Antarctica cloud cover for October 2003 from GLAS satellite lidar profiling

Bright surfaces and low surface temperature limit the study of Antarctica cloud cover by passive techniques. Starting in 2003 the Geoscience Laser Altimeter System (GLAS) provides the first measurements of polar clouds by satellite lidar. From the GLAS data the presence and height of all clouds are detected, and in the case of transmissive clouds that predominate in the Antarctica, the thickness is also found. Initial results for October 2003 data are summarized. There are two basic cloud types profiled: stratus below 3 km and cirrus form clouds with cloud top altitude and thickness tending at 12 km and 1.3 km. Zonal average cloud fraction varies from over 93% for ocean and coastal regions to a consistent average of 40% over the East Antarctic plateau and 60 - 90% over West Antarctica. Differences between the zonal average GLAS and MODIS cloud fractions are as much as 40% over the continent.