Future drought probabilities in the Greater Alpine Region based on COSMO-CLM experiments - spatial patterns and driving forces

In this study we assess future drought probabilities in the Greater Alpine Region based on four regional climate model simulations with COSMO-CLM forced by ECHAM5 and HadCM3 under different emission scenarios. As a drought indicator, the Standardized Precipitation Evapotranspiration Index is applied. The evaluation of a hindcast run show reasonable skill of the CCLM in simulating the evolution of dry and wet phases, although decreasing skill towards the East of the Alpine domain is apparent. The results of the scenario investigations indicate a considerably higher probability for droughts averaged over the study region, but with rather diverse patterns north and south of the Alps. This signal is mainly emerging from the warm season months, whereas in winter nearly no change is detected. By differentiating between precipitation and temperature as the driving forces of the considerable drying trends in summer we found precipitation as the relevant driver north of and in the Alps, whereas we detected that temperature, as a proxy for evapotranspiration, is the main factor for the southern and eastern areas.