Highly resolved effects of whistler-mode hiss waves in March 2013

Abstract:

We present a simulation of effects of whistler-mode waves on radiation belt electrons for the entire month of March 2013. Frequency dependent wave intensities as well as ambient plasma density are obtained from the EMFISIS Waves instrument onboard the Van Allen Probes using fine temporal (8 hours) and spatial (0.1L) resolutions. Pitch angle diffusion that produces electron scattering is computed using the Lyons et al. [1972] model, from L=1.8 to L=5.5 and energy in [0.05, 6] MeV. Electron lifetimes are deduced from the steady state of electron pitch angle diffusion. Such a computation requires 4000 thousands processors during 10 hours. It leads to a fine description of the hiss effects in the plasmasphere and in its exterior neighborhood. Losses follow a complex and dynamic filamentary structure, imposed by the wave properties (mainly frequency and amplitude), that sculpts the slot as such. Their daily structure in the (E-L) plane is characteristic [Lyons & Thorne, 1973], dynamic, and similar to recent slot observations from the Van Allen probes [Reeves et al., 2015]. Low energy electrons are less influenced by intense hiss scattering below L=4, which favors their travel down to the vicinity of the Earth, explaining thus the existence of a wide inner belt. On the other hand MeV electrons evolve in a more hostile environment that will depopulate them as they migrate from L~5 down to L~2.5. Ultra-relativistic electrons are not sensible to hiss waves before two and three Earth radii.