Heavy, large-scale precipitation events and associated flooding represent one of the most impactful natural hazards for society in Europe. The most extreme precipitation events are very rare but are projected to increase in a warmer future climate. The intensification of such events is linked to both the increased atmospheric moisture content and atmospheric circulation changes. The latter is largely uncertain across multiple models, even for extreme precipitation events with return periods of about 1 year. This project aims to investigate projected future changes of daily precipitation events in European river basins with return periods of 100 years by analysing large ensemble simulations from global climate models. The future changes will be decomposed into a thermodynamic and a dynamic contribution and the uncertainties will be quantified separately by inter-model differences. Projected changes in the dynamical processes will be linked to synoptic-scale circulation patterns based on composite analyses and cyclone tracking. Synoptic storylines will be constructed to exemplify worst case scenarios of potentially large projected precipitation changes and their underlying circulation changes in order to point out the most relevant of these dynamical mechanisms. Finally, since floods in large rivers often occur due to precipitation accumulation over longer periods, the dependence of the results on the length of the accumulation period for up to several days will be investigated.

Website: MExRain

Institution: Institute of Meteorology, Freie Universität Berlin (FUB)

Contact: Prof. Dr. Stephan Pfahl, Dr. Florian Ruff