[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-07] Study for EMIC wave-particle interactions in the radiation belts during the May 2024 storm using data from the PWING ground network, Arase, and POES satellites

*Chae-Woo Jun¹, Yoshizumi Miyoshi¹, Tomoaki Hori¹, Kazuo Shiokawa¹, Khan-Hyuk Kim², Jacob Bortnik³, Larry Lyons³, Iku Shinohara⁴, Ayako Matsuoka⁵, Yoshiya Kasahara⁶, Shoya Matsuda⁶, Yasumasa Kasaba⁷, Mariko Teramoto⁸, Kazuhiro Yamamoto¹, Atsuki Shinbori¹ (1.Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan, 2.Kyung-Hee University, Suwon, Korea, 3.Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, USA, 4.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan, 5.Kyoto University, Kyoto, Japan, 6.Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan, 7.Graduate School of Science, Tohoku University, Sendai, Japan, 8.Kyushu Institute of Technology, Iizuka, Japan)

Keywords:The May 2024 storm, EMIC waves, Precipitation of energetic protons and relativistic electrons by EMIC wave-particle interaction, Multi-points observations using data from the PWING ground chain, Arase, and POES satellites

The May 2024 storm with a minimum Dst of -412 nT was recorded as one of the largest geomagnetic storms in recent decades, causing various geomagnetic phenomena, such as the penetration of the enhanced ring current particles into the deep inner magnetosphere, the acceleration and loss of radiation belt electrons, and the generation of various plasma waves, etc. Electromagnetic ion cyclotron (EMIC) waves, also known as Pc1 waves, play an important role in the loss processes of energetic ring current protons and relativistic electrons in the radiation belts through pitch-angle scattering. In this study, we present observations of EMIC wave activity during the great geomagnetic storm on May 2024, using data from the PWING ground-based observation network, POES, and Arase satellites. We found that the Arase satellite detected various EMIC waves, which differed depending on the storm phase. High-frequency EMIC waves with frequencies above 5 Hz were predominantly observed at L<3 during the main and early recovery phase, indicating that energetic particles had penetrated regions close to the Earth. POES observations revealed significant 30-80 keV proton precipitation events at L~2 during the main phase. PWING ground-based observations exhibit special types of Pc1 pulsations at sub-auroral and low-latitudinal stations, which frequencies higher than those of typical Pc1 waves. The variation in Pc1 wave frequency shows a relationship with the plasmapause locations and inner boundary of 20-50 keV proton flux. We will investigate the evolution of the ring current protons and their contribution to the generation of EMIC waves during the storm. We will discuss the impact of storm-time EMIC wave-particle interactions on the loss of energetic protons and relativistic electrons in the radiation belts. The observations provide new insights into the generation processes of EMIC waves and the inner magnetospheric dynamics during intense geomagnetic storms.