Response of the Ionosphere-Plasmasphere Coupling to the September 2017 Storm: What Erodes the Plasmasphere so Severely?

Yuki Obana, Naomi Maruyama, Atsuki Shinbori, Kumiko K. Hashimoto, Mariangel Fedrizzi, Masahito Nosé, Yuichi Otsuka, Nozomu Nishitani, Tomoaki Hori, Atsushi Kumamoto, Fuminori Tsuchiya, Shoya Matsuda, Ayako Matsuoka, Yoshiya Kasahara, Akimasa Yoshikawa, Yoshizumi Miyoshi, Iku Shinohara

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


We report an extreme erosion of the plasmasphere arising from the September 2017 storm. The cold electron density is identified from the upper limit frequency of upper hybrid resonance waves observed by the Plasma Wave Experiment instrument onboard the Exploration of energization and Radiation in Geospace/Arase satellite. The electron density profiles reveal that the plasmasphere was severely eroded during the recovery phase of the storm and the plasmapause was located at L = 1.6–1.7 at 23 UT 8 September 2017. This is the first report of deep erosion of the plasmasphere (LPP < 2) with the in situ observation of the electron density. The degree of the severity is much more than what is expected from the relatively moderate value of the SYM-H minimum (−146 nT). We attempt to find a possible explanation for the observed severe depletion by using both observational evidence and numerical simulations. Our results suggest that the middle latitude electric field had penetrated from the high-latitude storm time convection for several hours. Such an unusually long-lasting penetration event can cause this observed degree of severity.

Original languageEnglish
Pages (from-to)861-876
Number of pages16
JournalSpace Weather
Issue number6
Publication statusPublished - 2019 Jun


  • erosion of plasmasphere
  • ionosphere
  • magnetic storm
  • midlatitude trough minimum
  • penetration of electric field
  • plasmasphere

ASJC Scopus subject areas

  • Atmospheric Science


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