Holes in the ionosphere caused by the Tonga undersea volcanic eruption: connection between the lithosphere and space revealed by new observational techniques


A research group led by Designated Assistant Professor Dr. Atsuki Shinbori, Dr. Takuya Sori, Associate Professor Dr. Yuichi Otsuka, Designated Associate Professor Dr. Satoko Nakamura, and Professor Dr. Yoshizumi Miyoshi analyzed observation data obtained from the Arase satellite, the Global Navigation Satellite System (GNSS), the Himawari weather satellite, and the ionospheric radars
As a result, several holes in the ionosphere with an electron density depletion of one or two orders of magnitude appeared over Japan after the initial arrival of air pressure waves triggered by the Tonga volcanic eruption. The Arase satellite observational result revealed that the holes in the ionosphere extended to a higher altitude of 2000 km in space. A primary cause of the formation of holes in the ionosphere is the upward motion of the ionosphere due to the air pressure waves. The ionospheric variation began approximately 1-2 hours before the initial arrival of the air pressure waves. This study reveals the generation mechanism of holes in the ionosphere caused by atmospheric disturbances associated with the Tonga volcanic eruptions. The holes in the ionosphere also cause radio interference and are a critical phenomenon in space weather research. It is widely known that space weather phenomena that lead to radio interference are caused by solar activity, such as solar flares. Still, the results of the present study indicate that natural phenomena on the earth’s surface, such as large-scale eruptions, should be included in space weather research.
The research results will be published in Scientific Reports, a comprehensive international journal, on May 22, 2023.

Atsuki Shinbori, Takuya Sori, Yuichi Otsuka, Michi Nishioka, Septi. Perwitasari, Takuo Tsuda, Atsushi Kumamoto, Fuminori Tsuchiya, Shoya Matsuda, Yoshiya Kasahara, Ayako Matsuoka, Satoko Nakamura, Yoshizumi Miyoshi, Iku Shinohara, Generation of equatorial plasma bubble after the 2022 Tonga volcanic eruption, Scientific Reports, 2023.