Signatures of Auroral Potential Structure Extending Through the Near-Equatorial Inner Magnetosphere

S. Imajo, Y. Miyoshi, K. Asamura, I. Shinohara, M. Nosé, K. Shiokawa, Y. Kasahara, Y. Kasaba, A. Matsuoka, S. Kasahara, S. Yokota, K. Keika, T. Hori, M. Shoji, S. Nakamura, M. Teramoto

Research output: Contribution to journalArticlepeer-review


The auroral acceleration region plays an important role in the magnetosphere-ionosphere coupling system. In this study, signatures of an auroral U-shaped potential structure were found for the first time in the near-equatorial inner magnetosphere by the Arase satellite at ∼6.0 RE geocentric distance and 11° magnetic latitude. The observed magnetic and electric field variations corresponded to the equatorward motion of the upward field-aligned current and converging perpendicular electric field. Examining the three-dimensional velocity distribution function of H+ and O+ ions, we demonstrate that upflowing ion beams were significantly deflected in an east-west direction with a perpendicular velocity up to ∼80 km/s, which is consistent with the ExB drift velocity. A simple particle drift model with the inferred auroral perpendicular potential presents a new kink-like drift path of ions from the magnetotail, implying that the auroral potential structure has a great impact on particle dynamics in the near-earth plasma sheet.

Original languageEnglish
Article numbere2022GL098105
JournalGeophysical Research Letters
Issue number10
Publication statusPublished - 2022 May 28


  • auroral acceleration region
  • inner magnetosphere
  • plasma convection
  • upflowing ion beam

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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