Dispersive magnetosheath-like ion injections in the evening sector on January 11, 1997

Research output: Contribution to journalArticleScientificpeer-review


  • I. Sandahl
  • HEJ Koskinen
  • AM Malkki
  • T.I. Pulkkinen
  • EY Budnik
  • AO Fedorov
  • LA Frank
  • JB Sigwarth

Research units

  • University of Colorado Boulder
  • Swedish Institute of Space Physics
  • University of Helsinki
  • University of Iowa
  • Finnish Meteorological Institute
  • Russian Academy of Sciences


While the plasma cloud of the January 1997 CME event was passing the Earth, the Interball Auroral Probe (Interball-2) crossed the duskside auroral oval toward a contracted polar cap. The PROMICS-3 plasma instrument observed several consecutive dispersion ramps of magnetosheath-like protons over a wide range of magnetic local times (16-21 MLT). The last dispersion ramps were observed at later local times than previously reported, likely caused by the extreme conditions during a period when the magnetosphere was immersed in the dense plasma cloud. The Polar/VIS images of the oval show a very contracted polar cap. During the first clear dispersion event energetic oxygen ions were detected. They were also observed by the the particle detectors of Polar which was in close conjugation with Interball-2 right at this moment. We suggest that the dispersion ramps are signatures of ion injections formed by impulsive entry of magnetosheath ions through the duskside flank into the magnetosphere during a period of strongly northward IMF and contracted polar cap.


Original languageEnglish
Pages (from-to)2569-2572
Number of pages4
JournalGeophysical Research Letters
Issue number14
Publication statusPublished - 15 Jul 1998
MoE publication typeA1 Journal article-refereed

ID: 3012748