Multiple polar cap arcs: Akebono (Exos D) observations

T. Obara, T. Mukai, H. Hayakawa, K. Tsuruda, A. Matsuoka, A. Nishida, H. Fukunishi, L. Zhu, J. Sojka, D. Crain

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Akebono (Exos D) observations demonstrate that polar cap arcs sometimes have a fine structure, that is, multiple (double or triple) arcs with spacing of a few tens of kilometers. The multiple polar cap arcs are dominantly observed in the nightside polar cap region, suggesting that low background conductance favors the appearance of the structured arcs. A relationship between the spacing and the average energy of the precipitating electrons is investigated. Results show that a higher energy leads to a wider spacing. Akebono observations also show the existence of a downward current region embedded between upward current regions (arcs). Comparison of the observations with results from a coupled magnetosphere-ionosphere Sun-aligned arc model is made, which shows good qualitative agreement between the modeling and observational results on the spacing-energy dependence and the effect of background ionospheric conductance.

Original languageEnglish
Pages (from-to)645-653
Number of pages9
JournalRadio Science
Issue number3
Publication statusPublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Earth and Planetary Sciences(all)
  • Electrical and Electronic Engineering


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