Effects of aqueous organosulfur chemistry on particulate methanesulfonate to non-sea salt sulfate ratios in the marine atmosphere

Abstract

The oxidation of dimethyl sulfide (DMS, CH 3 SCH 3) in the atmosphere could influence climate by affecting cloud condensation nuclei concentrations and cloud properties. This work focuses on elucidating the importance of DMS-cloud interactions, especially the poorly understood aqueous phase chemical transformations of DMS oxidation products. For this purpose, we incorporate an oxidation mechanism of atmospheric DMS and its products within the modeling framework of a trajectory ensemble model (TEM). Both marine cumulus and stratocumulus clouds are considered. It is found that the aqueous phase reactions of sulfur compounds contribute >97% of methanesulfonate (MS, CH 3 (O)S(O)O -) and >80% of non-sea salt sulfate (NSS) production in particles and that about 30% of total MS and NSS production is from the aqueous phase oxidation of the organosulfur compounds. The aqueous phase methanesulfinate (MSI, CH 3 S(O)O -) + Cl 2 - reaction is found to be more important than MSI + OH as an MS source. The MS + OH reaction could consume almost 20% of MS and produce about 8% of total NSS within 3 days under typical marine atmospheric conditions. Copyright 2006 by the American Geophysical Union.