Statistics of Whistler-mode Waves in the Near-Earth Plasma Sheet

Electromagnetic whistler-mode waves are among the wave modes mainly responsible for energetic electron scattering and acceleration in the inner magnetosphere and near-Earth plasma sheet. Although whistler-driven electron precipitation significantly contributes to diffuse aurora at large L-shells of ~ 9-13, all existing empirical models of whistler-mode waves are limited to the inner magnetosphere, at L<9. This study aims to utilize more than ten years of Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations to investigate main properties of whistler-mode waves in the near-Earth plasma sheet. We reveal relations between wave intensity (Bw^2) and characteristics of the anisotropic electron population. We showed that in 99% of whistler wave events, the observed Bw^2, mean wave frequency <f>, and wave spectrum width Δf are consistent with expectations from the quasi-linear theory of wave-particle resonant interactions. Based on these statistics, we built an empirical model of Bw^2, <f>, and Δf as a function of L-shell and MLT. This model extends existing inner magnetosphere models to a higher L-shell range.