Microphysical properties of Antarctic polar stratospheric clouds and their dependence on tropospheric cloud systems

Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat satellite measurements are used to investigate the impact of tropospheric high and deep clouds on the microphysical properties of polar stratospheric clouds (PSCs) over Antarctica during the 2006 and 2007 winters. Based on the attenuated lidar scattering ratio and PSC depolarization ratio (delta'), PSCs are classified into supercooled ternary solution (STS), Mix 1, Mix 2, and ice classes with significantly different microphysical properties in terms of the PSC backscattering coefficient (beta(532)) for 532 nm, the color ratio (beta(1064)/beta(532)), and delta'. In the early stages of the PSC season, STS accounts for more than 50% of the total PSCs, but the Mix 1, Mix 2, and ice classes become more common in the late season. During the late PSC season, close to 70% of PSCs are formed in association with high and deep tropospheric cloud systems, indicating the important role of tropospheric weather systems in Antarctic PSC formation. Tropospheric cloud systems also affect the microphysical properties of PSCs by affecting the relative occurrence of different PSC classes, especially during September and October. Our results also show that there are noticeable differences in color ratio and beta(532) (at the 0.05 significance level) for the ice class and Mix 2 (late season only) for PSCs associated and not associated with high and deep tropospheric cloud systems. These results indicate that the impact of tropospheric meteorology on PSC formation should be fully considered to better understand interannual variations and recovery of the Antarctic ozone hole.