The effects of overshooting convection on mixing within the tropical tropical tropopause layer in idealised climate states

A series of cloud-resolving simulations are performed to study the impact of spatial/and or temporal inhomogeneity of tropical deep convection, in particular convective overshoots that penetrate into the tropical tropopause layer, on upper tropospheric/lower stratospheric (UTLS) temperature structure and trends under surface warming. Two sets of simulations are studied: one in which the sea surface temperature (SST) is increased uniformly, and a second in which convective updrafts are intensified periodically by introducing an island-like surface with a fixed-diurnal cycle while the surrounding SST is unchanged. All simulations are run to radiative-convective equilibrium so as to capture the mean-state response at larger time scales. We discuss the implications of our results for the interpretation of observed and modelled trends in the UTLS.