EMIC Waves Induced by the Enhancement of Solar Wind Dynamic Pressure and Subsequent Relativistic Electron Precipitation

Electromagnetic ion cyclotron (EMIC) wave plays an important role in precipitating relativistic electrons. In this study, we analyze an EMIC wave event on 6 November 2015 that extended over 6 hours in local time and the amplitude of this EMIC wave is about 3nT. Solar wind dynamic pressure enhancement excites EMIC waves, and whistler mode chorus waves are observed at the same time. When the EMIC wave occurs, the flux of relativistic electrons with pitch angle around 90° increases and the flux of small-pitch-angle relativistic electrons decreases. We calculate the electron PSD, which proves that EMIC wave leads to relativistic electron precipitation. Our result indicates that the large-amplitude EMIC wave will lead to nonlinear wave-particle interaction, thus leading to relativistic electron precipitation. When the wave amplitude is larger, the nonlinear wave-particle interaction becomes stronger.