Van Allen Probes EMFISIS Waves
Chorus from 2012-11-28

This phenomenon is called chorus and is similar to other examples obtained by the Van Allen Probes. However, during this time the Van Allen Probe B spacecraft is about 16 degrees south of Earth's magnetic equator, hence, the chorus has propagated quite some distance from its source at the equator. These chorus elements are at a relatively low frequency, partly because of the high latitude of the spacecraft. Also, the elements have longer durations and do not drift in frequency as rapidly as they typically do. This may be due to the long distance from their source. Chorus is thought to interact with energetic electrons in the outer Van Allen radiation belts in complex ways. The Van Allen Probes mission is designed to bring a better understanding of how these wave accelerate the electrons.

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