Influence of large-scale circulation and local feedbacks on extreme summer heat in Argentina in 2022/23

Abstract

The summer of 2022/23 in Argentina set a record with ten heatwaves. Here, we compare the synopticand thermodynamic conditions of the four heatwaves with the largest spatial extent using ERA5reanalysis data. All heatwaves were associated with mid-level anticyclonic anomalies but withdifferent characteristics: three were quasi-stationary high-pressure systems, while one was transient.We also find that enhanced surface fluxes strongly influenced the daily temperature evolution.Furthermore, we perform an attribution exercise using the analogue technique to measure thecontributions of atmospheric circulation, soil moisture, and climate change. For quasi-stationaryevents, the main contribution came from the circulation (up to 2 °C relative to random flow in thepresent climate). Conversely, the transient heatwave showed a stronger association with extreme soilmoisture deficits, with an estimated increase of ~+1 °C relative to wetter conditions. Climate changehas also increased the intensity of heatwaves by +0.5 to +1.2 °C relative to previous decades.