Polar Cloud and Climate Observations by the Geoscience Laser Altimeter System

Scheduled for launch in December, 2001 the ICESat (Ice, Cloud and Elevation Satellite) mission will utilize the Geoscience Laser Altimeter System (GLAS) to provide continuous laser sounding of the earth's atmosphere from space for the first time. These measurements will provide an unprecedented global data set on the vertical structure of clouds and aerosols which will greatly aid research efforts aimed at understanding the effects of clouds and aerosols on climate and their role in climate change. The similarity between polar clouds and the underlying snow-covered surfaces in both the visual and infrared portions of the electromagnetic spectrum has limited reliable interpretation of satellite-based cloud imaging and retrievals in the high latitudes; the GLAS data will facilitate unambiguous cloud-detection. Other polar applications of this data include the detection of cloudless ice-crystal precipitation, believed to be the dominant source of precipitation in large areas of the Antarctic plateau, and the monitoring of inter-annual changes in surface elevations of the ice sheets over Antarctica and Greenland.