 W m-2 (5 W m-2) and total advective heat flux divergence of -2 to -14 W m-2 (5 W m-2). The latter are independently confirmed by direct estimates using wind stress data and drifters for the Gulf of Mexico and eastern North Pacific subregions.
Etherton, B.J., and S.D. Aberson. Ensemble based data assimilation of observations of Hurricane Humberto. Preprints, 9th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface, San Diego, CA, January 9-13, 2005. American Meteorological Society, Boston, 5 pp. (2005).
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No abstract.
Feely, R.A., and R. Wanninkhof. Global repeat hydrographic/CO2/tracer surveys in support of CLIVAR and global carbon cycle objectives: Carbon inventories and fluxes, pp. 149-168. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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No abstract.
Feely, R.A., and R. Wanninkhof. The global ocean carbon cycle: Inventories, sources, and sinks, pp. 42-56. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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The ocean plays a major role in the global carbon cycle as it is a vast reservoir of carbon, naturally exchanges carbon with the atmosphere, and consequently takes up a substantial portion of anthropogenic carbon from the atmosphere. In response to the need for an integrated investigation of the carbon cycle in the oceans, the CLIVAR/CO2 Repeat Hydrography and NOAA Underway pCO2 Measurements Programs were established to document the trends in carbon uptake and transport in the global oceans. The CLIVAR/CO2 Repeat Hydrography Program consists of a systematic re-occupation of select hydrographic sections to quantify global changes in storage and transport of heat, fresh water, carbon dioxide (CO2), chlorofluorocarbon tracers and related parameters. Three North Atlantic cruises in 2003 marked the beginning of the U.S. effort by reoccupying selected hydrographic sections on decadal time-scales. Early results from these cruises showed significant changes in oxygen and carbon dioxide and several other measurable parameters since the last global survey in the 1990s. The increases of DIC in the Subtropical Mode waters (STMW) are greater than expected from invasion of anthropogenic CO2 from the atmosphere and may be the result of decadal changes in the local circulation in the North Atlantic.
Feely, R.A., L.D. Talley, G.C. Johnson, C.L. Sabine, and R.H. Wanninkhof. Repeat hydrography cruises reveal chemical changes in the North Atlantic. EOS, Transactions, American Geophysical Union, 86(42):399, 404-405 (2005).
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The U.S. contribution to a large international effort to document long-term trends in carbon storage and transport in the global oceans by reoccupying selected hydrographic sections on decadal timescales began with three North Atlantic cruises in 2003. The initial results from these reoccupation cruises have shown significant long-term changes in oxygen, carbon dioxide (CO2), and several other measurable parameters since the last global survey, which occurred in 1993. The ocean has a memory of the climate system and is second only to the Sun in affecting variability in the seasons and long-term climate change. The ocean stores an estimated 1000 times more heat than the atmosphere, and 50 times more carbon. Additionally, the key to possible abrupt climate change may lie in deep-ocean circulation.
Garzoli, S.L., and R.L. Molinari. Surface drifter program, pp. 169-174. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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No abstract.
Goes, M., R.L. Molinari, I. da Silveira, and I. Wainer. Retroflections of the North Brazil Current during February 2002. Deep-Sea Research, Part I, 52(4):647-667 (2005).
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Retroflections of the North Brazil Current (NBC) are examined using observational data collected in the western tropical Atlantic between 35°W-44°W and 11°S-7°N. Acoustic Doppler Current profiler, conductivity temperature depth oxygen and expendable bathythermograph data were obtained during a cruise conducted in February 2002. The water column was separated into two layers, the upper layer from the sea-surface to the 24.5 isopycnal and lower layer from the 24.5 to the 26.8 isopycnal. The upper layer includes the NBC, the South Equatorial Current, the North Equatorial Countercurrent (NECC) and a portion of the Equatorial Undercurrent (EUC). The lower layer includes the North Brazil Undercurrent (NBUC), the South Equatorial Undercurrent (SEUC), the North Equatorial Undercurrent (NEUC) and another portion of the EUC. With respect to earlier work, the data show that: (1) the SEUC is primarily fed by waters from a recirculation gyre on its northern boundary with some minor transport retroflecting from the NBUC; (2) the EUC is fed primarily by southern hemisphere waters that retroflect from the NBC, but there is some northern hemisphere water in the near surface flow that connects the EUC and NEUC during this cruise; (3) the NECC during this cruise has no connection to the NBC and is fed by northern hemisphere waters originating in the North Equatorial Current; and (4) the majority of the upper layer NBC that crosses 44°W does not appear to retroflect from the boundary farther north to return equatorward. New results include: (1) quantification, for this period, of the amount of transport in the single current core at 44°W that is comprised of waters from the southern (9.2 Sv) and northern hemispheres (5.2 Sv); (2) demonstration that the single core of eastward flow at 44°W and 41°W separates into the NEUC and EUC by 35°W, with the former composed of northern hemisphere waters and the latter southern hemisphere waters; (3) demonstration that the precursor to the EUC (NEUC) at 44°W and 41°W accelerates (decelerates) by 35°W; and (4) depiction of the potential vorticity (PV) field showing that the PV front at 44°W has separated into a front of higher PV values coincident with NEUC and a low PV core at 35°W coincident with the EUC.
Goodwin, K.D. Assay and remote sensor development for molecular biological water quality monitoring. Proceedings, 2004 National Beaches Conference, San Diego, CA, October 13-14, 2004. Environmental Protection Agency (EPA-823-R-05-001), 268-273 (2005).
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Molecular tools are a promising means to provide rapid and accurate monitoring of coastal water quality. We are developing three nucleic acid hybridization assays to identify and monitor nuisance organisms (bacterial and algal) in coastal waters. A microplate assay returns a rapid colorimetric result and provides moderate throughput at relatively low cost. A Luminex Xmap system rapidly provides high throughput and the potential to screen for a large number of targets simultaneously. Electrochemical detection is a cutting edge technology suitable to the size, power, and cost requirements of remote sensing. An overview of the development and application of these technologies will be presented.
Goodwin, K.D., S.A. Cotton, G. Scorzetti, and J.W. Fell. A DNA hybridization assay to identify toxic dinoflagellates in coastal waters: Detection of Karenia Brevis in the Rookery Bay National Estuarine Research Reserve. Harmful Algae, 4(2):411-422 (2005).
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A DNA hybridization assay was developed in microtiter plate format to detect the presence of toxic dinoflagellates in coastal waters. Simultaneous detection of multiple species was demonstrated using Karenia brevis, Karenia mikimotoi, and Amphidinium carterae. Molecular probes were designed to detect both K. brevis and K. mikimotoi and to distinguish between these two closely related species. The assay was used to detect K. brevis in coastal waters collected from the Rookery Bay National Estuarine Research Reserve. Assay results were verified by species-specific PCR and sequence analysis. The presence/absence of K. brevis was consistent with microscopic observation. Assay sensitivity was sufficient to detect K. brevis in amounts defined by a regional monitoring program as "present" (<1000 cells/L). The assay yielded quick colorimetric results, used a single hybridization temperature, and conserved the amount of genomic DNA utilized by employing one set of PCR primers. The microplate assay provides a useful tool to quickly screen large sample sets for multiple target organisms.
Goodwin, K.D., R. Tokarczyk, F.C. Stephens, and E.S. Saltzman. Description of toluene inhibition of methyl bromide biodegradation in seawater and isolation of a marine toulene oxidizer that degrades methyl bromide. Applied and Environmental Microbiology, 71(7):3495-3503 (2005).
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Methyl bromide (CH3Br) and methyl chloride (CH3Cl) are important precursors for destruction of stratospheric ozone, and oceanic uptake is an important component of the biogeochemical cycle of these methyl halides. In an effort to identify and characterize the organisms mediating halocarbon biodegradation, we surveyed the effect of potential cometabolic substrates on CH3Br biodegradation using a 13CH3Cl incubation technique. Toluene (160 to 200 nM) clearly inhibited CH3Br and CH3Cl degradation in seawater samples from the North Atlantic, North Pacific, and Southern Oceans. Furthermore, a marine bacterium able to co-oxidize CH3Br while growing on toluene was isolated from subtropical western Atlantic seawater. The bacterium, Oxy6, was also able to oxidize o-xylene and the xylene monooxygenase (XMO) pathway intermediate 3-methylcatechol. Patterns of substrate oxidation, lack of acetylene inhibition, and the inability of the toluene 4-monooxygenase (T4MO)-containing bacterium Pseudomonas mendocina KR1 to degrade CH3Br ruled out participation of the T4MO pathway in Oxy6. Oxy6 also oxidized a variety of toluene (TOL) pathway intermediates such as benzyl alcohol, benzylaldehyde, benzoate, and catechol, but the inability of Pseudomonas putida mt-2 to degrade CH3Br suggested that the TOL pathway might not be responsible for CH3Br biodegradation. Molecular phylogenetic analysis identified Oxy6 to be a member of the family Sphingomonadaceae related to species within the Porphyrobacter genus. Although some Sphingomonadaceae can degrade a variety of xenobiotic compounds, this appears to be the first report of CH3Br degradation for this class of organism. The widespread inhibitory effect of toluene on natural seawater samples and the metabolic capabilities of Oxy6 indicate a possible link between aromatic hydrocarbon utilization and the biogeochemical cycle of methyl halides.
Hankin, S.C., R.A. Feely, A. Kozyr, and T.-H. Peng. An end-to-end management system for ocean pCO2 measurements, pp. 181-186. In Annual Report on the State of the Ocean and Ocean Observing System for Climate (FY-2004), D.M. Stanitski (ed.). NOAA Office of Climate Observation, Silver Spring, MD, 422 pp. (2005).
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No abstract.
Hitchcock, G.L., T.N. Lee, P.B. Ortner, S.R. Cummings, C.R. Kelble, and E. Williams. Property fields in a Tortugas eddy in the southern Straits of Florida. Deep-Sea Research, Part I, 52(12):2195-2213 (2005).
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Sea surface temperature imagery, ship-based surveys, and moored current meters described the passage of a Tortugas eddy as it moved east at ca. 6 km day-1 through the southern Straits of Florida (SSF). In mid-April 1999, the eddy SST signature extended across half the width of the Straits. While in the western SSF, the eddy center was ca. 30 km seaward of the outer reef. The upper pycnocline, the subsurface chlorophyll a maximum (SCM), and nutricline shoaled from ca. 80 m at the eddy edge to <60 m at the center. Maximum chlorophyll-a concentrations in the SCM were highest near the eddy center, at 1 mg m-3, although the depth-integrated concentrations (mg m-2) were similar across the feature. Nutrient-density relationships show nitrate+nitrite, phosphate, and silicate decreased to detection limits at sigmat <25.0; the SCM was centered near this isopycnal surface. As the Eddy passed Looe Key (81.5°W), the alongshore currents reversed to the west. During this period high-nutrient, cool waters shoaled near the bottom on the outer reef. By early May, the eddy SST signature was compressed into a thin band of cool surface waters off the middle to upper Keys. As the feature moved towards shore in the middle to upper Florida Keys, the nitrate+nitrite and chlorophyll concentrations increased in bottom waters along the outer reef. Processes such as internal tidal bores and breaking internal waves are likely responsible for delivering nutrients from Tortugas eddies to the outer reef in the middle to upper Keys.
Hu, C., J.R. Nelson, E. Johns, Z. Chen, R.H. Weisberg, and F.E. Muller-Karger. Mississippi River water in the Florida Straits and in the Gulf Stream off Georgia in summer 2004. Geophysical Research Letters, 32(14):L14606, doi:10.1029/2005GL022942 (2005).
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A coherent plume from the Mississippi River was detected in MODIS imagery in July-October 2004 extending from the eastern Gulf of Mexico into the Florida Straits (FS), and reaching the Gulf Stream (GS) off Georgia. The plume was sampled from ships in the FS and the GS. In early August, the plume was about 10-20 km wide in the western FS and about 50 km wide off Georgia. The FS ship survey (16-26 August) documented a 50 km, 10-20 m deep band with anomalies in surface salinity (-0.8), temperature (0.5°C), and surface chlorophyll concentration (2x) relative to FS waters outside the plume. Nutrient concentrations were only slightly higher in the FS plume and there was no apparent increase in colored dissolved organic matter. We estimate that the plume carried some 23% (~2778 m3 s-1) of the Mississippi River discharge between July and September 2004 into the GS.
Hu, C., F.E. Muller-Karger, C. Taylor, K.L. Carder, C. Kelble, E. Johns, and C.A. Heil. Red tide detection and tracing using MODIS fluorescence data: A regional example in southwest Florida coastal waters. Remote Sensing of Environment, 97(3):311-321 (2005).
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Near real-time data from the MODIS satellite sensor was used to detect and trace a harmful algal bloom (HAB), or red tide, in southwest Florida coastal waters from October to December 2004. MODIS fluorescence line height (FLH in W m-2 m-1 sr-1) data showed the highest correlation with near-concurrent in situ chlorophyll-a concentration (Chl in mg m-3). For Chl ranging between 0.4 to 4 mg m-3 the ratio between MODIS FLH and in situ Chl is about 0.1 W m-2 m-1 sr-1 per mg m-3 chlorophyll (Chl = 1.255 (FLH x 10)0.86, r = 0.92, n = 77). In contrast, the band-ratio chlorophyll product of either MODIS or SeaWiFS in this complex coastal environment provided false information. Errors in the satellite Chl data can be both negative and positive (3-15 times higher than in situ Chl), and these data are often inconsistent either spatially or temporally due to interferences of other water constituents. The red tide that formed from November to December 2004 off southwest Florida was revealed by MODIS FLH imagery and was confirmed by field sampling to contain medium (104 to 105 cells L-1) to high (>105 cells L-1) concentrations of the toxic dinoflagellate Karenia brevis. The FLH imagery also showed that the bloom started in mid-October south of Charlotte Harbor, and that it developed and moved to the south and southwest in the subsequent weeks. Despite some artifacts in the data and uncertainty caused by factors such as unknown fluorescence efficiency, our results show that the MODIS FLH data provide an unprecedented tool for research and managers to study and monitor algal blooms in coastal environments.
Johns, E., R.H. Smith, P.B. Ortner, T.N. Lee, C.R. Kelble, and N. Melo. Real-time oceanographic and meteorological observations in the Florida Keys National Marine Sanctuary. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 133-134 (2005).
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No abstract.
Johns, E., R.H. Smith, P.B. Ortner, T.N. Lee, C.R. Kelble, and N. Melo. Salinity variability in south Florida coastal waters, 1995-2005. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 135-136 (2005).
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No abstract.
Kelble, C.R., P.B. Ortner, G.L. Hitchcock, and J.N. Boyer. Attenuation of photosynthetically available radiation (PAR) in Florida Bay: Potential for light limitation of primary producers. Estuaries, 28(4):560-571 (2005).
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Light attenuation in marine ecosystems can limit primary production and determine the species composition and abundance of primary producers. In Florida Bay, the importance of understanding the present light environment has heightened as major upstream water management restoration projects have been proposed and some are already being implemented. We analyzed a two-yearr (2001-2003) data set of the light attenuation coefficient (Kt) and its principal components (water, chromophoric dissolved organic matter [CDOM], tripton, phytoplankton) obtained at 40 stations within Florida Bay, calibrated synoptic underway data to produce high spatial resolution maps, examined the potential for light limitation, and quantified the individual effect of each component upon light attenuation. Tripton was the dominant component controlling light attenuation throughout Florida Bay, whereas the contribution of chlorophyll a and CDOM to Kt was much smaller in all regions of Florida Bay. It was possible to accurately estimate the light attenuation coefficient from component concentrations, using either a mechanistic or a statistical model with root mean square errors of 0.252 or 0.193 m-1, respectively. Compared to other estuaries, Florida Bay had the lowest overall Kt and the greatest relative contribution from tripton. Comparing the recent data to a study of Florida Bay's light environment conducted in 1993-1994, we found that overall water clarity in the Bay increased significantly, indicated by a nearly three-fold decrease in Kt, as a result of lower tripton concentrations, although the percent contribution of each of the components to Kt is unchanged. Only the northwest corner of Florida Bay, an area comprised of approximately 8% of the Bay's total area, was found on average to have sufficient light attenuation to limit the growth of seagrasses. This is much less extensive than in 1993-1994, when seagrass growth was potentially limited by light at over 50% of the stations sampled.
Kelble, C.R., E.M. Johns, P.B. Ortner, W.K. Nuttle, T.N. Lee, C.D. Hittle, and R.H. Smith. Salinity patterns of Florida Bay. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 137-138 (2005).
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No abstract.
Kim, D.-O., K. Lee, S.-D. Choi, H.-S. Kang, J.-Z. Zhang, and Y.-S. Chang. Determination of diapycnal diffusion rates in the upper thermocline in the North Atlantic Ocean using sulfur hexafluoride. Journal of Geophysical Research, 110(C10):C10010, doi:10.1029/2004JC002835 (2005).
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The apparent diapycnal diffusivity below the wind-driven surface mixed layer of the ocean was determined in an anticyclonic eddy in the eastern North Atlantic using sulfur hexafluoride (SF6) tracer data collected in June 1998. In this tracer experiment, the downward penetration of SF6 was measured for three weeks following the deliberate injection of SF6 in the surface mixed layer. The resulting data were used to constrain the one-dimensional Fickian diffusion model to estimate the diapycnal diffusivity. The model also includes the lateral diffusion component so that it can more accurately represent the time evolution of the SF6 concentrations along the isopycnal surface. This affects the estimation of the diapycnal diffusivity. For the upper thermocline immediately below the surface mixed layer we estimated the diapycnal diffusivity for the three-week period as 0.3 0.2 cm2 s-1 at a buoyancy frequency of 8.2 cph.
Knabb, R.D., J.-G. Jiing, C.W. Landsea, and W.R. Seguin. The Joint Hurricane Testbed (JHT): Progress and future plans. Preprints, 9th Symposium on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface, San Diego, CA, January 9-13, 2005. American Meteorological Society, Boston, 3 pp. (2005).
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No abstract.
LaGier, M.J., C.A. Scholin, J.W. Fell, J. Wang, and K.D. Goodwin. An electrochemical RNA hybridization assay for detection of the fecal indicator bacterium Escherichia coli. Marine Pollution Bulletin, 50(11):1251-1261(2005).
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Monitoring waters for indicator bacteria is required to protect the public from exposure to fecal pollution. Our proof-of-concept study describes a method for detecting fecal coliforms. The coliform Escherichia coli was used as a model fecal indicator. DNA probe-coated magnetic beads in combination with the electrochemical monitoring of the oxidation state of guanine nucleotides should allow for direct detection of bacterial RNA. To demonstrate this concept, we used voltammetry in connection with pencil electrodes to detect isolated E. coli 16S rRNA. Using this approach, 107 cells of E. coli were detected in a quantitative, reproducible fashion in 4 h. Detection was achieved without a nucleic acid amplification step. The specificity of the assay for coliforms was demonstrated by testing against a panel of bacterial RNA. We also show that E. coli RNA can be detected directly from cell extracts. The method could be used for on-site detection and shows promise for adaptation into automated biosensors for water-quality monitoring.
Landsea, C.W. Hurricanes and global warming. Nature, 438(7071):E11-E12 (2005).
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No abstract.
Lee, S.-K., D.B. Enfield, and C. Wang. Ocean general circulation model sensitivity experiments on the annual cycle of Western Hemisphere warm pool. Journal of Geophysical Research, 110(C9):C09004, doi:10.1029/2004JC002640 (2005).
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A series of ocean general circulation (OGCM) model experiments is carried out using a hybrid coordinate ocean model (HYCOM) to determine the annual cycle of Western Hemisphere Warm Pool (WHWP) heat budget and to assess the appropriateness of commonly used surface flux data sets in driving HYCOM simulations of the WHWP. Among the eight surface heat flux data sets addressed in this study, we find that the simulated SST is closest to the observations when the Southampton constrained (SHC) heat flux data are used, consistent with the conclusion of the data-based study of Enfield and Lee (2005). However, the modeled thermocline water is warmer and its stratification is weaker than observed regardless of the surface heat flux data used, possibly because of the low vertical resolution of the model used in this study. A preliminary heat budget analysis suggests that the surface net heat flux serves as the dominant forcing mechanism in the WHWP regions except in the equatorial Atlantic, where advective processes associated with the equatorial cold tongue are more important. A process of winter overturning that warms the upper layer by convection marks the Gulf of Mexico, while horizontal advection is of little importance there. The eastern north Pacific and Caribbean are affected significantly by vertical and horizontal advection during the onset and peak phases, slowing down the warming considerably.
Lee, T.N., E.M. Johns, N. Melo, R.H. Smith, P.B. Ortner, D. Smith, and N. Smith. On Florida Bay hypersalinity and water exchange. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 123-124 (2005).
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No abstract.
Legeais, J.-F., S. Speich, M. Arhan, I. Ansorge, E. Fahrbach, S.L. Garzoli, and A. Klepikov. The baroclinic transport of the Antarctic Circumpolar Current south of Africa. Geophysical Research Letters, 32(24):L24602, doi:10.1029/2005GL023271 (2005).
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Five hydrographic transects at nominal longitudes 0°E and 30°E, and 14 expendable bathythermograph (XBT) sections near the former longitude are used to study the baroclinic transport of the Antarctic Circumpolar Current (ACC) between Africa and Antarctica. The bottom-referenced geostrophic transport between the Subtropical Front and the ACC Southern Boundary is 147 10 Sv. Estimating the transport from the XBTs using a technique previously employed south of Australia proves delicate because of an irregular bathymetry and water mass variations. It nevertheless confirms ACC transports around 150 Sv. Gathering these and other estimates from the Atlantic sector suggests that, while North Atlantic Deep Water is injected in the current west of 35°W, a partially compensating loss of Deep Circumpolar Water occurs east of this longitude. Another transport increase from 0°E to 30°E might reflect southward transfer across the Subtropical Front south of the Agulhas retroflection.
Li, J.-L., D.E. Waliser, J.H. Jiang, D.L. Wu, W. Read, J.W. Waters, A.M. Tompkins, L.J. Donner, J.-D. Chern, W.-K. Tao, R. Atlas, Y. Gu, K.N. Liou, A. Del Genio, M. Khairoutdinov, and A. Gettelman. Comparisons of EOS MLS cloud ice measurements with ECMWF analyses and GCM simulations: Initial results. Geophysical Research Letters, 32(18):L18710, doi:10.1029/2005GL023788 (2005).
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To assess the status of global climate models (GCMs) in simulating upper-tropospheric ice water content (IWC), a new set of IWC measurements from the Earth Observing System's Microwave Limb Sounder (MLS) are used. Comparisons are made with ECMWF analyses and simulations from several GCMs, including two with multi-scale-modeling framework. For January 2005 monthly and daily mean values, the spatial agreement between MLS and ECMWF is quite good, although MLS estimates are higher by a factor of 2-3 over the western Pacific, tropical Africa, and South America. For the GCMs, the model-data agreement is within a factor of 2-4 with larger values of disagreement occurring over eastern Pacific and Atlantic ITCZs, tropical Africa, and South America. The implications arising from sampling and uncertainties in the observations, the modeled values, and their comparison are discussed. These initial results demonstrate the potential usefulness of this data set for evaluating GCM performance and guiding development efforts.
Li, Q.P., J.-Z. Zhang, F.J. Millero, and D.A. Hansell. Continuous colorimetric determination of trace ammonium in seawater with a long-path liquid waveguide capillary cell. Marine Chemistry, 96(1-2):73-85 (2005).
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An automated method for routine determination of nanomolar ammonium in seawater has been developed using segmented flow analysis coupled with a 2-m-long liquid waveguide capillary cell. Conventional photometric detector and autosampler were modified for this method. The optimal concentrations of the reagents and parameters for the development of indophenol blue are discussed. The method has low detection limit (5 nM), high precision (5% at 10-100 nM) and the advantage of rapid analysis of a large number of samples. The method has been used to examine the distribution of ammonium in Florida Bay and Biscayne Bay.
Lumpkin, R., and Z. Garraffo. Evaluating the decomposition of tropical Atlantic drifter observations. Journal of Atmospheric and Oceanic Technology, 22(9):1403-1415 (2005).
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Because the tropical Atlantic is characterized by regions of strong seasonal variability that have been sampled inhomogeneously by surface drifters, Eulerian averages of these Lagrangian observations in spatially fixed bins may be aliased. In the Pacific, this problem has been circumvented by first calculating seasonal or monthly means. In the Atlantic, such an approach is of limited value because of the relatively sparse database of drifter observations. As an alternative, a methodology is developed in which drifter-observed currents and sea surface temperatures are grouped into bins and, within each bin, simultaneously decomposed into a time-mean, annual and semiannual harmonics, and an eddy residual with a nonzero integral time scale. The methodology is evaluated using a temporally homogeneous SST product and in situ SST observations, and also using simulated drifter observations in an eddy-resolving model of the Atlantic Ocean. These analyses show that, compared to simple bin averaging, the decomposition developed herein yields significantly improved estimates of time-mean values in regions of strong seasonal variability. The methodology can also successfully estimate the distribution of the seasonal harmonics' amplitude and phase throughout much of the tropical Atlantic.
Lumpkin, R., and S.L. Garzoli. Near-surface circulation in the tropical Atlantic Ocean. Deep-Sea Research, Part I, 52(3):495-518 (2005).
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A recent data set of surface drifter observations in the tropical Atlantic Ocean is analyzed with a methodology that groups the observations into bins and, within each bin, simultaneously decomposed them into a time-mean, annual and semiannual harmonics, and an eddy residual with non-zero integral time scale. Features of the time-mean circulation and its seasonal variations are resolved at unprecedented scales, for both total and Ekman-removed velocities. The drifter observations reveal the branches of the South Equatorial Current (SEC) which merge with the North Brazil Current (NBC), correlated annual fluctuations in the strengths of the NBC retroflection, western North Equatorial Countercurrent (NECC) and SEC, and flow along the Guyana coast, and strong semiannual variations in the equatorial band of the central basin. Conduits are traced which link seasonal variations of the equatorial current system's strength with the northern and southern hemisphere subtropical gyres. These findings update key results of the two decade-old SEQUAL/FOCAL programs, and allow generation of a new monthly climatology of near-surface currents in the tropical Atlantic Ocean.
Majumdar, S.J., S.D. Aberson, C.H. Bishop, R. Buizza, M.S. Peng, and C.A. Reynolds. A comparison of adaptive observing guidance for Atlantic tropical cyclones. European Centre for Medium-Range Weather Forecasts, Technical Memorandum No. 482, 24 pp. (2005).
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Airborne adaptive observations have been collected for more than two decades in the neighborhood of tropical cyclones, to attempt to improve short-range forecasts of cyclone track. However, only simple subjective strategies for adaptive observations have been used, and the utility of objective strategies to improve tropical cyclone forecasts remains unexplored. Two objective techniques that have been used extensively for mid-latitude adaptive observing programs, and the current strategy based on the ensemble deep-layer mean (DLM) wind variance, are compared quantitatively using two metrics. The ensemble transform Kalman filter (ETKF) uses ensembles from NCEP and ECMWF. Total-energy singular vectors (TESVs) are computed by ECMWF and the Naval Research Laboratory, using their respective global models. Comparisons of 78 guidance products for two-day forecasts during the 2004 Atlantic hurricane season are made, on both continental and localized scales relevant to synoptic surveillance missions. The ECMWF and NRL TESV guidance identifies similar large-scale target regions in 90% of the cases, but are less similar to each other in the local tropical cyclone environment (56% of the cases) with a more stringent criterion for similarity. For major hurricanes, all techniques usually indicate targets close to the storm center. For weaker tropical cyclones, the TESV guidance selects similar targets to those from the ETKF (DLM wind Variance) in only 30% (20%) of the cases. ETKF guidance using the ECMWF ensemble is more like that provided by the NCEP ensemble (and DLM wind variance) for major hurricanes than for weaker tropical cyclones. Minor differences in these results occur when a different metric based on the ranking of fixed storm-relative regions is used.
Mason, D.M., T.B. Johnson, C.J. Harvey, J.F. Kitchell, S.T. Schram, C.R. Bronte, M.H. Hoff, S.T. Lozano, A.S. Trebitz, D.R. Schreiner, E.C. Lamon, and T. Hrabik. Hydroacoustic estimates of abundance and spatial distribution of pelagic prey fishes in western Lake Superior. Journal of Great Lakes Research, 31(4):426-438 (2005).
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Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) are a valuable prey resource for the recovering lake trout (Salvelinus namaycush) in Lake Superior. However, prey biomass may be insufficient to support the current predator demand. In August 1997, we assessed the abundance and spatial distribution of pelagic coregonines and rainbow smelt in western Lake Superior by combining a 120 kHz split beam acoustics system with midwater trawls. Coregonines comprised the majority of the midwater trawl catches and the length distributions for trawl caught fish coincided with estimated sizes of acoustic targets. Overall mean pelagic prey fish biomass was 15.56 kg ha-1 with the greatest fish biomass occurring in the Apostle Islands region (27.98 kg ha-1), followed by the Duluth Minnesota region (20.22 kg ha-1), and with the lowest biomass occurring in the open waters of western Lake Superior (9.46 kg ha-1). Biomass estimates from hydroacoustics were typically 2-134 times greater than estimates derived from spring bottom trawl surveys. Prey fish biomass for Lake Superior is about order of magnitude less than acoustic estimates for Lakes Michigan and Ontario. Discrepancies observed between bioenergetics-based estimates of predator consumption of coregonines and earlier coregonine biomass estimates may be accounted for by our hydroacoustic estimates.
McNeil, C., D. Katz, R. Wanninkhof, and B. Johnson. Continuous shipboard sampling of gas tension, oxygen, and nitrogen. Deep-Sea Research, Part I, 52(9):1767-1785 (2005).
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A novel shipboard gas tension device (GTD) that measures total dissolved air pressure in ocean surface waters is described and demonstrated. In addition, an improved method to estimate dissolved N2 levels from simultaneous measurements of gas tension, dissolved O2, water temperature, and salinity is described. Other than a flow-through plenum, the shipboard GTD is similar to the previously described moored-mode GTD (McNeil et al., 1995, Deep-Sea Research, Part I, 42:819-826). The plenum has an integrated water-side screen to protect the membrane and prevent the membrane from flexing in super-saturated near surface waters. The sampling scheme uses a well mixed and thermally insulated 15 L container that is flushed by the ship's seawater intake at a rate of 3-15 L min-1. Dissolved gas sensors are placed inside this container and flushed with a small recirculation pump. Laboratory data that characterize the response of the modified GTD are presented. The modified GTD has a constant, isothermal, characteristic (e-folding) response time of typically 112 min at 20°C. The response time decreases with increasing temperature and varies by 35% over a temperature range of 5-35°C. Results of field measurements, collected on the R/V Brown between New York and Puerto Rico during September 2002, are presented and provide the first look at co-variability in surface ocean N2, O2, and CO2 levels over horizontal length scales of several kilometers. Dissolved N2 concentrations decreased by approximately 16% as the ship sailed from the colder northern continental shelf waters, across the Gulf Stream, and into the warmer northwestern Atlantic Ocean. Historical database measurements, buoy time series, and satellite imagery, are used to aid interpretation of the dissolved gas levels.
Meinen, C.S. Meridional extent and interannual variability of the Pacific Ocean tropical-subtropical warm water exchange. Journal of Physical Oceanography, 35(3):323-335 (2005).
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Altimetric observations of sea surface height anomaly (SSHA) from the TOPEX/Poseidon and ERS satellites, hydrography, and the ECMWF and Florida State University wind products are used to track warm water (>20°C) as it is exchanged between the equatorial Pacific Ocean and the higher latitudes during 1993-2003. The large El Nio event of 1997-1998 resulted in a significant discharge of warm water toward the higher latitudes within the interior of the Pacific Ocean. The exchange of anomalous warm water volume with the Northern Hemisphere appears to be blocked under the intertropical convergence zone, consistent with most current ideas on the time-mean tropical-subtropical exchange. Little of the warm water discharged northward across 5° and 8°N during the 1997-1998 El Nio event could be traced as far as 10°N. To the south, however, these anomalous volumes of warm water were visible at least as far as 20 S, primarily in the longitudes around 130°-160°W. In both hemispheres most of the warm water appeared to flow westward before returning to the Tropics during the recharge phase of the El Nio-La Nia cycle. The buildup of warm water in the Tropics before the 199798 El Nio is shown to be fed primarily by warm water drawn from the region in the western Pacific within 5°S-15°N. The exchange cycle between the equatorial band and the higher latitudes north of the equator leads the cycle in the south by 6-8 months. These results are found in all three datasets used herein, hydrography, altimetric observations of SSHA, and Sverdrup transports calculated from multiple wind products, which demonstrates the robustness of the results.
Meinen, C.S. Temporal sampling: How many sections are needed to quantify the mean transport and structure of a meandering current? Journal of Atmospheric and Oceanic Technology, 22(4):476-489 (2005).
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Two years of observations from an array of 16 inverted echo sounders deployed south of Australia near 51°S, 143.5°E are combined with hydrographic observations from the region to estimate the differences in baroclinic transport, as well as temperature and velocity structure, that result from trying to estimate the true mean using a limited number of snapshot sections. The results of a Monte Carlo-type simulation suggest that over a 350-km distance, completely spanning the Subantarctic Front (SAF) at most times, a minimum of six temporally independent sections would be required to determine the baroclinic transport mean (surface to 4000 db) of the observed 2-yr period to within an accuracy of 10% when the sections are averaged in either an Eulerian (geographic) or stream coordinates manner. However, even with 10 sections during a 2-yr period the details of the mean velocity and temperature structures obtained can be quite different than the "true" 2-yr mean structure, regardless of whether the sections are averaged in either Eulerian or stream coordinates. It is estimated that at least 20 independent sections would be required during a 2-yr period in order to determine the baroclinic velocity structure to within an accuracy of 10%, irrespective of whether they are averaged in Eulerian or stream coordinates. Implications for future sampling strategies and for inverse modeling analyses are discussed.
Melo, N., T.N. Lee, E. Johns, R.H. Smith, P.B. Ortner, and D. Smith. Recent measurements of salinity, flow, and sea level variability in western basins of Florida Bay-Rabbit and Twin Key Basins. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 141-142 (2005).
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No abstract.
Mestas-Nunez, A.M., C. Zhang, and D.B. Enfield. Uncertainties in estimating moisture fluxes over the Intra-Americas Sea. Journal of Hydrometeorology, 6(5):696-709 (2005).
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This study estimates discrepancies in moisture flux divergence in the Intra-Americas Sea (IAS; including the Gulf of Mexico and the Caribbean Sea) calculated using sounding observations, the NCEP Eta high-resolution regional analysis, and the NCEP-NCAR coarse-resolution global reanalysis. The main purpose of this exercise is to quantify the uncertainties in the global reanalysis when it is used to calculate annual and interannual variability of moisture flux divergence in the region. An accurate estimate of moisture flux divergence is crucial to evaluate whether the IAS serves as a water vapor source for rainfall over the adjacent land. Using the three datasets, the uncertainties of calculated moisture flux divergence due to the design of the boundary of the area, mathematical algorithms, and spatial and temporal resolutions are quantified. The results show that the large seasonal and interannual variability in moisture flux divergence estimated using the NCEP-NCAR reanalysis is not compromised by these uncertainties. Therefore, NCEP-NCAR reanalysis, with its global coverage and long-term record, can be used to provide the best estimate of short climate variability of moisture flux divergence available to date. Further comparisons are made of the moisture flux divergence based on the NCEP-NCAR reanalysis with previous estimates using single-year sounding observations, as well as with multiyear estimates based on global datasets of surface evaporation and precipitation. It is shown that the previous estimates using single-year sounding observations bear large uncertainties because of interannual variability. Large uncertainties also exist in datasets of surface global evaporation and precipitation.
Michaels, P.J., P.C. Knappenberger, and C.W. Landsea. Comments on "Impacts of CO2-induced warming on simulated hurricane intensity and precipitation: Sensitivity to the choice of climate model and convective scheme." Journal of Climate, 18(23):5179-5182 (2005).
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In a simulation of enhanced tropical cyclones in a warmer world, Knutson and Tuleya make several assumptions that are not borne out in the real world. They include an unrealistically large carbon dioxide growth rate, an overly strong relationship between sea surface temperature and hurricane intensity, and the use of a mesoscale model that has shown little to no useful skill in predicting current-day hurricane intensity. After accounting for these inaccuracies, a detectable increase in Atlantic hurricane intensity in response to growing atmospheric greenhouse gas levels during this century becomes unlikely.
Mooers, C.N.K., C.S. Meinen, M.O. Baringer, I. Bang, R. Rhodes, C.N. Barron, and F. Bub. Cross validating ocean prediction and monitoring systems. EOS, Transactions, American Geophysical Union, 86(29):269, 272-273 (2005).
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With the ongoing development of ocean circulation models and real-time observing systems, routine estimation of the synoptic state of the ocean is becoming feasible for practical and scientific purposes. The models can assist in ocean monitoring and regional dynamics studies, but only after they have been validated. For the first time, beginning 1 November 2004, independent ocean model estimates of the Florida Current (FC) volume transport are available, in real time, for cross validation with observed transport variations forced by cold front passages, tropical cyclones, and other weather systems. The FC flows poleward through the Straits of Florida and ultimately becomes the Gulf Stream. The FC originates from both the large-scale, wind-driven circulation of the North Atlantic subtropical gyre and the trans-equatorial Atlantic thermohaline overturning circulation (i.e., the "global conveyor belt"). The FC is constrained by Florida to the north and/or west and by Cuba and the Bahamas to the south and east, respectively (Figure 1).
Morrison, I., S. Businger, F.D. Marks, P.P. Dodge, and J.A. Businger. An observational case for the prevalence of roll vortices in the hurricane boundary layer. Journal of the Atmospheric Sciences, 62(8):2662-2673 (2005).
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Doppler velocity data from the WSR-88D radar during four hurricane landfalls are analyzed to investigate the presence of organized vortices in the hurricane boundary layer (HBL). The wavelength, depth, magnitude, and track of velocity anomalies were compiled through analysis of Doppler velocity data. The analysis reveals alternating bands of enhanced and reduced azimuthal winds that are closely aligned with the mean wind direction. Resulting statistics provide compelling evidence for the presence of organized secondary circulations or boundary layer rolls across significant areas during four hurricane landfalls. The results confirm previous observations of the presence of rolls in the HBL. A potential limitation of the study presented here is the resolution of the WSR-88D data. In particular, analysis of higher resolution data (e.g., from the Doppler on Wheels) is needed to confirm that data aliasing has not unduly impacted the statistics reported here. Momentum fluxes associated with the secondary circulations are estimated using the covariance between the horizontal and vertical components of the wind fluctuations in rolls, with resulting fluxes 2-3 times greater than estimated by parameterizations in numerical weather prediction models. The observational analysis presented here, showing a prevalence of roll vortices in the HBL, has significant implications for the vertical transport of energy in hurricanes, for the character of wind damage, and for improvements in numerical simulations of hurricanes.
Nuissier, O., R.F. Rogers, and F. Roux. A numerical simulation of Hurricane Bret on 22-23 August 1999 initialized with airborne Doppler radar and dropsonde data. Quarterly Journal of the Royal Meteorological Society, 131(605):155-194 (2005).
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This study concerns the simulation of Hurricane Bret on 22-23 August 1999 with the MesoNH non-hydrostatic, two-way interactive, quadruply nested grid mesoscale model. A 30-h integration, from 0000 UTC 22 August to 0600 23 August, covers the period of maximum intensity over the Gulf of Mexico and landfall over Texas. Special attention is paid to the initial conditions from which the model is integrated. A balanced vortex, derived from airborne Doppler radar data, is used to replace the ill-defined cyclone in the large-scale analysis. In addition, the analyzed humidity field over the Gulf of Mexico is modified in accordance with specific dropsonde observations. A comparison between the simulated storm track and intensity for three different numerical experiments shows that the inclusion of the radar-derived vortex and high spatial resolution are necessary to obtain a realistic simulation. After an initial period of adjustment, the simulation with the inserted radar-derived vortex and high resolution produces a storm only 10 hPa weaker than the observation after 24 h, compared to the control run that was nearly 50 hPa weaker at the same time. The characteristics of this simulated storm at mature stage are then presented, with particular emphasis placed on the processes that modulate the intensity of the inner core region.
Olsen, A., R. Wanninkhof, J.A. Trinanes, and T. Johannessen. The effect of wind speed products and wind speed-gas exchange relationships on interannual variability of the air-sea CO2 gas transfer velocity. Tellus B, 57(2):95-106 (2005).
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The lack of a firm relationship between wind speed (U10) and gas transfer velocity (k) is considered to be one of the factors that hinders accurate quantification of interannual variations of ocean-atmosphere CO2 fluxes. In this paper, the interannual variations of k of using four different k-U10 parameterizations are examined using wind speed data from the NCEP/NCAR reanalysis project. The extent to which interannual variations are faithfully reproduced in the NCEP/NCAR data is also investigated. This is carried out through comparison with QuikSCAT data. Compared with 4 years of QuikSCAT data, NCEP/NCAR data reproduce interannual k variations, although the absolute magnitude of k is underestimated. Interannual k variation shows great sensitivity to selection of k-U10 parameterization, and in the Westerlies it changes by a factor of three depending on k-U10 parameterization. Use of monthly mean winds speeds leads to overestimation of interannual k variations compared with k variations computed using 6-hourly wind speeds and the appropriate k-U10 parameterization. Even though the effect of changing k-U10 parameterization is large enough to be an issue that needs to be considered when computing interannual air-sea CO2 flux variations through combining estimates of k with data for the air-sea CO2 gradient, it is not sufficient to bridge the gap between such estimates and estimates based on analyses of atmospheric oxygen, CO2, and delta13C data. Finally, it is shown that the ambiguity in the relationship between wind speed and k introduces an uncertainty in interannual flux variations comparable to a bias of interannual DELTApCO2 variations of at most 5 µatm.
Palmer, D.R. Acoustical scattering from constituents of an ocean plume located near a boundary surface. IEEE Transactions on Geoscience and Remote Sensing, 43(4):770-777 (2005).
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A formalism exists for estimating the intensity recorded by a sonar system due to scattering from a ocean plume of suspended, nonspherical scatterers in the Rayleigh region. In this paper we extend this framework to include the possibility that the plume is located near a planar ocean boundary. Using the theory of isoperimetric inequalities, bounds are obtained for the magnitude of the scattering amplitude that are independent of shape and the aspect of the individual plume constituents. Two examples are considered to illustrate the application of the analysis; scattering from the particulates that comprise black smoker hydrothermal plumes and scattering from bubbles.
Palmer, D.R., and P.A. Rona. Acoustical imaging of deep ocean hydrothermal flows. In Sounds in the Sea: From Ocean Acoustics to Acoustical Oceanography, H. Medwin (ed.). Cambridge University Press, 551-563 (2005).
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No abstract.
Peltola, E., R. Wanninkhof, R. Feely, R. Castle, D. Greeley, J.-Z. Zhang, F. Millero, N. Gruber, J. Bullister, and T. Graham. Inorganic carbon, nutrient, and oxygen data from the R/V Ronald H. Brown Repeat Hydrography Cruise in the Atlantic Ocean: CLIVAR CO2 section A16N_2003a (4 June-11 August 2003), A. Kozyr (ed.). Oak Ridge National Laboratory/Carbon Dioxide Information Analysis Center, ORNL/CDIAC-149, NDP-085, 36 pp. (2005).
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This report presents methods and analytical and quality control procedures for nutrient, oxygen, and inorganic carbon system parameters performed during the A16N_2003a cruise, which took place from June 4 to August 11, 2003 aboard NOAA Ship R/V Ronald H. Brown under auspices of the National Oceanic and Atmospheric Administration (NOAA). The first hydrographic leg (June 19-July 10) was from Reykjavik, Iceland, to Funchal, Madeira, Portugal along the 20°W meridian, and the second leg (July 15-August 11) continued operations from Funchal, Portugal to Natal, Brazil, on a track southward and ending at 6°S, 25°W. The research was the first in a decadal series of repeat hydrography sections jointly funded by NOAA and the National Science Foundation (NSF) as part of the CLIVAR/CO2/hydrography/tracer program. Samples were taken from up to 34 depths at 150 stations. The data presented in this report includes the analyses of water samples for total inorganic carbon (TCO2), fugacity of CO2 (fCO2), total alkalinity (TALK), pH, nitrate (NO3), nitrite (NO2), phosphate (PO4), silicate (SiO4), and dissolved oxygen (O2). The R/V Ronald H. Brown A16N_2003a data set is available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center (CDIAC). The NDP consists of the oceanographic data files and this printed documentation, which describes the procedures and methods used to obtain the data.
Peng, T.-H. Anthropogenic CO2 in the ocean. Scientia Marina, 69(suppl. 1):85-96 (2005).
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The focus of this review article is on the anthropogenic CO2 taken up by the ocean. There are several methods of identifying the anthropogenic CO2 signal and quantifying its inventory in the ocean. The DELTA-C* method is most frequently used to estimate the global distribution of anthropogenic CO2 in the ocean. Results based on analysis of the data set obtained from the comprehensive surveys of inorganic carbon distribution in the world oceans in the 1990s are given. These surveys were jointly conducted during the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS). This data set consists of 9,618 hydrographic stations from a total of 95 cruises, which represents the most accurate and comprehensive view of the distribution of inorganic carbon in the global ocean available today. The increase of anthropogenic CO2 in the ocean during the past few decades is also evaluated using direct comparison of results from repeat surveys and using the statistical method of Multi-parameter Linear Regression (MLR). The impact of increasing oceanic anthropogenic CO2 on the calcium carbonate system in the ocean is reviewed briefly as well. Extensive studies of CaCO3 dissolution as a result of increasing anthropogenic CO2 in the ocean have revealed several distinct oceanic regions where the CaCO3 undersaturation zone has expanded.
Piekle, R.A., Jr., C.W. Landsea, M. Mayfield, J. Laver, and R. Pasch. Hurricanes and global warming. Bulletin of the American Meteorological Society, 86(11):1571-1575 (2005).
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This paper reviews recent research on tropical cyclones and climate change from the perspective of event riskthe physical behavior of storms; vulnerabilitythe characteristics of a system that creates the potential for impacts, but are independent of event risk; and also outcome riskthe integration of considerations of vulnerability with event risk to characterize an event that causes losses. The paper concludes that with no trend identified in various metrics of hurricane damage over the 20th century, it is exceedingly unlikely that scientists will identify large changes in historical storm behavior that have significant societal implications, though scientists may identify discernible changes in storm behavior. Looking to the future, until scientists conclude (a) that there will be changes to storms that are significantly larger than observed in the past, (b) that such changes are correlated to measures of societal impact, and (c) that the effects of such changes are significant in the context of inexorable growth in population and property at risk, then it is reasonable to conclude that the significance of any connection of human-caused climate change to hurricane impacts necessarily has been and will continue to be exceedingly small.
Powell, M.D., G.A. Soukup, S. Cocke, S. Gulati, N. Morisseau-Leroy, S. Hamid, N.M. Dorst, and L. Axe. State of Florida hurricane loss projection model: Atmospheric science component. Journal of Wind Engineering and Industrial Aerodynamics, 93(8):651-674 (2005).
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The State of Florida has developed an open, public model for the purpose of probabilistic assessment of risk to insured residential property associated with wind damage from hurricanes. The model comprises atmospheric science, engineering, and financial/actuarial components and is planned for submission to the Florida Commission on Hurricane Loss Projection Methodology. The atmospheric component includes modeling the track and intensity life cycle of each simulated hurricane within the Florida threat area. When a model storm approaches within a damage threshold distance of a Florida zip code location, the wind field is computed by a slab model of the hurricane boundary layer coupled with a surface layer model based on the results of recent GPS sonde research. A time series of open terrain surface winds is then computed for each zip code in the threatened area. Depending on wind direction, an effective roughness length is assigned to each zip code based on the upstream fetch roughness as determined from remotely sensed land cover/land use products. Based on historical hurricane statistics, thousands of storms are simulated allowing determination of the wind risk for all residential zip code locations in Florida. The wind risk information is then provided to the engineering and loss models to assess damage and average annual loss, respectively.
Proni, J.R., V. Fox-Norse, S.J. Stamates, and J.F. Craynock. Innovative applications of ocean acoustics and other technologies for marine water quality monitoring and assessment: Effluent plume studies of the MWRA Outfall. Proceedings, 14th Biennial Coastal Zone Conference, New Orleans, LA, July 17-21, 2005. NOAA Coastal Services Center, CD-ROM, 7 pp. (2005).
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No abstract.
Rudnick, D.T., P.B. Ortner, J.A. Browder, and S.M. Davis. A conceptual ecological model of Florida Bay. Wetlands, 25(4):870-883 (2005).
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Florida Bay is a large and shallow estuary that is linked to the Everglades watershed and is a target of the Greater Everglades ecosystem restoration effort. The conceptual ecological model presented here is a qualitative and minimal depiction of those ecosystem components and linkages that are considered essential for understanding historic changes in the Bay ecosystem, the role of human activities as drivers of these changes, and how restoration efforts are likely to affect the ecosystem in the future. The conceptual model serves as a guide for monitoring and research within an adaptive management framework. Historic changes in Florida Bay that are of primary concern are the occurrence of seagrass mass mortality and subsequent phytoplankton blooms in the 1980s and 1990s. These changes are hypothesized to have been caused by long-term changes in the salinity regime of the Bay that were driven by water management. However, historic ecological changes also may have been influenced by other human activities, including occlusion of passes between the Florida Keys and increased nutrient loading. The key to Florida Bay restoration is hypothesized to be seagrass community restoration. This community is the central ecosystem element, providing habitat for upper trophic level species and strongly influencing productivity patterns, sediment resuspension, light penetration, nutrient availability, and phytoplankton dynamics. An expectation of Everglades restoration is that changing patterns of freshwater flow toward more natural patterns will drive Florida Bay's structure and function toward its pre-drainage condition. However, considerable uncertainty exists regarding the indirect effects of changing freshwater flow, particularly with regard to the potential for changing the export of dissolved organic matter from the Everglades and the fate and effects of this nutrient source. Adaptive management of Florida Bay, as an integral part of Everglades restoration, requires an integrated program of monitoring, research to decrease uncertainties, and development of quantitative models (especially hydrodynamic and water quality) to synthesize data, develop and test hypotheses, and improve predictive capabilities. Understanding and quantitatively predicting changes in the nature of watershed-estuarine linkages is the highest priority scientific need for Florida Bay restoration.
Sabine, C.L., R.M. Key, A. Kozyr, R.A. Feely, R. Wanninkhof, F.J. Millero, T.-H. Peng, J.L. Bullister, and K. Lee. Global ocean data analysis project (GLODAP): Results and data. Oak Ridge National Laboratory/Carbon Dioxide Information Analysis Center, ORNL/CDIAC-145, NDP-083, 110 pp. (2005).
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During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment, the Joint Global Ocean Flux Study, and the Ocean Atmosphere Carbon Exchange Study. Most of the cruises included various inorganic carbon species among the suite of routinely measured parameters. Both during and after the field work, a group of U.S. scientists collaborated to synthesize the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Both measured results and calculated quantities were merged into common-format data sets, segregated by ocean. The carbon data were subjected to rigorous secondary quality control procedures, beyond those typically performed on individual cruise data, to eliminate systematic biases in the basin-scale compilations. For comparison purposes, each ocean data set included results from a small number of high-quality historical cruises. The calibrated 1990s data were used to estimate anthropogenic CO2, potential alkalinity, chlorofluorocarbon (CFC) water mass ages, CFC partial pressure, bomb-produced radiocarbon, and natural radiocarbon. The calibrated-merged data were used to produce objectively gridded global property maps designed to match existing climatologies for temperature, salinity, oxygen, and nutrients. Both the data sets and the gridded products are available from the Carbon Dioxide Information Analysis Center (CDIAC). Here we summarize important details of the data assembly, calibration, calculations, and mapping. The synthesis was carried out one ocean at a time, progressing from the Indian to the Pacific and ending with the Atlantic. The entire synthesis required about five years. During that period, new methods were developed and old ones modified. At the same time, the data set itself changed and expanded. Many of the GLODAP results are already published. Rather than repeat what is published, we concentrate here on summarizing important details of the data assembly and mapping. In particular, we focus on the procedural differences that evolved as the individual basin data sets were compiled and developments in the data set that have not been covered in the individual publications. Some of the GLODAP publications are attached as appendices. The GLODAP data set described here (Gv1.1) is available free of charge as a numeric data package (NDP-83) from CDIAC. The data, and any subsequent updates, are also available through the GLODAP web site (http://cdiac.ornl.gov/oceans/glodap/Glodap_home.htm). The GLODAP bottle data files are available in flat ASCII file data format, in Ocean Data View (ODV) format, and through the CDIAC live access server (LAS); the gridded data files are available in flat ASCII and NetCDF data file formats and through CDIAC LAS.
Schmid, C. Impact of combining temperature profiles from different instruments on an analysis of mixed layer properties. Journal of Oceanic and Atmospheric Technology, 22(10):1571-1587 (2005).
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For a joint analysis of temperature profiles from floats, expendable bathythermographs (XBTs), and other instruments (e.g., thermistor chains), the consistency of the profiles from the different sources needs to be ensured to avoid results with systematic errors. In this study, profiles from the different instrument types are compared after they passed through a series of quality control tests. The different methods for quality control are presented. After ensuring that only high-quality profiles remain in the dataset, a statistical analysis of the temperature differences between adjacent profiles (in space and time) is performed. Potential regional differences, as well as possible differences between the various float types, are addressed. Finally, the impact of combining the profiles from floats with those from other instruments on gridded fields of the mixed layer temperature, thickness, and heat budget is discussed. It is found that the joint analysis yields more reliable results for the gridded fields and the heat storage rate. A large part of this improvement is a result of the reduced seasonal bias.
Schmid, C., B. Bourles, and Y. Gouriou. Impact of the equatorial deep jets on estimates of zonal transport in the Atlantic. Deep-Sea Research, Part II, 52(3-4):409-428 (2005).
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The structure and variability of the zonal equatorial flow in the Atlantic is studied on the basis of velocity profiles obtained with lowered Acoustic Doppler Current Profilers during multiple surveys. The vertical extent of the zonal currents is found to vary considerably. It can be as small as 100 m or as large as 1000 m. In the Atlantic, vertical scales of 400-600 m have been associated with the equatorial deep jets (they are also frequently called deep jets or stacked jets). Typical amplitudes of the zonal velocity are about 20 cm s-1. An analysis of quasi-synoptic surveys indicates that the zonal extent of most jets is likely to be at least 27°. They can rise or deepen from west to east, although the deepening was observed more often and is often more pronounced. The west to east deepening can be as large as 320 m/10°. Basin-wide mean depth changes of the jets are mostly on the order of 50 m/10°, and the largest depth changes are typically observed between 35° and 23°W. The existence of these changes indicates that vertically propagating, equatorially trapped, waves might be one cause for the jet structure. However, the dependence of the slope on the longitude indicates that other processes must be involved as well. The typical vertical extent of the jets is small enough to result in several direction changes of the zonal flow in the Antarctic Intermediate Water (AAIW) and the North Atlantic Deep Water (NADW) layer. From transport estimates for 14 meridional sections it is found that the transport for the westward component of the flow within the AAIW layer (500-1000 m) can be as large as -24 Sv (1Sv = 106 m3 s-1) within 1° of the equator. For the eastward component of the flow in the AAIW layer the transport can be as large as 8 Sv. Adding the transport components for each section results in a range of total AAIW transports from -24 to 7 Sv. This suggest that the annual mean transport of AAIW is westward. The only months with eastward total transports are June and July. This is consistent with earlier Lagrangian and some other observations that indicated that the AAIW flow along the equator is governed by an annual cycle. In the NADW layer (1200-3900 m) the transport for the westward (eastward) flow can be as large as -25 Sv (23 Sv) within 1° of the equator. This results in a range of total NADW transports from -10 to 18 Sv. The variations of the total transports of AAIW and NADW are anti-correlated, with a correlation coefficient of -0.86. Since only eight sections reached deep enough to allow transport estimates in the NADW layer, it is more difficult to come to a conclusion about the mean transport in this layer than for the transport in the AAIW layer (for the latter layer 14 sections were available). Nevertheless, the obtained estimates suggest that the total NADW transport may be eastward.
Shaji, C., C. Wang, G.R. Halliwell, and A. Wallcraft. Simulation of tropical Pacific and Atlantic Oceans using a Hybrid Coordinate Ocean Model (HYCOM). Ocean Modelling, 9(3):253-282 (2005).
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The climatological annual cycle of the tropical Pacific and Atlantic Oceans is simulated using the HYbrid Coordinate Ocean Model (HYCOM) configured in a non-uniform horizontal grid spanning 30°S-65.5°N and 102°E-15°E. The model is initialized with climatological summer temperature and salinity and is forced by climatological atmospheric fields derived from the COADS and ECMWF ERA-15 reanalysis. The model is spun up for 20 years to reach a reasonable steady state in the primary region of interest from 20°S to 20°N, and year 20 is analyzed. The COADS simulation is primarily analyzed because it is slightly better in more respects than the ECMWF simulation, particularly in the representation of upper-ocean thermal structure. The model generally reproduces the seasonal variability of major circulation features in both oceans reasonably well when compared to climatologies derived from several observational datasets (surface drifters, TAO mooring array, COADS, Levitus, Pathfinder SST), and when compared to other model simulations. Model evaluation is complicated by the fact that the different climatologies, including the atmospheric reanalysis climatologies that drive the model, are averaged over different time intervals. In the tropics, the model thermocline reproduces the observed zonal slopes and meridional ridges/troughs in the thermocline. The simulated Equatorial Undercurrent compares favorably to observations, but is slightly deeper than observed. The model overestimates temperature in the Pacific warm pool regions, both west and east, by more than 1°C when compared to all observed climatologies. The model also tends to overestimate temperature in the eastern equatorial cold tongues in both the Atlantic and Pacific, with this overestimate being confined to a very small region of the far eastern Pacific during winter. This overestimate varies substantially depending on which observed climatology is used for the comparison, so model limitations are only partly responsible for the simulated-observed temperature differences in the cold tongues.
Shoosmith, D.R., M.O. Baringer, and W.E. Johns. A continuous record of Florida Current temperature transport at 27°N. Geophysical Research Letters, 32(23):L23603, doi:10.1029/2005GL024075 (2005).
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As part of a newly funded international program to monitor ocean heat transport at mid-latitudes in the North Atlantic, a continuous estimate of the temperature transport of the Florida Current is required. Since 1982, volume transports have been inferred from voltage measurements monitored by submarine telephone cables across the Straits of Florida. Electromagnetic induction theory suggests that the cable voltage should actually give a more direct measure of conductivity transport than pure volume transport. Due to the strong dependence of conductivity on temperature, this would, in theory, result in a direct and continuous estimate of the Florida Current temperature transport. This hypothesis is investigated using data from a large number of temperature and velocity sections (58) across the Florida Current at the cable location, leading to a new calibration of the voltage signal for the temperature transport of the Florida Current, crucial for trans-basin heat flux estimates.
Smith, R.H., E. Johns, P.B. Ortner, T.N. Lee, C.R. Kelble, and N. Melo. Satellite-tracked surface drifter trajectories reveal the spatial and temporal current variability of south Florida. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 148-149 (2005).
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No abstract.
Smith, R.H., E.M. Johns, S.R. Cummings, P.B. Ortner, C.R. Kelble, N. Melo, and T.N. Lee. The influence of the 2005 hurricane season on water quality in Florida Bay and surrounding coastal waters. Proceedings, 2005 Florida Bay and Adjacent Marine Systems Science Conference, Duck Key, FL, December 11-14, 2005. University of Florida, 146-147 (2005).
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No abstract.
Soneira, G. AMVER/SEAS 2000 update, June 2005. Mariners Weather Log, 49(2):8-9 (2005).
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No abstract.
Susskind, J., and R. Atlas. Atmospheric soundings from AIRS/AMSU in partial cloud cover. In Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XI, S.S. Shen and P.E. Lewis (eds.). Proceedings, SPIE, 5806:587-598 (2005).
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