CCN FORMATION FROM DMS OXIDATION WITHOUT SO2 ACTING AS AN INTERMEDIATE

An alternate pathway for generating cloud condensation nuclei (CCN) in the remote marine boundary layer (MBL) from the oxidation of biogenic ally-derived dimethyl sulfide (DMS) is proposed. This pathway invokes the production of H2SO4 from DMS without SO2 serving as an intermediat e in the oxidation sequence. The H2SO4 thus produced then undergoes bi molecular nucleation to form tiny sulfate condensation nuclei (CN). Th ese CN rapidly grow to sizes sufficiently large to act as CCN. While C CN production from SO2. appears to be inefficient, model calculations indicate that the alternate pathway is capable of generating significa nt numbers of new CCN in the MBL within a two to three day time period . The alternate pathway also suggests a strong coupling between oceani c emissions of DMS and the number of CCN in die MBL.