Atmospheric Turbulence in the Upper Troposphere and Lower Stratosphere From Airborne Observations During the DCOTSS Field Campaign

Turbulence in the upper troposphere and lower stratosphere (UTLS) plays an important role in total energy dissipation and in the transport and mixing of heat, momentum, and atmospheric constituents while also posing significant hazards to aviation. In this study, we leverage high-altitude in situ observations from the NASA Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign—including data acquired near convection and at altitudes rarely covered by commercial aircraft—to investigate turbulence and its potential link to UTLS composition. We find that strong turbulence occurs frequently within 2 km above the tropopause, which corresponds to 1–2 km above deep convective cloud tops, particularly within moist convective plumes characterized by enhanced water vapor. The occurrence of strong turbulence increases with proximity to convection with elevated frequencies persisting out to 100 km from convective cores. In particular, enhanced turbulence potential occurs near UTLS convective outflows, which is supported by favorable environmental factors such as strong vertical wind shear, flow deformation, and large divergence tendencies. Furthermore, although turbulence intensity and water vapor are generally weakly correlated, positive correlations occur more frequently near the tropopause and under strong vertical wind shear, suggesting that turbulent mixing may contribute to localized stratospheric moistening under certain atmospheric conditions. The findings demonstrate the utility of high-altitude in situ observations for advancing our understanding of UTLS turbulence and its influence on atmospheric composition, with implications not only for climate but also for future high-altitude aviation applications.