Radial Diffusion as a Potential Source and Loss Mechanism of Relativistic Electrons in the Outer Radiation Belt
AEROSPACE CORP EL SEGUNDO CA ENGINEERING AND TECHNOLOGY GROUP
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The loss mechanisms responsible for the sudden depletions of the outer electron radiation belt are examined based on observations and radial diffusion modeling. SAMPEX data for Oct-Dec 2003, indicates that depletions are correlated with increases in geomagnetic activity and are also correlated with sudden increases in the solar wind dynamic pressure. Multi-channel HEO observations show that depletions at higher L are seen at energies as low as a few hundred keV. For the same events, high-energy proton channels also show decrease in fluxes at higher L-values. These observations are consistent with outward radial diffusion driven by the loss to magnetopause at L4. We further examine the viability of the outward radial diffusion loss by comparing CRRES observations with a radial diffusion model simulation. Model-data comparison shows that flux variation near geosynchronous orbit can be effectively propagated by the outward radial diffusion to L4 and can account for the main phase storm depletions.
- Atmospheric Physics