Growth and global persistence of stratospheric sulfate aerosols from the 2022 Hunga Tonga-Hunga Haápai 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 photometric 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 µm) is identified at >20 stations of the southern hemisphere until December 2022 (time of writing). Nevertheless, one year 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

“…(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).…”

“…(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.…”

“…It was suggested that the initial estimate could have missed a large amount of already converted SO 2 and estimates of up to 1.5 Tg have been speculated on (Legras et al., 2022; Sellitto et al., 2022). Several estimates of the average size of the aerosols and of their evolution ranging from 0.2 to 1 μm have been provided from satellite retrievals and in situ measurements (Baron et al., 2023; Boichu et al., 2023; Khaykin et al., 2022; Kloss et al., 2022; Legras et al., 2022; Schoeberl et al., 2022; Taha et al., 2022). Such dispersion has considerable impact on the persistence of aerosols in the stratosphere and their radiative impact (Sellitto et al., 2022; Zhang et al., 2022; Zhu et al., 2022).…”

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

“…Specifically, Biochu et al. (2024) combined Himawari‐8 geostationary thermal infrared imagery with CALIPSO lidar to identify 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 validation in the current study.…”