JpGU-AGU Joint Meeting 2017

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-EM16] [EE] Physics of Inner Magnetosphere Coupling

2017年5月24日(水) 13:45 〜 15:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:Danny Summers(Memorial University of Newfoundland)、Jichun Zhang(University of New Hampshire Main Campus)、海老原 祐輔(京都大学生存圏研究所)、桂華 邦裕(東京大学大学院理学系研究科地球惑星科学専攻)、Aleksandr Y Ukhorskiy(Johns Hopkins University Applied Physics Laboratory)、Dae-Young Lee(Chungbuk Natl Univ)、Yiqun Yu(Beihang University)、三好 由純(名古屋大学宇宙地球環境研究所)

[PEM16-P09] Response of relativistic electron microbursts to the arrival of high speed solar wind streams and its relation to flux variation of radiation belt electrons

*栗田 怜1三好 由純1J. B. Blake2R. H. W. Friedel3 (1.名古屋大学宇宙地球環境研究所、2.The Aerospace Corporation, CA, USA、3.Los Alamos National Laboratory, NM, USA)

キーワード:radiation belt, high speed solar wind streams, radiation belt dropout

Relativistic electron microbursts are short-lived bursty precipitations of relativistic electrons observed by low-altitude satellite in the radiation belt. They are considered as a consequence of pitch angle scattering of radiation belt electrons by discrete whistler-mode emissions known as chorus. Microbursts are frequently observed during geomagnetic storms and previous studies show that atmospheric loss through microbursts appears to contain enough electrons to deplete the radiation belt. They suggest that microburst is an important loss process of radiation belt electrons during the main phase of geomagnetic storms. Microbursts are also frequently observed during high-speed solar wind stream (HSS) events, while important solar wind parameters for the frequent microburst precipitations have not been well understood. We perform a superposed epoch analysis of the microburst occurrence during HSS events, considering the polarity of interplanetary magnetic field (IMF) and solar wind speed according to the method used by Miyoshi and Kataoka (2008). We find the most frequent microburst precipitations during the highest-speed solar wind streams with a southward offset of IMF (SBZ-fast HSS events), indicating that both the southward IMF and fast solar wind are important for enhanced microburst precipitations. We also demonstrate that fluxes of radiation belt electrons with energies from hundreds keV up to 7 MeV preferentially increase during the SBZ-fast HSS events. The result suggests that loss through microbursts is not major loss process of radiation belt during the HSS events. We conclude that relativistic electron microbursts can be a proxy of acceleration of MeV electrons by chorus.