P102     Comparison of Wind Speed Forecasts from MM5 and WRF ARW Ensemble Prediction Systems over the Iberian Peninsula

Fish, A.K., D. Santos-Munoz, F. Valero, Universidad Complutense de Madrid, Spain

A ten member short range ensemble prediction system has been created based on the WRF model using the ARW dynamic core.  The SREPS is a multi-analysis, multi-physics system using 5 different physics configurations, and 2 sets of initial conditions provided by the ECMWF IFS, and NCEP GFS systems. The SREPS is based on an earlier system developed by Santos et al using the Penn State MM5 model, in order to make a comparison of the two systems the same domains and vertical structure was used, and where possible the same physics parameterisations. The SREPS is composed of an outer domain with a 30 km resolution covering the North Atlantic, and a two way nested domain with a 10km horizontal resolution covering the Iberian Peninsula. 36 hour simulations have been produced for a 4 month period from 1st September 2006, to the 31st of December 2006. The SREPS 10m wind speeds were verified at 73 sites across the Iberian Peninsula, with measurements every 6 hours.

The WRF based ensemble has been shown to outperform the MM5 SREPS, obtaining better results at both 1 and 2 sigma levels, and lower RMSE and BIAS scores. The improvements in quality are likely to be as a result of improvements in the dynamics of the models.