Dimethyl sulfide in the arctic atmosphere

Dimethyl sulfide (DMS), sulfur dioxide, non-sea-salt sulfate, and various aerosol properties were measured during three field programs (two airborne and one ground-based) near Barrow and Deadhorse (Prudhoe Bay), Alaska. The two airborne sampling programs took place in spring and early summer, and the ground-based measurements spanned an entire summer. DMS concentrations in the Arctic atmosphere ranged from a few parts per trillion by volume (pptv) in spring and fall to higher values in summer (generally a few tens of pptv with occasional peaks of 100 to 300 pptv). In addition, DMS concentrations were measured during the spring near Resolute in seawater below the ice and in ice-algae and kelp cultures. The seawater samples taken from below the ice in spring had DMS concentrations comparable to those in other oceanic regions. Taken together, these measurements show that the Arctic Ocean is potentially a substantial source of DMS, which likely becomes important as sea ice melts in the early summer. Local atmospheric concentrations increased throughout the summer, peaking in August. In regions where accumulation mode aerosols have been scavenged (e.g., by low-level stratus clouds, which are common during the Arctic summer), evidence of rapid new particle production was observed. The seasonal cycle of atmospheric DMS closely resembles that of fine particles observed at Barrow, Alaska, and Alert, Northwest Territories, Canada. This finding indicates that DMS is likely an important precursor to the types of particles that dominate the background arctic aerosol in summertime. These results, together with those from several recently published studies of arctic aerosol, are combined to yield a consistent picture of the role of locally emitted DMS in the production of atmospheric aerosols in the Arctic in summer.