Stratospheric transport and residence time of Hunga volcanic aerosol

The January 2022 eruption of Hunga injected unprecedented volumes of water vapor (150 Tg) and modest sulfur dioxide (SO₂) into the stratosphere, producing accelerated sulfate aerosol formation in the early plume. As the aerosols gradually spread into the global stratosphere, the role of water vapor, among other factors in the spread and residence time of the sulfate aerosols, remained unclear. We used multisatellite observations to better understand the role of water vapor in the spread and lifetime of Hunga volcanic aerosols. Stratospheric circulation transported the plumes to ~26 km within the polar vortices—the Antarctic by August 2022 and the Arctic by January 2023—with the arrival of aerosols lagging behind that of water vapor by months. Even though high injection altitudes (58 km) and strong Brewer–Dobson circulation contributed to prolonging the residence time of aerosols, the water vapor enhanced particle growth and thus accelerated gravitational settling, with the half lifetime of aerosols being 14 months. Our analysis revealed a critical trade-off: after the eruption of the Hunga volcano, an extremely high injection height and strong upward motion slowed the removal of aerosols, but extreme water vapor loading still had a certain impact on the half lifetime of the aerosols. These findings highlight the role of water vapor in the persistence of aerosols from submarine eruptions.