Contribution of light-absorbing impurities in snow to Greenland albedo decrease

The surface energy and mass balance of the Greenland Ice Sheet largely depends on the albedo of snow. The Greenland ice sheet albedo has declined over the past decade and this decrease has been attributed to enhanced snow metamorphism. However, satellite data from the multispectral sensors MODIS and MERIS revealed that the albedo at high elevation in springtime has also decreased in the most recent years. Using spectral analysis and a snow model, our study shows that this decrease can be explained by an increase in light-absorbing impurity content in snow. Several sources of impurities can be considered. Enhanced dust transport from snow free-areas in the Arctic that are experiencing earlier melting of seasonal snow cover may be a contributor to the increase. The impact of the albedo decrease on Greenland Ice Sheet mass balance is estimated using a detailed snow model.