A new DEM of the Austfonna ice cap by combining differential SAR interferometry with ICESat laser altimetry

We present a new digital elevation model (DEM) of the Austfonna ice cap in the Svalbard Archipelago, Norwegian Arctic. Previous DEMs derived from synthetic aperture radar (SAR) and optical shape-from-shading have been tied to airborne radio echo-sounding surface profiles from 1983 which contain an elevation-dependent bias of up to several tens of metres compared with recent elevation data. The new and freely available DEM is constructed purely from spaceborne remote sensing data using differential SAR interferometry (DInSAR) in combination with ICESat laser altimetry. Interferograms were generated from pairs of SAR scenes from the one-day repeat tandem phase of the European Remote Sensing Satellites 1/2 (ERS-1/2) in 1996. ICESat elevations from winter 2006-08 were used as ground control points to refine the interferometric baseline. The resulting DEM is validated against the same ground control points and independent surface elevation profiles from Global Navigation Satellite Systems (GNSS) and airborne laser altimetry, yielding root mean square (RMS) errors of about 10 m in all cases. This quality is sufficient for most glaciological applications, and the new DEM will be a baseline data set for ongoing and future research at Austfonna. The technique of combining satellite DInSAR with high-resolution satellite altimetry for DEM generation might also be a good solution in other glacier regions with similar characteristics, especially when data from TanDEM-X and CryoSat-2 become available.