Recent Progress in Modeling of TTL Water Vapor and Clouds

Much progress has been made regarding the processes that control water vapor and clouds in the tropical tropopause layer (TTL), owing to the increased availability of observations and advances in modeling over the past few decades.  In particular, various modeling techniques have been developed over the years to investigate the relative importance of processes such as deep convection, large-scale and cloud radiative heating, wave-driven temperature variations, and cloud microphysics.  The models range in complexity and scope, from a three-dimensional chemical transport model to trajectory-based calculations with detailed cloud microphysics and convective influence.  Each modeling approach has its advantages and disadvantages, which together, has provided guidance on the level of detail required to adequately represent TTL processes in global climate models.  This talk will highlight recent progress in understanding the relative importance of numerous transport and microphysical processes that control TTL water vapor and clouds from a modeling perspective.  An overview of the modeling work on this topic and outstanding questions that remain will be discussed.