Arctic Winter Thin Ice Clouds Using RAMS, CloudSat, and CALIPSO

The Polar regions are an integral part of Earth's energy budget, however they are poorly understood mainly due to their remoteness and lack of observations. The recent launch of two successful satellites, CloudSat and CALIPSO, into the A-Train constellation are providing excellent insight into wintertime clouds and precipitation at the Poles. One distinguishable characteristic seen from satellite data during Arctic winter and spring is an optically thin cloud containing ice crystals large enough to precipitate out. These "thin ice clouds" (TIC) occur in regions most affected by anthropogenic pollution. It is hypothesized that the anthropogenic pollution, likely sulfuric acid, coat the available ice forming nuclei (IN) and render them as inactive particles. Therefore, the effective IN concentrations are reduced in these regions and there is less competition for the same available moisture and large ice crystals form in relatively small concentrations. The ice crystals grow large enough for fall-out and dehydrates the Arctic atmosphere. We use Colorado State University's Regional Atmospheric Modeling System (RAMS) configured as a large eddy simulation (LES) version to simulate these TIC's. RAMS contains three grids with the finest resolution of 50m, which can adequately resolve all relevant microphysical processes. By performing sensitivity experiments to recreate the observed microphysical quantities based on both CloudSat and CALIPSO, we extract the initial conditions to further understand the potential for precipitation dehydration and the effects of aerosol on this process.