2022 Tonga Volcanic Eruption Induced Global Propagation of Ionospheric Disturbances via Lamb Waves

Abstract

The Tonga volcano eruption at 04:14:45 UT on 2022-01-15 released enormous amounts of energy into the atmosphere, triggering very significant geophysical variations not only in the immediate proximity of the epicenter but also globally across the whole atmosphere. This study provides a global picture of ionospheric disturbances over an extended period for at least 4 days. We find traveling ionospheric disturbances (TIDs) radially outbound and inbound along entire Great-Circle loci at primary speeds of ∼300–350 m/s (depending on the propagation direction) and 500–1,000 km horizontal wavelength for front shocks, going around the globe for three times, passing six times over the continental US in 100 h since the eruption. TIDs following the shock fronts developed for ∼8 h with 10–30 min predominant periods in near- and far- fields. TID global propagation is consistent with the effect of Lamb waves which travel at the speed of sound. Although these oscillations are often confined to the troposphere, Lamb wave energy is known to leak into the thermosphere through channels such as atmospheric resonance at acoustic and gravity wave frequencies, carrying substantial wave amplitudes at high altitudes. Prevailing Lamb waves have been reported in the literature as atmospheric responses to the gigantic Krakatoa eruption in 1883 and other geohazards. This study provides substantial first evidence of their long-duration imprints up in the global ionosphere. This study was enabled by ionospheric measurements from 5,000+ world-wide Global Navigation Satellite System (GNSS) ground receivers, demonstrating the broad implication of the ionosphere measurement as a sensitive detector for atmospheric waves and geophysical disturbances.

Intense Equatorial Electrojet and Counter Electrojet Caused by the 15 January 2022 Tonga Volcanic Eruption: Space‐ and Ground‐Based Observations

“…The disturbance responsible for the observed EEJ and CEJ signatures is most likely related to atmospheric gravity wave activities that were produced by the Tonga volcanic eruption and detected globally within the first few hours of the eruption (Yuen et al, 2022). This volcanic eruption generated a broad spectrum of atmospheric waves, such as gravity waves, that propagated into the upper atmosphere and even affected the F-region ionosphere (Themens et al, 2022;Zhang et al, 2022). By combining space-and ground-based observations, our analysis shows that this disturbance propagated outward (mainly eastward at our observation locations) from the volcano eruption site with a propagation speed in the order of ∼350-400 m/s.…”

The 15 January 2022 Hunga Tonga Eruption History as Inferred From Ionospheric Observations

“…• Ionospheric total electron content (TEC) data reveal that the 15 January 2022 Hunga Tonga volcanic eruption involved at least five large explosions between 4 and 5UT • From TEC observations, we estimate the onset time to be 04:05:54UT and the main explosion energy release of 9-37 Megatons trinitrotoluene equivalent • The eruption-driven shock wave caused an unprecedentedly strong and long-lasting depletion in the ionosphere eruption also generated large ionospheric disturbances that propagated around the world (Themens et al, 2022;Zhang et al, 2022).…”

Impacts of the January 2022 Tonga Volcanic Eruption on the Ionospheric Dynamo: ICON‐MIGHTI and Swarm Observations of Extreme Neutral Winds and Currents

“…As such, the ionosphere, readily observed by ground-based instruments, can function as a sensitive monitor of atmospheric disturbances. Initial Total Electron Content (TEC) observations have reported Traveling Ionospheric Disturbances (TIDs) propagating globally for many hours and even days after the Tonga eruption (Aa et al, 2022;Lin et al, 2022;Themens et al, 2022;Zhang et al, 2022). Estimates of the horizontal wavelength of TIDs in the far field (i.e., at distances >3,000 km from the eruption) range from 300 to 1,000 km (Wright et al, 2022;Zhang et al, 2022).…”

“…Initial Total Electron Content (TEC) observations have reported Traveling Ionospheric Disturbances (TIDs) propagating globally for many hours and even days after the Tonga eruption (Aa et al, 2022;Lin et al, 2022;Themens et al, 2022;Zhang et al, 2022). Estimates of the horizontal wavelength of TIDs in the far field (i.e., at distances >3,000 km from the eruption) range from 300 to 1,000 km (Wright et al, 2022;Zhang et al, 2022). Additionally, Soares et al (2022) reported oscillations of the geomagnetic field observed by a ground-based magnetometer 835 km from Tonga, which are attributed to short-period modulation (3-5 min) of ionospheric currents.…”