Two- and Three-Dimensional Propagation Characteristics of Co-Volcanic Ionospheric Disturbances Induced by the 2022 Tonga Volcano Eruption Using Dense GNSS Network Data

Abstract

On 15 January 2022, the submarine volcano in Hunga Tonga-Hunga Ha’apai (hereinafter Tonga volcano) erupted at 04:14 universal time. This study investigated the two- and three-dimensional co-volcanic ionospheric disturbances (CVIDs) induced by the strong Tonga volcano. Based on dense Global Navigation Satellite System network data in Australia, the two-dimensional detrended total electron content maps were first generated by using the Savitzky-Golay filtering method. Using a compressed sensing-based computerized ionospheric tomography approach, the three-dimensional ionospheric electron densities were reconstructed. After the eruption, the distinctive CVIDs began to be mostly observed over southeastern Australia, about 4,000 km from the volcano. Two patterns of observable CVIDs, that is, fast-mode and slow-mode CVIDs, traveled outward from the Tonga volcano at speeds of 600–850 and 200–350 m/s, respectively. The slow-mode CVIDs were related to the Lamb and secondary gravity waves, while the fast-mode CVIDs were related to acoustic waves. Three-dimensional reconstruction results demonstrated that as the CVIDs propagated upward, the electron densities fluctuated at most altitude-longitude slices, and the wave-like propagating patterns were clearly observed around the peak ionospheric heights of 260–340 km. At the peak ionospheric height, the ionospheric parameters derived from the two ionosondes over Australia also detected similar wave-like features. Two-dimensional and three-dimensional observational evidence of the Tonga-induced CVIDs enhances research on volcanic eruption effects over the upper ionosphere.