Upward propagation of gravity waves and ionospheric perturbations triggered by the 2022 Hunga-Tonga volcanic eruption

Abstract

Using an atmosphere–ionosphere coupled model (GAIA), atmospheric and ionospheric perturbations triggered by the 2022 Hunga-Tonga volcanic eruption are studied. Our result shows that ionospheric perturbations are caused by neutral wind perturbations associated with gravity waves. Gravity waves with horizontal phase speeds of 200–310 m/s are excited in the troposphere near the Hunga-Tonga volcano, and propagate upward into the thermosphere. While the amplitude of the eruption-generated gravity waves is small in the troposphere (~ 1 m/s), the amplitude of the gravity waves increases exponentially with height because of the exponential decrease of the density, reaching 60‒80 m/s at 300 km height. General features of the TIDs appeared in GNSS–TEC observations reported in earlier studies are reproduced fairly well. We can conclude that the eruption-generated gravity waves whose horizontal phase velocity is close to the sound speed play an important role in thermospheric and ionospheric perturbations after the Hunga-Tonga volcano eruption.