Geomagnetic micropulsations with periods from 0.03 to 10 seconds in the auroral zones with special reference to conjugate-point studies
Conspicuous micropulsations in the auroral zones with periods from 0.03 to 10 seconds are studied using data obtained by the Pacific Naval Laboratory and Stanford University during January 1961. For periods less than 0.3 second bursts of oscillations frequently occur superimposed on the background level of ELF noise. These bursts are considered to be of extra-atmospheric origin because of their conjugate relationships. For periods between 0.3 and 10 seconds four typical classes are defined: burstlike micropulsations, with quite a wide range of frequencies, which appear at the onset of a polar storm or bay (noise burst); pearl, beating-type micropulsations, occurring intermittently so that they form separate bunches (PP); continuous micropulsations, typically found in the forenoon, with periods from 0.3 to 3 seconds (CPsp); and continuous micropulsations, typically found in the afternoon, with periods from 3 to 10 seconds (CPlp). Not every polar storm or bay is accompanied by noise bursts. Noise bursts are found only at the onset of polar storms or bays occurring around or before local midnight. Separate bunches of pearl, beating-type micropulsations are attributed to a bouncing agent whose bouncing period of a few minutes can be determined from ine time lag of their occurrences in conjugate areas. If the agent repeatedly excites micropulsations, they are continuous, although sometimes a correlation analysis between conjugate points indicates a bouncing period similar to that of PP. Possible physical mechanisms are suggested for these four classes of micropulsations. (auth)
- Research Organization:
- Univ. of British Columbia, Vancouver
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-025443
- OSTI ID:
- 4697167
- Journal Information:
- Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: 11 Vol. 68; ISSN 0148-0227
- Publisher:
- American Geophysical Union
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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