Surface configuration of the Antarctic ice sheet in the sector 30゜E - 80゜E using SEASAT altimetry data

摘要

Using Interim Geophysical Data Record (IGDR) of SEASAT radar altimetry, a configuration map of the Antarctic ice sheet in the area bounded by 30°and 80°E and latitude 72°S is compiled. A total of 7480 footprint data of every second sampling (6.62km apart) along 63 subsatellite groundtracks are obtained in the area. The area was divided into rectangles with side lengths of 0.1°in latitude and 0.4°in longitude, and the average elevation above sea level by SEASAT altimetry data within the rectangle is used for computer-aided contouring. Since the height error for 147 crossover points on the ice sheet was±6.7m in standard deviation, and height errors from slope-induced effect and other sources were 20m, the contour interval of 100m was chosen for an inland area higher than 500m above sea level. The obtained configuration resembles the map published by the Scott Polar Research Institute (1983). A total of 157 ground survey data from triangulation survey, satellite Doppler positioning and previously published topographic map are used to estimate an overall accuracy of the obtained configuration map. The ground survey height is on an average 2.2m lower than the SEASAT-derived elevation with a standard deviation of ±21.5m, which may reflect the limited data quality of IGDR without retracking correction of the return-pulse waveform. Drawing orthogonals to the contours, ice drainage basins are determined and they are slightly different from the previous ones defined by the over-snow traverse surveys.