First detection of aerosols of the Hunga Tonga eruption in the Northern Hemisphere stratospheric westerlies.

The Hunga Tonga-Hunga Ha'apai underwater volcano(20.54°S,175.38°W hereinafter referred to as Hunga Tonga)located near the South Pacific island of the Kingdom of Tonga erupted violently on 15 January 2022 at～04:15 coordinated universal time(UTC).The Hunga Tonga eruption generated an umbrella cloud approximately 500 km in diameter at its maximum extent,and the volcanic plume reached～58 km,likely making this eruption the most prominent explosion recorded since the 1991 eruption of Pinatubo[1]and arousing great attention from the scientific community.Volcanic eruptions can affect weather and climate both regionally and glob-ally,such as by reducing the diurnal cycle of surface air tempera-tures,reducing tropical precipitation,and inducing global cooling,stratospheric ozone depletion,and enhanced surface ultra-violet radiation[2].The main mechanism is related to volcanic ash particles and especially sulfur species(e.g.,SO2,H2S)that are injected into the stratosphere and oxidized to H2SO4,which in turn are converted to aqueous sulfuric acid aerosols.Aerosols scatter shortwave radiation and block it from reaching the surface,absorb longwave radiation,and provide sites for heterogeneous chemistry.Due to the weak vertical circulation in the stratosphere,volcanic eruptions that inject ash and SO2 into the stratosphere may lead to enhanced aerosol concentrations lasting up to several years[2,3].