| Abstract |
To investigate the oxidation chemistry of dimethylsulfide (DMS) in the marine atmosphere, atmospheric DMS, SO2, as well as several DMS oxidation products in aerosol phase such as non-sea-salt sulfate (nss-SO4), methanesulfonate (MSA), and dimethylsulfoxide (DMSOp) have been measured during the Albatross campaign in the Atlantic Ocean from October 9 to November 2, 1996. Long-range transport, local sea-to-air flux of DMS (F DMS), marine boundary layer (MBL) height variation, and photochemistry were found to be the major factors controlling atmospheric DMS concentration which ranged from 29 to 396 parts per trillion by volume (pptv) (mean of 120±68 pptv) over the cruise. The spatial variability of MSA and DMSOp follows the latitudinal variations of F DMS. A 2-day period of intensive photochemistry associated with quite stable atmospheric conditions south of the equator allowed the observation of anticorrelated diurnal variations between DMS and its main oxidation products. A chemical box model describing sulfur chemistry in the marine atmosphere was used to reproduce these variations and investigate coherence of experimentally calculated fluxes F DMS with observed DMS atmospheric concentrations. The model results reveal that the measured OH levels are not sufficient to explain the observed DMS daytime variation. Oxidizing species other than OH, probably BrO, must be involved in the oxidation of DMS to reproduce the observed data. |
