Intense nighttime flux from the plasmasphere during a modest magnetic storm

Michael N. Vlasov, Michael C. Kelley, Jonathan J. Makela, Michael J. Nicolls

Research output: Contribution to journalArticlepeer-review


An analytical-numerical model is created for two nights during Space Weather Month in September 1999. On one of these nights, after the midnight collapse over the Arecibo Observatory, the plasma density remained quite high in spite of a very sharp decrease in the F2 peak height. In order to support this high density against recombination, a very high plasma flux from the plasmasphere, a value of about 6 × 108 cm-2 s-1, is needed. Initially, data assimilation attempts did not allow such a flux (see Ionospheric data assimilation: recovery of strong mid-latitudinal density gradients, J. Atmos. Sol.-Terr. Phys., this issue). We believe the high flux results from a well-developed equatorial fountain and an Appleton anomaly well north of its usual location. The latter is consistent with both the large plasma gradient over Arecibo and the enhanced Jicamarca electric field (see Midlatitude plasma and electric field measurements during Space Weather Month, September 1999. J. Atmos. Sol.-Terr. Phys., this issue).

Original languageEnglish (US)
Pages (from-to)1099-1105
Number of pages7
JournalJournal of Atmospheric and Solar-Terrestrial Physics
Issue number10
StatePublished - Jul 2003
Externally publishedYes


  • F region
  • Ionosphere-plasmasphere coupling
  • Ionospheric modeling
  • Magnetic storm
  • Midlatitude plasma flux

ASJC Scopus subject areas

  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science


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