Evaluating the Impacts of Storm-Scale and Environmental Factors on Stratosphere-Troposphere Exchange Associated with Deep Mid Latitude Convection

Stratosphere-troposphere exchange (STE) plays a crucial role in Earth’s climate and atmospheric chemistry. The Brewer-Dobson circulation, tropical convection, and extratropical cyclones have long been recognized as important mechanisms for STE; however, the critical role of deep midlatitude convection in STE gained appreciation only in recent decades. Tropopause overshooting convection in the extratropics is especially important for stratospheric water vapor budgets because its radiative forcing sensitivity is greatest there. Thus, it is essential to understand what factors influence the strength and prevalence of overshooting storms and associated STE. The Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign over the central U.S. during the summers of 2021 and 2022 was the first large-scale field campaign for which sampling the stratosphere immediately after overshooting convection via aircraft was a primary focus, resulting in the most extensive dataset on STE in midlatitude overshooting convection to date. The goal of our research is to use this dataset in combination with radar and satellite data to investigate the relationships between observed lower stratosphere composition change and various storm and environmental characteristics (e.g. storm mode, tropopause height, storm top height, depth of overshooting above the tropopause, presence or absence of an above anvil cirrus plume (AACP)). We use back trajectories to link aircraft observations to prior storms to complete our analysis. Preliminary results show that the strength of measured water vapor enhancements decreases as the time between the storm and measurements increases, indicating the increasing importance of dilution from mixing of the injected air into the background stratosphere over time. In addition, the most extreme enhancements occur where the tropopause height is low (and tropopause temperature is high), especially for AACP-producing storms. We also observed greater magnitudes and depths of water vapor enhancements overall for AACP-producing storms.