Moisture transport by convective overshoots in the tropical tropopause layer

Abstract Deep convection overshooting the tropical tropopause offers the potential for significant transport of moisture into the tropical tropopause layer (TTL) by avoiding the cold‐point temperature constraint on water vapour concentration. As vertical transport through the TTL largely sets global stratospheric composition, convective hydration is an important but debated pathway. In this review, we discuss evidence of convective hydration of the TTL and its mechanism, highlighting recent advances in understanding. We summarise recent estimates for the contribution of convective hydration to the stratospheric water vapour budget and highlight open questions that may be addressed in future research.