9421096 Warren This project is the continuation of an integrated study of the optical and physical properties of the antarctic snow surface. It has several components which concern the processes by which global climatic variability is imprinted into the proxy data recorded in the antarctic ice. It is based on a very successful three-year field effort during which the principal investigator acquired a substantial body of data, including the effect of surface roughness (sastrugi orientation) on the angular distribution of reflected sunlight, the spectral distribution of thermal infrared radiation, the mechanism of dry deposition of atmospheric sulfates in the snow surface, and the isotopic composition of hoarfrost. The primary emphasis will be on the production of a climatology of the long-wave and short-wave radiation budget at the surface, to include the contributions of carbon dioxide, ozone, water vapor, clouds, and atmospheric ice crystals. Radiative transfer models will be tested under both clear-sky and cloudy-sky conditions, and a monthly climatology of spectral and total long-wave cloud radiative forcing at the surface will be determined. These results will feed into global programs studying the Earth's radiation budget, providing the coldest and driest surface end member conditions. In addition, interface temperature profiles will be analyzed for differing mechanisms of heat transfer in snow, and sulfate aerosol measurements will be studied to assess the contribution of wind pumping to the deposition of trace elements in the snow. ***
