Future intensification of precipitation and wind gust associated thunderstorms over Lake Victoria

Van de Walle, Jonas; Thiery, Wim; Brogli, Roman; Martius, Olivia; Zscheischler, Jakob; van Lipzig, Nicole P.M. (2021). Future intensification of precipitation and wind gust associated thunderstorms over Lake Victoria. Weather and climate extremes, 34, p. 100391. Elsevier 10.1016/j.wace.2021.100391

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Severe thunderstorms affect more than 30 million people living along the shores of Lake Victoria (East Africa). Thousands of fishers lose their lives on the lake every year. While deadly waves are assumed to be initiated by severe wind gusts, knowledge about thunderstorms is restricted to precipitation or environmental proxies. Here we use a regional climate model run at convection-permitting resolution to simulate both precipitation and wind gusts over Lake Victoria for a historical 10-year period. In addition, a pseudo global warming simulation provides insight into the region’s future climate. In this simulation, ERA5’s initial and boundary conditions are perturbed with atmospheric changes between 1995–2025 and 2070–2100, projected by CMIP6’s ensemble mean. It was found that future decreases in both mean precipitation and wind gusts over Lake Victoria can be attributed to a weaker mean mesoscale circulation that reduces the trigger for over-lake nighttime convection and decreases the mean wind shear. However, an intensification of extremes is projected for both over-lake precipitation and wind gusts. The observed 7 %K−1 Clausius–Clapeyron extreme precipitation scaling is ascribed to increased water vapor content and a compensation of weaker mesoscale circulations and stronger thunderstorm dynamics. More frequent wind gust extremes result from higher wind shear conditions and more compound thunderstorms with both intense rainfall and severe wind gusts. Overall, our study emphasizes Lake Victoria’s modulating role in determining regional current and future extremes, in addition to changes expected from the Clausius–Clapeyron relation.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography
08 Faculty of Science > Institute of Geography > Physical Geography > Unit Impact
08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography > Physical Geography

UniBE Contributor:

Romppainen-Martius, Olivia and Zscheischler, Jakob

Subjects:

900 History > 910 Geography & travel
500 Science > 530 Physics

ISSN:

2212-0947

Publisher:

Elsevier

Language:

English

Submitter:

Yannick Barton

Date Deposited:

24 Feb 2022 16:27

Last Modified:

27 Feb 2022 01:56

Publisher DOI:

10.1016/j.wace.2021.100391

BORIS DOI:

10.48350/165210

URI:

https://boris.unibe.ch/id/eprint/165210

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