Fig. 2

Examples of high-resolution spectrograms of lower-band chorus / exohiss. Panels a–f show the trace of the power spectral density matrix of the three magnetic field components as a function of frequency and time, obtained from 6 seconds long continuous burst mode intervals of the EMFISIS Waves instrument on Van Allen Probe A, for events marked 2a–f in Fig. 1. Spacecraft position and locally measured electron cyclotron frequency \({f}_{{ce}}\) are given on the top of each panel. Overplotted dashed and solid lines show the frequency interval of lower-band exohiss/chorus between 0.1 and 0.5 \({f}_{{ce}0}\), where the equatorial electron cyclotron frequency \({f}_{{ce}0}\) is estimated using Eq. 2. The waveforms, from which panels a–f have been obtained were transformed into stereo wave files (stored on https://doi.org/10.6084/m9.figshare.29433323.v1) using two magnetic field components perpendicular to the local magnetic field line.