DOI

We present a comprehensive study of a sequence of two substorms and multiple pseudobreakups using optical, magnetic and incoherent scatter radar measurements, energetic particles from two geosynchronous satellites and particle and field data from the Geotail spacecraft located at X-gsm similar to -86 R-E. Following conventional nomenclature, we classified as pseudobreakups those auroral breakups which did not exhibit significant poleward expansion (<2 degrees magnetic latitude). Auroral intensifications following substorm breakups were also observed, and were classified separately. Pseudobreakups were found not to differ from substorm breakups in longitudinal extent (from 1.3 to 6.1 hours of magnetic local time), or in duration (from 5 to 16 minutes). In general, the ionospheric currents producing ground magnetic disturbances were more intense during substorms than pseudobreakups, We found that pseudobreakups are;associated with the same magnetospheric processes as substorm breakups which involve current wedge formation, midlatitude magnetic Pi2 pulsations and energetic particle injections at the geosynchronous altitude. Moreover, pseudobreakups are associated with magnetic reconnection in the near-Earth region, evidenced by the typical subsequent detection of a plasmoid at Geotail. This implies that the magnetotail volume influenced by a pseudobreakup is quite large in radial distance. We conclude that there is no definitive qualitative distinction between pseudobreakups and substorms but there is a continuum of states between the smell pseudobreakups and large substorms.

Original languageEnglish
Article number1999JA900118
Pages (from-to)12263-12287
Number of pages25
JournalJournal of Geophysical Research
Volume104
Issue numberA6
DOIs
StatePublished - 1 Jun 1999

    Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Paleontology

    Research areas

  • DEEP GEOMAGNETIC TAIL, ENERGETIC ION BURSTS, MAGNETOSPHERIC SUBSTORMS, MAGNETOTAIL, SIGNATURES, ONSET, PLASMOIDS, RECONNECTION, DYNAMICS, PARTICLE

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