Simultaneous Observations of EMIC Waves, ELF/VLF Waves, and Energetic Particle Precipitation during Multiple Compressions of the Magnetosphere

Abstract

Simultaneous observations of ELF/VLF and EMIC waves from Van Allen Probe satellites in the daytime Earth’s magnetosphere and on the ground during multiple compressions of the magnetosphere due to the fluctuations of the dynamic pressure of the solar wind are considered. Each magnetospheric compression leads to the generation of a wave burst in these frequency ranges. Based on data on the spectral and amplitude characteristics of the waves, measurements of the magnetic field, and the cold plasma density, the pitch-angle diffusion coefficients of protons and electrons in the vicinity of the loss cone are calculated. It is shown that ELF waves with frequencies of <1 kHz may be responsible for precipitation of energetic (>30 keV) electrons; VLF waves at frequencies of 2–5 kHz may be responsible for precipitation of electrons with energy of ~1 keV. The EMIC waves observed from satellites and on the ground are related to the precipitation of protons with energies of 10–100 keV. The particle energies that correspond to the maxima of the diffusion coefficient are compared with the energies of the charged particles precipitating into the ionosphere, which were determined based on data from low-orbit POES satellites, and it is shown that they are in a good agreement with each other.