Study of the Surface Heat Budget of the Weddell Sea using a Radiative TransferModel during the Austral Winter 1994

摘要

This study uses rawinsonde soundings and irradiance measurements taken in theWeddell Sea during the 1994 ANZFLUX experiment. A radiative transfer model was used to determine the influence of aerosols, cloud droplet size and water content on the radiative heat budget of the Weddell Sea. The modeled irradiances were compared with observations, and the model calculated the upward longwave irradiance from the Weddell Sea ice pack. Turbulent heat fluxes were calculated and combined with radiative terms to provide a net heat flux at the ice surface. While turbulent heat flux is the major factor affecting the Weddell Sea's heat budget in windy conditions, during calm conditions longwave radiative transfer becomes important. The modeled downward irradiances were compared to results obtained from empirical equations developed for the Weddell Sea during the winter. The atmosphere above the Weddell Sea appears to have an aerosol structure similar to marine environments. Stratus clouds over the Weddell Sea appear to be made up of cloud droplets with an effective radius of 2.5 microns and a water concentration close to 0.05 grams per cubic meter. The dominant terms in the surface heat budget are the longwave irradiances with the upward longwave term being the largest.