Equinoctial and solstitial averages of magnetospheric relativistic electrons: A strong semiannual modulation

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • University of Colorado Boulder
  • Finnish Meteorological Institute
  • NASA Goddard Space Flight Center
  • Aerospace Corporation

Abstract

Data from SAMPEX, POLAR, and other spacecraft shows that high energy electrons (E greater than or similar to 1 MeV) vary in a highly coherent way throughout the entire outer radiation zone of the Earth (2.5 less than or similar to L less than or similar to 6.5). These data are used to perform long-term analysis of the flux variations of E>2 MeV electrons throughout the outer trapping zone. Averages are performed over 3-month intervals centered on the spring and fall equinoxes and on the winter and summer solstices. Modulation is found such that equinoctial fluxes of electrons are nearly a factor of three larger than the solstitial fluxes based upon a superposed epoch analysis for 1992-1999. These semiannual modulations of relativistic electron fluxes are compared with concurrent solar wind data and are examined in terms of prior models of geomagnetic activity modulation. It is concluded that both southward IMF component merging (Russell-McPherron) and Kelvin-Helmholtz instability considerations (Boller-Stolov) may play important roles.

Details

Original languageEnglish
Pages (from-to)3193-3196
Number of pages4
JournalGeophysical Research Letters
Volume26
Issue number20
Publication statusPublished - 15 Oct 1999
MoE publication typeA1 Journal article-refereed

    Research areas

  • GEOMAGNETIC ACTIVITY, OUTER MAGNETOSPHERE, STORMS, ISTP, WIND

ID: 3011074