SENSITIVITY OF THE ANTARCTIC SEA-ICE DISTRIBUTION TO ITS ADVECTION INA GENERAL-CIRCULATION MODEL

A dynamic-thermodynamic sea ice model is used and coupled with an atmo spheric general circulation model to simulate the seasonal cycle of th e global sea ice distribution. We have run the coupled system and obta in a creditable seasonal simulation of the Antarctic sea ice. To under stand the role of ice advection on the seasonal cycle of Antarctic sea ice in the coupled system, results from the thermodynamic-only (T) se a ice model have been compared with those from the dynamic thermodynam ic (DT) sea ice model. The seasonal cycle of sea ice differs between t he two models. When ice motion is eliminated sea ice becomes more comp act and thinner, and sea ice is more extensive in summer. A number of previous studies have examined the effect of ice dynamics on sea ice s imulations with prescribed atmospheric conditions. Here experiments ha ve been performed with a fully coupled atmosphere sea ice system and a lso using prescribed daily atmospheric forcing and monthly mean atmosp heric forcing, to examine the differences of the sensitivity of the ic e advection between the coupled and forcing models. Similar difference s have been observed between DT and T in the forcing models but the ma gnitude is smaller than in the fully coupled model, and with monthly m ean atmospheric forcing the difference is least. These differences hig hlight the importance of the inclusion of ice advection when undertaki ng studies using a fully interactive atmosphere sea ice model, or usin g prescribed daily/monthly atmospheric conditions to force a sea ice m odel for the Antarctic.