Principal Investigator: T. P. Carsey
Collaborating scientist(s):
G. R. Harvey (retired)
P.-Y. Whung
M. Springer-Young (retired)
Objective: Determine processes controlling ozone (O3) and carbon monoxide (CO) concentrations in the remote marine boundary layer.
Rationale: Whereas the oceans are generally considered regions of ozone destruction, it is clear that elevated ozone from continental plumes can extend for very long distances into the marine boundary layer (Parrish et al., Science 259, 1436-1438, 1993). Measurements of O3 and CO (a monitor of continental influence and significant in hydroxyl radical chemistry) provide an important test of current understanding of tropospheric photochemistry. These data are also important constraints for global chemical models.
Method: Ozone and CO have been measured in remote regions of the Pacific, North and South Atlantic, and Indian Oceans. using a variety of state-of-the-art instruments. These data have been interpreted in the context of meteorological (Piotrowicz, et al., 1991; Carsey, et al., 1994) and simple photochemical models (Carsey, et al., 1995a. The task is a component of NOAA's Radiatively-Important Trace Species (RITS) program.
1992 ASTEX / MAGE Cruise
The OCD atmospheric chemistry group helped organize and participated in the NOAA component of the IGAC-sponsored ASTEX/MAGE experiment in the summer of 1992 aboard the R/V MALCOLM BALDRIGE (Hubert et al., 1994). The photochemical environment over the North Atlantic during the summer of 1992 was found to result in the destruction of ozone while encountering plumes of polluted air from the European and American continents, as well as during clean air episodes. O3/CO ratios were considerably higher than those observed in the continental U.S. and in Sable Island, indicating increased ozone probably arising from stratospheric input. (Carsey et al, 1995).

In a related study, measurements of hydrogen peroxide (H2O2) were obtained over the N. Atlantic Ocean during ASTEX/MAGE in conjunction with a research group from France. H2O2 is a significant component of reactions significant to ozone production and destruction.

O3 + hv arrow O(1D)
O(1D) + H2O arrow H2O2
H2O2 + hv arrow 2OH
HO2 +HO2 arrow H2O2 + O2
In the last equation, production of H2O2 competes with ozone production, i.e.,
HO2 +NO arrow NO2 + OH
NO2 + hv arrow O(3P)
O(3P) + NO arrow O3 + NO2

H2O2 was found to be uncorrelated with other chemistries except during Lagrangian #2, in which air was sampled which had originated over Europe a few days previous; during that episode H2O2 was low (due to competing reactions from HNO3 formation). The application of H2O2 as a clean air indicator, to complement black carbon and Radon, was also investigated (Martin et al., 1995).

1993 North Atlantic Cruise
In 1993, OCD organized a cruise in the North Atlantic (Iceland to Miami). In the accompanying graphic, the concentration of ozone as measured aboard the R/V Malcolm Baldrige during a cruise in the North Atlantic during September of 1993 (Carsey, et al., 1994b). Ozone concentrations averaged 31.7 ppbv (range 3.9 to 59.8 ppbv). Rapid elevations of ozone (and other concentrations) were observed at the onset of continental plumes on 6-Sept, 10-Sept, and 12-Sept. A complete description of the cruise data, including cruise information, sampling and analytical descriptions, and graphical and tabular data lists, is given in a data report (Carsey et al., 1995b). Chemical and aerosol results are currently being prepared for additional publications.

1995 Atlantic / Indian Ocean Cruise
OCD co-organized and participated in a research cruise in the North and South Atlantic Oceans and western Indian Ocean during winter / spring of 1995. The cruise track was designed to study the South Atlantic while biomass burning is at a minimum, as well as the Indian Ocean prior to monsoon development. Ozone has been measured beginning with departure from Miami in February and continuing for all legs of the cruise. During selected legs of the cruise, ozone and nitrogen dioxides were also measured, as well as ozone profiles using sondes (with R. Dickerson, U. Md.).

Key reference:
Carsey, T. P., M. L. Farmer, V. Ross III, M. Springer-Young, and M. Zetwo. Significant Trace Species in the Boundary Layer of the North Atlantic During September, 1993. Presented at the Fall, 1994 AGU meeting in San Francisco, CA, 5 Dec 1994 (Eos 75, 95, 1994).

Carsey, T. P., M. L. Farmer, C. J. Fischer, A. Mendez, A. A. Pszenny, V. Ross III, P.-Y. Whung, M. Springer-Young, and M. P. Zetwo. Atmospheric Chemistry Measurements from the 1992 ASTEX/MAGE Cruise, 30-May-1992 through 21-July 1992, Cruise Number 91-126. NOAA Data Report ERL AOML-26, 1994.

Carsey, T. P., M. L. Farmer, C. J. Fischer, A. Mendez, Victor B. Ross, M. Springer-Young, and M.P. Zetwo. Atmospheric Chemistry Measurements during Leg 4, 1993 North Atlantic Cruise, R/V Malcolm Baldrige. NOAA Data Report,  NOAA Data Report ERL AOML-28, 1996.

Carsey, T. P., D. D. Churchill, M. L. Farmer, C. J. Fischer, A. A. Pszenny, V. B Ross, E. S. Saltzman, M Springer-Young, and B. Bonsang. Nitrogen Oxides and Ozone Production in the North Atlantic Marine Boundary Layer. J. Geophys. Res. 102, 10653-10665, 1997.

Piotrowicz, S. R., H. Bezdek, G. Harvey, and M. Springer-Young. On the ozone minimum over the equatorial Pacific Ocean. J. Geophys. Res. 96, 18679-18687, 1991.

Pszenny, A. A., T. P. Carsey, P. Y. Whung, M. P. Zetwo, M. L. Farmer, and C. J. Fischer. Measurements of various chemical concentrations in the marine boundary layer during the 1992 ASTEX/MAGE experiment. Presented at the 1994 AGU Spring Meeting, May 25, 1994 (Eos 75, 89, 1994).

Martin, D., M. Tsivou, B. Bonsang, C.Abonnel, T. Carsey, M. Springer-Young, and A. Pszenny. H2O2 in the Marine Atmospheric Boundary Layer during the ASTEX/MAGE experiment in the eastern subtropical North Atlantic. J. Geophys. Res. 102, 6003-6015, 1997.

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