Preliminary results of a micropulsation experiment at conjugate points

Abstract

(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.

Satellite observations of Pc 1 pearl waves: The changing paradigm

“…This status was mainly based, aside of the erroneous analogy with VFL whistlers, on one claimed piece of evidence: the early observation that the Pc 1 wave packets in conjugate locations at the opposite ends of a field line are seen alternately (Yanagihara, 1963;Gendrin and Troitskaya, 1965;Obayashi, 1965). Admittedly, such an anti-phasing would be naturally explained by the BWP model.…”

Recent progress in understanding Pc1 pearl formation

“…This picture was considered consistent with characteristic period of Pc1 pulses as detected by ground-based stations. Moreover, it was reported that the wave-intensity envelopes at conjugate ground-based sites were approximately in ''antiphase'' (e.g., Gendrin and Troitskaya, 1965;Obayashi, 1965;Saito, 1969). This fact implied the existence of only one wave packet in the absence of its symmetric counterpart.…”

“…One of classical examples of pearl emissions detected at conjugate locations on the ground (afterGendrin and Troitskaya, 1965).…”

New constraints on theories of Pc1 pearl formation

“…Later, during the second phase of Pc1 studies, it was reported that the individual wave packets constituting a pearl necklace are seen alternately in the two opposite hemispheres [ Yanagihara, 1963;Gendrin and Troitskaya, 1965]. This soon led to the suggestion [Obayashi, 1965] However, several other theories of pearl for•nation have been proposed.…”