On the capability of RegCM to capture extremes in long term regional climate simulation -: comparison with the observations for Czech Republic

We analyze daily precipitation and temperature extremes over the Czech Republic in a regional climate simulation for the 40-year period of 1961-2000 carried out with the RegCM3 regional climate model. The model is run at 45 km grid interval and is driven by NCEP/NCAR reanalysis lateral boundary conditions. Comparison with station data shows that the model performs reasonably well in simulating the frequency of daily precipitation events of medium to high intensity as well as the precipitation intensities (return levels) of long return periods, with the exception of mountain stations. While this is attributed mainly to the relatively coarse representation of topography across the area of the Czech Republic, the parameterization of convection can be another reason. The model underestimates daily maximum temperature (especially in the warm seasons) and as a result the occurrence of heat waves (high temperature episodes). The performance of the model improves in the simulation of daily minimum temperature and cold wave events. In order to apply this regional model to the simulation of extreme events over the complex terrain as for Czech Republic we recommend that a higher resolution is used in order to better describe the topography of the Czech Republic and that the daily maximum temperature bias is reduced.