European Summer Synoptic Circulations and Their Observed 2022 and Projected Influence on Hot Extremes and Dry Spells
Douville, Hervé
Matschullat, Jörg
DOI: https://doi.org/10.1029/2023GL104580
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11308
Abstract
In 2022, western Europe experienced its hottest summer on record and widespread dry conditions, with substantial impacts on health, water and vegetation. We use a reanalysis to classify daily mean sea level pressure fields and to investigate the influence of synoptic circulations on the occurrence of temperature extremes and dry days. Summer 2022 featured an above‐normal occurrence of anticyclones extending from the British Isles to the Baltic countries, as well as enhanced easterly, southerly and low‐flow conditions which contributed to the observed extremes over southern and western Europe. While the hot summer of 2022 is only partially explained by circulation anomalies, such anomalies played a key role in the exceptional occurrence of dry days. The comparison with summer circulation anomalies projected by twenty global climate models moreover suggests that future circulation changes will further exacerbate hot and dry extremes over Europe.
Plain Language Summary: In 2022, western Europe recorded its hottest summer up to date since preindustrial times. At the same time, widespread dry conditions caused dramatic impacts on human health, water resources, crop yields and wildfires. This was partly enhanced by the human–caused cumulative emissions of greenhouse gases, but also potentially by large‐scale circulation anomalies that may also be triggered by global warming. By grouping distinct weather patterns, we find that many extreme hot days during the summer of 2022 over well‐defined parts of Europe were favored by anomalous transport of hot and dry air masses or persistent low‐wind conditions. These weather patterns were essential but not the dominant factor that led to the occurrence of extreme temperatures. Yet, they played a key role in enhancing the number of dry days. We also find that the weather patterns observed in summer 2022 will become more common in coming decades if greenhouse gas emissions remain without reduction. This would further worsen hot and dry extremes in summer over Europe.
Key Points :
European summer 2022 hot extremes have been enhanced by an anomalous occurrence of distinct circulation types over different subdomains
Predominant circulation anomalies also contributed to the exceptional number of dry days, as much as local, mostly thermodynamical effects
Such anomalous circulations will become more common, thus further worsening European hot and dry extremes
Subjects
hot summer 2022hot extremes
circulation types
circulation classification
climate change
atmospheric circulation