Black carbon in Arctic snow and ice and its effect on surface albedo

University Of Washington, Seattle WA

Investigators

Abstract

Warren 0612636 Two decades ago, measurements of the black carbon (BC) content of snow on land and sea in the western Arctic suggested that BC was responsible for possible reductions of albedo of 0-4%. However, more recent measurements suggest that the BC content of snow in the Arctic Ocean may have changed. The PIs propose an updated, pan-arctic survey, during which samples will be taken near the time of maximum snow depth on the Arctic Ocean, in tundra areas of Russia, Alaska, and Canada, in both wet-snow and dry-snow zones of the Greenland Ice Sheet, and on ice caps in Iceland. Both project personnel and volunteer researchers will be involved in the sampling. Glacier ice will be sampled in summer in the ablation zone of the Greenland Ice Sheet, since there is evidence that its albedo is reduced by BC. Snow samples will be taken at several vertical levels through the snowpack. At one or more locations snow samples will be collected over the course of the melting season, to document the vertical redistribution of BC. BC is usually hydrophobic. As the snow melts, BC may tend to concentrate at the surface, where it has a greater effect on albedo than if uniformly distributed. The effect of BC on the surface albedo will be estimated both regionally and seasonally. Air sampling concurrent with snowfall events will be carried out at one or more locations, to determine the scavenging ratio, which is needed in atmospheric transport models that link emissions of aerosols to deposition in precipitation. The distribution of BC throughout the arctic snowmass and its seasonal variability may have important effects on climate variability due to their influence on albedo. The information provided by this project will be useful both for the further development and for the skill assessment of climate models.