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Control of the innermost electron radiation belt by large‐scale electric fields
- Source :
- Journal of Geophysical Research: Space Physics. 121:8417-8427
- Publication Year :
- 2016
- Publisher :
- American Geophysical Union (AGU), 2016.
-
Abstract
- Electron measurements from the MagEIS instruments on Van Allen Probes, for kinetic energies ∼100 to 400 keV, show characteristic dynamical features of the innermost ( L≲1.3) radiation belt: rapid injections, slow decay, and structured energy spectra. There are also periods of steady or slowly increasing intensity and of fast decay following injections. Local time asymmetry, with higher intensity near dawn, is interpreted as evidence for drift shell distortion by a convection electric field of magnitude ∼0.4 mV/m during geomagnetically quiet times. Fast fluctuations in the electric field, on the drift time scale, cause inward diffusion. Assuming they are proportional to changes in Kp, the resulting diffusion coefficient is sufficient to replenish trapped electrons lost by atmospheric scattering. Major electric field increases cause injections by inward electron transport. An injection associated with the June 2015 magnetic storm is consistent with an enhanced field magnitude ∼5 mV/m. Subsequent drift echoes cause spectral structure.
- Subjects :
- Geomagnetic storm
Physics
010504 meteorology & atmospheric sciences
Field (physics)
Electron
01 natural sciences
symbols.namesake
Geophysics
Space and Planetary Science
Electric field
Van Allen radiation belt
Local time
0103 physical sciences
symbols
Van Allen Probes
Diffusion (business)
Atomic physics
010303 astronomy & astrophysics
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 21699402 and 21699380
- Volume :
- 121
- Database :
- OpenAIRE
- Journal :
- Journal of Geophysical Research: Space Physics
- Accession number :
- edsair.doi...........b1329232c846958660f5f38310d97f58