Growth and global persistence of stratospheric sulfate aerosols from the 2022 Hunga Tonga-Hunga Ha'apai volcanic eruption

Abstract

Stratospheric sulfate aerosols play a key role on atmospheric chemistry and Earth’s radiation budget, but their size distribution, a critical parameter in climate models, is generally poorly-known. We address such gap for the 2022 Hunga Tonga-Hunga Ha’apai (HT-HH) volcanic eruption by exhaustively analyzing a set of satellite observations together with photometric ground observations from the worldwide open-access AERONET network. We document a rapid growth of HT-HH sulfate aerosols in the days following eruption, faster than observed for other stratospheric eruptions, likely due to the exceptional hydration of the stratosphere by this phreatomagmatic eruption. An unusual aerosol fine mode (peak radius in 0.3-0.5 microns) is identified at 20 stations of the southern hemisphere until May 2023 (time of writing). Nevertheless, 1.4 years after eruption, HT-HH sulfate aerosols remain smaller than 1991 Pinatubo particles. Smaller aerosols backscatter more efficiently visible light and sediment more slowly than larger particles, implying stronger and longer-lasting negative radiative forcing.

Observation of the Aerosol Plume From the 2022 Hunga Tonga—Hunga Ha'apai Eruption With SAGE III/ISS

“…Our size estimate is compatible with other estimates of large sizes from radiative remote sensing or in situ measurements of the core part of the plume (r eff > 0.3 μm for Baron et al (2023) and r eff ≈ 0.5 μm for Kloss et al (2022) and Boichu et al (2023)) about 10 days after the eruption while a very few measurements with smaller sizes have also been reported for early dates (Boichu et al, 2023;Khaykin et al, 2022) or peripherical parts of the plume (Kloss et al, 2022). We retain that the stable distribution measured from SAGE III was established just after the fast initial conversion to sulfates.…”

“…The unusual size distribution of aerosols is related to the fast conversion of SO 2 to sulfates and possible sustained condensation/coagulation under very moist conditions documented by, for example, Legras et al (2022) and modeled by Zhu et al (2022). The size distribution is characterized by larger particles than recent stratospheric volcanic eruptions, like Raikoke and others, but smaller than for the Pinatubo (Boichu et al, 2023), with an unusually small mode width. The top of the atmosphere radiative impact has been estimated dominated by the warming of water vapor during the first months after the eruption (Sellitto et al, 2022).…”

Evolving Particles in the 2022 Hunga Tonga—Hunga Ha'apai Volcano Eruption Plume

“…We note also that shortly after we originally submitted the current paper, a paper appeared that used different datasets to reach conclusions similar to key aspects of the results presented here. Specifically, Boichu et al (2023) combined Himawari‐8 geostationary thermal infrared imagery with CALIPSO lidar to infer ash on 15 January, and subsequently smaller, but initially rapidly growing, stratospheric aerosol with estimated 0.3–0.5 μm radius, which they interpret as sulfate and track for up to 1.4 years thereafter. They support their satellite‐data interpretation with measurements from multiple low‐latitude AERONET stations, including the Lucinda and Learmonth stations that we use for validating the MISR retrievals in the current study.…”