Interpreting the Mass Balance of the Greenland Ice Sheet

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Abstract OPP-9807521 van der Veen One of the major challenges in glaciology is to develop scenarios for the future evolution of polar ice sheets. This effort requires accurately measuring the current mass balance of the major ice sheets and an understanding of the causes of any imbalances. In this study, two-dimensional flow models will be developed and tested to aid in the interpretation of the mass balance results. The objective is to make interpretations of mass-balance results for the ice sheet if it should accrete, recede, or remain the same. Each of these scenarios for mass imbalance will be modeled so that the sensitivity of model predictions to parameter variations can be readily evaluated. The models will be applied to the Petermann and Humboldt glaciers in northwest Greenland, for which a suite of data is available that can be used to test and validate the models. An eight hundred year old ice core record will be used to help obtain a high-resolution climate record for the region. Existing data over the Petermann and Humboldt glaciers and their catchment basins will be analyzed to better understand glacier dynamics. The Petermann glacier is the main outlet glacier in northern Greenland, but very little is known about the dynamics of this fast-moving glacier. The lower 60 km is floating and appears to be moving unimpeded through the fjord. Above the grounding line, there is a marked change in surface topography overlying a deep subglacial trench. suggesting a change in flow. The longitudinal velocity profile becomes compressive downstream of the grounding line, but transverse velocity profiles indicate that lateral drag is not important in that region. Recent mapping of the position of the grounding line of the Petermann glacier indicates retreat.