EGU21-9359
https://doi.org/10.5194/egusphere-egu21-9359
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Impact of tropical tropopause layer cooling trend on extreme deep convection in Asian-African sector

Kunihiko Kodera1, Nawo Eguchi2, Rei Ueyama3, Beatriz Funatsu4, Marco Gaetani5, and Christopher Taylor6
Kunihiko Kodera et al.
  • 1Meteorological Research Institute, Climate Research, Tsukuba, Japan (kodera.kk@gmail.com)
  • 2Research Institute for Applied Mechanics Kyushu University, Kasuga, 816-8580, Japan (nawo@riam.kyushu-u.ac.jp)
  • 3NASA Ames Research Center, Moffett Field, 94035-0001, USA (rei.ueyama@nasa.gov)
  • 4CNRS, Université de Nantes, UMR 6554 LETG, Campus du Tertre Nantes, 44312, France (bmf.amit@gmail.com)
  • 5University School for Advanced Studies IUSS, Pavia, 27100, Italy (marco.gaetani@latmos.ipsl.fr)
  • 6UK Centre for Ecology and Hydrology, Wallingford, OX10 8BB, UK (cmt@ceh.ac.uk)

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 a 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 show that the changes since the 1980s involve a cooling trend in the tropical lower stratosphere and tropopause layer, combined with a warming in the troposphere. This feature is similar to that which might result from increased greenhouse gas levels. It is suggested that the decrease in the vertical temperature gradient in the tropical tropopause region enhances extreme deep convection where penetrating convection is frequent, whereas tropospheric warming suppresses the shallower convection. The essential feature of the recent changes over the tropics is therefore the depth of convection, rather than the total amount of surface precipitation. This could enhance cooling in the lower stratosphere through decrease in ozone concentration.

 

How to cite: Kodera, K., Eguchi, N., Ueyama, R., Funatsu, B., Gaetani, M., and Taylor, C.: Impact of tropical tropopause layer cooling trend on extreme deep convection in Asian-African sector, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9359, https://doi.org/10.5194/egusphere-egu21-9359, 2021.

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