Details

Autor(en) / Beteiligte

• Gasque, L. Claire
• Wu, Yen‐Jung
• Harding, Brian J.
• Immel, Thomas J.
• Triplett, Colin C.

Titel

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

Ist Teil von

• Geophysical research letters, 2022-09, Vol.49 (18), p.n/a

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2022

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• 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 E⃗×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. Plain Language Summary The Hunga Tonga‐Hunga Ha'apai volcano eruption on 15 January 2022 sent seismic waves rippling through the Earth, launched tsunamis across the Pacific, and drove waves globally through the atmosphere. The atmospheric waves traveled into space, where they impacted the ionosphere, which extends from ∼80 to 1,000 km above Earth's surface and is composed of ionized gas. Using observations from the National Aeronautics and Space Administration's Ionospheric Connection Explorer, we show that the eruption dramatically modified charged particle motion in the ionosphere thousands of kilometers away from Tonga well before any atmospheric waves arrived. These changes are likely driven by strong electric fields generated near the volcano and transmitted along the Earth's magnetic field. A simple model suggests that the electric fields are generated by a fast neutral wind wavefront expanding away from the volcano. These observations are the first in‐situ measurements of the immediate ionospheric electrodynamic effects of a volcanic eruption, and will help calibrate models of the event, improving our understanding of how energy moves between the lower atmosphere and space. Key Points Extremely large ion drift velocities are observed ∼4,000 km from Tonga less than an hour post‐eruption, before any atmospheric wave arrived The ion drifts are driven by volcanically forced polarization electric fields transmitted along Earth's magnetic field via Alfvén waves The drift signature is consistent with the dynamo effect of an expanding atmospheric wave with a >200 m/s amplitude