Tracing the impact of drought on the Western Mediterranean's record-shattering Spring 2023 heatwave
- 1Eurac Research, Center for Climate Change and Transformation, Bolzano, Italy (marc.lemusicanovas@eurac.edu)
- 2Hydro-Climate Extremes Lab, Ghent University, Ghent, Belgium
- 3Instituto Dom Luiz, University of Lisbon, Lisbon, Portugal
The western Mediterranean region experienced an exceptional and unprecedented early heatwave in April 2023, shattering historical temperature records, particularly in the Iberian Peninsula and northwestern Africa. This event serves as a stark illustration of a drought–heatwave compound event. In this study, we explore the soil moisture–temperature interactions that underpinned this event, using the most up-to-date observations and robust statistical analysis. Our findings reveal that soil moisture deficit preconditions, concurring with a strong subtropical ridge as a synoptic driver, significantly contributed to the amplification of this record-breaking heatwave. Specifically, we estimate that the most extreme temperature records would have been 4.53 times less likely and 2.19°C lower had the soils been wet. The dynamics of the land-atmosphere interactions during the heatwave showed a pronounced soil moisture-temperature coupling, with reduced soil moisture leading to increased sensible heat flux, which significantly increased air temperatures. Employing the flow analogues technique, we further demonstrated that similar atmospheric conditions in the past, under dry soil moisture conditions, consistently resulted in higher temperature extremes compared to those under wet conditions.
Importantly, our results indicate that in terms of land–atmosphere coupling during extreme events, semiarid regions in spring can behave like temperate regions during summer when soil moisture content is more variable. Therefore, our findings suggest that in these semiarid regions, including other Mediterranean climate regions where hot–dry compound events are aggravating (e.g., California, central Chile), soil moisture may be a good diagnostic of spring heatwave risk and hold potential for subseasonal heatwave forecasting.
Reference:
Lemus-Canovas, M., Insua-Costa, D., Trigo, R.M. et al. Record-shattering 2023 Spring heatwave in western Mediterranean amplified by long-term drought. npj Clim Atmos Sci 7, 25 (2024). https://doi.org/10.1038/s41612-024-00569-6
How to cite: Lemus-Canovas, M., Insua-Costa, D., Trigo, R. M., and Miralles, D. G.: Tracing the impact of drought on the Western Mediterranean's record-shattering Spring 2023 heatwave, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1010, https://doi.org/10.5194/ems2024-1010, 2024.
