日本地球惑星科学連合2018年大会

講演情報

[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-P15] Transport and acceleration of electrons trapped in the inner magnetosphere in response to interplanetary shock

*池田 拓也1海老原 祐輔1田中 高史2 (1.京都大学生存圏研究所、2.九州大学大学院理学府)

Interplanetary (IP) shock is known to disturb directly energetic trapped electrons in the inner magnetosphere. Recently, it has been pointed out that electrons are accelerated due to interaction with whistler mode waves. The whistler mode waves are excited by anisotropic electrons in the keV-range. It may be possible that the IP shock influences the keV-range electrons, enhancing the energetic electrons indirectly. To understand the direct and indirect processes, we need to track the overall evolution of the electrons from keV to MeV ranges in response to the IP shock. In this paper, we used The global MHD simulation (Tanaka, 2015; Ebihara and Tanaka, 2015) and Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model (Fok et al., 2014). In MHD simulation, as the boundary condition to obtain steady state magnetosphere, solar wind velocity (Vsw) is 400 km/s, density (Nsw) is 5 /cm3 and interplanetary magnetic field (IMF) is 5 nT and northward. For imitation IP shock, we made Vsw sqrt 6 times, Nsw 6 times and IMF southward. In CIMI model, as the initial condition, we used AE8 model and kappa distribution (κ= 4) and the boundary condition is from MHD simulation. We found that the temperature anisotropy increased at four points (MLT = 12, L = 4.7 : MLT = 0, L = 5.2 : MLT = 0, L = 4.5 : MLT = 8, L = 5). At MLT = 12, L = 4.7, shock-induced E-field accelerated electrons and the flux of electrons with energy more than 1 keV increased, resulting in temperature anisotropy over 0.4. At MLT = 0, L = 5.2, convection E-field accelerated electrons and the flux of electrons with energy about 15 keV increased, resulting in temperature anisotropy over 0.5. At MLT = 0, L = 4.5, substorm-induced E-field accelerated electrons and the flux of electrons with energy about 20 keV increased, resulting in temperature anisotropy over 1.7. At MLT = 8, L = 5.0. the flux of electrons energy with about 100 keV and 1 keV increased, resulting in temperature anisotropy over 0.4. Addition to this, we should consider the temperature anisotropy of the electrons what have the resonance velocity with chorus waves. We call this temperature anisotropy as A-. We will reveal the time change of A- and electrons what is the cause of A- increasing.