Japan Geoscience Union Meeting 2024

Presentation information

[E] Poster

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

[P-EM13] Dynamics of the Inner Magnetospheric System

Sun. May 26, 2024 5:15 PM - 6:45 PM Poster Hall (Exhibition Hall 6, Makuhari Messe)

convener:Kunihiro Keika(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo ), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Theodore E Sarris(Democritus University of Thrace), Evan G Thomas(Dartmouth College)


5:15 PM - 6:45 PM

[PEM13-P12] Spatial development of subauroral polarization stream associated with a pseudobreakup: SuperDARN and Arase observations

*Tomoaki Hori1, Keisuke Hosokawa2, Nozomu Nishitani1, Atsuki Shinbori1, Yoshizumi Miyoshi1, Mariko Teramoto3, Yuki Obana4, Akira Sessai Yukimatu5, Kunihiro Keika6, Satoshi Kasahara6, Shoichiro Yokota7, Satoko Nakamura1, Yasumasa Kasaba8, Atsushi Kumamoto8, Fuminori Tsuchiya8, Shoya Matsuda9, Yoshiya Kasahara9, Ayako Matsuoka10, Yoichi Kazama11, S.-Y. Wang11, Sunny W. Y. Tam12, Chae-Woo Jun1, Iku Shinohara13 (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.University of Electro-Communications, 3.Kyushu Institute of Technology, 4.Kyushu University, 5.National Institute of Polar Research, 6.The University of Tokyo, 7.Osaka University, 8.Tohoku University, 9.Kanazawa University, 10.WDC for Geomagnetism, Kyoto, Kyoto University, 11.Academia Sinica, Taiwan, 12.National Cheng Kung University, Taiwan, 13.JAXA/ISAS)

Keywords:Earth, Ionosphere, Magnetosphere, Substorm

This study investigates how subauroral polarization streams (SAPS) develop longitudinally and latitudinally in association with a pseudobreakup on the basis of simultaneous conjugate observations made primarily by Super Dual Auroral Radar Network (SuperDARN) in the ionosphere and the Arase and geosynchronous satellites in the inner magnetosphere. In the event of interest during the 2022 Fall SuperDARN-Arase campaign, SuperDARN observed that SAPS appeared and readily intensified at magnetic latitudes of ~67° to ~72° in the evening sector and then expanded azimuthally toward the dusk sector. A close examination shows that SAPS intensified in the dusk sector first at latitudes slightly higher than the ionospheric footprint of Arase situated in the same magnetic local time (MLT) sector, and subsequently the SAPS expanded toward lower latitudes and reached the Arase's footprint. Interestingly, Arase detected drifting clouds of energetic ions at each of the SAPS intensification and the subsequent equatorward expansion, while one of the Geostationary Operational Environmental Satellites (GOES) completely missed any signature of energetic ion injection, despite that the GOES was located at the same MLT but slightly (~0.5 RE) inward of Arase. Considering the simultaneous occurrence of a pseudobreakup seen from ground imager and geomagnetic field data, the observations strongly suggest that intermittent injections of energetic ions occurred at a later MLT and have drifted westward through the Arase location, leading to the observed evolution of SAPS there by supplying downward field-aligned current to the subauroral region. As evident from the GOES observations, the injections did not reach the geosynchronous orbit probably due to a weak electric field associated with the pseudobreakup.