The proposed work will study the role of Antarctic clouds in the global climate system. It is proposed to increase the realism of simulated Antarctic clouds in the NCAR CCM3. Satellite and ground-based observations will be analyzed to enhance the understanding of Antarctic clouds. On the basis of these, a number of changes will be implemented in the model; the local and remote impacts of these changes will be examined by conducting CCM3 sensitivity runs. The study will result in the CSM producing more realistic atmospheric variability as well as better simulation of sea ice behavior and associated thermohaline circulation of the Southern Ocean in climate change scenarios. The work is important because it will lead to better modeling of processes in the Southern Oceans.