Observations of antarctic polar stratospheric clouds by the Geoscience Laser Altimeter System (GLAS)

We present the first satellite lidar observations of Polar Stratospheric Clouds (PSCs). During late September and early October 2003, GLAS frequently observed type I and II PSCs over western Antarctica. At the peak of this activity on September 29 and 30 we investigate the vertical structure, horizontal coverage and general characteristics of the PSCs using the GLAS data. The PSCs were found to cover a relatively large area in a region where enhanced PSC frequency has been noted by previous PSC climatology studies. We also show near simultaneous measurements from the POAM III and SAGE II satellites that confirm the presence of type I and II PSCs in the same region. The area of PSC formation was found to coincide with the coldest temperatures and highest geopotential height in the lower stratosphere. In addition, extensive cloudiness was seen within the troposphere below the PSCs indicating that tropospheric disturbances played a role in their formation.