Observations of cold magnetospheric ions at geosynchronous orbit during times of high activity
Flowing, cold magnetospheric ions have been observed in conjunction with geosynchronous orbit magnetopause crossings since the earliest ATS and OGO missions. The authors have reported on the occurrence and convection of low-energy (10-100 eV) ions seen by multiple satellites in association with geosynchronous orbit magnetopause and low-latitude boundary layer (LLBL) encounters. More generally, Los Alamos 3-D plasma instruments observe these ions following storm sudden commencements (SSCs), when activity levels are high. The ions appear to be convecting radially outward and usually westward at speeds of a few to several tens of kilometers per second. Often the energy spectra reveal peaks at energies appropriate for cold convecting H{sup +}, He{sup +} and O{sup +}. The occurrence frequency distribution of these dense cold ions is peaked near 1400 LT, with an overall range from 1000 to beyond 1800 LT. This local time distribution is greatly skewed from the overall plasmaspheric distribution, which peaks closer to 1800 LT. Multisatellite observations show that the ions are seen first at late afternoon local times and then at progressively earlier and earlier local times (though usually no earlier than 1000 LT). This apparent evolution in local time suggests that the late-afternoon plasmaspheric plasma moves out and dawnward during times of increased magnetospheric activity. The three-satellite observations also allow the authors to track cold plasma convection at multiple points in the magnetosphere, and potentially provide a glimpse of the large-scale convection pattern.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- National Aeronautics and Space Administration, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10188128
- Report Number(s):
- LA-UR-94-3223; CONF-9406192-4; ON: DE95000936; TRN: 94:021025
- Resource Relation:
- Conference: 8. international symposium on solar terrestrial physics,Sendai (Japan),6-10 Jun 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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