Science Highlights

Thunderstorms Enhance Tropospheric Ozone by Wrapping and Shedding Stratospheric Air

Recent observations during the Deep Convective Cloud and Chemistry (DC3) campaign provided the first unambiguous evidence that the tropopause reaching thunderstorms bring ozone-rich stratospheric air down to the troposphere. Figure 1 shows the wrapping and shedding of ozone-rich stratospheric air near the cloud edge of a MCS, measured by the dial ozone lidar onboard the NASA DC-8 research aircraft. The fine-scale transport from the stratosphere may be a significant source of upper troposphere ozone complementing the in situ production of ozone in convective outflow regions. However, this fine-scale transport poses a significant challenge to global models that do not resolve storm scale dynamics, yet it is important to include such a representation because of the effect of ozone in the upper troposphere on the atmospheric radiation budget and on the tropospheric oxidizing capacity.



Figure 1. The vertical distribution of upper tropospheric ozone mixing ratio (upper) measured by DIAL along approximately 30 minutes (~ 400 km in distance) of the DC-8 flight. Note the cross section is shown in reversed time scale to illustrate the cross section from west to east. The black color indicates the region when the DIAL ozone channel produced no data due to cloud attenuation.  In situ ozone is shown by the color of the flight track.  The depolarization ratio (lower panel) from the DIAL 355 nm wavelength channel provides a signature of cloud/storm edge and outflow pattern in the neighborhood of the storm.  The outflow structure shown in light blue is most consistent with low number density of ice particles, which complements the stretching and shedding shown in the ozone structure (upper panel).

Reference:

Pan, L. L., C. R. Homeyer, S. B. Honomichl,B. A. Ridley, M. Weisman, M. Barth, J. W. Hair, M. A. Fenn, C. F. Butler, G. S. Diskin, J. H. Crawford, T. B. Ryerson, I. B. Pollack, and H. Huntrieser (2014), Thunderstorms Enhance Tropospheric Ozone by Wrapping and Shedding Stratospheric Air, Geophys. Res. Lett. , 41, 7785–7790, doi:10.1002/2014GL061921.