Van Allen Probes EMFISIS Waves
Whistlers from 2013-06-13 00:25

The Van Allen Probes EMFISIS Waves instruments detected these signals with three orthogonal magnetic antennas (Bu, Bv, Bw) during UTC hour 00 of June 13, 2013. This is another nice collection of whistlers which originate with lightning discharges on Earth. The broad-band signal propagates along magnetic field lines through the thin ionized gasses of space which allow the higher frequencies to travel faster than the lower frequencies. This results in a frequency dispersion and the characteristic high-to-low whistling tone, reminiscent of science fiction sound effects (just in time for summer movies).

The animation shows a frequency-time spectrogram of the data with a moving cursor that indicates the time position of the audio track.