Analysis and Impact of the Hunga Tonga-Hunga Ha’apai Stratospheric Water Vapor Plume

On Jan. 15, 2022, the Hunga Tonga-Hunga Ha’apai eruption injected SO2 and H2O into the 31 middle stratosphere. The eruption produced a persistent mid-stratospheric sulfate aerosol and H2O layer mostly confined to Southern Hemisphere (SH) tropics (Eq. to 30°S). These layers are still present in the tropics 5 ½ months after the eruption. The SH tropical confinement is simulated using a trajectory model. Measurements following the eruption show that the H2O layer is slowly rising while the aerosol layer is descending. The H2O layer’s upward movement is consistent with the residual vertical velocity. Gravitationally settling explains the descent of the aerosol layer. A -4K temperature anomaly coincident with the H2O enhancement is observed and is caused by thermal adjustment to the additional H2O IR cooling. A simple model of volcanic water injection at the time of the eruption simulates the observed vertical distribution H2O.