Articles | Volume 15, issue 1
Atmos. Chem. Phys., 15, 297–304, 2015
https://doi.org/10.5194/acp-15-297-2015
Atmos. Chem. Phys., 15, 297–304, 2015
https://doi.org/10.5194/acp-15-297-2015

Research article 13 Jan 2015

Research article | 13 Jan 2015

A global non-hydrostatic model study of a downward coupling through the tropical tropopause layer during a stratospheric sudden warming

N. Eguchi1, K. Kodera2, and T. Nasuno3 N. Eguchi et al.
  • 1Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan
  • 2Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
  • 3Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan

Abstract. The dynamical coupling process between the stratosphere and troposphere in the tropical tropopause layer (TTL) during a~stratospheric sudden warming (SSW) in boreal winter was investigated using simulation data from a global non-hydrostatic model (NICAM) that does not use cumulus parameterization. The model reproduced well the observed tropical tropospheric changes during the SSW, including the enhancement of convective activity following the amplification of planetary waves. Deep convective activity was enhanced in the latitude zone 20–10° S, in particular over the southwest Pacific and southwest Indian Ocean. Although the upwelling in the TTL was correlated with that in the stratosphere, the temperature tendency in the TTL changed little due to a compensation by diabatic heating originating from cloud formation. This result suggests that the stratospheric meridional circulation affects cloud formation in the TTL.

Short summary
The dynamical coupling process between stratosphere and troposphere in the tropical tropopause layer (TTL) during stratospheric sudden warming (SSW) was investigated using simulation data of global non-hydrostatic model (NICAM) that does not use cumulus parameterization. The results suggested that increased stratospheric tropical upwelling associated with SSW induced decreased static stability in TTL, which contributes to increased convective activity and changes in its large-scale organizations
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