Phillips, Thomas听1听;听Steffen, Konrad听2听;听Rajaram, Harihar听3
1听CIRES, ESOC, University of Colorado
2听CIRES, ESOC, University of Colorado
3听University of Colorado
The Greenland Ice Sheet experiences a large amount of melt each summer forming moulins and a well developed en-glacial water network. Is this en-glacial network a new network each year or does it remain at least partially open over winter, allowing the melt water of the following year to use the same network, thus enhancing efficiency of en-glacial water transport? We try to answer these questions by exploring the potential influence of the winter snow layers and water bodies in the ice at the end of the melt season on the thermal regime during the winter. During the summer months the short wave radiation warms the surface of the Greenland ice sheet generating surface melt. Melt water penetrating deep into the ice can potentially carry some of the energy to depth. In the Arctic regions snow plays a major role in protecting the underlying surface from losing too much energy to the cold winter atmosphere. In addition, if some of the water entering moulins and crevasses does not reach the bed, but is rather stored in water bodies within the ice at the end of the melt season, the ice sheet will experience a large local latent heat flux that may moderate the cooling of ice during the winter months. In this study we use temperature profiles of the upper 10 meters of ice as well as a two dimensional heat transfer model to simulate the seasonal thermal evolution of an ablation zone. This area of the Greenland Ice Sheet experienced annual snow thicknesses of approximately 80cm. We simulate the temperature variation with time and depth for different years considering the amount of available melt water and the insulating snow height in winter. The possibility of a positive feedback between ice sheet warming due to radiation and melt water in the summer, increased snow cover accumulation and reduced cooling in winter is discussed.
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