CCN formation from DMS oxidation without SO[sub 2] acting as an intermediate

An alternate pathway for generating cloud condensation nuclei (CCN) in the remote marine boundary layer (MBL) from the oxidation of biogenically-derived dimethyl sulfide (DMS) is proposed. This pathway invokes the production of H[sub 2]SO[sub 4] from DMS without SO[sub 2] serving as an intermediate in the oxidation sequence. The H[sub 2]SO[sub 4] thus produced then undergoes bimolecular nucleation to form tiny sulfate condensation nuclei (CN). These CN rapidly grow to size sufficiently large to act as CCN. While CCN production from SO[sub 2] appears to be inefficient, model calculations indicate that the alternate pathway is capable of generating significant numbers of new CCN in the MBL within a two to three day time period. The alternate pathway also suggests a strong coupling between oceanic emissions of DMS and the number of CCN in the MBL. 31 refs., 3 figs.