Comparison of Greenland Ice Sheet topography measured by TOPSAR and airborne laser altimetry

A digital elevation model (DEM) produced from airborne interferometric synthetic aperture radar (TOPSAR) data of a 5 km/spl times/65 km region of the Greenland Ice Sheet is compared with multiple airborne laser altimeter profiles of the same surface. TOPSAR-derived elevation values were calculated on a 10 m/spl times/10 m grid. Surface topography at wavelengths greater than one kilometer is accurately reproduced. A planar adjustment of -8 m with along-track and cross-track tilts of 0.17 and 2.4 m/km, respectively, is required to match the two elevation data sets. Residual noise of the TOPSAR data at subkilometer wavelengths is less than two meters. This study underscores the need for independent elevation data for controlling TOPSAR elevation surveys.