Fitzpatrick, RGJ orcid.org/0000-0002-2562-3373, Parker, DJ orcid.org/0000-0003-2335-8198, Marsham, JH orcid.org/0000-0003-3219-8472 et al. (10 more authors) (2020) What Drives the Intensification of Mesoscale Convective Systems over the West African Sahel under Climate Change? Journal of Climate, 33 (8). pp. 3151-3172. ISSN 0894-8755
Abstract
Extreme rainfall is expected to increase under climate change, carrying potential socioeconomic risks. However, the magnitude of increase is uncertain. Over recent decades, extreme storms over the West African Sahel have increased in frequency, with increased vertical wind shear shown to be a cause. Drier midlevels, stronger cold pools, and increased storm organization have also been observed. Global models do not capture the potential effects of lower- to midtropospheric wind shear or cold pools on storm organization since they parameterize convection. Here we use the first convection-permitting simulations of African climate change to understand how changes in thermodynamics and storm dynamics affect future extreme Sahelian rainfall. The model, which simulates warming associated with representative concentration pathway 8.5 (RCP8.5) until the end of the twenty-first century, projects a 28% increase of the extreme rain rate of MCSs. The Sahel moisture change on average follows Clausius–Clapeyron scaling, but has regional heterogeneity. Rain rates scale with the product of time-of-storm total column water (TCW) and in-storm vertical velocity. Additionally, prestorm wind shear and convective available potential energy both modulate in-storm vertical velocity. Although wind shear affects cloud-top temperatures within our model, it has no direct correlation with precipitation rates. In our model, projected future increase in TCW is the primary explanation for increased rain rates. Finally, although colder cold pools are modeled in the future climate, we see no significant change in near-surface winds, highlighting avenues for future research on convection-permitting modeling of storm dynamics.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 American Meteorological Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
Keywords: | Africa; Convection; Wind shear; Precipitation; Climate change; Climate models |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number EU - European Union 603502 Royal Society No External Reference NERC (Natural Environment Research Council) NE/M003574/1 NERC (Natural Environment Research Council) NE/B505538/1 NERC (Natural Environment Research Council) NE/E003826/1 NERC (Natural Environment Research Council) NE/G018499/1 NERC (Natural Environment Research Council) NE/M017176/1 NERC (Natural Environment Research Council) NE/M020126/1 NERC (Natural Environment Research Council) NE/M02038X/1 Met Office Not Known Met Office L4161 |
Depositing User: | Symplectic Publications |
Date Deposited: | 15 Jan 2020 12:19 |
Last Modified: | 29 Aug 2021 20:16 |
Status: | Published |
Publisher: | American Meteorological Society |
Identification Number: | 10.1175/JCLI-D-19-0380.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:155668 |