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

The Tonga eruption of 15 January 2022 has released a long-lived stratospheric plume of sulfate aerosols. More than 17 months after, we focus on the high quality data series of SAGE III (Stratospheric Aerosol and Gas Experiment) on board the International Space Station (ISS) to determine the mean radius and size distribution of the aerosols and their total mass. The persisting volcanic aerosols-with a mode width of 1.25 and an effective radius of 0.4 & mu;m-differ from the significantly smaller background aerosols and from those measured during recent stratospheric eruptions. The sulfuric acid mass between 50 & DEG;S and 30 & DEG;N is estimated to be very stable in spite of considerable redistribution in latitude at a value of 0.66 & PLUSMN; 0.1 Tg, corresponding to an initial sulfur dioxide emission of 0.44 Tg. Such properties are expected to facilitate the persistence of a climate warming due to the volcanic water vapor. We study the stratospheric aerosol plume produced by the Hunga Tonga-Hunga Ha'apai eruption on 15 January 2022 based on the high quality solar occultation measurements of the instrument SAGE III (Stratospheric Aerosol and Gas Experiment) onboard the International Space Station. These data reveal that the aerosol sizes are about twice as large as after other documented volcanic eruptions and that the total mass of H2SO4 in the liquid droplets of sulfate in the stratosphere has been very stable from March 2022, when it started to be well homogeneized in longitude, to November 2022, when it started to decay. The total mass of 0.66 Tg of H2SO4 is in good agreement with the early estimates of a stratospheric emission of 0.4-0.5 Tg of SO2. The implication is that the aerosol radiative impact will not mask the persisting warming effect of the water vapor injected in the stratosphere by the eruption. The extinction of the stratospheric plume of the 2022 Tonga eruption is well modeled by a unimodal distribution of sulfate particlesThe effective radius of the aerosols is large with values close to 0.4 & mu;m, and a mode width of 1.25, from March 2022 to June 2023We estimate a total H2SO4 mass in stratospheric sulfate aerosols of about 0.66 corresponding to 0.44 Tg of SO2 initially injected