HR: 14:55h
AN: C33A-06    [Abstracts]
TI: Black Carbon in Arctic Snow: Preliminary Results from Recent Field Measurements
AU: * Warren, S G
EM: sgw@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences, MS 351640, University of Washington, Seattle, WA 98195, United States
AU: Grenfell, T C
EM: tcg@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences, MS 351640, University of Washington, Seattle, WA 98195, United States
AU: Radionov, V F
EM: vradion@aari.nw.ru
AF: Arctic and Antarctic Research Institute, 38 Bering Street, St. Petersburg, LEN 199397, Russian Federation
AU: Clarke, A D
EM: tclarke@soest.hawaii.edu
AF: University of Hawaii, Department of Oceanography 1000 Pope Road, Honolulu, HI 96822, United States
AB: Annual snowpacks act to amplify variations in regional solar heating of the surface due to positive feedback processes associated with areal melting and precipitation. Small amounts of black carbon (BC) in the snow can reduce the albedo and modulate shortwave absorption and transmission affecting the onset of melt and heating of the snow pack. The effect of black carbon on the albedo of snow in the Arctic is estimated to be up to a few percent. The only prior survey of arctic snow was that of Clarke and Noone in 1983-84. We have begun a wide- area survey of the BC content of arctic snow in order to update and expand the 1983/84 survey. Samples of snow have been collected in mid to late spring when the entire winter snowpack was accessible. The samples have been melted and filtered, and the filters analyzed for absorptive impurities. To date, sites in Alaska, Canada, Greenland, and in the Arctic Basin have been sampled. In March and April 2007 we also carried out a field program at four sites in northwestern Russia as part of the International Polar Year. Preliminary results based on visual comparison with the standard filters indicate that the snow cover in arctic North America and the Beaufort Sea have lower BC concentrations now than 20 years ago while levels in Greenland are about the same. Background levels of BC in Russia are approximately twice those in North America consistent with modeling predictions of Flanner et al., 2007. More accurate values of absorption will be obtained by measurement of spectral transmission of the filters, which will also allow the relative contributions of BC and soil dust to be determined.
UR: http://www.atmos.washington.edu/sootinsnow
DE: 0726 Ice sheets
DE: 0736 Snow (1827, 1863)
DE: 0740 Snowmelt
DE: 0750 Sea ice (4540)
DE: 0764 Energy balance
SC: Cryosphere [C]
MN: 2007 Fall Meeting