Snow accumulation on Greenland estimated from ERS scatterometer data

Radar cross section measurements over Greenland by the scatterometer of the European Remote Sensing satellites (ERS-1 and ERS-2) between August 1991 and March 1997 have been analysed. For large areas especially in the transition region between the percolation and dry-snow zone an almost linear decrease of up to 0.75 dB/year in normalized radar cross section was observed. This reduction can be attributed to increasing attenuation of the radar backscatter due to dry-snow accumulation on the firn of the percolation zone. A 2-layer radar backscatter model accounting for the measurement parameters of the ERS scatterometers and considering a firn layer buried by dry-snow was used to estimate the thickness of the dry-snow layer and to derive a snow accumulation rate. The spatial pattern and absolute values of accumulation rates so inferred agree well with recent synthesis of ground-based observations.