A weighting proposal for an ensemble of regional climate models over Europe driven by 1961-2000 ERA40 based on monthly precipitation probability density functions

Abstract

Present climate over Europe is simulated by 12 regional climate models (RCMs), forced by ERA40 reanalysis. A method is proposed to score models from the 1961-1990 monthly precipitation cumulative density functions (CDFs) for each season and eight chosen subregions, compared with the CRU observational database. Ensemble CDF curves compare well against observations for all the subregions and seasons. Higher percentiles (heavy precipitation amounts) show a larger spread among results. Important differences in scores are obtained among models, regions and seasons. Applying the scores to compute 1991-2000 weighted ensemble precipitation, results are slightly closer to observations than the direct (unweighted) ensemble, and some cases show a larger improvement. © 2009 Royal Meteorological Society.