[P-EM11] Dynamics of the Inner Magnetospheric System

[PEM11-09] Multipoint Measurement of Fine-Structured EMIC Waves by Arase, Van Allen Probe A, and Ground Stations

*Shoya Matsuda¹, Yoshizumi Miyoshi², Yoshiya Kasahara¹, Lauren W Blum³, Chris Colpitts⁴, Kazushi Asamura⁵, Yasumasa Kasaba⁶, Ayako Matsuoka⁷, Fuminori Tsuchiya⁶, Atsushi Kumamoto⁶, Mariko Teramoto⁸, Satoko Nakamura², Masahiro Kitahara², Iku Shinohara⁵, Geoffrey D Reeves⁹, Harlan Spence¹⁰, Kazuo Shiokawa², Tsutomu Nagatsuma¹¹, Shin-ichiro Oyama^2,12, Ian R Mann¹³ (1.Kanazawa University, 2.Institute for Space-Earth Environmental Laboratory, Nagoya University, 3.University of Colorado Boulder, 4.University of Minnesota, 5.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 6.Tohoku University, 7.Kyoto University, 8.Kyushu Institute of Technology, Kitakyushu, 9.Los Alamos National Laboratory, 10.University of New Hampshire, 11.National Institute of Information and Communications Technology, 12.National Institute of Polar Research, 13.University of Alberta)

Keywords:Arase satellite, Van Allen Probes, PWING, CARISMA, EMIC waves

Electromagnetic ion cyclotron (EMIC) waves are an important plasma waves that control energetic ion and relativistic electron precipitations in the terrestrial inner magnetosphere. We successfully measured latitudinally propagating EMIC waves using multipoint measurement data observed by Japanese Arase, U.S. Van Allen Probes, the PWING ground based magnetometer, and the CARISMA magnetometer array during a field-line conjunction event on 18 April 2019. By comparing the footprints and wave spectra obtained by the aforementioned spacecraft and ground stations, we concluded that the observed EMIC wave activity was spatially localized (185 km latitudinal width at an auroral altitude of 100 km) and the spatial scale of the wave propagation duct was smaller (<80 km) than the EMIC wave activity region. The estimated latitudinal width of the propagation duct is consistent with a comprehensive study of the isolated proton auroras (IPAs) by Sakaguchi et al. (2015), suggesting that IPAs are a visual manifest of wave-particle interaction regions. We also found that the clear heating of protons with local pitch-angles of approximately 30 and 150 degrees was detected by Arase concurrently with the appearance of fine-structured EMIC waves. This thermal ion distribution was also observed in the equatorial region by ECT/HOPE aboard Van Allen Probe A. Additionally, the thermal He⁺ heating was observed coincident with fine-structured EMIC waves.