Interannual variations of light-absorbing particles in snow on Arctic sea ice

Samples of snow on sea ice were collected in springtime of the 6 years 2008-2013 in the region between Greenland, Ellesmere Island, and the North Pole (82 degrees N -89 degrees N, 0 degrees W-100 degrees W). The meltwater was passed through filters, whose spectral absorption was then measured to determine the separate contributions by black carbon (BC) and other light-absorbing impurities. The median mixing ratio of BC across all years' samples was 4 +/- 3 ng g(-1), and the median fraction of absorption due to non-BC absorbers was 36 +/- 11%. Variances represent both spatial and interannual variability; there was no interannual trend in either variable. The absorption Angstrom exponent, however, decreased with latitude, suggesting a transition from dominance by biomass-burning sources in the south to an increased influence by fossil-fuel-burning sources in the north, consistent with earlier measurements of snow in Svalbard and at the North Pole.