Stratospheric aerosol formed by intense volcanism–sea interaction during the 2022 Hunga Ha’apai eruption

Abstract

The Hunga Tonga eruption on 15 January 2022 (HT-22) induced vigorous volcano–sea interaction. Here we study the stratospheric aerosol and water vapor resulting from the eruption using satellite-based instruments: the CALIOP lidar and the Microwave Limb Sounder (MLS). We investigate the stratospheric relative humidity following the record-breaking water vapor injections from the HT-22 eruption and the particle size of the aerosol. The HT-22 eruption injected its effluents into the deep Brewer–Dobson (BD) branch causing several years of stratospheric perturbation. The long duration and the aerosol concentration (among the highest) make the HT-22 eruption the strongest stratospheric aerosol event since the 1991 Mt. Pinatubo eruption despite a modest SO2 injection explaining only ∼ 30 % of the aerosol optical depth (AOD) from the HT-22 eruption according to our estimates. The stratospheric AOD level was established after 2 weeks, or possibly even earlier, which is a short time compared with the usual 2–3 months required to reach the maximum AOD following volcanic eruptions. We discuss the sources of the aerosol from the HT-22 eruption in relation to the low emission of SO2, its e-folding time, and volcanological observations of strong interactions with the sea containing not only water but also high concentrations of dissolved substances.