Japan Geoscience Union Meeting 2025

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[E] Oral

P (Space and Planetary Sciences ) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

Sun. May 25, 2025 10:45 AM - 12:15 PM 303 (International Conference Hall, Makuhari Messe)

convener:Keisuke Hosokawa(Department of Communication Engineering and Informatics, University of Electro-Communications), Huixin Liu(Earth and Planetary Science Division, Kyushu University SERC, Kyushu University), Yuichi Otsuka(Institute for Space-Earth Environmental Research, Nagoya University), Loren Chang(Department of Space Science and Engineering, National Central University), Chairperson:Takeshi Sakanoi(Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University), Elvira Astafyeva(Institut de physique du Globe de Paris)

11:30 AM - 11:45 AM

[PEM12-04] Detecting the plasma bubble at Western Australia in the MWA data

★Invited Papers

*Yoshiura Shintaro1, Yuichi Otsuka2, Cathryn M Trott3, Dev Null3, Nozomu Nishitani2, Keitaro Takahashi4, Michi Nishioka4, Septi Perwitasari5, Atsuki Shinbori2 (1.National Astronomical Observatory of Japan, 2.Institute for Space-Earth Environmental Research (ISEE), 3.Curtin University,, 4.Kumamoto University, 5.National Institute of Information and Communications Technology )

Keywords:Plasma bubble, Ionosphere, Global Navigation Satellite Systems , Murchison Widefield Array

In this talk, we report the detection of a plasma bubble feature using astronomical radio images. During a magnetic storm on 2023 December 1, Total Electron Content (TEC) maps derived from Global Navigation Satellite Systems (GNSS) data revealed the propagation of the plasma bubble over Western Australia. The significant turbulence in the ionosphere not only disturb the GPS data but also impacts radio astronomical observations. In particular, for radio interferometers consisting of multiple antennas, ionospheric distortions introduce severe errors in the phase of observed data. Consequently, the apparent positions of astronomical sources shift and vary on short time scales. We found the significant distortion of radio sources in MWA data on 2023 December 1. The Murchison Widefield Array (MWA) is a low-frequency radio interferometer located in Western Australia. With its exceptionally wide field of view (approximately 20 deg x 20 deg), the MWA can simultaneously measure the positional shifts of multiple radio sources. Our analysis reveals a duct like structure with a size of roughly 50 km (east-west) propagating across the field of view with a velocity of roughly 100 m/s. The rate of TEC change index shows significant TEC fluctuations at the same time. These results strongly suggest that the duct-like structure is caused by a plasma bubble extending across Western Australia. Furthermore, one of the bright radio source inside the duct was observed to split into multiple components exhibiting rapid time variability. We interpret this phenomenon as diffraction caused by small-scale structures within the plasma bubble.