Properties of water-only, mixed-phase, and ice-only clouds over the South Pole

Downwelling spectral infrared radiances were measured by the Polar Atmospheric Emitted Radiance Interferometer (P-AERI) during 2001 as part of the South Pole Atmospheric Radiation and Cloud Lidar Experiment (SPARCLE). In addition, a micro-pulse lidar was operated by NASA as part of the Micro-Pulse Lidar Network (MPLNET). The lidar provides cloud-base height, and in many cases, cloud-top height, since clouds over South Pole are typically optically thin. The P-AERI radiances and the MPL data are used, along with routine radiosonde profiles, to retrieve cloud microphysical properties (cloud optical depth, effective radius, and cloud phase). In-situ measurements made by a Hydrometeor Videosonde (HYVIS) are used to validate the retrievals under certain conditions. We find that water-only and mixed-phase clouds exist over South Pole in the summertime and into the autumn. The frequency of occurrence of clouds with different phase types will be presented. Variations in the optical depth and effective radii as a function of season will also be presented.