Sub-audible Geomagnetic Fluctuations

Duffus, H. J.; Nasmyth, P. W.; Shand, J. A.; Wright, Charles

doi:10.1038/1811258a0

Cited by 25 publications

(7 citation statements)

References 3 publications

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“…2.7), (3) similar mixing tendency of Pc3 with Pc4 (cf. Another type, ELF whistlers, exhibit either rising, falling or fluctuating tones from about 2 Hz to probably a few tens of Hz (Duffus, Nasmyth et al, 1958;Yamashita, 1967;Glangeaud, 1967;Yanagihara and Shimizu, 1969). Section 6), and so on.…”

Section: Resultsmentioning

confidence: 99%

Geomagnetic pulsations

1969

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Section: Resultsmentioning

confidence: 99%

Geomagnetic pulsations

1969

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“…The existence of distinctive quasi-sinusoidal low-amplitude oscillations of the earths magnetic field in a limited frequency interval around 1 cps has been recognized for some time (Troitskaya, 1957;Duffus et al 1958;Benioff, 1960), but until very recently practically nothing was known about their origin. However, in the past few years advances in experimental technique have revealed enough new properties of these signals, called "pearls" by Troitskaya and hydromagnetic (hm) emissions by , to enable the construction of quantitative models of their generation and propagatio propagation.…”

Section: Introductionmentioning

confidence: 99%

Recent Investigations of Hydromagnetic Emissions Part II. Theoretical Interpretation

Wentworth¹

1966

J. geomagn. geoelec

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Recent experimental and theoretical work suggests the hypothesis that hydromagnetic (hm) emissions are hydromagnetic wave packets guided by field lines as they bounce back and forth between hemispheres of the earth. As such they are analogous to whistlers, and one test of the hypothesis is the quantitative calculation of plasma densities in the outer magnetosphere and their comparison with whistler densities closer to the earth.Many hm emission exhibit measurable dispersion when displayed in the form of sonagrams (frequency vs time displays). In such cases, the measurement of group bounce times at two different emission frequencies can be combined with an accurate model of the magnetosphere to determine the zero-frequency (Alfven) bounce period and the equatorial cyclotron frequency above which the wave cannot propagate. These two quantities uniquely define the field line along which the hm emission propagated and the integrated plasma density along that field line.Analysis of 9 events showed they occurred on field lines crossing the equatorial plane between 4 and 10 earth radii, and showed equatorial plasma densities in agreement with extrapolated whistler "knee" densities.

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“…micropulsations [Duffus et al, 1958;Tepley, 1961;Gendrin and Stefant, 1962a, b;Wentworth, 1962, 1963;Campbell, 1963;Pope, 1964a; ..... i,..,.... Amundsen, 1964]. Its great advantage is to give a striking picture of the frequency-time str~cture of the emISSIOns.…”

Section: The Sonagraph Has Often Been Used To Analyzementioning

confidence: 99%

Preliminary results of a micropulsation experiment at conjugate points

Gendrin¹,

Troitskaya²

1965

J. RES. NATL. BUR. STAN. SECT. D. RAD. SCI.

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(Rece iv ed Fe bru ar y 3, 1965)This pape r s umm a ri zes th e preliminary res ults ob tai ne d b y diffe re nt sc ie nti s ts workin g a t th e tw o In s titutes on a co mm o n program co nce rn e d ma inl y with mi cropu lsati on s tudies be tw ee n tw o conju ga te a reas a t a geo ma gne ti c la ti tud e of 57°. Morphological studi es and di gital co mputations of corre la tio n fun c ti o ns are made on th e ba s is of the c hart reco rd s obtai ne d at the two st atio ns . Th e s ig nal be in g reco rded ind e pe nd e nt ly on mag ne ti c tape, s pec tral a na lyses a re a vailab le a lso. The principal co nclu s ions a re the fo ll ow in g:Pc 1 e ve nt s occ ur s imult a neous ly at th e two stat ions, th e amplitud e be ing s tro nger in th e north e rn he mi s phe re for the pe r iod s tud ied (J an uary a nd Fe bruar y 1964). Th e fre qu e nc ies of the osc illati ons, and more gen e ra ll y the spectral sha pe of the s ig na l as a fun c ti on of tim e , a re ve r y s imilar a t th e two st a tions. The tra in s of osc ill atio ns a re tim e-s hift ed be twee n the tw o he mi s pheres by a pproxim a te ly hal f the re pe titi on pe riod , confirmin g so me oth e r expe rim e ntal res ult s a nd ex cludin g so me t heo ri es. The co rre lati on fun c tion me thod see ms to be ab le to giv e more de ta il s a bout the spati a l a nd tim e re lations be tw ee n phe nomena in two co njugat e areas .So me results co nce rning the po lariza tion a t a s in gle s tati on and the p hase re lat ions be t wee n diffe re nt points are a lso giv e n.

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Sub-audible Geomagnetic Fluctuations

Cited by 25 publications

References 3 publications

Geomagnetic pulsations

Geomagnetic pulsations

Recent Investigations of Hydromagnetic Emissions Part II. Theoretical Interpretation

Preliminary results of a micropulsation experiment at conjugate points

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