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 middle stratosphere. The eruption produced a persistent mid-stratospheric sulfate aerosol layer, mostly below 26 km, confined to Southern Hemisphere (SH) tropics. Coincident with, and slightly above the aerosol layer, an enhanced H2O layer is also observed. The SH tropical confinement is simulated using a trajectory model. Measurements over several months following the eruption show that the H2O layer is slowly rising while the aerosol layer is descending. The H2O layer upward movement is consistent with the vertical velocity at these altitudes. Gravitationally settling explains the descent of the aerosol layer. A cold 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 H2O.