Improved elevation change measurement of the Greenland ice sheet from satellite radar altimetry

Elevation change measurements from satellite altimetry for the southern Greenland ice sheet (south of 72/spl deg/N) are re-examined after incorporating technical advancements that significantly improve measurement accuracy. A spatial average of 33,610 crossover points between the Seasat and Geosat altimeters yields a 5.4/spl plusmn/0.4 cm/yr growth rate from 1978 to 1988. This is over four times smaller than previously reported results. Large spatial variations in elevation change from -7 to +20 cm/yr are observed over the ice sheet for the first time. Interannual variations in elevation change of 5-10 cm/yr are also observed. Given the large spatial and interannual variations in elevation change, the 5.4/spl plusmn/0.4 cm/yr growth rate is too small to determine whether or not the Greenland ice sheet is undergoing a long-term change due to a warmer polar climate.