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GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 14, PAGES 2151–2154, 1999

High Energy Ions and Electrons Upstream from the Earth’s Bow Shock and their Dependence on Geomagnetic Conditions: Statistical Results Between Years 1982-1988

G. C. Anagnostopoulos

Demokritos University of Thrace, Department of Electrical and Computer Engineering, Xanthi 67100, Greece


G. Kaliabetsos

Demokritos University of Thrace, Department of Electrical and Computer Engineering, Xanthi 67100, Greece


G. Argyropoulos

Demokritos University of Thrace, Department of Electrical and Computer Engineering, Xanthi 67100, Greece


E. T. Sarris

Demokritos University of Thrace, Department of Electrical and Computer Engineering, Xanthi 67100, Greece


Abstract

We present initial results from a statistical analysis of 2034 energetic (50 -220 keV) ion events observed by the IMP-8 spacecraft upstream from the Earth’s bow shock during a 6 years period. The most important findings are the following: (1) the percentage Pe of high intensity energetic ion events accompanied by the presence of relativistic (≥ 220 keV) electrons is ∼80% (for all geomagnetic conditions), and increases significantly with increasing the index Kp of geomagnetic activity, (2) high intensity energetic ion events most often (∼93%) show spectra extending up to energies E>∼300 keV, (3) a percentage of ∼71.5% of events display non-inverse energy dispersion of ion intensities. The above results, as well as additional results discussed in the text, suggest that a percentage as high as ∼80% of high intensity 50-220 keV ion events in our statistical sample have an origin within the magnetosphere.

Received 18 November 1998; accepted 23 March 1999.


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Citation: Anagnostopoulos, G. C., G. Kaliabetsos, G. Argyropoulos, and E. T. Sarris (1999), High Energy Ions and Electrons Upstream from the Earth’s Bow Shock and their Dependence on Geomagnetic Conditions: Statistical Results Between Years 1982-1988, Geophys. Res. Lett., 26(14), 2151–2154.