RT Journal Article
T1 The unprecedented late-summer 2023 heatwave in southeastern South America: attribution and future projection of similar events
A1 Kim, Woon Mi
A1 Simpson, Isla R.
A1 Terray, Laurent
A1 Collazo Inglesini, Soledad Maribel
AB In March 2023, southeastern South America (SESA) experienced a severe heatwave with its maximum intensity exceeding four standard deviations from the climatological mean. 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◦C) and thermodynamic effect (58%, 4.75◦C), 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. The persistence of the circulation anomalies is also noticeable during the period. The contribution of the long-term temperature trend is 9% (0.78◦C). In CMIP6 future simulations, the number of March heatwaves increases, but the relative frequency of March-2023-like dry-hot heatwaves decreases, largely due to projected increases in soil moisture. The contributions of the temperature trends and circulation anomalies are larger, while the thermodynamic effects related to soil-temperature feedback are reduced. The finding suggests that future March heatwaves are driven by increases in temperatures with reduced roles of soil moisture. However, uncertainty exists in future soil moisture projections, indicating the need for more understanding of changes in heatwaves in the region.
PB Elsevier
SN 2212-0947
YR 2025
FD 2025
LK https://hdl.handle.net/20.500.14352/122974
UL https://hdl.handle.net/20.500.14352/122974
LA eng
NO Kim, W.M., Simpson, I.R., Terray, L., Collazo, S., 2025. The Unprecedented Late-Summer 2023 Heatwave in Southeastern South America: Attribution and future projection of similar events. Weather and Climate Extremes 48, 100772. https://doi.org/10.1016/j.wace.2025.100772
NO WMK: Swiss National Science Foundation, project grant number P500PN_206653.SC: SAFETE project,  European Union’s Horizon 2020, Marie Skłodowska-Curie grant agreement No 847635 (UNA4CAREER).NSF National Center for Atmospheric Research, National Science Foundation, United States, Cooperative Agreement 1852977.
NO Swiss National Science Foundation
NO European Commission
NO National Science Foundation, United States
DS Docta Complutense
RD 21 dic 2025