HEAT BUDGET AND DECAY OF CLEAN AND SEDIMENT-LADEN SEA ICE OFF THE NORTHERN COAST OF ALASKA

摘要

The heat budget and decay of sea ice is strongly affected by the albedo of the surface in the melting season. Sea ice with a high sediment load, as often observed in Arctic coastal regions, has a much lower albedo than clean ice and snow, absorbing a higher fraction of incoming solar radiation. Here, we report measurements of warming and ablation of clean and sediment-laden ice near Barrow, Alaska. After melting of the snow cover, albedos of 0.41 and 0.29 were observed on clean and dirty sea ice. Higher extinction coefficients of sediment-laden sea ice result in absorption of 74 % of the incoming solar radiation within the uppermost 20 cm of the ice. Temperature records show that seasonal warming of the sediment-laden ice is delayed significantly by absorption of radiation in the uppermost layers. However, our observations also indicate that despite greater snow depths over sediment-laden ice, surface ablation rates were higher for dirty than for clean ice.