Tracking the Influence of Stratospheric Air in Aircraft Campaigns

Lesley Ott

The DISCOVER-AQ aircraft campaigns were designed to study the impact of air pollution near Earth’s surface. During the July, 2011 deployment in the DC-Baltimore area, research aircraft also observed high ozone from a source they didn’t expect – the stratosphere. Stratospheric air is richer in ozone and lower in CO and H2O than tropospheric air (grey shading left panel). Rapid downward transport of stratospheric air can increase ozone mixing ratios near the surface, but these events occur mostly in the western U.S. during spring. GEOS-5 simulations with stratospheric tracers show that these events affect the East Coast during summer, too, and were likely responsible for high ozone observed between 2 and 4 km on July 27 (right).

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