Wet-bulb temperature extremes locally amplified by wet soils

Chagnaud, G. ORCID: https://orcid.org/0009-0003-8732-0815; Taylor, C. ORCID: https://orcid.org/0000-0002-0120-3198; Jackson, L.S. ORCID: https://orcid.org/0000-0001-8143-2777; Birch, C.E. ORCID: https://orcid.org/0000-0001-9384-2810; Marsham, J.H. ORCID: https://orcid.org/0000-0003-3219-8472; Klein, C. ORCID: https://orcid.org/0000-0001-6686-0458. 2025 Wet-bulb temperature extremes locally amplified by wet soils. Geophysical Research Letters, 52 (8), e2024GL112467. 12, pp. 10.1029/2024GL112467

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Official URL: https://doi.org/10.1029/2024GL112467

Abstract/Summary

Wet-bulb temperature extremes (WTEs) occur due to a combination of high humidity and temperature, and are hazardous to human health. Alongside favourable large-scale conditions, surface fluxes play an important role in WTEs; yet, little is known about how land surface heterogeneity influences them. Using a 10-year, pan-African convection-permitting model simulation, we find that most WTEs have spatial extents less than 2,000 km2. They occur preferentially over positive soil moisture anomalies (SMA) typically following rainfall. The wet-bulb temperature is locally amplified by 0.5–0.6 degrees C in events associated with smaller-scale SMA (50 km across) compared to events with larger-scale SMA (300 km across). A mesoscale cifrculation, resulting from stronger spatial contrasts of sensible heat flux, more efficiently concentrates moist, warm air in a shallower boundary layer. This mechanism could explain the underestimation of peak Twb values in coarser-resolution products. The role of antecedent SMA from recent rainfall may help issue localized early warnings.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2024GL112467
UKCEH and CEH Sections/Science Areas:	Water and Climate Science (2025-)
ISSN:	0094-8276
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
NORA Subject Terms:	Earth Sciences Meteorology and Climatology
Related URLs:	Dataset Dataset Code Code
Date made live:	08 May 2025 11:31 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539395

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1029/2024GL112467

UKCEH and CEH Sections/Science Areas:

Water and Climate Science (2025-)

ISSN:

0094-8276

Additional Information. Not used in RCUK Gateway to Research.:

Open Access paper - full text available via Official URL link.

NORA Subject Terms:

Earth Sciences
Meteorology and Climatology