Tropical Water Fluxes Dominated by Deep Convection Up to Near Tropopause Levels

Abstract In the tropics, the tropopause is exceptionally cold and air entering the stratosphere is dehydrated down to a few parts per million leading to the extreme dryness of Earth’s stratosphere. Deep convection typically detrains a few kilometers below the tropopause, but the few storms that may reach up to the tropopause could have an outsize effect on water vapor, other chemically important trace species, and clouds. However, little progress has been made to quantify the role of these storms due to challenging conditions for observations, and computational limitations. Here we provide the first global observational estimate of the convective ice flux at near tropical tropopause levels by using spaceborne lidar measurements and pioneering a method to convert from lidar measurement to ice flux information. Our estimate indicates that the upward ice flux in deep convection dominates moisture transport almost all the way up to the cold point tropopause.