日本地球惑星科学連合2019年大会

講演情報

[E] 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-EM13] 内部磁気圏

2019年5月29日(水) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:海老原 祐輔(京都大学生存圏研究所)、Danny Summers(Memorial University of Newfoundland)、三好 由純(名古屋大学宇宙地球環境研究所)、齊藤 慎司(名古屋大学 大学院理学研究科)

[PEM13-P16] An extreme erosion of the plasmasphere during the 7–10 September 2017 storm

*尾花 由紀1丸山 奈緒美2,3新堀 淳樹4橋本 久美子5Fedrizzi Mariangel2,3能勢 正仁4大塚 雄一4西谷 望4堀 智昭4熊本 篤志6土屋 史紀6松田 昇也7松岡 彩子7笠原 禎也8吉川 顕正9三好 由純4篠原 育7 (1.大阪電気通信大学、2.University of Colorado Boulder、3.NOAA Space Weather Prediction Center、4.名古屋大学、5.吉備国際大学、6.東北大学、7.宇宙航空研究開発機構、8.金沢大学、9.九州大学)

キーワード:プラズマ圏、内部磁気圏、磁気圏電離圏結合

We report an extreme erosion of the plasmasphere arising from the September 2017 storm. The cold electron density is identified from the upper limit frequency of UHR waves observed by the HFA of the PWE instrument onboard the Arase spacecraft. The HFA provides the spectrograms of electric fields in a frequency range from 10 kHz to 10 MHz with an 8-sec time resolution (Kasahara et al., 2018; Kumamoto et al., 2018). Such wide frequency coverage allows observation of the UHR frequency even deep inside the plasmasphere.
The electron density profiles reveal that the plasmasphere was severely eroded during the recovery phase of the storm and the plasmapause was located at L~1.7 at 23 UT on 8 Sep 2017. This is the first report of such deep erosion of the plasmasphere (LPP<2) with the in-situ observation of the electron density. The degree of the severity is much more than what is expected from the SYM-H minimum (–146 nT) of the event.
We further study absolute GNSS-TEC, ground-based magnetic field, the doppler velocity obtained from the SuperDARN Hokkaido Radars to investigate the location of the midlatitude ionospheric trough, the penetration of the convection electric field to the equator and middle latitudes, respectively. Our results suggest that the middle latitude electric field was penetrated from the high-latitude storm time convection for several hours. Futhermore, the Ionosphere-Plasmasphere-Electrodynamics (IPE) model (Sun et al., 2015; Maruyama et al., 2016) is used to understand the dynamics of the plasmasphere. The IPE results suggest that the middle latitude electric field penetrates from the high-latitude storm time convection that lasts for several hours can explain the degree of severity during the September 7-11 2017 storm.