ATSC colloquium: Thurs, 25 January, EN6085A, 3:00 pm.

Numerical Prediction of an Antarctic Severe Wind Event with the Weather Research and Forecasting (WRF) Model

The maturing Weather Research and Forecasting Model (WRF) for numerical weather prediction is applied for the first time to the polar regions, in the context of the real-time Antarctic Mesoscale Prediction System (AMPS), which supports the United States Antarctic Program.  Investigated are the behavior of the Advanced Research WRF (ARW) in a high-latitude setting and the model's ability   to capture a prominent Antarctic weather event.   Also explored is the impact of the assimilation of MODIS (Moderate Resolution Imaging Spectroradiometer) atmospheric motion vectors on ARW Antarctic forecasts.  The simulation results are analyzed and the statistical significance of error differences assessed.

It is found that with the proper consideration of MODIS data the ARW can accurately simulate a major Antarctic event, the May 2004 McMurdo windstorm.  While the model captures the synoptic setting and basic trajectory of the cyclone driving the episode, mesoscale differences in the evolution of the low pressure system significantly affect the forecast results.  It is seen that both targeted data assimilation and grid resolution refinement can enhance the prediction of surface winds.  The assimilation of MODIS observations can clearly improve the forecast of a high-impact Antarctic weather event, although filtering accounting for instrument channel, observation height, and surface type is necessary.  The results demonstrate the polar potential of the WRF model, as well as benefits to high-resolution, mesoscale, Antarctic forecasts from the careful assimilation of nontraditional, polar satellite observations.