Plain Language Summary
The Hunga Tonga-Hunga Ha’apai (HT) submarine volcanic eruption on
January 15, 2022, produced aerosol and water vapor plumes in the
stratosphere. These plumes have persisted in the Southern Hemisphere.
Following the eruption, we believe that the strong water vapor cooling
forced an equatorial Rossby wave whose circulation pushed the eruption
plume into the Northern Hemisphere. Then, in April and May 2022, the
descending quasi-biennial oscillation transported more of the water
vapor plume across the equator and widened the latitudinal extent of the
aerosol plume. The spring 2022 change in the HT plume distribution shows
the importance of forced Rossby waves and the QBO in stratospheric
interhemispheric transport.