講演情報
[PEM13-P22]あらせ観測に基づいた二つの中規模磁気嵐におけるリングカレントイオンと電子フラックスの比較研究
*尾花 由紀1、吉川 顕正1、丸山 奈緒美2、新堀 淳樹3、中村 紗都子3、Jun Chae-Woo3、堀 智昭3、三好 由純3、橋本 久美子4、熊本 篤志5、北原 理弘5、土屋 史紀5、笠原 禎也6、松岡 彩子7、風間 洋一8、Wang Shiang-Yu8、浅村 和史9、篠原 育9、横田 勝一郎10、桂華 邦裕11、笠原 慧11 (1.九州大学、2.University of Colorado Boulder、3.名古屋大学、4.吉備国際大学、5.東北大学、6.金沢大学、7.地磁気世界資料解析センター、8.Academia Sinica、9.宇宙科学研究所、10.大阪大学、11.東京大学)
キーワード：
内部磁気圏、プラズマ圏、環電流
Using the low-energy and mid-energy plasma instrument (LEPi, LEPe, MPEi, MEPe) onboard the Arase satellite, we can comprehensively investigate the fluxes of electrons and ions with different energies. Also, the in-situ electron density can be estimated by using the upper hybrid resonance frequencies detected from the plasma wave spectrum obtained by the plasma wave experiment (PWE).
The geomagnetic storm that commenced on 8 September 2017 has a Dst minimum of -147nT and appears to be a medium-sized magnetic storm at first glance, but it is known that it was a peculiar magnetic storm in various ways. For example, it is an extreme erosion of the plasmasphere to around L=1.5, and a strong SAPS generation.
Our previous research suggested that this extreme erosion of the plasmasphere was the result of a convective electric field that continued to penetrate into the magnetic equatorial region for more than 6 hours, however, the reason for the continuation of the convection field was unclear. We therefore compare the evolution of ring current particles during this peculiar magnetic storm to the magnetic storm which commenced on 25 August 2018, which has a similar Dst minimum (-175nT).
The following are the current results.
The nightside plasmasphere was almost entirely eroded during the main phase of the 2017 storm. On the other hand, the plasmasphere was eroded to around L = 2.5 in the main phase of the 2018 storm. Furthermore, in the main phase of the 2018 storm, H+, He+, and O+ in the energy range of 10-180 keV and electrons in the energy range 7-25 keV show a sharp increase around L~4, so that the plasma sheet injection seems to stop around L~4. On the other hand, in the main phase of the 2017 storm, the ion flux peaked around L~3 and gradually decreased to around L~2. At the 2017 storm, fluxes of the 50-180 keV H+ and 10-120 keV O+ increased significantly around L=2-4.
In this talk, we will show the details of the evolution of ring current electrons and ion fluxes, and discuss how the characteristics of the two geomagnetic storms are different.
The geomagnetic storm that commenced on 8 September 2017 has a Dst minimum of -147nT and appears to be a medium-sized magnetic storm at first glance, but it is known that it was a peculiar magnetic storm in various ways. For example, it is an extreme erosion of the plasmasphere to around L=1.5, and a strong SAPS generation.
Our previous research suggested that this extreme erosion of the plasmasphere was the result of a convective electric field that continued to penetrate into the magnetic equatorial region for more than 6 hours, however, the reason for the continuation of the convection field was unclear. We therefore compare the evolution of ring current particles during this peculiar magnetic storm to the magnetic storm which commenced on 25 August 2018, which has a similar Dst minimum (-175nT).
The following are the current results.
The nightside plasmasphere was almost entirely eroded during the main phase of the 2017 storm. On the other hand, the plasmasphere was eroded to around L = 2.5 in the main phase of the 2018 storm. Furthermore, in the main phase of the 2018 storm, H+, He+, and O+ in the energy range of 10-180 keV and electrons in the energy range 7-25 keV show a sharp increase around L~4, so that the plasma sheet injection seems to stop around L~4. On the other hand, in the main phase of the 2017 storm, the ion flux peaked around L~3 and gradually decreased to around L~2. At the 2017 storm, fluxes of the 50-180 keV H+ and 10-120 keV O+ increased significantly around L=2-4.
In this talk, we will show the details of the evolution of ring current electrons and ion fluxes, and discuss how the characteristics of the two geomagnetic storms are different.