Ionospheric disturbances observed over Japan following the eruption of Hunga Tonga-Hunga Ha’apai on 15 January 2022

• Published in: Earth, planets, and space Vol. 74; no. 1; pp. 1 - 9
• Main Author: Saito, Susumu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 21.04.2022; Springer; Springer Nature B.V; SpringerOpen
• Subjects: 2. Aeronomy; Acoustic waves; Amplitudes; Earth and Environmental Science; Earth Sciences; Environmental aspects; Express Letter; Geology; Geophysics/Geodesy; Global navigation satellite system; Ionosphere; Ionospheric irregularities; Ionospheric traveling ionospheric disturbance; Irregularities; Navigation satellites; Navigation systems; Perturbation; Pressure; Recent Advances in Scientific Application of GNSS Array Data; Surface pressure; Total Electron Content; Traveling ionospheric disturbances; Volcanic eruptions; Volcano eruption; Wave fronts; Wave propagation; Japan; Tonga; Volcano eruption; Ionospheric traveling ionospheric disturbance; Ionospheric irregularities
• ISSN: 1880-5981; 1343-8832; 1880-5981
• DOI: 10.1186/s40623-022-01619-0

Traveling ionospheric disturbances (TIDs) were observed over Japan by using Global Navigation Satellite System (GNSS) receiver network data after the eruption of Hunga Tonga-Hunga Ha’apai in Tonga on 15 January 2022. Two types of TIDs with different characteristics were observed as perturbation in the total electron content (TEC). The first one arrived at Japan which are located about 7800 km away from Hunga Tonga-Hunga Ha’apai about 3 h after the eruption. The amplitude was about ± 0.5 TECU. The wavefronts was in the NNE–SSW direction and propagated in the WNW direction (– 69 ∘ counter-clockwise from the north) at 250 m s - 1 . The wavelength was estimated as 400 km. The second one arrived at Japan about 7 h after the eruption. The amplitude was about ± 1.0 TECU. The wavefronts was in the NE–SW direction and propagated in the NW direction (– 53 ∘ counter-clockwise from the north) at 270 m s - 1 . The wavelength was longer than the first one and was estimated as 800 km. The first one were associated with ionospheric irregularities represented by the rate of TEC index (ROTI). In contrast, the second one did not have irregularities all over the TIDs, but in only a limited region. The arrival of the first TID was too early for the atmospheric acoustic waves to arrive, while the arrival of the second TIDs approximately coincided with the arrival of surface pressure enhancement. To understand the mechanisms of the TIDs, further studies with wide-area observations as well as numerical calculations are necessary. TIDs and ionospheric irregularities after volcanic eruption could be threats to GNSS-based systems especially for those which utilize carrier-phase measurements. Graphical Abstract