P53  Verification of WRF wind speeds over South Africa

Weston, Michael, Theo Fischer, and Abdul Ebrahim, EScience Associates

We run WRF for two regions of South Africa: the Western Cape and the Highveld. The Western Cape represents a baroclinic atmosphere, is adjacent to a cold ocean current and is characterised by complex terrain. The Highveld typically has a barotropic atmosphere, is in the interior and is generally flat terrain. We evaluate wind speeds from WRF against observations in both regions. Wind direction is modelled well for both regions. However, evaluation of wind speed produces mixed results. For the Western Cape, WRF performs well for wind speeds at 60m a.g.l, slightly underestimating high wind speeds. However, at 10m a.g.l WRF slightly over predicts wind speeds. For the Highveld region, WRF consistently over predicts wind speeds at 10m a.g.l. A comparison of MM5 data against WRF indicates that MM5 also over estimates wind speed for the Highveld region. Further investigation is required to determine possible causes of over estimating wind speed over the Highveld. These include: Evaluate input meteorological data, evaluate surface characteristics, parametrisation tests and obtaining more observed upper air data for model evaluation.