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Long Period Ionospheric Disturbances Induced by Atmospheric Pressure Waves From the 2022 Tonga Volcanic Eruption.

The 15 January 2022 Tonga-Hunga volcanic eruption was very violent and it was recorded by seismometers all over the globe. The corresponding pressure disturbances and induced ionospheric disturbances traveled all over the globe. We analyzed global ionospheric changes induced by the eruption using GPS data derived - Total Electron Content (TEC), together with the surface pressure data from the stations along a great circle through Tonga, and from polar regions. Unlike the co-seismic ionospheric disturbances, volcanic eruption-induced ionospheric variations are seen even in the polar regions. Co-occurrence of TEC and surface pressure changes at polar regions suggests that the former are pressure-induced. The study infers that the pressure anomalies propagated throughout the globe with a velocity of ∼320 m/s and guided the ionospheric disturbances.

The hodochrone of normalized (a) ionospheric VTEC on 15 January 2022 depicting the propagation of the ionospheric disturbances (filtered VTEC) throughout the globe. The red colour dashed line shows the onset time of the volcano eruption. The black and magenta solid lines show the propagation velocities at 0.7 and 0.32 km/s. The colour scale shows the normalized power. (b) Atmospheric surface pressure waves showing the lamb wave propagation using data from 58 GNSS stations with meteorological sensors starting from the Tonga-Hunga island to various regions around the globe superimposed on VTEC associated with the eruption.

The ionospheric irregularities induced by multiple volcanic eruptions lasted for more than 3 hr. The main eruption was preceded by anomalous changes in pressure and the characteristics of the anomaly are distinct from the eruption signal, possibly indicating the preparatory phase of the eruption.

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