Open ocean DMS air/sea fluxes over the eastern South Pacific Ocean C. A. Marandino1,*, W. J. De Bruyn2, S. D. Miller3, and E. S. Saltzman1 1Dept. of Earth System Science, University of California, Irvine, Irvine, CA, USA 2Dept. of Physical Science, Chapman University, Orange, CA, USA 3Center for Atmospheric Research, SUNY, Albany, Albany, NY, USA *now at: IFM-GEOMAR Marnie Biogeochemie/Chemische Ozeanographie in Kiel, Germany
Abstract. Air/sea fluxes of dimethylsulfide (DMS) were measured by eddy correlation
over the Eastern South Pacific Ocean during January 2006. The cruise track
extended from Manzanillo, Mexico, along 110° W, to Punta Arenas, Chile.
Bulk air and surface ocean DMS levels were also measured and gas transfer
coefficients (kDMS) were computed. Air and seawater DMS measurements
were made using chemical ionization mass spectrometry (API-CIMS) and a
gas/liquid membrane equilibrator. Mean surface seawater DMS concentrations
were 3.8±2.2 nM and atmospheric mixing ratios were 340±370 ppt.
The air/sea flux of DMS was uniformly out of the ocean, with an average
value of 12±15 μmol m−2 d−1. Sea surface concentration
and flux were highest around 15° S, in a region influenced by shelf
waters and lowest around 25° S, in low chlorophyll gyre waters. The DMS
gas transfer coefficient exhibited a linear wind speed-dependence over the
wind speed range of 1 to 9 m s−1. This relationship is compared with
previously measured estimates of k from DMS, CO2, and dual tracer data
from the Atlantic and Pacific Ocean, and with the NOAA/COARE gas transfer
model. The model generated slope of k vs. wind speed is at the low end of
those observed in previous DMS field studies.
Citation: Marandino, C. A., De Bruyn, W. J., Miller, S. D., and Saltzman, E. S.: Open ocean DMS air/sea fluxes over the eastern South Pacific Ocean, Atmos. Chem. Phys., 9, 345-356, doi:10.5194/acp-9-345-2009, 2009.