Magnetosonic Waves Observed by the Van Allen Probe‐A Satellite: The Chirikov Resonance Overlap Criterion

Magnetosonic waves (MSWs) can be discrete or continuous in a time-frequency spectrogram. For MSWs that satisfy the Chirikov resonance overlap criterion (CROC), spectrum regarded as and hence quasi-linear theory employed to calculate corresponding electron diffusion coefficient; otherwise, contribution of each harmonic emission coefficient should calculated separately. From Van Allen Probe-A (RBSP-A) burst mode observations taken between January 2014 December 2017, total 21,766 MSW events were selected for statistical analysis, among which 314 (1.44%) are found not CROC. The satisfying CROC mainly distributed range L ∼ 4 6 outside plasmapause, they all have frequency gap (e.g., difference ≥2 fcH two bands).