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Geomagnetic micropulsations with periods from 0.03 to 10 seconds in the auroral zones with special reference to conjugate-point studies

1963; American Geophysical Union; Volume: 68; Issue: 11 Linguagem: Inglês

10.1029/jz068i011p03383

2156-2202

K. Yanagihara,

Geomagnetism and Paleomagnetism Studies

Journal of Geophysical Research (1896-1977)Volume 68, Issue 11 p. 3383-3397 Geomagnetic micropulsations with periods from 0.03 to 10 seconds in the auroral zones with special reference to conjugate-point studies K. Yanagihara, K. YanagiharaSearch for more papers by this author K. Yanagihara, K. YanagiharaSearch for more papers by this author First published: 1 June 1963 https://doi.org/10.1029/JZ068i011p03383Citations: 33AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract Conspicuous micropulsations in the auroral zones with periods from 0.03 to 10 seconds have been 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: (1) Burstlike micropulsations, with quite a wide range of frequencies, which appear at the onset of a polar storm or bay (noise burst). (2) Pearl, beating-type micropulsations, occurring intermittently so that they form separate bunches (PP). (3) Continuous micropulsations, typically found in the forenoon, with periods from 0.3 to 3 seconds (CPsp). (4) 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 the 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. References Axford, W. J., C. O. Hines, A unifying theory of high-latitude geophysical phenomena and geomagnetic storms, Can. J. Phys., 39, 1433–1464, 1961. Balser, M., C. A. 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