Seasonal and interannual elevation change measurement of the Greenland ice sheet from satellite radar altimetry

Measurements from the Geosat satellite altimeter are analyzed to quantify the magnitude of seasonal and interannual variations in ice-sheet surface elevation for the southern Greenland ice sheet. The authors examined the seasonal signal using the first two years of the Geosat-ERM (Nov. 1986 to Nov. 1988) dataset. Several complete sinusoidal cycles are observed in the dataset and comprise the annual cycle over the two-year time period. The amplitude of the seasonal signal varies between /spl plusmn/10 cm in 1987 and /spl plusmn/15 cm in 1988. The timing of elevation increases and decreases is consistent between the two annual cycles. Interannual variations were determined by dividing each year of the Geosat-ERM data into four 3-month seasons. The variations were then calculated by comparing mean elevation changes by crossing data from the same season of each year. The results show that year-to-year variations of -4 to +8 cm occur over this two-year dataset.