Pseudobreakup and substorm onset: Observations and MHD simulations compared

T.I. Pulkkinen, DN Baker, M Wiltberger, C Goodrich, RE Lopez, JG Lyon

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The global conditions during a moderate geomagnetic disturbance event on May 15, 1996, are examined by comparing data from several ground-based instruments and inner tail satellites with global MHD simulations of the same event. The ground-based data show two substorm intensifications about 40 min apart, the first one being small and localized (a pseudobreakup) and the second leading to a major rearrangement of both the ionospheric auroral distribution and the magnetotail configuration. The simulation shows that during the pseudobreakup, open field lines were reconnecting in the midtail, but the flows were mainly tailward and very few effects were observable in the inner magnetosphere. The result that pseudobreakups can be associated with activity producing topological changes in the tail is an important new aspect that has not been discussed in earlier studies. Both the observations and the simulation show two distinct regions of activity: a thin current sheet in the inner tail magnetically connected with the auroral bulge and a reconnection region in the midtail associated with the most intense electrojet currents.

Original languageEnglish
Pages (from-to)14847-14854
Number of pages8
JournalJournal of geophysical research: Space physics
Volume103
Issue numberA7
DOIs
Publication statusPublished - 1 Jul 1998
MoE publication typeA1 Journal article-refereed

Keywords

  • INTERPLANETARY MAGNETIC-FIELD
  • GROWTH-PHASE
  • EARTHS MAGNETOSPHERE
  • GEOMAGNETIC TAIL
  • EXPANSION ONSET
  • MAGNETOTAIL
  • SHEET
  • RECONNECTION
  • CONVECTION
  • PARTICLE

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