Электродинамические процессы в высоких широтах: материалы междунарордного симпозиума «Полярные геомагнитные явления», 25-31 мая 1986 г., Суздаль, СССР / Междунар. геодез. и геофиз. союз, Междунар. ассоц. геомагнетизма и аэрономии ; Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т ; [редкол.: О. М. Распопов (отв. ред.). и др.]. - Апатиты : Кольский филиал АН СССР, 1988.

(2) A transition region where the auroral motion changes direction is located b etween the daytime and nighttime auroras. The arcs of dusktime-type (dominated by the green line and equatorward motion) and daytime type (domin ated by red line and poleward motion) can be observed simultaneously at duak hours during magnetic disturbances (Vorobjev et a l . ,1981j Rezhenov et al., 1979). The same situation, though less pronounced, is observed also at dawn hours (see F i g . 13)« D u r i n g quiet magnetic conditions, discontinuities may occur at prenooa and afternoon hours (Feldstein and St a r k o v , 1967). (3) The I M P effect is that the variations at the front point give rise to synchronous motions of the oval Wi t h a minor delay ( ~ 10-20 min). The positive and negative B z values give rise to poleward and equatorward motions,'respectively. Su c h variations are especially distinct wh e n magneto- spheric disturbances are absent or at a relatively constant level (see Pig. 2a, За, 4& і 6a, and 10). (4) The effect of substorm-associated magnetic activity is an equator ward shift of the entire luminosity band w i t h increasing magnetic disturb ances. Therefore, the rapid IMF-dependent variations of the position of the auroral oval occur at different latitudes corresponding to different activity levels (see F i g . 14)• (5) The pattern of substorm-time dayside auroral dynamics needs further study. In individual oases, no explicit features were found In the daytime a urora dynamios during the active phase, contrary to the nighttime pattern (Akasofu,1977). According to V orobjev et al.(1976), however, the luminosity on the dayside exhibits three peaks during a substorm. The first peak arises at the beginning of the substorm growth phase and the second peak appears at the very onset of the breakup phase (TQ ). The third, and the m a i n peak is delayed by 30-50 m i n relative to T Q . ACKNOWLEDGMENT. It is a great pleasure to thank R.C.Elphic (the Univer sity of California) and R.Rijnbeek (Imperial College, London) for providing IMF data from, respectively, the satellites ISEE-2 (principal investigators C.T.Russell) an d AMPTB-UKS (p.i.s D . S o u t h w o o d ) . Magnetograms from N y Alesund and Bjornoya were provided by S.Berger (the University of Tromso). Magnetic recordings from Hornsund, obtained from the Po l i s h A cademy of Sciences, Warszawa, Poland (A.W.Wernik) are also gratefully acknowledged. Magnetograms from College and Churchill are obtained from W D C - B 2 , Moscow. I42