The impact of tropical tropopause cooling on Sahelian extreme deep convection

Kodera, Kunihiko; Eguchi, Nawo; Ueyama, Rei; Funatsu, Beatriz M.; Gaetani, Marco; Taylor, Christopher M. ORCID: https://orcid.org/0000-0002-0120-3198. 2021 The impact of tropical tropopause cooling on Sahelian extreme deep convection. Journal of the Meteorological Society of Japan, 99 (4). 1127-1139. 10.2151/jmsj.2021-055

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Abstract/Summary

Previous studies have suggested that the recent increase in tropical extreme deep convection, in particular over Asia and Africa during the boreal summer, has occurred in association with cooling in the tropical lower stratosphere. The present study is focused on the Sahel region of West Africa, where an increased occurrence of extreme precipitation events has been reported over recent decades. The results indicate that the changes over West Africa since the 1980s involve a cooling trend in the tropical lower stratosphere and tropopause layer, combined with warming in the troposphere. This feature is similar to that which might result from increased greenhouse-gas levels but is distinct from the interannual variation of precipitation associated with the transport of water vapor from the Atlantic Ocean. It is suggested that the decrease in the vertical temperature gradient in the tropical tropopause region enhances extreme deep convection over the Sahel, where penetrating convection is frequent, whereas tropospheric warming suppresses the shallower convection over the Guinea Coast. Therefore, the essential feature of the recent changes over West Africa is the depth of convection rather than the total amount of surface precipitation.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.2151/jmsj.2021-055
UKCEH and CEH Sections/Science Areas:	Hydro-climate Risks (Science Area 2017-)
ISSN:	0026-1165
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	Sahel, recent trend, tropical tropopause layer, deep convection, land precipitation
NORA Subject Terms:	Meteorology and Climatology
Date made live:	21 May 2021 11:00 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/530224

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