Plasmaspheric hiss waves are a dominant source of scattering for keV – MeV radiation belt electrons within the plasmasphere. Previous simulation and modeling work concerning hiss waves has often incorporated them via particle-based parameterizations (e.g., L-shell). However, recent work has shown that not only is hiss wave power loosely dependent on L-shell, but that proximity to the plasmapause may yield more accurate wave power distributions as it pertains to the modeling and scattering of electrons. This work serves to expand upon those previous studies by creating a low frequency (20 – 150 Hz) hiss wave model and incorporating a previously crafted high frequency (> 150 Hz) hiss wave model based on plasmapause location, proximity to the plasmapause, and Kp activity level. Diffusion coefficients created using this method produced shorter lifetimes for electrons between ~300 keV – 4 MeV than their L-sorted counterparts. Furthermore, 3D-simulations using and comparing the different hiss wave models (plasmapause sorting vs. L-sorting) find that the plasmapause based approach yields more accurate results when compared to Van Allen Probe-A observations.

Fast-localized electron loss, resulting from interactions with electromagnetic ion cyclotron (EMIC) waves, can produce deepening minima in phase space density (PSD) radial profiles. Here, we perform a statistical analysis of local PSD minima to quantify how readily these are associated with radiation belt depletions. The statistics of PSD minima observed over a year are compared to the Versatile Electron Radiation Belts (VERB) simulations, both including and excluding EMIC waves. The observed minima distribution can only be achieved in the simulation including EMIC waves, indicating their importance in the dynamics of the radiation belts. By analyzing electron flux depletions in conjunction with the observed PSD minima, we show that, in the heart of the outer radiation belt (L*<5), up to 45% of multi-MeV electron depletions are associated with PSD minima, demonstrating that fast localized loss by interactions with EMIC waves are a common and crucial process for ultra-relativistic electron populations.

During geomagnetic storms, the rapid depletion of the high-energy (several MeV) outer radiation belt electrons is a result of loss to the interplanetary medium through the magnetopause, outward radial diffusion and loss to the atmosphere due to wave-particle interactions. We have performed a statistical study of 110 storms using pitch angle resolved electron flux measurement from the Van Allen Probes mission and found that inside of the radiation belt (L*=3-5) the number of storms that result in depletion electrons with equatorial pitch angle α=30 is higher than number of storms that result in depletion of electrons with equatorial pitch angle α=75. We conclude that this is an indication of electron scattering by electromagnetic ion cyclotron waves. At the outer edge of the radiation belt (L* >= 5.2) the number of storms that result in depletion is also large (~40-50%), supporting the significance of the magnetopause shadowing effect and outward radial transport.