Local Acceleration of Multi‐MeV Electrons Inside Earth's Impenetrable Barrier During the May 2024 Superstorm
Abstract The inner radiation belt ( L* < 3) has long been considered an impenetrable barrier to ultra‐relativistic electrons. Here we show that this barrier can be breached under extreme space weather conditions. Using continuous near‐equatorial observations from the Arase satellite, we show that the May 2024 superstorm rapidly generated multi‐MeV electrons deep inside the inner magnetosphere. Phase space density profiles reveal the development of a local maximum at L* ∼ 3, providing evidence that local in situ acceleration established multi‐MeV electron source before supplying inward and outward radial diffusion. Simultaneous observations of intense chorus waves under a strongly depleted plasma region, maintained by enhanced convection and a negative ionospheric storm, are consistent with chorus‐driven local acceleration. These findings demonstrate that local acceleration can establish a multi‐MeV electron source inside the impenetrable barrier under extreme space weather conditions.
Authors
- Shinji Saito (ORCID: https://orcid.org/0000-0002-6116-9964)
- Takefumi Mitani (ORCID: https://orcid.org/0000-0003-0492-3104)
- Yoshiya Kasahara (ORCID: https://orcid.org/0000-0002-9304-8235)
- Shoya Matsuda (ORCID: https://orcid.org/0000-0003-4778-8897)
- Iku Shinohara (ORCID: https://orcid.org/0000-0003-2700-0353)
- Kazuhiro Yamamoto (ORCID: https://orcid.org/0000-0002-2515-8643)
- Fuminori Tsuchiya (ORCID: https://orcid.org/0000-0003-3386-6794)
- Naritoshi Kitamura (ORCID: https://orcid.org/0000-0002-2397-273X)
- Atsuki Shinbori (ORCID: https://orcid.org/0000-0002-6018-7431)
- Dedong Wang (ORCID: https://orcid.org/0000-0002-4213-4037)
- M. Teramoto (ORCID: https://orcid.org/0000-0001-5983-1149)
- Satoshi Kurita (ORCID: https://orcid.org/0000-0002-1553-9557)
- Atsushi Kumamoto (ORCID: https://orcid.org/0000-0002-3988-1488)
- Tomoaki Hori (ORCID: https://orcid.org/0000-0001-8451-6941)
- Ryuho Kataoka (ORCID: https://orcid.org/0000-0001-9400-1765)
- Chae‐Woo Jun (ORCID: https://orcid.org/0000-0003-2914-2910)
- Yoshizumi Miyoshi (ORCID: https://orcid.org/0000-0001-7998-1240)
- A. Matsuoka (ORCID: https://orcid.org/0000-0001-5777-9711)
- T. Takashima
- N. Higashio
Institutions
- Kanazawa University (JP)
- Okinawa Institute of Science and Technology Graduate University (JP)
- Tohoku University (JP)
- Kyushu Institute of Technology (JP)
- Kyoto University (JP)
- Japan Aerospace Exploration Agency (JP)
- Kyung Hee University (KR)
- GFZ Helmholtz Centre for Geosciences (DE)
- Institute for Space-Earth Environmental Research, Nagoya University (JP)
- National Institute of Information and Communications Technology (JP)
Publication Details
- Journal
- Geophysical Research Letters
- Published
- 2026-10-26
- DOI
- https://doi.org/10.1029/2026gl125879
- Primary Topic
- Ionosphere and magnetosphere dynamics
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Japan Society for the Promotion of Science