Compound North American Cold and European Wind Extremes in ERA5 and CMIP6 Historical and Future Simulations. Part 1: Surface Extremes

Abstract This study investigates the co‐occurrence of North American cold spells and stormy weather in Europe, which we quantify here in terms of extreme wind days (EWDs). We consider both ERA5 reanalysis data and four CMIP6 climate models in the historical period and SSP5‐8.5 scenario. Three distinct regional relationships are identified in ERA5: East Canada cold spells are followed by increased EWD occurrence in the British Isles; Central Canada cold spells are preceded by increased EWD occurrence in Iberia; and East U.S. cold spells are both preceded and followed by increased EWD occurrence in Iberia. These relationships are modulated by distinct large‐scale atmospheric circulation patterns. While the CMIP6 models generally reproduce the large‐scale patterns associated with the regional cold spells, their representation of the spatial and temporal pattern of associated EWDs is variable. In particular, the models underestimate EWDs preceding cold spells. Under SSP5‐8.5, all models project a weakening of North American cold spells and most show a decrease in maximum wind speeds on EWDs, although one of the better representations of historical wind extremes comes from a model projecting an increase in EWD intensity for the British Isles. Despite considering a strong warming scenario, we find no robust change in the co‐occurrence of North American cold spells and European EWDs in the future.