A statistical-dynamical downscaling procedure for global climate simulations

Summary A statistical-dynamical downscaling procedure for global climate simulations is described. The procedure is based on the assumption that any regional climate is associated with a specific frequency distribution of classified large-scale weather situations. The frequency distributions are derived from multi-year episodes of low resolution global climate simulations. Highly resolved regional distributions of wind and temperature are calculated with a regional model for each class of large-scale weather situation. They are statistically evaluated by weighting them with the according climate-specific frequency. The procedure is exemplarily applied to the Alpine region for a global climate simulation of the present January climate.List of Symbols west-east mesh size in geographic coordinates south-north mesh size in geographic coordinatesN number of large-scale weather classesn number of regional-scale event classesp pressureP probabilityØ large-scale event regional-scale eventq_v specific humidity potential temperatureu west-east wind componentv south-north wind componentAbbreviations AGL above ground level - LT local time - UTC universal time coordinatedWith 13 Figures