[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-08] Variations of energetic electrons via nonlinear interactions with lower-band chorus emissions around the Earth’s outer radiation belt

*Yikai Hsieh¹, Yoshiharu Omura¹ (1.Reserach Institute for Sustainable Humanosphere, Kyoto University)

Keywords:nonlinear wave-particle interaction, whistler mode chorus emissions, electron acceleration, electron precipitation

Energetic electron accelerations and precipitations in the Earth's outer radiation belt are highly associated with wave-particle interactions between whistler mode chorus waves and electrons. Two nonlinear processes, which change the energy and pitch angle of electrons effectively, take place in whistler mode wave-particle interactions. One is the nonlinear scattering, which makes electron energy slightly smaller. The other is the nonlinear trapping, which makes effective energy gain of the resonant electrons. We utilized the Green's function method to reproduce the wave-particle interactions in the radiation belt and investigate the electron acceleration and precipitation interacting with both parallel and obliquely propagating chorus emissions. The formation processes and the loss processes of the outer radiation belt electron fluxes interacting with consecutive chorus emissions are traced by applying the convolution integrals for the Green's functions. In the acceleration parts, MeV electrons are generated promptly due to the combination of cyclotron resonance and Landau resonance of oblique chorus waves. We compare the precipitation phenomena between parallel waves and oblique waves, and the results show that oblique chorus emissions lead to more electron precipitation than that led by parallel chorus emissions. Furthermore, we found that the acceleration process is stronger than the loss process, indicating that the radiation belt becomes stronger under the wave-particle interaction between chorus emissions and electrons comprehensively.