Estimation of auroral emission altitude in the region of the ISS magnetic footprint during a relativistic electron precipitation event observed by ISS-CALET

Earth, Planets and Space

卷:78

Express Letter

Kyutaro Yanagisawa¹  Ryuho Kataoka²  Kanako Seki³  Daniel Whiter⁴  Yoshizumi Miyoshi⁵  Kazuo Shiokawa⁵  Martin Connors⁶  Shoji Torii⁷  Satoshi Nakahira⁸  Takeshi Sakanoi⁹  Raju Aryal⁶  Alessandro Bruno¹⁰  Lauren W. Blum¹¹ 

[1] Waseda Research Institute for Science and Engineering, Waseda University, 17 Kikui-cho, Shinjuku-ku, 162-0044, Tokyo, Japan

[2] Department of Physics and Astronomy, Athabasca University, T9S 3A3, Athabasca, AB, Canada

[3] Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8904, Tokyo, Japan

[4] Department of Physics and Astronomy, University of Southampton, University Road, SO17 1BJ, Southampton, UK

[5] Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, 252-5210, Sagamihara, Kanagawa, Japan

[6] Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan

[7] Laboratory for Atmospheric and Space Physics and Department of Aerospace Engineering Sciences, University of Colorado Boulder, 1234 Innovation Drive, 80303-7814, Boulder, CO, USA

[8] Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna, Kunigami District, 904-0495, Okinawa, Japan

[9] Institute for Space-Earth Environmental Research, Nagoya University, Furo-Cho, Chikusa-ku, 464-8601, Nagoya, Aichi, Japan

[10] Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza Aoba, Aoba-Ku, 980-8578, Sendai, Miyagi, Japan

[11] Heliophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, 20771, Greenbelt, MD, USA

关键词: Electron precipitation;    Atmospheric ionization;    Aurora;    Stereoscopy;    Space weather forecast;   

DOI  :  10.1186/s40623-026-02507-7

 received in 2026-01-18, accepted in 2026-07-17,  发布年份 2026

来源: Springer

【 摘 要 】

We report a multi-MeV relativistic electron precipitation (REP) event as observed by the CALorimetric Electron Telescope and the Monitor of All-sky X-ray Image aboard the International Space Station, together with low-cost twin all-sky auroral imagers installed at Athabasca, Canada. We find that visible auroral emissions near the ISS magnetic footprint during REP events are not frequent—observed in only two of 10 conjugate REP events during our survey period from September 2024 to September 2025—and that one case, on 3 May 2025, featured diffuse aurora near the ISS magnetic footprint. Using two independent stereoscopic methods, we estimate the auroral emission height to be ~90 km, which is typically produced by tens-of-keV electron precipitation. Combined with the MeV electron precipitation detected by CALET, such broadband electron precipitation from tens-of-keV to MeV is consistent with the hypothesis of chorus-driven REP events. The emission altitude shows no systematic latitudinal variation, which is not consistent with field-line curvature scattering type energy-dispersed precipitation. The combined space- and ground-based observations contribute to a better understanding of the spatial context of wave–particle interaction associated with the REP events.Graphical Abstract

【 授权许可】

CC BY   
© The Author(s) 2026

【 图 表 】