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Ann. Geophys., 20, 957-965, 2002
www.ann-geophys.net/20/957/2002/
© European Geosciences Union 2002
The relativistic electron response in the outer radiation belt during magnetic storms
R. H. A. Iles1, A. N. Fazakerley1, A. D. Johnstone1, N. P. Meredith1, and P. Bühler2
1Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, UK
2Paul Sherrer Institut, Laboratory for Astrophysics, 5232 Villigen PSI, Switzerland
Correspondence to: R. H. A. Iles (rhi@mssl.ucl.ac.uk)
Abstract. The relativistic electron
response in the outer radiation belt during magnetic storms has been studied in
relation to solar wind and geomagnetic parameters during the first six months
of 1995, a period in which there were a number of recurrent fast solar wind
streams. The relativistic electron population was measured by instruments on
board the two microsatellites, STRV-1a and STRV-1b, which traversed the
radiation belt four times per day from L ~ 1 out to L ~ 7 on
highly elliptical, near-equatorial orbits. Variations in the E > 750
keV and E > 1 MeV electrons during the main phase and recovery phase
of 17 magnetic storms have been compared with the solar wind speed,
interplanetary magnetic field z-component, Bz , the
solar wind dynamic pressure and Dst *. Three different types of electron
responses are identified, with outcomes that strongly depend on the solar wind
speed and interplanetary magnetic field orientation during the magnetic storm
recovery phase. Observations also confirm that the L-shell, at which the peak
enhancement in the electron count rate occurs has a dependence on Dst *.
Key words. Magnetospheric physics
(energetic particles, trapped; storms and substorms) – Space plasma physics
(charged particle motion and accelerations)
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