Oral Presentation

Spatial Distributions of EMIC Waves Depending on Geomagnetic Conditions During the Van Allen Probes and ERG era

Author(s): C.-W Jun, Y. Miyoshi, C. Yue, J. Bortnik, L. Lyons, Y. Nishimura, C. Kletzing, Y. Kasahara, Y. Kasaba, S. Matsuda, M. Shoji, F. Tsuchiya, A. Kumamoto, A. Matsuoka, and I. Shinohara

Presenter: Chae-Woo Jun (Institute for Space-Earth Environmental Research (ISEE), Nagoya University)

To understand the generation and propagation processes of Electro-Magnetic ion cyclotron (EMIC) waves in the magnetosphere, we performed a study of spatial distributions of EMIC waves using combined observations based on the Van Allen Probes (RBSP) and Exploration of energization and Radiation in Geospace (ERG) satellite. From 2017 to 2018, we identified EMIC wave events observed by both satellite missions and categorized them with respect to wave bands (H+ and He+ EMIC waves) and relative satellite locations from the plasmasphere (inside and outside the plasmasphere). We found significant dependence of EMIC wave distributions on geomagnetic conditions. H+ EMIC waves outside the plasmasphere have two clear peak occurrence regions in the noon sector at L~7-8 during the recovery phase and in the morning sector at L>8 during the non-storm intervals. He+ EMIC waves inside the plasmasphere are dominantly observed in the noon-afternoon sector during the main phase. In the presentation, we show the details of spatial distributions of EMIC waves and discuss possible drivers for generating EMIC waves depending on geomagnetic conditions.