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Strong Evidence of Heterogeneous Processing on Stratospheric Sulfate Aerosol in the Extrapolar Southern Hemisphere Following the 2022 Hunga Tonga-Hunga Ha'apai Eruption
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  • Michelle L. Santee,
  • Alyn Lambert,
  • Lucien Froidevaux,
  • Gloria L Manney,
  • Michael J. Schwartz,
  • Luis Millan,
  • Nathaniel J Livesey,
  • William G. Read,
  • Frank Werner,
  • Ryan A. Fuller
Michelle L. Santee
Jet Propulsion Laboratory

Corresponding Author:[email protected]

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Alyn Lambert
Jet Propulsion Lab (NASA)
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Lucien Froidevaux
JPL/California Institute of Technology, California, USA
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Gloria L Manney
Northwest Research Associates
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Michael J. Schwartz
Jet Propulsion Laboratory, California Institute of Technology
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Luis Millan
Jet propulsion laboratory
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Nathaniel J Livesey
Jet Propulsion Laboratory
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William G. Read
Jet Propulsion Lab (NASA)
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Frank Werner
Jet Propulsion Laboratory, California Institute of Technology
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Ryan A. Fuller
Jet Propulsion Lab, Caltech
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Abstract

The January 2022 eruption of Hunga Tonga-Hunga Ha’apai (HT-HH) caused the largest enhancement in stratospheric aerosol loading in decades and produced an unprecedented enhancement in stratospheric water vapor, which led to strong stratospheric cooling that in turn induced changes in the large-scale circulation. Here we use satellite measurements of gas-phase constituents together with aerosol extinction to investigate the extent to which the thick aerosol, excess moisture, and strong cooling enabled heterogeneous chemical processing. In the southern tropics, unambiguous signatures of substantial chlorine and nitrogen repartitioning appear over a broad vertical domain almost immediately after the eruption, with depletion of N2O5, NOx, and HCl accompanied by enhancement of HNO3, ClO, and ClONO2. After initially rising steeply, HNO3 and ClO plateau, maintaining fairly constant abundances for several months. These patterns are consistent with the saturation of N2O5 hydrolysis, suggesting that this reaction is the primary mechanism for the observed composition changes. The southern midlatitudes and subtropics show similar but weaker enhancements in ClO and ClONO2. In those regions, however, effects of anomalous transport dominate the evolution of HNO3 and HCl, obscuring the signs of heterogeneous processing. Perturbations in chlorine species are considerably weaker than those measured in the southern midlatitude stratosphere following the Australian New Year’s fires in 2020. The moderate HT-HH-induced enhancements in reactive chlorine seen throughout the southern middle and low-latitude stratosphere, far smaller than those in typical winter polar vortices, do not lead to appreciable chemical ozone loss; rather, extrapolar lower-stratospheric ozone remains primarily controlled by dynamical processes.
09 May 2023Submitted to ESS Open Archive
25 May 2023Published in ESS Open Archive