Atmospheric & Environmental Chemistry Seminars

Observational Constraints on the Impact of Deep Convection on Lower Stratospheric Composition over the U.S. in Summer

Jessica Smith, Harvard

Apr 9, 2021
12:00 pm to 1:00 pm | Remote

Abstract: Deep convective storms with sufficient energy to overshoot the local tropopause level provide a mechanism for the rapid transport of radiatively and chemically important trace species from near the surface to the lower stratosphere.Tropospheric air can contain aerosols, water, and trace gases, including halogen precursors implicated in stratospheric ozone loss. The impact of these storms, which occur on small temporal and spatial scales, depends upon their transport efficiency, their frequency, and their interaction with the larger-scale circulation of the stratosphere. North America during summer stands out globally for its frequency of cross-tropopause convection. High-resolution regional records from ground-based radar networks and geostationary satellite observing systems provide information on the frequency and distribution of convective overshoots. Furthermore, both satellite observations and in situ data acquired aboard NASA's ER-2 aircraft demonstrate that cross-tropopause convection leads to localized enhancements in stratospheric humidity over the U.S. These convective storm systems and their impact are the focus of NASA’s Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) mission, with ER-2 flights scheduled to begin in the summer of 2021. In the present analysis, in situ water vapor data and simultaneous measurements of long-lived trace species obtained during prior aircraft campaigns are used to constrain the quantity of water and tropospheric air delivered to the stratosphere by individual convective storm systems.


Viral Shah


Viral Shah