Simulation study of atmosphere-ionosphere variations driven by the eruption of Hunga Tonga-Hunga Ha'apai on 15 January 2022

The volcano of Hunga Tonga-Hunga Ha'apai in Tonga erupted on 15 January 2022, generating severe disturbances in the atmosphere and the ionosphere. This event provided us with large amount of data of the atmosphere and the ionosphere, and various kinds of observational studies have been made. Recently several simulation studies have also been made to reproduce and understand the atmosphere-ionosphere variations driven by the volcanic eruption. Although the simulation studies have reproduced the global variations of the atmosphere and the ionosphere successfully, phenomena related with acoustic waves have not been fully investigated. We employed an axisymmetric three-dimensional nonhydrostatic atmospheric model and the whole atmosphere-ionosphere coupled model GAIA. We found that the simulation can produce various kinds of atmospheric waves generated by the eruption, such as acoustic waves, gravity waves, Lamb waves, Pekeris waves, and TIDs concentrically propagating from the eruption site, and atmospheric oscillations with a period of a few minutes. In addition, the results indicate that the eruption generates supersonic shock waves in the volcanic region, leading to the extremely large vertical oscillations in the thermosphere and ionosphere above the volcanic eruption region.