A New Database of Extreme European Winter Windstorms

Abstract. European windstorms pose a significant threat to people, infrastructure and the natural environment. Several windstorms in the recent past have caused substantial damages, and losses associated with extreme windstorms may increase with climate change. Characterizing the footprints of destructive windstorms is thus key to providing quantitative estimates of storm-related economic losses. To that end, we have developed a new, publicly available database of extreme European windstorm footprints for the extended winter season during 1995–2015. In contrast to previously compiled European windstorm databases, we include storm footprints derived from four different data sets, rather than a single source: the ERA5 reanalysis, the COSMO-REA6 reanalysis for Europe, the COSMO-Climate Limited-area Mode regional climate model driven by ERA5 on the EURO-CORDEX domain, and simulation output from the same model but on an enlarged Germany domain with higher horizontal resolution. The database includes both the footprints themselves, expressed as the relative daily maximum wind gusts associated with a storm event, and the daily maximum wind gusts in absolute magnitude associated with the footprints. We derived and included the storm footprints associated with the 50 most extreme storms, or Top50 storms, identified within each of the four input data sets. We applied a consistent methodology, the storm loss index, across input data sets for identifying storm footprints and assessing their severity. This enables a direct comparison between the footprints derived from the different input sources, eases future efforts to extend the time record of the database or to include additional input data sets, and enables assessment of uncertainty in the footprints. Moreover, since we derived the Top50 storms from each input on its native horizontal resolution, the database also allows to characterize the impact that horizontal resolution can have on footprint identification and severity assessment. Our database thus supports both the research community and the insurance industry in exploring the data set and resolution dependence of assessments of extreme storm hazards.