A modeling study of an Antarctica polynya event.

An event of polynya at Terra Nova Bay (TNB),occurring from 15 July to 17 July 2006, is simulated by arecent version of the mesoscale Eta model. Simulationresults and observational data describe the surface conditionsduring the period. The spatial and temporal structureof the atmospheric boundary layer in response to the warmarea of the polynya is also investigated. Numerical experimentsshow that the latter influences significantly the windintensity, the temperature and the specific humidity of theair over Terra Nova Bay. The significant heating of the lowatmosphere results in a three-dimensional anomaly in thebaric field, which extends far in the Ross Sea, embedded inthe complex pressure field obtained by the Eta model alsowithout taking into account the polynya. A turbulentkinetic energy plume, indicating turbulent mixing, and anincreased vertical diffusion of horizontal momentum arealso simulated over the polynya. The downward flux ofhigh momentum air and the modified pressure gradientforce change the wind speed at low level over TNB.