Previous theoretical studies have shown that dayside chorus can produce butterfly distribution of energetic electrons in the Earth＇s radiation belts by preferentially accelerating medium pitch angle electrons, but th...Previous theoretical studies have shown that dayside chorus can produce butterfly distribution of energetic electrons in the Earth＇s radiation belts by preferentially accelerating medium pitch angle electrons, but this requires the further confirmation from high- resolution satellite observation. Here, we report correlated Van Allen Probes data on wave and particle during the 1 I-13 April, 2014 geomagnetic storm. We find that a butterfly pitch angle distribution of relativistic electrons is formed around the location L = 4.52, corresponding to the presence of enhanced dayside chorus. Using a Gaussian distribution fit to the observed chorus spectra, we calculate the bounce-averaged diffusion rates and solve two-dimensional Fokker-Planck equation. Numerical results demonstrate that acceleration by dayside chorus can yield the electron flux evolution both in the energy and butterfly pitch angle distribution comparable to the observation, providing a further evidence for the formation of butterfly distribution of relativistic electrons driven by very low frequency （VLF） plasma waves.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41531072,41404130,41504125&41674166)
文摘Previous theoretical studies have shown that dayside chorus can produce butterfly distribution of energetic electrons in the Earth＇s radiation belts by preferentially accelerating medium pitch angle electrons, but this requires the further confirmation from high- resolution satellite observation. Here, we report correlated Van Allen Probes data on wave and particle during the 1 I-13 April, 2014 geomagnetic storm. We find that a butterfly pitch angle distribution of relativistic electrons is formed around the location L = 4.52, corresponding to the presence of enhanced dayside chorus. Using a Gaussian distribution fit to the observed chorus spectra, we calculate the bounce-averaged diffusion rates and solve two-dimensional Fokker-Planck equation. Numerical results demonstrate that acceleration by dayside chorus can yield the electron flux evolution both in the energy and butterfly pitch angle distribution comparable to the observation, providing a further evidence for the formation of butterfly distribution of relativistic electrons driven by very low frequency （VLF） plasma waves.
