Effects of latitudinal distributions of particle density and wave power on cyclotron resonant diffusion rates of radiation belt electrons

Danny Summers,Binbin Ni

doi:10.1186/bf03352825

Abstract

Abstract We evaluate cyclotron resonant interactions of radiation belt electrons with VLF chorus, plasmaspheric ELF hiss and electromagnetic ion cyclotron (EMIC) waves. We assume that the Earth’s magnetic field is dipolar and that each wave mode has a Gaussian spectral density. The dependence of the resonant electron diffusion rates on the latitudinal distributions of particle density and wave power is examined. We find that while the diffusion rates can be sensitive to the latitudinal distributions of density and wave power, in general the sensitivity depends on wave mode, equatorial pitch-angle, electron energy and L-shell. We determine the effects of the latitudinal distributions of density and wave power on the electron precipitation loss timescale due to combined scattering by VLF chorus, ELF hiss and EMIC waves. Accurate modeling of radiation belt electron dynamics requires observational data on the global distributions of particle number density and wave power.

Highlights

Electrons in the Earth’s outer radiation belt (3 < L < 7)undergo cyclotron resonant interactions with various modes of plasma wave including whistler-mode chorus, plasmaspheric hiss and electromagnetic ion cyclotron (EMIC) waves, e.g., see Summers et al (2007a, b) and references therein
We find that while the diffusion rates can be sensitive to the latitudinal distributions of density and wave power, in general the sensitivity depends on wave mode, equatorial pitch-angle, electron energy and L-shell
We utilize the bounce-averaged diffusion coefficients given by Summers et al (2007a) to determine how diffusion rates for radiation belt electrons depend on the latitudinal distributions of particle density and wave power

Summary

Introduction

Electrons in the Earth’s outer radiation belt (3 < L < 7)undergo cyclotron resonant interactions with various modes of plasma wave including whistler-mode chorus, plasmaspheric hiss and electromagnetic ion cyclotron (EMIC) waves, e.g., see Summers et al (2007a, b) and references therein. We find that while the diffusion rates can be sensitive to the latitudinal distributions of density and wave power, in general the sensitivity depends on wave mode, equatorial pitch-angle, electron energy and L-shell.

Results

Conclusion