Abstract
On Jan. 15, 2022, the Hunga Tonga-Hunga Ha’apai (HT) eruption injected
SO2 and water into the middle stratosphere. Shortly
after the eruption, the water vapor anomaly moved northward toward and
across the equator. This northward movement appears to be due to a
Rossby wave forced by the excessive IR water vapor cooling. Following
the early eruption stage, persistent mid-stratospheric water vapor and
aerosol layers were mostly confined to Southern Hemisphere (SH) tropics
(Eq. to 30°S). However, during the spring of 2022, the westerly phase of
the tropical quasi-biennial oscillation (QBO) descended through the
tropics. The HT water vapor and aerosol anomalies were observed to again
split across the equator coincident with the descent of the QBO shear
zone. This split occurred because of the enhanced meridional transport
circulation associated with the QBO. Neither transport event can be
reproduced using MERRA2 assimilated winds.