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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 28, issue 3
Ann. Geophys., 28, 849–859, 2010
https://doi.org/10.5194/angeo-28-849-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 28, 849–859, 2010
https://doi.org/10.5194/angeo-28-849-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.

  22 Mar 2010

22 Mar 2010

Low altitude energetic electron lifetimes after enhanced magnetic activity as deduced from SAC-C and DEMETER data

S. Benck1, L. Mazzino2, M. Cyamukungu1, J. Cabrera1, and V. Pierrard1,3 S. Benck et al.
  • 1Center for Space Radiations (CSR), Chemin du Cyclotron, 2, 1348 Louvain-la-Neuve, Belgium
  • 2University of Alberta, Department of Physics, 11322 – 89 Avenue, Edmonton Alberta, Canada
  • 3Belgian Institute for Space Aeronomy (BISA), Ringlaan-3-Avenue Circulaire, 1180 Brussels, Belgium

Abstract. When flux enhancements of energetic electrons are produced as a consequence of geomagnetic storm occurrence, they tend to vanish gradually when the magnetic activity calms down and the fluxes decay to quiet-time levels. We use SAC-C and DEMETER low altitude observations to estimate the energetic electron lifetimes (E=0.16–1.4 MeV, L=1.6–5, B=0.22–0.46 G) and compare the decay rates to those observed at high altitude. While crossing the radiation belts at high latitude, the SAC-C and DEMETER instruments sample particles with small equatorial pitch angles (αeq<18° for L>2.5) whereas the comparison is done with other satellite data measured mainly in the equatorial plane (for αeq>75°). While in the inner belt and in the slot region no significant lifetime differences are observed from the data sets with different αeq, in the outer belt, for the least energetic electrons (<500 keV), the lifetimes are up to ~3 times larger for the electrons with the equatorial pitch-angle close to the loss cone than for those mirroring near the equator. The difference decreases with increasing energy and vanishes for energies of about 1 MeV.

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