Simulation of the climate of the XX century in the Alpine space

The purpose of this work is the analysis of the capabilities of the Limited Area Model COSMO-CLM in simulating the main features of the observed climate over an area characterized by complex orography. Two sets of simulations of the XX century climate have been carried out, at a spatial resolution of 14 km, in order to provide a detailed description of the climate variability on local scale, useful for impact studies. A first experimental set-up consists of a set of simulations driven by the boundary conditions provided by the global model SINTEX-G. Our aim is to test the capability of this experimental set in realistically reproducing the main characteristics of the Alpine region climate under present climate conditions in order to provide a reliable tool for future climate scenario investigations. A second set of simulations has been carried out, driven by ERA40 reanalysis, in order to test the influence of the global model boundary conditions. Results are shown in terms of 2-m temperature and total precipitation and they are compared with two observational datasets: CRU and ARPA Piedmont. A good capability of the model in reproducing both the mean field and the seasonal cycle of temperature is observed, while the precipitation is affected by accuracy problems, related to the resolution. Though the model resolution is fine enough to reproduce fairly well the intensity of winter precipitation, it often fails in its localization. As far as summer precipitation is concerned, the model resolution appears too coarse to simulate the localized convection, which characterizes summer precipitation over Alps.