In a new ACPD article, N. Eguchi et al. use the NICAM global non-hydrostatic model to investigate the dynamical coupling between the stratosphere and troposphere in the tropical tropopause layer (TTL) during a stratospheric sudden warming (SSW) in boreal winter. The model reproduced the observed tropical tropospheric changes well, including the enhancement of convective activity following the amplification of planetary waves. They found that deep convective activity was enhanced from 10-20°S and although this upwelling in the TTL was correlated with that occurring in the stratosphere, the TTL temperature tendency was controlled mainly by diabatic heating originating from cloud formation. This suggests that the stratospheric meridional circulation affects cloud formation in the TTL. The full abstract can be found here.