Rapid Volcanic Modification of the E‐Region Dynamo: ICON's First Glimpse of the Tonga Eruption

Abstract

The 15 January 2022 Hunga Tonga‐Hunga Ha'apai volcano eruption drove global atmospheric waves that propagated into space and impacted the ionosphere. Here we show immediate large‐scale electrodynamic effects of the eruption using observations from the National Aeronautics and Space Administration's Ionospheric Connection Explorer. We report extreme zonal and vertical trueE⃗×B⃗ $\vec{E}\times \vec{B}$ ion drifts thousands of kilometers away from Tonga within an hour of the eruption, before the arrival of any atmospheric wave. The measured drifts were magnetically connected to the ionospheric E‐region just 400 km from Tonga, suggesting that the expanding wavefront created strong electric potentials which were transmitted along Earth's magnetic field. A simple theoretical model suggests that the observed drifts are consistent with an expanding wave with a large (>200 m/s) neutral wind amplitude. These observations are the first direct detection in space of the immediate electrodynamic effects of a volcanic eruption and will help constrain future models of impulsive lower atmospheric events.

Primary and Secondary Gravity Waves and Large‐Scale Wind Changes Generated by the Tonga Volcanic Eruption on 15 January 2022: Modeling and Comparison With ICON‐MIGHTI Winds

“…The medium-scale GWs have c H ∼ 100-250 m/s, while the large-scale GWs have c H ∼ 200-600 m/s; thus the medium and large-scale GW meridional velocity From Figure 7a, the GWs which reach z = 200 km at early times (5:00-8:00 UT) have c H ∼ 600 m/s and τ r ∼ 30-40 min, and are located near Tonga, 𝐴𝐴  ≤ 5000 km, in agreement with observations (for example, Themens et al, 2022). (This phase speed is also consistent with ICON observations of large-amplitude (>100 m/s) plasma drifts conjugate to the eruption's near-field within an hour of the eruption, for which the inferred driving neutral wind perturbations propagated at 600 ± 50 m/s (Gasque et al, 2022)). However by 13 UT, the fastest GWs which reach this altitude have somewhat slower speeds of c H ∼ 500 m/s, much larger periods of τ r ∼ 6 hr, and are located far from Tonga: 𝐴𝐴  = 10, 000 − 12, 000 km.…”

“…They estimated large along-track wavelengths of λ track ∼ 3,000-5,000 km at z > 120 km. Gasque et al (2022) inferred neutral horizontal wind velocities of >200 m/s in the E region (z ∼ 120 km) at approximately ∼400 km from Tonga shortly after the Tonga eruption by analyzing ionospheric dynamo-induced plasma drifts measured by ICON's Ion Velocity Meter.…”

Large‐Scale Disturbances in the Upper Thermosphere Induced by the 2022 Tonga Volcanic Eruption

“…The intense TIDs at ∼350 m/s speeds were found to be consistent with that of Lamb waves and propagated around the globe three times (S. R. Zhang et al., 2022). Due to the extreme change in the thermospheric winds and the associated equatorial electric field disturbance, equatorial ionization anomalies (EIAs) were found to be suppressed and reshaped after the eruption (Aa, Zhang, Wang, et al., 2022; Gasque et al., 2022; Harding et al., 2022; Le et al., 2022). Significant equatorial plasma bubbles (EPBs) and irregularity activities were observed (Aa, Zhang, Erickson, et al., 2022; Hong et al., 2022; Sun et al., 2022), and the ionospheric disturbances in the conjugate hemisphere were also suggested (Lin et al., 2022).…”

Tongan Volcanic Eruption Induced Global‐Scale Thermospheric Changes Observed by the GOLD Mission

“…The eruption also released an enormous amount of energy (∼10–20 EJ estimated by Wright et al., 2022) into the atmosphere. In addition to the lower atmosphere, the eruption's signature was also detected in the mesosphere (Proud et al., 2022) and the Thermosphere‐Ionosphere (e.g., Aa et al., 2022; Gasque et al., 2022; Harding et al., 2022; Lin et al., 2022; Themens et al., 2022; Zhang et al., 2022). A supersonic pressure wave emanating radially from the volcano was observed in tropospheric water vapor images (Figure 1 in Amores et al., 2022) and at weather stations globally (Burt, 2022).…”