[P-EM16] Dynamics of Earth's Inner Magnetosphere and Initial Results from Arase

[PEM16-08] Postmidnight purple auroral rays and longitudinally-wide Pc1 pulsations observed at the CIR-associated solar-wind density enhancement on March 21, 2017

★Invited Papers

*塩川 和夫¹、尾崎 光紀²、門倉 昭³、遠藤 友⁴、坂野井 健⁴、栗田 怜¹、三好 由純¹、大山 伸一郎¹、Schofield Ian⁵、Connors Martin⁵、Ruohoniemi J. Michael⁶、Baishev D. G.⁷、Pashinin A⁸、Shevtsov B⁹、Poddelsky Igor⁹、Engebretson Mark¹³、Raita Tero¹⁴、田中 良昌³、篠原 育¹⁰、寺本 万里子¹、野村 麗子¹¹、藤本 晶子¹²、松岡 彩子¹⁰、東尾 奈々¹¹、高島 健¹⁰ (1.名古屋大学宇宙地球環境研究所、2.金沢大学、3.国立極地研究所、4.東北大学、5.アサバスカ大学、6.バージニア工科大学、7.IKFIA、8.ISTP、9.IKIR、10.JAXA宇宙科学研究所、11.宇宙航空研究開発機構、12.九州大学、13.アウグスブルク大学、14.ソダンキラ観測所)

キーワード：磁気嵐、共回転相互作用領域、紫のオーロラレイ構造、Pc1地磁気脈動

Corotating Interaction Regions (CIR) associated with the high-speed solar wind from solar coronal holes are one of the outstanding structures in the solar wind that can cause geomagnetic storms. This paper reports two unique features, i.e., postmidnight purple auroral rays and global Pc1 geomagnetic pulsations, observed at the beginning of the CIR storm of March 21, 2017, based on the first campaign observation of our new (PWING) longitudinal ground network with the Arase satellite. The purple auroral rays were observed at ~0315-0430 UT (~03-04 magnetic local time) in the northeastern sky at Husafell, Iceland (magnetic latitude: 64.9^oN). We suggest that the entry of high-density solar-wind plasma into the magnetotail caused the purple auroral rays in the sunlit ionosphere. The Pc1 geomagnetic pulsations at frequencies of 0-0.5 Hz were observed after ~00 UT over a wide longitudinal range of 13 hours of local times from midnight to afternoon sectors at subauroral latitudes associated with the CIR arrival.