Physics Open ocean DMS air / sea fluxes over the eastern South Pacific Ocean
- ISSN: 1680-7324
- DOI: 10.5194/acp-9-345-2009
Air/sea fluxes of dimethylsulfide (DMS) were measured by eddy correlation over the Eastern South Pa- cific 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 com- puted. Air and seawater DMS measurements were made us- ing chemical ionization mass spectrometry (API-CIMS) and a gas/liquid membrane equilibrator. Mean surface seawa- ter DMS concentrations were 3.8±2.2nM 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±15µmolm−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 lin- ear wind speed-dependence over the wind speed range of 1 to 9ms−1. This relationship is compared with previ- ously 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.