Compound Extreme Wind and Precipitation Events in Europe

Abstract: The simultaneous occurrences of several extreme events, known as compound extremes, are often associated with greater impact than univariate extremes. Flooding and windstorms are widespread hazards in Europe which can lead to severe property damage and fatalities. During winter, extreme wind and precipitation often co-occur, since they are associated with a common driver, namely extratropical cyclones. In this project, the occurrences of compound wind and precipitation events in Europe are investigated using the ERA5 reanalysis dataset. The analysis covers the years 1979-2019 with a focus on boreal winter. Areas that experience the highest occurrence of compound wet-windy extremes are the west coast of Norway, the Iberian peninsula, parts of central Europe, and southeast of the Black Sea. A few case studies are discussed with the purpose to give an idea of the magnitude of possible impacts. Further, the relationship between extreme wind and precipitation events and the North Atlantic Oscillation (NAO) is presented. During days with positive NAO, extreme precipitation and wind events occur in the central and northern parts of Europe while the negative phase brings extreme wind and precipitation to the southern parts of Europe. Lastly, a short analysis to discover changes in the occurrences of compound precipitation and wind events for the two periods 1979-1999 and 2000-2019 is performed. The result showed no clear changes. The number of compound extremes does not seem to vary for the two periods.