VERIFICATION OF STATISTICAL-DYNAMICAL DOWNSCALING IN THE ALPINE REGION

A statistical-dynamical downscaling procedure for global climate simul ations is verified for the greater Alpine region. This procedure links global and regional model simulations using frequencies of large-scal e weather types in order to derive the regional climate corresponding to a given global climate. The results from multi-year global simulati ons or large-scale analyses are classified into a set of large-scale w eather types. Regional model simulations are carried out once for each class. The model output fields are weighted with the frequencies of t he corresponding weather type to give the regional climate. As downsca ling procedures transmit errors in the global climate simulation to th e regional scale, the verification of the statistical-dynamical proced ure is based on large-scale observational data, in our case a decade o f daily ECMWF (European Centre for Medium Range Weather Forecasts) ana lyses. The downscaled results are compared with local observations for the same decade. The verification shows that the downscaling procedur e is able to reproduce climatological features of the observed regiona l distributions of wind and temperature. However, the downscaled regio nal distribution of precipitation exhibits major deficiencies. Possibl e reasons are discussed and further improvements of the statistical-dy namical downscaling procedure are previewed.