Observations of the atmospheric sulfur cycle on SAGA 3

Abstract

During the Soviet/American Gases and Aerosols (SAGA) 3 program in February and March 1991 we measured a wide variety of sulfur compounds simultaneously in the equatorial Pacific marine boundary layer. We made measurements of atmospheric dimethyl sulfide (DMS), sulfur dioxide (SO2), and size‐resolved aerosol non‐sea‐salt sulfate (NSS), and methane sulfonate (MSA). Some of our observed ratios contradict commonly held views of the marine sulfur cycle: the large DMS/NSS ratio implies that NSS may not be the primary product of DMS oxidation under some conditions. 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 ratio also supports the idea that most NSS was not formed from SO2. Although our measured ratios of MSA/NSS were similar to previous observations in this region, much of the MSA was contained on supermicron particles, in contrast to both the NSS and the earlier MSA observations at higher latitudes. This implies that MSA/NSS ratios in ice cores may not accurately reflect the MSA/NSS ratios in their source areas.