Fig. 5

Van Allen Probe B/EMFISIS observations of (a, b) the dynamic power spectra of wave amplitudes in the directions perpendicular and parallel to the local magnetic field, c wave normal angle with respect to the magnetic field, and d wave ellipticity, from 02:00 UT to 09:30 UT on 12 September 2017. Positive (negative) values of the wave ellipticity indicate right-handed (left-handed) polarization. Values of the wave normal angle and the ellipticity are shown only when degree of polarization is greater than or equal to 0.8. Magenta lines indicate local cyclotron frequencies of H⁺, He⁺, and O⁺ ions. e–h Same as in a–d but for the Arase/MGF observations during 03:00–11:00 UT on 12 September 2017