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MMM SEMINAR NCAR

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WRF Over Antarctica: Simulations of the May 2004 Windstorm at McMurdo

Jordan G. Powers

Mesoscale and Microscale Meteorology Division, NCAR

Since 2000 the Antarctic Mesoscale Prediction System (AMPS) effort  in MMM has served the United States Antarctic Program by providing real-time mesocale NWP guidance in support of science and logistics in Antarctica.  The system has used the PSU/NCAR MM5 with multiple forecast grids over the continent and has employed a polar physics package.  AMPS now looks to introduce the Weather Research and Forecasting (WRF) in replacement of the MM5, and thus testing has commenced on the application of WRF to Antarctica.

WRF is applied in simulations of the 16 May 2004 extreme wind event at McMurdo Station, Antarctica.  Winds of up to 250 kph/160 mph caused extensive damage in and around McMurdo, and the motivation for the event was thetransit of a deep synoptic low across the Ross Ice Shelf and passing east of Ross Island.  A brief observational analysis of the case will first be presented.  WRF simulations of the case then aim to reveal how well the next-generation model can capture this event, how it compares to the AMPS MM5, and how assimilation of MODIS (Moderate-Resolution Imaging Spectroradiometer) polar winds with WRF 3DVAR affects its performance.  Sensitivity tests with varying physics and combinations of assimilated datasets and quality control are performed.  It is found that WRF captures aspects of the event, but mesoscale differences in cyclone evolution are important.  WRF, however, does improve on the MM5's handling of the case.  The assimilation of MODIS polar winds improves the results, although it is found that the application of specific data restrictions is necessary.

Thursday, 19 May 2005, 3:30 PM

Refreshments 3:15 PM

NCAR-Foothills Laboratory

3450 Mitchell Lane

Bldg 2 Auditorium (Rm1022)