Wind over Terra Nova Bay (Antarctica) during a polynya event: Eta model simulations and satellite microwave observations

. A study of Terra Nova Bay (TNB) winter polynya, based on the combined use of satellite observations and limited area model simulations, is presented. First, data from passive microwave observations are used to investigate the polynya area daily variability. Second, the Eta model is run to simulate the low-level wind over a defined TNB polynya, located in according to the satellite images, during the period 15-17 September 2003. A preliminary set up of initial and boundary conditions is used. The Eta model is initialized with the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses, with the National Centers for Environmental Prediction (NCEP) of the U.S. National Weather Service data and with information from satellite images providing a realistic extension of the polynya under study. The Eta model simulates a katabatic wind system which develops qualitatively in agreement with the polynya extent, as shown in the satellite images during the same period. The results demonstrate the strong effect of the polynya when included in the initialization of model integrations: the low-level wind is intensified by the presence of the warm area corresponding to the polynya, it is spatially variable and significantly different from one simulated along the coast of the Nansen Ice Sheet. The results of numerical simulations with different surface temperatures in the polynya area are shown as well, thus an assessment of the range of variability of the wind intensity in relation to the polynya surface temperature is provided.