The unprecedented late-summer 2023 heatwave in Southeastern South America: Attribution and future projection of similar events

The timing of the occurrence was also unusual, as it occurred in the late summer. This study examines the contributing factors to the March 2023 SESA heatwave using a dynamical adjustment approach based on constructed atmospheric circulation analogs from the ERA5 reanalysis.

Additionally, we assess changes in March heatwaves in the Coupled Model Intercomparison Project 6 (CMIP6) Shared Socioeconomic Pathways 3-7.0 climate simulations using the same method. The dynamical adjustment indicates that the largest contributors to the heatwave are circulation anomalies (on average 33%, 2.72 ) and thermodynamic effect (58%, 4.75 ), primarily linked to soil-temperature feedback. This result supports that extremely dry soil from the ongoing multi-year drought played a role in amplifying the heatwave intensity.