Analysis and Impact of the Hunga Tonga‐Hunga Ha'apai Stratospheric Water Vapor Plume

Abstract On 15 January 2022, the Hunga Tonga‐Hunga Ha'apai eruption injected SO 2 and H 2 O into the middle stratosphere. The eruption produced a persistent mid‐stratospheric sulfate aerosol and H 2 O layer mostly confined to Southern Hemisphere (SH) tropics (Eq. to 30°S). These layers are still present in the tropics 5½ months after the eruption. The SH tropical confinement is simulated using a trajectory model. Measurements following the eruption show that the H 2 O layer is slowly rising while the aerosol layer is descending. The H 2 O layer's upward movement is consistent with the residual vertical velocity. Gravitationally settling explains the descent of the aerosol layer. A −4 K temperature anomaly coincident with the H 2 O enhancement is observed and is caused by thermal adjustment to the additional H 2 O IR cooling. A simple model of volcanic water injection at the time of the eruption simulates the observed vertical distribution H 2 O.