Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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InSAR Measurements of Crustal Deformation Near Jakobshavn Isbrae, Greenland

Lin Liu, John Wahr, Ian Howat, Shfaqat Abbas Kahn, and Ian Joughin

Jakobshavn Isbrae, one of the largest outlet glaciers in Greenland, has been undergoing significant changes in dynamic behaviors, characterized by dramatic thinning, rapid acceleration in flow speed and large glacier terminus retreats, in recent years. These changes are probably related to an observed climate warming in this area. GPS measurements at two sites (KAGA and ILUL) near Jakobshavn Isbrae indicate crustal uplift caused by the dramatic unloading of ice. To place a constraint on ice loss estimate, we apply InSAR (Interferometric Synthetic Aperture Radar) to Canadian RADARSAT-1 SAR data to study crustal deformation (2004-2007) over a 50 km x 100 km area near Jakobshavn Isbrae. Because both the orbital errors and the crustal deformation have long-wavelength spatial patterns, the absolute crustal motion cannot be determined. Instead, we empirically fit satellite baselines and remove the long-wavelength orbital errors from both the data and a deformation model based on independent ice loss measurements. Three ground control points, including the crustal motion measurements at the permanent GPS station KAGA, are used as in the baseline fitting, using the method of Lagrange Multipliers. Three sets of comparisons show good agreements between the InSAR results and the model. The residuals are useful for further improvement of the ice mass loss model derived from airborne laser altimetry measurements.