Tonga underwater volcanic eruptions disrupted satellite signals, study finds

An international team led by Designated Assistant Professor Atsuki Shinbori and Professor Yoshizumi Miyoshi of the Institute for Space-Earth Environmental Research (ISEE), Nagoya University, in collaboration with NICT, The University of Electro-Communications, Tohoku University, Kanazawa University, Kyoto University, and ISAS, had the perfect opportunity to test this theory during the Tonga volcano eruption.  

They validated their hypothesis by using the Himawari-8 satellite to track air pressure wave arrivals, the Arase satellite to track EPBs, and ground-based ionospheric measurements to track ionospheric mobility.

A startling finding was made by the study team: Atmospheric pressure waves connected to plasma bubble formation were recorded several minutes to hours before ionospheric oscillations. This raises questions about the geosphere, atmospheric, and cosmosphere coupling model and points to the need for changes.

“Our new finding is that the ionospheric disturbances are observed several minutes to hours before the initial arrival of the shock waves triggered by the Tonga volcanic eruption,” Shinbori said in an official statement. “This suggests that the propagation of the fast atmospheric waves in the ionosphere triggered the ionospheric disturbances before the initial arrival of the shock waves. Therefore, the model needs to be revised to account for these fast atmospheric waves in the ionosphere.” 

Significance for space weather and disaster prevention

This study has implications that go beyond the confines of science. The study emphasizes how crucial it is for space weather forecast models to take into account observations of ionospheric disruptions brought on by earthquakes, volcanic eruptions, and other occurrences. These disruptions can cause satellite broadcasting and communication systems to malfunction, highlighting the need for better disaster preventive measures.

Study Abstract: 

Equatorial plasma bubbles are a phenomenon of plasma density depletion with small-scale density irregularities, normally observed in the equatorial ionosphere. This phenomenon, which impacts satellite-based communications, was observed in the Asia-Pacific region after the largest-on-record January 15, 2022 eruption of the Tonga volcano. We used satellite and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by the Tonga volcanic eruption could cause the emergence of an equatorial plasma bubble. The most prominent observation result shows a sudden increase of electron density and height of the ionosphere several ten minutes to hours before the initial arrival of the air pressure wave in the lower atmosphere. The propagation speed of ionospheric electron density variations was ~ 480–540 m/s, whose speed was higher than that of a Lamb wave (~315 m/s) in the troposphere. The electron density variations started larger in the Northern Hemisphere than in the Southern Hemisphere. The fast response of the ionosphere could be caused by an instantaneous transmission of the electric field to the magnetic conjugate ionosphere along the magnetic field lines. After the ionospheric perturbations, electron density depletion appeared in the equatorial and low-latitude ionosphere and extended at least up to ±25° in geomagnetic latitude.