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Nicolle Britland

Nasa image of Petterman Glacier taken 30/8/07MSc in Geography


Surface climatology and ablation on the floating section of the Petermann Glacier, Greenland, 2002-2006


Dr Nicolas Cullen


The Greenland Ice Sheet is currently experiencing unprecedented warming, which has led to significant changes in its mass balance. While the interior of the ice sheet is thought to be in balance, or even thickening, the margins are thinning at a rate exceeding the accumulation occurring at higher elevations. This thinning is most pronounced on outlet glaciers, many of which form floating ice tongues. Theses ice masses are not only subjected to warming from the atmosphere, but also from the ocean below. The Petermann Glacier is the largest of these, with a length of up to 70 km being afloat. Previous studies have established that basal melt into the ocean is the predominant form of mass loss; however there is no existing data describing the surface melt regime, nor the climatology. This study aims to fill these knowledge gaps, primarily using Greenland Climate Network (GCNet) data from an AWS located on the floating surface. The data record spans from Julian Day 156, 2002 through to JD 121, 2006. Measurements of incoming and outgoing shortwave radiation, net radiation, relative humidity, air temperature and wind speed at two levels, as well as surface height measurements will be used to construct a comprehensive climatology for this location. A proxy-air temperature record has been established with data from Alert Station located on Ellesmere Island, from 1951 to present. The resulting timeseries indicates greatest warming has occurred during autumn and winter months over this period. It is intended that a degree day model will be produced, using surface height and albedo data to calculate the number of positive degree days, and degree day factors for ice and snow. This will then be distributed across the entire ice tongue using a DEM. Recent satellite images show a series of large cracks traversing the glacier, and are expected to cause extensive ice loss when they propagate the entire width. Which such large changes imminent, an understanding of the surface processes occurring prior to (potential) collapse will be of importance in understanding the extent to which surface melt affects the stability of this ice tongue.




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