JpGU-AGU Joint Meeting 2017

Presentation information

Print

[EE] Poster

P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM16] [EE] Physics of Inner Magnetosphere Coupling

Wed. May 24, 2017 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Danny Summers(Memorial University of Newfoundland), Jichun Zhang(University of New Hampshire Main Campus), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Kunihiro Keika(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo ), Aleksandr Y Ukhorskiy(Johns Hopkins University Applied Physics Laboratory), Dae-Young Lee(Chungbuk Natl Univ), Yiqun Yu(Beihang University), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University)

[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

*Satoshi Kurita1, Yoshizumi Miyoshi1, J. B. Blake2, R. H. W. Friedel3 (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.The Aerospace Corporation, CA, USA, 3.Los Alamos National Laboratory, NM, USA)

Keywords: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.