On the simultaneity of substorm onset between two hemispheres

A. Morioka, Y. Miyoshi, F. Tsuchiya, H. Misawa, Y. Kasaba, T. Asozu, S. Okano, A. Kadokura, N. Sato, H. Miyaoka, K. Yumoto, G. K. Parks, F. Honary, J. G. Trotignon, P. M.E. Décréau, B. W. Reinisch

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Simultaneous observations of auroral kilometric radiation from the Northern and Southern Hemispheres showed some cases in which the buildup of field-aligned acceleration occurred only in one hemisphere at the substorm onset. This indicates that a substorm does not always complete the current system by connecting the cross-tail current with both northern and southern ionospheric currents. Conjugate auroral observations showed that in one case, the auroral breakup in the Northern and Southern Hemispheres was not simultaneous; rather, they occurred a few minutes apart. This time difference in the breakup between two hemispheres suggests that the local auroral ionosphere controls auroral breakup in each hemisphere independently. The evidence in this study may indicate that the buildup of the field-aligned acceleration region at the auroral breakup does not result only from the magnetospheric process and that the auroral ionosphere finally controls and/or ignites the substorm onset, that is, the auroral breakup.

Original languageEnglish
Article numberA04211
JournalJournal of Geophysical Research: Space Physics
Issue number4
Publication statusPublished - 2011

ASJC Scopus subject areas

  • Space and Planetary Science
  • Geophysics


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