Does the braking of the fast plasma flow trigger a substorm? A study of the August 14, 1996, event

S. Ohtani, R. Yamaguchi, H. Kawano, F. Creutzberg, J. B. Sigwarth, L. A. Frank, T. Mukai

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

In a substorm event of August 14, 1996, the Geotail satellite was at XGSM ∼ -10 RE aligned with the GOES 8 satellite in the X direction in the premidnight sector. Two Pi2 onsets were identified. Whereas the first onset was associated with a pseudobreakup, an auroral bulge developed following the second onset. At the pseudobreakup Geotail observed a fast (>900 km/s) plasma flow along with dipolarization, but the geosynchronous magnetic field became stretched subsequently. In contrast, for the main onset, the magnetic field dipolarized at GOES 8, although the associated total (time-integrated) transport of magnetic flux at Geotail was no stronger than that for the pseudobreakup. It is suggested that the braking of the fast flow does not necessarily cause tail current disruption in a large scale, and there is an additional (or alternative) condition to suffice for an initial brightening to develop to a global substorm.

Original languageEnglish
Article number1721
JournalGeophysical Research Letters
Volume29
Issue number15
DOIs
Publication statusPublished - Aug 1 2002

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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