Seasonal variations of Antarctic clouds observed by CloudSat and CALIPSO satellites

The multiyear lidar and radar measurements obtained from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat between June 2006 and May 2010 were used to investigate the seasonal and interannual variabilities of the vertical and horizontal cloud distributions, cloud top height above ground (Htop) thickness (CTH), effective radius (re), and ice water content (IWC) over the southern high latitudes poleward of 60°S. The collocated lidar and radar data were used to derive the cloud mask, which was used to classify the clouds into four classes according to the cloud base height above ground (Hbase) and CTH. The Amundsen/Bellingshausen Sea region showed the highest cloud occurrence (>80%) and Antarctic Plateau had lowest cloud occurrence (<30%). The low-level clouds accounted for more than 60% of the total cloudiness, and their occurrence was greater during summer than during winter, but deep and high-level cloud occurrence, CTH, and Htop were greater during winter than during summer. CTH and Htop of deep and high-level clouds were greater over ocean than over land, but both CTH and Htop of low-level clouds were greater over land than over ocean. The mean IWCs for high-level clouds over land and ocean were 0.85 (2.0) and 1.3 (3.1) mg/kg, respectively, and the mean re over land and ocean were 18.0 (22.1) and 21.5 (26.4) mm, respectively, for winter (summer). The study provides a high-quality data set of cloud properties over the Antarctic region to improve our understanding and model simulations of Antarctic clouds.