Evaluation of the mean and extreme precipitation regimes from the ENSEMBLES regional climate multimodel simulations over Spain

Abstract

A state-of-the-art ensemble of regional climate model (RCM) simulations provided by the European Union?funded project ENSEMBLES is used to test the ability of RCMs to reproduce the mean and extreme precipitation regimes over Spain. To this aim, ERA-40-driven simulations at 25 km resolution are compared with the 20 km daily precipitation grid Spain02, considering the period 1960-2000. This gridded data set has been interpolated from thousands of quality-controlled stations capturing the spatial variability of precipitation over this RCM benchmark-like area with complex orography and influence of both Atlantic and Mediterranean climates. The results show a good representation of the mean regimes and the annual cycle but an overestimation of rainfall frequency leading to a wrong estimation of wet and dry spells. The amount of rainfall coming from extreme events is also deficient in the RCMs. The use of the multimodel ensemble improves the results of the individual models; moreover, discarding the worst performing models for the particular area and variable leads to improved results and reduced spread.