On the Propagation of Traveling Ionospheric Disturbances From the Hunga Tonga‐Hunga Ha'apai Volcano Eruption and Their Possible Connection With Tsunami Waves

• Published in: Geophysical research letters Vol. 50; no. 6
• Main Authors: Pradipta, Rezy, Carter, Brett A., Currie, Julie L., Choy, Suelynn, Wilkinson, Phil, Maher, Phillip, Marshall, Richard
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.03.2023; Wiley
• Subjects: Atmospheric waves; Direction; Earth; Earth ionosphere; Eruptions; Global positioning systems; GNSS; GPS; Ground stations; ionosonde; Ionosondes; Ionosphere; Ionospheric propagation; Propagation velocity; Radio signals; Ripple patterns; Ripples; Satellite navigation systems; Shock wave propagation; Shock waves; Spatial data; total electron content; Traveling ionospheric disturbances; Tsunamis; Velocity; Velocity distribution; Velocity profiles; Volcanic eruptions; volcano eruption; Volcanoes; Wave fronts; Tonga
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL101925

We report our analysis of ionospheric disturbances from the 15 January 2022 Tonga volcano eruption, using GPS data from the International GNSS Service network and ionosonde data in the Australian sector. Wave fluctuations with amplitudes of ∼1 TECU and altitude variations of ∼100 km were observed in the GPS and ionosonde data, respectively. In near‐field region around Tonga shortly after the eruption, our analysis reveals that the ionospheric disturbances had an azimuthally anisotropic velocity profile, with a peculiar minimum in southwestward direction. Close resemblance is identified between the velocity profile of near‐field ionospheric disturbances and the Tonga tsunami, suggesting a coupling between water and atmospheric waves. In far‐field, the disturbances propagated at ∼300 m/s, circling the globe for at least three days and possibly until 21 January 2022, in agreement with several previous reports of the event. Arrival times of ionospheric disturbances observed by GPS receivers and ionosondes provide consistent picture. Plain Language Summary Massive eruption of the Hunga‐Tonga volcano on 15 January 2022 generated tsunami waves in the ocean and shock waves in the Earth's atmosphere. The shock waves from the eruption also propagated upward into space and reached the Earth's ionosphere, creating some ripples. We detected these ionospheric ripples with the help of radio frequency signals transmitted from ground stations and from GPS satellites. The scientific measurement data were recorded by ionosonde stations around Australia, and by network of GPS receiver stations that are distributed internationally. While several previous research works have examined the global nature of the Tonga disturbances, here we contrasted the disturbance profiles in both near‐field and far‐field. Far away from the Tonga volcano, the ionospheric disturbances propagated uniformly with velocity close to 300 m/s in all directions around the globe. This pattern is consistent with previous reports. Near the Tonga volcano, however, these ionospheric ripples spread out unevenly, showing complex patterns whereby the wave speed varied with direction. The uneven ripple patterns in the ionosphere around Tonga were found to be correlated with the uneven tsunami wavefront within the Tonga basin. Key Points We investigated near‐field and far‐field traveling ionospheric disturbance (TID) from the 15 January 2022 Tonga volcano eruption using GPS total electron content and ionosondes TID velocity profile in near‐field around Tonga shows directional asymmetry, likely connected to the anisotropy of tsunami waves In far‐field, TID velocity profile isotropizes in all directions, approaching 300 m/s Lamb wave speed reported previously by others