[P-EM16] Dynamics of Earth's Inner Magnetosphere and Initial Results from Arase

[PEM16-20] Region-2 field-aligned current and ring current ions during storm main phase: Arase and AMPERE observations

*Shun Imajo¹, Masahito Nose¹, Ayako Matsuoka², Satoshi Kasahara³, Shoichiro Yokota⁴, Mariko Teramoto⁶, Kunihiro Keika³, Brian Anderson⁵, Tetsuo Motoba⁵, Reiko Nomura⁷, Akiko Fujimoto⁸, Iku Shinohara², Yoshizumi Miyoshi⁶ (1.Data Analysis Center for Geomagnetism and Space Magnetism, Graduate School of Science, Kyoto University, 2.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3.Graduate School of Science, The University of Tokyo, 4.Graduate School of Science, Osaka University, 5.The Johns Hopkins University Applied Physics Laboratory, 6.Institute for Space-Earth Environmental Research, Nagoya University, 7.Tsukuba Space Center, Japan Aerospace Exploration Agency, 8.International Center for Space Weather Science and Education, Kyushu University)

Keywords:magnetic storm, ring current, field-aligned current, magnetospheric-ionospheric coodinated observation

We present the first simultaneous in situ observation by the Arase satellite of the region-2 field-aligned currents (FACs) and the ring current during a storm main phase on 16 July 2017. The crossing of the postmidnight upward FAC with the maximum current density of 60 nA/m² at L~4.2 and MLAT~20^o was determined by a change in the azimuthal magnetic field. The peak of the FAC density was located in the inner part of the ring current derived from the plasma pressure. The current driven by the oxygen pressure significantly contributed to the ring current density, in particular in the inner part. The FAC density value and invariant latitude in the inner magnetosphere were consistent with the corresponding FAC on the ionosphere derived from the AMPERE (Active Magnetosphere and Planetary Electrodynamics Response Experiment), indicating a connection of FAC between these regions.