MEASUREMENT OF ATMOSPHERIC AEROSOLS IN THE MARINE BOUNDARY LAYER

Principal Investigator: T. P. Carsey

Objective: Determine processes controlling the chemical composition of boundary layer marine aerosols

Rationale: The chemical composition of marine aerosols has been the subject of a number of useful investigations, including the evaluation of long-range transport of anthropogenic constituents on the chemistry of the remote marine boundary layer (e.g., Whelpdale et al., 1994; Galloway et al., 1992). an understanding of gas-particle interactions (Ottley and Harrison, 1992; Pszenny, 1992), and the possible effect on primary productivity in the sea surface waters (Michaels et al., 1993). The effort at AOML/OCD has been aimed as using size-segregated aerosol chemical data to answer question concerning gas-to- particle reactions and depositional effects on the ocean.

Method: Size-segregated aerosol chemical data are obtained on open-ocean ship cruises and interpreted in the context of mesoscale meteorology via back trajectories and related chemical data. Aerosol samples are obtained with a six-stage Sierra high-volume cascade impactor or bulk sampler unit housed in identical anodized aluminum shelters. The equipment is usually mounted on a 10-m air sampling tower approximately 20 m above the water line of the NOAA research ship MALCOLM BALDRIGE. The 50% cut sizes (Dp50) for the cascade impactor as specified by the manufacturer are 3.6, 1.5, 0.75, 0.48, and 0.24 um radius for impactor stages 1-5; stage 6 collects all aerosols < 0.24 um. Samples are analyzed by ion chromatography for anions (SO4

, NO3-, Cl-, MSA [methane sulfonic acid]) and cations (Na

, K

, NH4

). In addition, non-seasalt sulfate (nssSO4

) and chloride deficit (defCl-) are computed (Carsey et al., 1995)

Accomplishment:
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 concentrations of nitrate, sulfate, and MSA ranged from 1-30, 5-150 and 0.25-3.0 nMol/m

(resp). The sulfate budget was found to be primarily influenced by anthropogenic sulfur (Pszenny et al., 1994; Carsey et al, 1994).

1993 North Atlantic Cruise
In 1993, OCD organized a cruise in the North Atlantic (Iceland to Miami). The accompanying graphic shows the concentration of non-seasalt sulfate (nssSO4) versus time (Carsey et al., 1995). Chemical and aerosol results are currently being prepared for publication.

1995 Atlantic / Indian Ocean Cruise
Bulk Aerosol samples were obtained during the Miami-South Africa stage of the 1995 Indian Ocean cruise and have been analyzed at AOML. Results are currently being processed. The bulk aerosol sampler aboard the MALCOLM BALDRIGE has continued to obtain bulk samples for subsequent analysis.

Key reference:
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, V. B. Ross, and M. Springer-Young. Atmospheric Chemistry Measurements during Leg 4 (RITS) of the 1993 North Atlantic Cruise. NOAA Data Report (in press, 1995).

Galloway, J., J. Penner, C. Atherton, J. Prospero, H. Rodhe, R. Artz, Y. Balkanski, H. Bingemer, R. Broast, S. Bergermeister, G. Charmichael, J. Chang, R. Charlson, S. Cober, W. Ellis, Jr., C. Fischer, J. Hales, D. Hastie, T. Iversen, D. Jacob, K. John, J. Johnson, P. Kasibhatla, J. Langner, J. Lelieveld, H. Levy, II, F. Lipschultz, J. Merrill, A. Michaels, J. Miller, J. Moody, J. Pinto, A. Pszenny, P. Spiro, L. Tarrason, S. Turner, and D. Whelpdale, 1992. Global Biogeochem. Cyc. 6, 77-100.

Huebert, B. J., A. Pszenny, and B. Blomquist, 1994. The ASTEX/MAGE experiment. J. Geophys. Res. (submitted).

Michaels, A., D. Siegel, R. Johnson, A. Knap, and J. Galloway, 1993. Episodic inputs of atmospheric nitrogen to the Sargasso Sea: contributions to new production and phytoplankton blooms. Global Biogeochem. Cyc. 7, 339-351.

Ottley, C., and R. Harrison, 1992. Atmosph. Env. 26A, 1689-1699.

Pszenny, A. A., 1992. Particle size distributions of methanesulfonate in the tropical Pacific marine boundary layer. J. Atm. Chem. 14, 273-284.

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).

Stunder, J., Artz, R., Rolph, G., Harris, J., and Merrill, J., 1990. Summary of meteorological conditions over the North Atlantic Ocean during GCE/CASE/WATOX Global Biogeochem. Cyc. 4, 121-132.

Whelpdale, D. M., and J. N. Galloway, 1994. Sulfur and reactive nitrogen oxide fluxes in the North Atlantic atmosphere. Global Biogeochem. Cyc. 8, 481-493, 1994.

Click here to return to the AOML project overview page.
Click here to return to the Predict & Assess Decadal to Centennial Change page.