NOAA-NASA collaboration to study the impact of convective storms and the North American Summer Monsoon on stratospheric chemistry

Global Monitoring Laboratory and NASA team up in the DCOTSS (Dynamics and Chemistry of the Summer Stratosphere) project to study the convective impact of the North American Monsoon Anticyclone on stratospheric composition and ozone depletion. The first science deployment takes place between July 12 and August 26, 2021.

Strong convective uplift created by thunderstorms can rapidly move water vapor and pollutants into the stratosphere. There, water vapor and aerosols can catalyze reactions that activate chlorine and bromine radicals from the breakdown of ozone-depleting substances. Uplifted pollutants also include short-lived ozone-depleting substances that dissociate into bromine and chlorine radicals.

As a result of additional moisture and aerosols in the lower stratosphere, chemical reactions can be similar to those in the polar stratosphere during winter, leading to stratospheric ozone depletion. The depletion process could happen quite rapidly compared to typical rates of ozone destruction outside the polar vortex. Also, the anticyclonic circulation can contain and prolong this chemistry over the North American monsoon region and release chemically processed air into the rest of the northern hemispheric stratosphere.

Pre-campaign activities started in May, in Palmdale, CA, with instrument integration and test flights. Scientists are currently in the field collecting in-situ measurements of trace gases, water vapor, aerosols, reactive species, and meteorological parameters.

The NASA ER-2 high-altitude aircraft (a converted U-2 aircraft for environmental research) will fly approximately 15 science flights during the deployment from Salina, Kansas. The aircraft instruments predominantly make measurements along horizontal flight tracks in the stratosphere and upper troposphere over the continental United States. Instrumented balloons are launched to provide vertical ozone and water vapor profiles from the surface to the middle stratosphere from Salina during ER-2 flights.

Another 8-week science deployment will take place in early to middle summer 2022. The data collected in these science deployments will help to quantify the importance of monsoonal convection on the composition and chemistry of the lower stratosphere as they relate to ozone depletion.