Topography-driven variations in backscatter strength and depth observed over the Greenland Ice Sheet with InSAR

ERS radar observations of the Greenland Ice Sheet have yielded images characterized by small-scale (~10 km) variations in backscatter. While these variations are associated with topography, they are not due to local incidence angle differences, since the undulations in topography are small enough (~tens of meters in height) that changes in slope amount to less than a degree; moreover the variations are independent of look direction. These variations are then caused by differences in terrain scattering properties. To investigate this phenomenon further, the authors utilize all three products of interferometric processing: phase (for topography), power, and correlation. The correlation images also show these variations. They find that one side of the “hill” has greater backscatter but with less decorrelation due to volume scatter than the other side. Coupled with prevailing wind data, this corresponds to the leeward and windward side, respectively. Through simple modeling of the observed changes in power and correlation, they derive estimates of variations in grain size and accumulation rates, and find a ~40% drop in accumulation between the windward and leeward sides