日本地球惑星科学連合2018年大会

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[EE] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM15] Dynamics in magnetosphere and ionosphere

2018年5月21日(月) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:田中 良昌(国立極地研究所)、堀 智昭(名古屋大学宇宙地球環境研究所)、中溝 葵(情報通信研究機構 電磁波研究所、共同)、尾崎 光紀(金沢大学理工研究域電子情報学系)

[PEM15-P24] 3D current system of eastward expanding auroral surges

*田中 良昌1小川 泰信1門倉 昭1Gustavsson Bjorn2Partamies Noora3Kauristie Kirsti4Whiter Daniel5Enell Carl-fredrik6Brandstrom Urban7Sergienko Tima7Kozlovsky Alexander8Vanhamaki Heikki9吉川 顕正10宮岡 宏1 (1.国立極地研究所、2.ノルウェー北極大学、3.スバールバル大学センター、4.フィンランド気象研究所、5.サウサンプトン大学、6.EISCAT科学協会、7.スウェーデン宇宙物理研究所、8.ソダンキュラ地球物理観測所、9.オウル大学、10.九州大学)

キーワード:オーロラトモグラフィ、3次元電流系、局所KRM法、磁気圏電離圏結合系、東向き拡大するオーロラサージ

We investigate three-dimensional (3D) current system of eastward expanding auroral surges (EEASs) observed by ground-based network of all-sky imagers and magnetometers in Fennoscandia on March 9, 2013. Three EEASs were observed intermittently at about 15-minute intervals in the post-midnight sector (01:55-02:40 MLT) by three monochromatic (428nm) all-sky EMCCD imagers at Tromso (69.6N, 19.2E), Norway, Kilpisjarvi (69.0N, 20.9E), Finland, and Abisko (68.4N, 18.8E), Sweden and the IMAGE chain magnetometers. These data set allowed us to retrieve the height-integrated ionospheric conductivity in the horizontal area of about 300km by 300km and ionospheric equivalent current at high-sampling (10-seconds) intervals. The ionospheric conductivity was estimated from 3D distribution of the 427.8nm volume emission rate, which was obtained by applying the auroral computed tomography (ACT) method to multiple auroral images, and some theoretical and empirical models. Furthermore, we calculated horizontal distributions of ionospheric current, field-aligned current (FAC), and electric field at 10-sec resolution by the local KRM method using the obtained height-integrated ionospheric conductivity and equivalent current. The results indicate that a pair of upward and downward FACs was accompanied by the EEASs and the divergence of the ionospheric Hall current due to the ununiform conductivity may be a significant component of FACs for EEASs.