The Effect of Convective Injection of Ice on Stratospheric Water Vapor in a Changing Climate

Stratospheric water vapor affects the Earth's radiative balance and stratospheric chemistry, yet its future changes are uncertain and not fully understood. The influence of deep convection on stratospheric water vapor remains subject to debate. This letter presents a detailed process-based model study of the impact of convective ice sublimation on stratospheric water vapor in response to CO2 forced climate change. The influence of convective injection is found to be limited by the vertical profile of temperature and saturation vapor pressure in the tropical tropopause layer, not by the frequency of occurrence. Lagrangian trajectory analysis shows the relative contributions to stratospheric water vapor from sublimation and large-scale transport are approximately unchanged when CO2 is increased. The results indicate the role of convective ice injection for stratospheric water vapor in a warmer climate remains constrained by large-scale temperatures.