Instantaneous Frequency Analysis on Nonlinear EMIC Emissions: Arase Observation

The electromagnetic ion cyclotron (EMIC) waves are generated by the temperature anisotropy of protons. Especially, the nonlinear wave particle interaction [1], [2] between the EMIC waves and protons causes the rising or falling frequencies and drastic proton scattering in the equatorial region[3]. Frequency sweep rate of the EMIC wave is a key parameter to analyze the affection on the ion scattering, however the estimation of the sweep rate is difficult from the Fourier dynamic spectrum due to the limitation between the frequency and temporal resolutions.