Abstrakt
We present simulations of the loss of radiation belt electrons by resonant pitch angle diffusion caused by whistler mode hiss waves for March 2013. Pitch angle diffusion coefficients are computed from the wave properties and the ambient plasma data obtained by the Van Allen Probes with a resolution of 8 h and 0.1 L shell.
Loss rates follow a complex dynamic structure, imposed by the wave and plasma properties. Hiss effects can be strong, with minimum lifetimes (of similar to 1 day) moving from energies of similar to 100 keV at L similar to 5 up to similar to 2 MeV at L similar to 2 and stop abruptly, similarly to the observed energy-dependent inner belt edge.
Periods when the plasmasphere extends beyond L similar to 5 favor long-lasting hiss losses from the outer belt. Such loss rates are embedded in a reduced Fokker-Planck code and validated against Magnetic Electron and Ion Spectrometer observations of the belts at all energy.
Results are complemented with a sensitivity study involving different radial diffusion and lifetime models. Validation is carried out globally at all L shells and energies.
The good agreement between simulations and observations demonstrates that hiss waves drive the slot formation during quiet times. Combined with transport, they sculpt the energy structure of the outer belt into an "S shape." Low energy electrons (< 0.3 MeV) are less subject to hiss scattering below L = 4.
In contrast, 0.3-1.5 MeV electrons evolve in an environment that depopulates them as they migrate from L similar to 5 to L similar to 2.5. Ultrarelativistic electrons are not affected by hiss losses until L similar to 2-3.