资源环境科技发展态势分析平台

We present a survey of the bifurcation of the Earth's energetic electron belt (tens of keV) using 6‐year measurements from Van Allen Probes. The inner energetic electron belt usually presents one‐peak radial structure with high flux intensity at L < ∼2.5, which however can be bifurcated to exhibit a double‐peak radial structure. By automatically identifying the events of bifurcation based on RBSPICE data, we find that the bifurcation is mostly observed at ∼30–100 keV with a local flux minimum at L=∼2.0–∼2.3 under relatively quiet geomagnetic conditions, typically after a significant flux enhancement due to radial diffusion or injections to L<∼2.5. The bifurcation typically lasts for a few days during quiet periods until interrupted by injections or radial diffusion. The L‐shell, energy and seasonal dependences of the occurrence of bifurcated inner electron belt support the important role of electron scattering by very‐low‐frequency transmitter waves in the bifurcation formation.