Research supported by this grant is under the auspices of the Arctic Systems Science (ARCSS) Global Change Research Program and is jointly sponsored by the Division of Ocean Sciences and the Office of Polar Programs. Work to be performed represents preliminary steps towards a major 5-year research project named SHEBA, which is envisioned to study the heat budget of the Arctic Ocean and its impact on global change. The primary goals of SHEBA are: (1) to develop, test and implement models of arctic ocean-atmosphere-ice processes that demonstrably improve simulations of the present day arctic climate, including its variability, using General Circulation Models (GCMs), and (2) to improve the interpre- tation of satellite remote sensing data in the Arctic for analysis of the arctic climate system and provide reliable data for model input, model validation and climate monitoring. Researchers at the University of California, San Diego will build an instrument that will measure the vertical and horizontal flux of heat and momentum under the sea ice at the location of the proposed ice camp in 1997. The proposed sonar system will provide accurate measurements of mixing processes that will improve the ability of models to predict the component of the heat budget of the Arctic that is produced within the ocean. ??