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The Evolutions and Large-scale Mechanisms of Summer Stratospheric Ozone Intrusion across Global Hotspots
  • Jae Won Lee,
  • Yutian Wu,
  • Xinyue Wang
Jae Won Lee
Lamont-Doherty Earth Observatory of Columbia University

Corresponding Author:[email protected]

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Yutian Wu
Lamont-Doherty Earth Observatory of Columbia University
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Xinyue Wang
University of colorado boulder
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Stratospheric ozone intrusions have a significant impact on surface ozone levels. Especially in summer, intrusions can contribute to extreme ozone events because of preexisting high ozone levels near the surface and cause serious health issues. Considering the increasing trend of surface ozone level, an understanding of stratospheric ozone intrusion is necessary. Previous studies mainly focused on the case studies, and general knowledge of the spatial structure and large-scale dynamics underlying these intrusions is lacking. Thus, based on the Whole Atmosphere Community Climate Model, version 6 (WACCM6) simulation and a stratospheric origin ozone tracer, we identify the global hotspots of stratospheric intrusions: North America, Africa, the Mediterranean, and the Middle East, and investigate the underlying large-scale mechanisms. From the trajectory analysis, we find that the upper-level jet drives isentropic mixing near the jet axis and initiates stratospheric ozone intrusion. Subsequently, climatological descent at the lower troposphere brings the ozone down to the surface, which explains the spatial preference of summertime stratospheric intrusion events. Apart from others, the Middle East shows a relatively fast descent, likely related to the Asian summer monsoon circulation.