[P-EM11] Dynamics of the Inner Magnetospheric System

[PEM11-04] Variations of the relativistic electrons of the outer belt and plasmasphere during the solar declining and minimum phase: Arase observations

*Yoshizumi Miyoshi¹, Satoshi Kurita², Ryuho Kataoka³, Shun Imajo², Tomoaki Hori¹, Satoko Nakamura¹, Mariko Teramoto⁴, Takefumi Mitani⁵, Iku Shinohara⁵, Kazushi Asamura⁵, Takeshi Takashima⁵, Nana Higashio⁵, Fuminori Tsuchiya⁶, Atsushi Kumamoto⁶, Shoya Matsuda⁷, Yoshiya Kasahara⁷, Ayako Matsuoka² (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Kyoto University, 3.NIPR, 4.Kyushu Institute of Technology, 5.JAXA, 6.Tohoku University, 7.Kanazawa University)

Keywords:Arase, radiation belts, plasmasphere

The Arase satellite has observed the inner magnetosphere from 2017 to present, which covers the declining phase and the minimum of the cycle 24 and the early rising phase of the cycle 25. Since past inner magnetosphere satellites near the equator did not cover the transition phase of two cycles, the Arase satellite has provided the unique data set of the outer belt as well as the plasmasphere. During the declining phase, the Arase satellite observed the outer belt variations associated with many coronal hole streams and several CME-driven storms. The semi-annual variations of the outer belt due to the Russel-McPherron effects are observed. The growing peak of the phase space density are observed in the heart of the outer belt and outside the plasmapause in average, which suggests that the internal acceleration process mainly works for the flux enhancements. In the early cycle 25, the Arase satellite observed the ground-minimum of the outer belt in which the flux of the MeV electrons is almost empty for a few months, and then the satellite observed significant enhancements of the outer belt associated with the storm activities of the cycle 25.