A Trajectory-Based Climatology of Common Large-Scale Transport Pathways for Convective Overshoots over the United States

It has been well demonstrated that overshooting convection impacts atmospheric composition within the upper troposphere and lower stratosphere (UTLS). Namely, increases in lower stratosphere water vapor and upper troposphere ozone from convection have received considerable attention. In the midlatitudes, overshoot occurrence peaks in the warm season and in the Northern Hemisphere is most common over the United States. To improve understanding of common large-scale transport pathways for overshoot air, this study examines 13 years of trajectory calculations for particles initialized in radar-observed overshoots from hourly observations across the United States. Transport characteristics for one, two, and three day forward trajectories are evaluated to determine common transport paths of overshoot air over the U.S. Common overshoot location and transport pathways are examined by month to gain a detailed understanding of the seasonality of overshoots and their common large-scale transport paths. Trajectories are also evaluated based on their potential temperature and geometric altitude to determine transport differences between the middle world and lowermost stratosphere. Analyzing the altitudes of common overshoot paths will also support flight planning activities for the upcoming Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign.