Rapid Volcanic Modification of the E-Region Dynamo: ICON’s First Glimpse
of the Tonga Eruption
Abstract
The 15 Jan 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 NASA’s Ionospheric Connection
Explorer. We report extreme zonal and vertical ExB 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.