Differences in geomagnetic storms driven by magnetic clouds and ICME sheath regions

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • Finnish Meteorological Institute
  • University of Helsinki
  • University of Calgary
  • Los Alamos Natl Lab, Los Alamos National Laboratory, United States Department of Energy (DOE)
  • Space Sciences Laboratory

Abstract

Twenty-eight geomagnetic storms driven by magnetic clouds or by sheath regions ahead of interplanetary coronal mass ejections are examined to address the dependence of the driver properties on the storm evolution and storm-substorm relationship. A superposed epoch analysis shows that the sheath-driven storms have stronger auroral activity, stronger magnetotail field stretching, and larger asymmetry in the inner magnetosphere field configuration. We suggest that the strong stretching during the sheath-driven storms leaves ions drifting Earthward from the plasma sheet on open drift paths, which limits the symmetric ring current growth. This decouples the substorm injections from the ring current enhancement, and can in part explain why there is no direct relationship between the auroral electrojet AL index and the midlatitude ring current Dst index.

Details

Original languageEnglish
Article number02105
Number of pages4
JournalGeophysical Research Letters
Volume34
Issue number2
Publication statusPublished - 23 Jan 2007
MoE publication typeA1 Journal article-refereed

    Research areas

  • SOLAR-WIND, MAGNETOSPHERIC CONVECTION, FIELD

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