Japan Geoscience Union Meeting 2023

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[E] Oral

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

[P-EM13] Dynamics of the Inner Magnetospheric System

Tue. May 23, 2023 3:30 PM - 4:45 PM 101 (International Conference Hall, Makuhari Messe)

convener:Kunihiro Keika(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo ), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Theodore E Sarris(Democritus University of Thrace), Evan G Thomas(Dartmouth College), Chairperson:Satoko Nakamura(Institute for Space-Earth Environmental Research, Nagoya University), Shoya Matsuda(Kanazawa University), Kazuhiro Yamamoto(Graduate School of Science, The University of Tokyo), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Kunihiro Keika(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo)

4:10 PM - 4:25 PM

[PEM13-11] Do the EMIC waves really heat thermal ions in the plasmasphere?

*Masafumi Shoji1, Yoshizumi Miyoshi1, Lynn M Kistler2, Kazushi Asamura3, Yasumasa Kasaba4, Ayako Matsuoka6, Yoshiya Kasahara5, Shoya Matsuda5, Fuminori Tsuchiya4, Atsushi Kumamoto4, Satoko Nakamura1, Chae-Woo Jun1, Iku Shinohara3 (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Univ. New Hampshire, 3.ISAS/JAXA, 4.Tohoku Univ., 5.Kanazawa Univ., 6.Kyoto Univ.)

Keywords:ion heating, EMIC wave

Electromagnetic ion cyclotron (EMIC) waves are generated through the cyclotron wave-particle interaction, affecting the plasma environment in the magnetosphere. Heating of the ions by EMIC waves in the inner magnetosphere has also been investigated by spacecraft observations by comparing variations of ion distribution and waves. The energy transfer between the plasma waves and ions can be quantitatively evaluated by calculating the inner product between the wave electric field vector and the ion velocity vector, so-called WPIA (wave-particle interaction analysis). We adapt the WPIA method to the Arase spacecraft data and investigate the statistical results of the WPIA and the spatial distribution of the positive qV・E region in the inner magnetosphere. Using 4.5 years data, we choose EMIC wave events associating proton or helium flux enhancements of which the WPIA analysis can be applied for the necessary data sets observed by the Arase satellite. The energization of proton occurs over wide conditions, while the strongest energization of proton appears at Kp = 0 with the energy around 10 eV. On the other hand, the helium heating takes place at higher Kp>4 and with higher energy of the helium (>~ 100 eV). In the low Kp case, the energization of the helium is weak. In the magnetosphere, the occurrence peaks of the proton heating events appear in the dayside and post noon regions. In the higher Kp case, we find the occurrence peaks of heating of both proton and helium close to the Earth, around L=3-4 while in the smaller Kp case, the peaks appear around the noon and dusk side. Comparing the possible theoretical mechanisms of the ion flux enhancement, we conclude that the contribution of the EMIC heating to the warm plasma inside the plasmasphere is not significant.