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Signatures of auroral potential structure extending through the near-equatorial inner magnetosphere
  • +13
  • Shun Imajo,
  • Yoshizumi Miyoshi,
  • Kazushi Asamura,
  • Iku Shinohara,
  • Masahito Nosé,
  • Kazuo Shiokawa,
  • Yoshiya Kasahara,
  • Yasumasa Kasaba,
  • Ayako Matsuoka,
  • Satoshi Kasahara,
  • Shoichiro Yokota,
  • Kunihiro Keika,
  • Tomoaki Hori,
  • Masafumi Shoji,
  • Satoko Nakamura,
  • Mariko Teramoto
Shun Imajo
Kyoto University

Corresponding Author:[email protected]

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Yoshizumi Miyoshi
Institute for Space-Earth Environmental Research, Nagoya University
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Kazushi Asamura
The Institute of Space and Astronautical Science
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Iku Shinohara
Japan Aerospace Exploration Agency
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Masahito Nosé
Nagoya University
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Kazuo Shiokawa
Institute for Space-Earth Environmental Research, Nagoya University
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Yoshiya Kasahara
Kanazawa University
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Yasumasa Kasaba
Tohoku University
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Ayako Matsuoka
Kyoto University
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Satoshi Kasahara
The University of Tokyo
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Shoichiro Yokota
Graduate School of Science, Osaka University
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Kunihiro Keika
The University of Tokyo
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Tomoaki Hori
Institute for Space-Earth Environmental Research (ISEE), Nagoya University
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Masafumi Shoji
Nagoya University
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Satoko Nakamura
Institute for Space-Earth Environmental Research, Nagoya University
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Mariko Teramoto
Kyushu Institute of Technology
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Abstract

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.