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Stratospheric chlorine processing after the unprecedented Hunga Tonga eruption
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  • Jun Zhang,
  • Peidong Wang,
  • Douglas Edward Kinnison,
  • Susan Solomon,
  • Jian Guan,
  • Yunqian Zhu
Jun Zhang
NSF National Center for Atmospheric Research

Corresponding Author:[email protected]

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Peidong Wang
Massachusetts Institute of Technology
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Douglas Edward Kinnison
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Susan Solomon
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Jian Guan
Massachusetts Institute of Technology
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Yunqian Zhu
University of Colorado Boulder
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Following the Hunga Tonga–Hunga Ha’apai (HTHH) eruption in January 2022, a significant reduction in stratospheric hydrochloric acid (HCl) was observed in the Southern Hemisphere mid-latitudes during the latter half of 2022, suggesting potential chlorine activation. The objective of this study is to comprehensively understand the substantial loss of HCl in the aftermath of HTHH. Satellite measurements along with a global chemistry-climate model are employed for the analysis. We find strong agreement of 2022 anomalies between the modeled and the measured data. The observed tracer-tracer relations between N2O and HCl indicate a significant role of chemical processing in the observed HCl reduction, especially during the austral winter of 2022. Further examining the roles of chlorine gas-phase and heterogeneous chemistry, we find that heterogeneous chemistry emerges as the primary driver for the chemical loss of HCl, with the reaction between HOBr and HCl on sulfate aerosols identified as the dominant loss process.
15 Feb 2024Submitted to ESS Open Archive
16 Feb 2024Published in ESS Open Archive