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.

а B,.nT 04,30 0300 05,30 ЦТ b Ф 78 -2- • 78 бХ/іТ Ов’зо 0900 0930 10Т00 UT б Х .п Т 05^0 Об'ОО '’Об'ЗО ЦТ -50 -50 Figure 10. The IMF В component variations inferred from the ISEE-3 data (curve 1); the dayaiae aurora position inferred from the Heisa Island observation data (curve 2) a 4-hour UT-to-MLT correction); the variations of the magnetic field northward component i n the midnight sector of the auroral zone at Churchill on December 8, 1978 (a) and December 31>1981 (b). aitivity. In such cases the equatorward boundary was found using the linear approximation shown by the dashed line. The position of auroras was compared wi t h the IMF B z-component va r i a tions considering the time delay which allows for the solar wind plasma pro pagation from the ISEE-3 position to the Earth's orbit. The correlation ana lysis for individual simultaneouo data of IMF-detection on board ISEE-1 and 3 has shown that the m aximum correlation coefficient corresponds to the time delay onfarred from the value of solar wind velocity, ДХ/Ѵ„ „ (Baker в • w • et al.,1983). The aolar wind velocity data have b e e n taken from Couzens and King (1986). The delay calculated in such a manner w a s allowed for by a shift of the time scale of the B„ variation with respect to the ground-based data (here and in the subsequent figure). The comparison between curves 1 and 2 in F i g . 10 (a) indicates that the variations in B a and in the aurora position are alike (the correlation coef ficient r=0,74). The December 13. 1979 ca s e . Figure 10 (b) shows the IMF B z-component variations, the aurora position during the 0500-0700 UT interval inferred from the Heiss Island ascafilm data, and the deviation of the geomagnetic field northward component intensity from the quiet level at Churchill. During the examined interval the IMF B^-component was negative and varied fr o m -1,2 nT to -3.5 nT. The aurorae were individual rays flaming in various nectors of the aky. The dashed line connecting the points of the southernmost auroras shows the poaition of the equatorward boundary. The nightside magnetic field was weakly disturbed during the examined period, a n d the magnetic bays typical of substorms we r e not observed in the auroral zone. The geomagnetic field northward component deviated by about -70 nT from the quiet level at Churchill. From the figure it is seen that the relationship between the B z inten sity variation and the aurora poaition ( a 0.6 correlation coefficient) was closer than between the aurora poaition and the magnetic activity level. The December 31. 1980 c a s e . The IMF B z-component (Fig.11 a) showed an abrupt fall from +8 nT to -10 nT of about 1,5-hour duration, whereupon the В -component got positive again and remained at the +8 nT level until 1000 2» UT. The auroras plotted using the Barentisburg ascafilras show variations of their equatorward boundary wh i c h were synchronous with B z and amounted to I35