From Atmospheric Circulation Features to Surface Extremes

The literature provides a wealth of metrics and indices meant to capture large‐scale and synoptic-scale atmospheric circulation features, including jet‐stream characteristics, cyclonic and anticyclonic Rossby wave breaking, atmospheric blocking, atmospheric rivers, fronts and more. Many studies relate these features to the occurrence of surface extremes. Often, separate studies relate different features to the same extremes in the same region. A systematic intercomparison of how strongly each feature relates to specific surface extremes remains largely lacking. Here, we utilise ERA5 reanalysis data to compare how multiple circulation features relate to temperature extremes in Europe. We find that cold spells in a large part of Europe are predominantly associated with high‐latitude blocking, yet that Rossby wave breaking plays an important role for cold spells in South-Eastern Europe. For warm extremes, blocking is the dominant feature in Northern and Southern Europe, wave breaking in Central and Eastern Europe, while different jet‐stream configurations dominate in Western Europe and Iberia. We further analyse the co-occurrence of different circulation features, to account for the fact that more than one may be present when any given surface extreme occurs. Finally, we extend the analysis to precipitation extremes in the global extratropics. Our results highlight that the atmospheric circulation feature(s) which display the strongest statistical connection to surface extremes is highly dependent on the type of extreme and region, and that multiple features should be considered in continental or larger-scale analyses. We also underscore that multiple features often co-occur in conjunction with surface extremes, and that disentangling their individual contributions can be challenging.