[P-EM09] Dynamics of Magnetosphere and Ionosphere

[PEM09-P04] Initial results of multi-event analysis of magnetosphere-ionosphere coupling for nighttime medium-scale traveling ionospheric disturbances

*川合 航輝¹、塩川 和夫¹、大塚 雄一¹、大山 伸一郎^1,2,3、Connors Martin⁴、笠原 禎也⁵、笠羽 康正⁶、新堀 淳樹¹、土屋 史紀⁶、熊本 篤志⁶、北原 理弘¹、小路 真史¹、中村 紗都子¹、松岡 彩子⁷、今城 峻¹、風間 洋一⁸、Wang Shing-Yu⁸、Tam Sunny W. Y.⁹、Chang Tzu-Fang⁹、Wang B. J.⁸、浅村 和史¹⁰、笠原 慧¹¹、横田 勝一郎¹²、桂華 邦裕¹¹、堀 智昭¹、Jun Chae-Woo¹、篠原 育¹⁰、三好 由純¹ (1.名古屋大学宇宙地球環境研究所、2.オウル大学、3.国立極地研究所、4.アサバスカ大学、5.金沢大学、6.東北大学、7.京都大学、8.中央研究院、9.国立成功大学、10.宇宙航空研究開発機構、11.東京大学、12.大阪大学)

キーワード：中規模伝搬戦電離圏擾乱、磁気圏-電離圏結合、あらせ衛星、大気光イメージャ

Medium-scale traveling ionospheric disturbances (MSTIDs) are propagating fluctuations of the electron density in the F-region ionosphere and can cause significant influence in the positioning using satellites such as Global Positioning System (GPS). MSTIDs generated by the E-region–F-region coupling and Perkins instabilities show mirrored structures at magnetically conjugate points in the two hemispheres at middle latitudes [e.g., Otsuka et al., GRL, 2004]. In such a case, the electric field variations associated with the MSTIDs probably mapped to the other hemisphere along geomagnetic field lines and they can be observed by magnetospheric satellites. Previously we have reported one such event of the conjugate observation of MSTIDs with the Arase satellite (Kawai et al., JpGU-AGU2020, 2020; Kawai et al., submitted to JGR, 2021). On the other hand, this study reports initial results on the analysis of four events with simultaneous observations of MSTIDs made by the Arase satellite and airglow imagers operated at Athabasca (54.60°N, 246.36°E), Canada on February 25, 2020, at Gakona (62.39°N, 214.78°E), Alaska on February 26, 2019, and at Kapuskasing (49.39°N, 277.81°E), Canada on January 11 and 26, 2019. In the first event at Athabasca, the Arase satellite observed electric field variations associated with airglow intensity deviations, similar to that reported by Kawai et al. [2021]. We projected these electric field variations onto the ionosphere, the direction of the E×B drift derived with the background magnetic field showed the opposite senses between bright and dark structures of the airglow intensity deviation of the MSTIDs taken by the airglow camera. However, electron density fluctuations observed the Arase did not clearly correspond to the airglow intensity deviation of MSTIDs. Similar analyses for the other three events are underway. As preliminary results, we found that the Arase did not necessarily observe the characteristic variations of the magnetospheric electric field variations and electron density fluctuations associated with the MSTID structures. Based on these results, our scientific objective is to reveal the necessary conditions under which variations of the electric field and electron density associated with MSTIDs propagate to the magnetosphere.