Large-Scale Drivers of Widespread Extreme Precipitation in Europe: Insights from High-Resolution Regional Climate Model Simulations

Although regional climate models (RCMs) have made significant advancements in simulating the spatiotemporal characteristics of precipitation and understanding mechanisms of precipitation changes over recent decades, concerns persist regarding their ability to accurately represent the large-scale atmospheric conditions associated with climate extremes. In light of this, the present study evaluates the performance of high-resolution RCM simulations in representing the characteristics of widespread extreme precipitation events and their associated large-scale synoptic systems across different complex orographic precipitation regimes in the Mediterranean and the European North Atlantic regions during 1980–2010. The RCM simulations are performed in the framework of the European-Coordinated Regional Climate Downscaling Experiment (EURO-CORDEX) at a horizontal resolution of approximately 12 km (0.11° × 0.11°) and constitute so-called evaluation experiments, i.e., simulations forced by large-scale information from a reanalysis. A set of high-resolution quality-controlled observational precipitation datasets compiled from higher density rain gauge station networks, along with E-OBS data, is used to evaluate the precipitation simulated by the RCMs. ... mehrWe found that the RCMs reproduced the observed total number and intensity of widespread extreme precipitation events to a great extent; however, there is variation or spread in the results among different RCMs. The study also emphasized the critical importance of systematically addressing model-specific discrepancies, as these variations can amplify intermodel spread and potentially lead to misleading conclusions. The general synoptic patterns that characterize widespread extreme precipitation include trough–ridge patterns with cyclonic features, advection of warm and moist air promoting rising motion, and enhanced moisture transport into the regions. Also, atmospheric river–like patterns of moisture transport originating from the Atlantic Ocean are identified, particularly in the European North Atlantic regions, and with contributions from the Mediterranean Sea in the Mediterranean regions. While RCMs reproduced the large-scale synoptic spatial patterns observed in ERA5 to a great extent, intermodel differences are evident in the spatial patterns and their magnitudes. We concluded that when driven by the same forcing, the RCMs, despite their many mutual differences, are, on the whole, capable in providing a robust and converging result when it comes to widespread extreme precipitation events.