Extreme wind climatology of winter storms in Germany

Abstract

A method for the assessment of the local hazard caused by large-scale winter storms is described in detail and applied to all of Germany. Spatially highly resolved wind fields of severe storm events in the climatological period from 1971 to 2000 are modeled by a statistical—dynamical downscaling approach with the Karlsruhe Atmospheric Mesoscale Model KAMM, using both ERA- 40 re-analysis and observation data. Hazard curves, including quantification of the uncertainties, are determined for all grid points with a distance of 1 km from the modeled wind fields by applying extreme value statistics. The hazard maps reveal critical regions with potentially extreme wind speeds depending on exposure, terrain height and land use. For an exceedance probability of 0.05 yr -1 that equals a return period of 20 yr, the maximum gusts range between 26 m s -1 in deep val- leys and >45 m s -1 near the coast as well as over the crests of the low mountain ranges. Particularly saddles, edges, flanks and summits feature a higher hazard for extreme wind speeds. Comparisons of model data and observations confirm the applicability and the high precision of the method.