Global Distribution of Discrete and Continuous Spectrum Equatorial Magnetosonic Waves Observed by the Van Allen Probe‐A

Abstract

AbstractMagnetosonic (MS) waves can either be discrete or continuous in the time‐frequency spectrogram. Through the observation from Van Allen Probe‐A spacecraft, the global distribution of discrete and continuous spectrum MS waves in the region L ∼ 3–6 is determined. According to our research, the continuous spectrum MS waves are greater in amplitude than discrete spectrum MS waves. Also, the impact of changes in geomagnetic activity on continuous spectrum MS waves is much more significant than discrete spectrum MS waves. Besides, it is also demonstrated that the strong discrete spectrum MS waves have a peak wave amplitude of ∼60 pT and an occurrence rate of ∼50% at the noon sector outside the plasmapause. In comparison, the strong continuous spectrum MS waves have a peak wave amplitude of ∼300 pT and an occurrence rate of ∼60% at the postnoon sector inside the plasmapause.