Ice Sheet Surface Topography of Greenland and Antarctic from ICESat Altimetry

Data from the Geoscience Laser Altimeter System (GLAS) on the Ice Cloud and land Elevation Satellite (ICESat) are used to calculate detailed topographic maps of Greenland and Antarctica. ICESat was launched on January 12th, 2003 and placed in an 8-day repeat orbit for calibration and validation activities. The initial dataset contained data from laser activation on February 20th to March 29th. In September of 2003, the spacecraft will collect data over another 8-day repeat cycle and then be maneuvered into a 91-day repeat orbit, which will provide denser groundtrack spacing in the lower latitude regions. The 94( inclination of ICESat allows for precision mapping of areas of the ice sheets where little detailed topography existed. Polar stereographic grids of Greenland and Antarctica at 5km resolution are created using a gridding procedure developed in support of previous altimetry missions. The resultant grids are compared with the 5km radar altimetry grids showing improved coverage in the higher latitudes and steeper terrain regions. The resulting Greenland gridded elevations are also compared with the data from the NASA Airborne Topographic Mapper (ATM). Slope vector plots calculated from the grids show ice sheet flow directions and are used to delineate ice sheet drainage basin boundaries. Sample maps with smaller spatial resolutions are created for some of the high-latitude areas with denser coverage to demonstrate the ultimate high-resolution capability of laser altimetry.