The electromagnetic dawn chorus is a phenomenon that occurs most often at or shortly after dawn local time. It is believed to be generated by a Doppler-shifted cyclotron interaction between anisotropic distributions of energetic (> 40 keV) electrons and ambient background VLF noise.[jargon] These energetic electrons are generally injected into the inner magnetosphere at the onset of the substorm expansion phase.[1][2] Dawn choruses occur more frequently during magnetic storms.
This phenomenon also occurs during aurorae, when it is termed an auroral chorus.
With the proper radio equipment, dawn chorus can be converted to sounds that resemble, coincidentally, birds' dawn chorus.
See also[edit]
- Auroral chorus
- Dawn chorus (birds)
- Hiss (electromagnetic)
- Whistler (radio)
- "Cluster One," a Pink Floyd track using sferics and dawn chorus as an overture
Notes[edit]
- ^ Nunn, D.; Omura, Y.; Matsumoto, H.; Nagano, I.; Yagitani, S. (1997). "The numerical simulation of VLF chorus and discrete emissions observed on the Geotail satellite using a Vlasov code" (PDF). J. Geophys. Res. 102 (A12): 27083–27098. Bibcode:1997JGR...10227083N. doi:10.1029/97JA02518.
- ^ Trakhtengerts, V. Y. (1999). "A generation mechanism for chorus emission". Ann. Geophys. 17 (1): 95–100. Bibcode:1999AnGeo..17...95T. doi:10.1007/s00585-999-0095-4.
Further reading[edit]
- Robert A. Helliwell (2006) [1965]. Whistlers and Related Ionospheric Phenomena. Dover Publications, Inc. ISBN 0-486-44572-0.
- Romero, R. (2008). Radio Nature. Potters Bar: Radio Society of Great Britain. pp. 39–40. ISBN 978-1-905086-38-2.
External links[edit]
- Stephen P. McGreevy's ground-based ELF-VLF recordings at the Library of Congress Web Archives (archived 2002-09-13)
- Natural VLF Radio - Sounds of Space Weather
- Space-Weather Sounds - the Mysterious and Beautiful Natural Radio Phenomena of Earth at the Wayback Machine (archived August 22, 2014)
- 2018 recording by NASA RBSP (Radiation Belt Storm Probe)
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