Ice-Sheet Thickening Observed by Satellite Altimetry (Abstract)

Abstract

The first set of sequential measurements by two different sets of satellite altimetry data indicate that the Greenland ice sheet, south of 65.1° north latitude, thickened at the rate of 35 ± 17 cm a⁻¹ during 1975 to 1978. The average change in surface elevation was calculated from the elevation differences determined at 525 locations observed by both GEOS-3 and Seasat radar altimeters. The observed thickening is consistent with the 8 cm a⁻¹ thickening previously measured in the accumulation zone, approximately 900 km farther north, during conventional, surface, survey methods. The increase in ice thickness suggests a higher precipitation than the long-term average, which is one possible result of a warmer climate in polar regions. The excess ice accumulation, in the 10 % of the Greenland ice sheet observed, is estimated to be 53 km³ a⁻¹, which is equivalent to a sea-level reduction of 0.15 mm a⁻¹. Additional, high-precision, sequential, altimetric measurements could be used to determine the overall mass balance of the Greenland and Antarctic ice sheets.