SPARC HTHH 2022-2025

Hunga Tonga-Hunga Ha’apai Impacts Activity

The Hunga Tonga-Hunga Ha’apai Impacts activity was established by SPARC (Stratosphere-troposphere Processes And their Role in Climate) to examine impacts of the Hunga Tonga-Hunga Ha’apai (HTHH) eruption of January 2022. HTHH was the most explosive volcanic eruption in the satellite era, and the water-rich plume presents an opportunity to understand the impacts on the stratosphere of a large magnitude explosive phreatomagmatic eruption. The wide range of satellite observations of the early stratospheric plume and its global dispersion will provide measurements to evaluate a range of models for their capabilities to represent stratospheric chemistry, aerosol and dynamics, in this case where both water vapor and aerosol are influencing radiative balances and stratospheric ozone.

There are numerous HTHH eruption observational and modeling studies that have been published, preprints of submitted papers, and new research in early stages. As the dispersed volcanic cloud continues to evolve and its impacts emerge, additional papers will be published. Because of the number and broad range of studies of the HTHH emissions and impacts, a SPARC limited-term cross-activity focused project is being organized to provide a forum for community discussions and synthesis, and to coordinate multi-model assessments. During this 3-year HTHH SPARC activity, the team will coordinate research activities and aim to write a special Hunga-Tonga impacts report for publication in late 2025. The report will directly feed into the upcoming 2026 UNEP/WMO Scientific Assessment of Ozone Depletion report, providing a benchmark synthesis of the impacts from the eruption. Interested scientists in the broader research community are welcomed to be involved in this activity.

This HTHH community assessment spans multiple research topics but is focused on the following three science themes:

  1. Plume evolution, dispersion and large-scale transport
  2. Impacts on stratospheric aerosols and the ozone layer
  3. Radiative forcings from the eruption and surface climate impacts
NCAR WACCM6 simulation
NCAR Whole Atmosphere Community Climate Model version 6 (WACCM6) simulation of HTHH water plume anomaly evolution from 2022 to 2025. Figure: Wandi Yu, University of Hampton; Xinyue Wang, NCAR; LASP Web Team

The final HTHH SPARC Report:

Initial chapters will document the stratosphere aerosol and ozone layer impacts in 2022, and analyze Antarctic ozone hole impacts expected also in 2023 and 2024, along with water vapor impacts via the upper atmosphere likely to continue into 2024 and 2025.

This HTHH community assessment spans multiple research topics but is focused on the following two science themes:

  1. Plume evolution, dispersion and large-scale transport;
  2. Impacts on and feedback from the earth system.

Potential chapters include: