Mesospheric temperature and circulation response to the Hunga Tonga-Hunga-Ha'apai volcanic eruption

Journal Article · Sat Nov 04 00:00:00 EDT 2023 · Journal of Geophysical Research: Atmospheres (Online)

DOI:https://doi.org/10.1029/2023JD039636· OSTI ID:2212860

Yu, Wandi ^[1]; Garcia, R. ^[2]; Yue, J ^[3]; Smith, Anne K. ^[2]; Wang, Xinyue ^[2]; Randel, William J. ^[2]; Qiao, Zishun ^[4]; Zhu, Yunqian ^[5]; Harvey, V. Lynn ^[6]; Tilmes, S ^[2]; Mlynczak, Martin G. ^[7]

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1. Hampton University, Hampton, VA (United States)
2. National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
3. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); The Catholic University of America, Washington, DC (United States)
4. Embry-Riddle Aeronautical University, Daytona Beach, FL (United States)
5. University of Colorado Boulder, CO (United States); University of Colorado Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO (United States)
6. University of Colorado, Boulder, CO (United States)
7. NASA Langley Research Center, Hampton, VA (United States)

The Hunga Tonga Hunga-Ha'apai (HTHH) volcanic eruption on 15 January 2022 injected water vapor and SO₂ into the stratosphere. Several months after the eruption, significantly stronger westerlies, and a weaker Brewer-Dobson circulation developed in the stratosphere of the Southern Hemisphere and were accompanied by unprecedented temperature anomalies in the stratosphere and mesosphere. In August 2022, the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instrument observed record-breaking temperature anomalies in the stratosphere and mesosphere that alternate signs with altitude. Ensemble simulations carried out with the Whole Atmosphere Community Climate Model (WACCM6) indicate that the strengthening of the stratospheric westerlies explains the mesospheric temperature changes. The stronger westerlies cause stronger westward gravity wave drag in the mesosphere. Although the enhanced gravity wave drag is partly balanced by a weakening of planetary wave forcing, the net result is an acceleration of the mesospheric mean meridional circulation. The stronger mesospheric circulation, in turn, plays a dominant role in driving the changes in mesospheric temperatures. This study highlights the impact of large volcanic eruptions on middle atmospheric dynamics and provides insight into their long-term effects in the mesosphere. On the other hand, we could not discern a clear mechanism for the observed changes in stratospheric circulation. In fact, an examination of the WACCM ensemble reveals that not every member reproduces the large changes observed by SABER. We conclude that there is a stochastic component to the stratospheric response to the HTHH eruption.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); National Oceanic and Atmospheric Administration (NOAA); USDOE Office of Science (SC)
• Grant/Contract Number: AC52-07NA27344; 80NSSC19K1214; AGS-1828589; AGS-1901126; NA17OAR4320101; NA22OAR4320151
• OSTI ID: 2212860
• Report Number(s): LLNL-JRNL-854522; 1082941
• Journal Information: Journal of Geophysical Research: Atmospheres (Online), Vol. 128, Issue 21; ISSN 2169-8996
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

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