资源环境科技发展态势分析平台

Abstract. We use a combination of space-borne instruments (CALIOP, OMPS-LP, IASI, MLS, ALADIN, GEOs) to study the unprecedented stratospheric plume after the Hunga Tonga eruption of 15 January 2022. The plume was formed of two initial clouds at 30 and 28 km mostly composed of sub-micronic sulphate particles without ashes, washed-out within the first hours. The large amount of water vapour injected led to a fast conversion of SO₂ to sulphates and the fast descent of the plume over the first three weeks. While SO₂ returned to background levels by the end of January, the sulphate plume persisted until June, mainly confined between 20° N and 35° S due to the zonal symmetry of the summer stratospheric circulation at 24–25 km. As they grew through hydration and coagulation, the sedimenting sulphate particles separated from the ascending moisture entrained in the Brewer-Dobson circulation. IASI-derived sulphate aerosol optical depths show that the aerosol plume was not simply diluted and dispersed passively but rather organized in concentrated patches. ALADIN-AEOLUS winds suggest that those structures, generated by shear-induced instabilities, are associated with vorticity anomalies. They likely enhance the duration and impacts of the plume.