The accuracy of satellite radar altimeter data over the Greenland Ice Sheet determined from airborne laser data

Abstract

The 336 days of the geodetic phase of ERS‐1 provides dense coverage, by satellite radar altimetry, of the whole of the Greenland ice sheet. These data have been used to produce a digital elevation model of the ice sheet. The errors present in the altimeter data were investigated via a comparison with airborne laser altimeter data an absolute accuracy typically in the range 2–10 cm ± 10 cm. Comparison of differences between the radar and laser derived elevations, showed a correlation with surface slope. The difference between the two data sets ranged from 84 cm ± 79 cm for slopes below 0.1 degrees, to 10.3 m ± 8.4 m for a slope of 0.7 degrees (the half power beam‐width of the ERS‐1 radar altimeter). An explanation for the behaviour of the difference as a function of surface slope is given in terms of the pattern of surface roughness on the ice sheet.