Novel Estimates of ULF Wave Radial Diffusion of Relativistic Electrons in the Radiation Belts using the Van Allen Probes, THEMIS and GOES

Abstract:

Ultra-Low Frequency (ULF) waves are critical in radial diffusion processes of relativistic electrons in the radiation belts and their Power Spectral Density as a function of L is an integral part of the radial diffusion coefficients and of assimilative models of the radiation belts. Using simultaneous measurements from two GOES geosynchronous satellites, three spacecraft of the THEMIS constellation and the two Van Allen probes, we calculate the Power Spectral Density of ULF pulsations at different L, through which we provide improved estimates of the diffusion coefficient due to compressional magnetic perturbations as a function of L and Kp. These results can have significant implications in better defining the regions where radial diffusion can be effective vs. the regions where it cannot account for the observed changes in the phase space density of relativistic electrons.