Auroral chorus

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An auroral chorus is a series of electromagnetic waves at frequencies which resemble chirps, whistles, and quasi-musical sounds in predominantly rising tones when played as pressure waves (sound), which are created by geomagnetic storms also responsible for the auroras. The electromagnetic waves are a type of Natural radio waves, vibrations of electric and magnetic energy occurring at the same frequency as sound.

Experiencing/Detecting[edit]

Auroral chorus can be detected primarily around the magnetic equator, specifically in two distinct frequency bands, one above the equatorial half gyro-frequency and one below it. The gyro-frequency ranges from 0.6 kHz to about 1.6 kHz. Distinguishable on high resolution wideband spectrographs, the wave amplitude grows linearly then switches to non-linear. Demonstrating a peak distribution near dawn, the auroral chorus is most detectable via ELF/VLF Radio receivers in the middle latitude around 30-60 degrees N. The most numerous recordings of the auroral chorus has been by the Iowa Plasma Wave Group. [1] They have released many audio interpretations of chorus recordings online along with spectrograph measurements.


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