Stratospheric Aerosol and Ozone Responses to the Hunga Tonga-Hunga Ha'apai Volcanic Eruption

The Hunga Tonga-Hunga Ha'apai (HTHH) eruption on 15 January 2022 was one of the most explosive volcanic events of the 21st century so far. According to satellite-based measurements, 0.4 Tg of sulfur dioxide (SO2) was injected into the stratosphere during the eruption. By using observations and model simulations, here we investigate changes in the chemical compositions of the stratosphere 1 year after the HTHH eruption and examine the key physical and chemical processes that influence the ozone (O-3) concentrations. Injected SO2 was oxidized into sulfate during the first 2 months, and transported from the tropics to the Antarctic by the Brewer-Dobson circulation within 1 year. In mid-to-low latitudes, enhanced sulfate aerosol increased O-3 concentrations in the middle stratosphere but declined in the lower stratosphere. In addition to the chemical processes, sulfate aerosols also reduced polar low-stratospheric O-3 concentrations through enhanced Antarctic upwelling anomalies.