OBSERVATIONS OF THE ATMOSPHERIC SULFUR CYCLE ON SAGA-3

During the Soviet/American Gases and Aerosols (SAGA) 3 program in Febr uary and March 1991 we measured a wide variety of sulfur compounds sim ultaneously in the equatorial Pacific marine boundary layer. We made m easurements of atmospheric dimethyl sulfide (DMS), sulfur dioxide (SO2 ), and size-resolved aerosol non-sea-salt sulfate (NSS), and methane s ulfonate (MSA). Some of our observed ratios contradict commonly held v iews of the marine sulfur cycle: the large DMS/NSS ratio implies that NSS may not be the primary product of DMS oxidation under some conditi ons. We also found MUCh More DMS than SO2, which may suggest that SO2 is not always an intermediate in DMS oxidation. The small SO2/NSS rati o also supports the idea that most NSS was not formed from SO2. Althou gh our measured ratios of MSA/NSS were similar to previous observation s in this region, much of the MSA was contained on supermicron particl es, in contrast to both the NSS and the earlier MSA observations at hi gher latitudes. This implies that MSA/NSS ratios in ice cores may not accurately reflect the MSA/NSS ratios in their source areas.