Evaluating the Impacts of Storm‐Scale and Environmental Factors on Stratosphere‐Troposphere Exchange Associated With Midlatitude Convection

Abstract Stratosphere‐troposphere exchange (STE) plays a crucial role in Earth's climate; however, the significance of small‐scale processes such as midlatitude convection to global STE remains understudied. Midlatitude tropopause‐overshooting convection is especially important to climate because it can enhance stratospheric water vapor, which has its greatest radiative forcing sensitivity in the extratropical lower stratosphere. Thus, it is essential to understand what factors influence the strength and prevalence of overshooting storms and associated STE. The U.S. Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign during 2021 and 2022 was the first large‐scale airborne primarily focused on sampling stratospheric impacts from overshooting convection. Our research utilizes the extensive DCOTSS data set in combination with radar, satellite, and environmental observations to investigate relationships between observed stratosphere composition change and storm and environmental characteristics. Our results demonstrate greater magnitudes of STE for above‐anvil cirrus plume (AACP)‐producing storms and mesoscale convective systems (MCSs). In addition, the most extreme enhancements in water vapor and other tropospheric gases occur where the tropopause height is low and the depth of overshooting is high, especially for AACP‐producing storms. We also investigate the impact of storm and environmental characteristics on pathways for hydration (air mass transport and mixing vs. ice sublimation), finding that they also modulate the frequencies of each process at different altitudes. Namely, mixing is found to be most prevalent in AACP‐producing storms and MCSs, which can help explain transport differences between water vapor and other gases.