Japan Geoscience Union Meeting 2021

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[E] Oral

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

[P-EM09] Dynamics of Magnetosphere and Ionosphere

Sun. Jun 6, 2021 10:45 AM - 12:15 PM Ch.05 (Zoom Room 05)

convener:Akiko Fujimoto(Kyushu Institute of Technology), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University), Yuka Sato(Nippon Institute of Technology), Aoi Nakamizo(Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology), Chairperson:Hiroshi Hasegawa(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Masaki N Nishino(Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science)

10:45 AM - 11:10 AM

[PEM09-08] A Case Study of Transversely Heated Low-Energy Helium Ions by EMIC Waves in the Plasmasphere

★Invited Papers

*Khan-Hyuk Kim1 (1.School of Space Research, Kyung Hee University)

Keywords:EMIC waves, Low-energy ion heating, Plasmasphere

The Van Allen Probe A spacecraft observed strong ~0.5-Hz helium (He+) band and weak ~0.8-Hz hydrogen (H+) band EMIC waves on 17 April 2018, at L = ~4.5-5.2, in the dawn sector, near the magnetic equator, and close to the plasmapause. We examined low-energy ion fluxes observed by the Helium Oxygen Proton and Electron (HOPE) instrument onboard Van Allen Probe A during the wave interval and found that low-energy He+ flux (< 10 eV) enhancements occur nearly simultaneously with He-band and H-band EMIC wave power enhancements in a direction mostly perpendicular to the background magnetic field without significant low-energy H+ and O+ flux variations. We suggest that cold He+ ions (<1 eV) are preferentially and transversely heated up 10 eV through the interaction with EMIC waves inside the plasmasphere. The low-Earth orbit spacecraft observed localized precipitations of energetic protons in the upper ionosphere at subauroral latitudes near the magnetic field footprint of Van Allen Probe A. Our observations provide a clear evidence that EMIC waves play an important role in the overall dynamics in the inner magnetosphere, contributing to the high-energy particle loss and low-energy particle energization.