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SURFACE ABLATION ON A FLOATING ICE TONGUE IN NORTHERN GREENLAND

CULLEN, NICOLAS J  CIRES, University of Colorado.
Huff, Russell  CIRES, University of Colorado.
Steffen, Konrad  CIRES, University of Colorado.

A combination of field data, remote sensing observations and modeling is enabling a detailed investigation of bottom and surface melt processes of a major outlet glacier in northern Greenland. The area of interest is the Petermann Gletscher (81 N, 60 W), one of the fastest flowing outlet glaciers in northern Greenland. The Petermann Gletscher is unique because it has a large floating section, or ice tongue, that is 20-km wide by 70-km long. To determine the mass balance of the floating section of the Petermann Gletscher both surface and bottom melting, as well as strain and tidal measurements, were made during 2 field seasons in 2002-3. Measurements from a transmitting automatic weather station installed on the floating section of the glacier before melt in 2002 show a surface lowering of 1.3 m yr-1, which agrees well with ablation stake data. The ablation over the entire floating section using a degree day model reveals that less than 2 km3 ice yr-1 is melted on the surface, which is about 15 % of total ice mass loss. This result confirms that basal melting is the most important process contributing to ice loss on the floating section of the Petermann Gletscher. Although surface melting does not appear to dominate the mass budget of the Petermann Gletscher, field observations indicate that it may be relevant towards weakening and fracturing the floating tongue.


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