Структура и динамика полярных токовых систем : материалы международного симпозиума «Полярные геомагнитные явления», 25-31 мая, Суздаль, СССР / Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т. – Апатиты : [б. и.], 1988.

(1982), Baker et al.(1983), Tsurutani et al.(1985), Maezawa and Murayama (1985) 9 ? Л ? using the functions В v, В v and fi =B vain e/2 1 . The common conclusion 3 s о ia that function £ provides the least agreement between the calculated and experimental activity indices. The use of the linear prediction filtering technique gives the same results (Iyemori et al.,1979i Clauer et al.,1981). 2 The findings on functions B gv and B 0v turned out to be ambiguous. According to Murayama (1982), Holzer and Slavin (1982), Maezawa and Murayama О (1985) the product B 0v gives the best results whereas Baker et al.(1983) and Tsurutani et al.(1985) did not find any distinction between the effects of p the functions B_v and В v . Maezawa and Murayama (1985) believe that the s s distinction may be lacked if both functions are in good correlation , for example when a solar wind velocity is almost constant. It may be noted that the middle-latitude indices of magnetic activity and of ring current give also quadratic dependence on velocity V gw (Maezawa and Murayama,1985). The beat correlation between auroral magnetic activity and solar wind parameters is observed for low level of activity (Clauer et al.,1981} Baker «t al.,1983). In all cases AL-index is predicted better than AU-index (Clauer et al.,1981). - One more clear evidence of velocity effect is presented by Sergeev et al. (1979) in his analysis of cases when the westward electrojet occurs above the Antarctic near-pole station Vostok at night time 20.00-02.00 MLT. The solar wind velocity proved to exceed 600 km/s in more than 90 % of such oases though the IMP characteristics such as absolute value |B| , changeability , and distribution of B z were the same as in cases of usual substonas. INFLUENCE OP THE IMP AZIMUTHAL COMPONENT ON THE MAGNETIC ACTIVITY. Effects of the azimuthal component turned out to be peculiar and ambiguous. They may change with season or level of activity and be different for various types of disturbance. Before analysis of these effects we shall examine the problem of interrelation between IMP В and В components. Usually B z and By components are taken as linear independent values. But it is true if the solar-ecliptic system of coordinates (SB) fixed to the sun is taken. However the situation will be quite different if we have solar- magnetosphere coordinate system (SM) usually used for the investigation of the solar wind-magnetosphere interaction. In this case the azimuthal component qtj» cjm By will give the contribution to the vertical component B z . The sign of this contribution, which is connected with the geomagnetic dipole inclination, is SM dependent on season; when By > 0 then S B 2 will be negative in spring and positive in autumn. It is a well known effect of Hussell-MoPherron (1973). Nevertheless this effect would have been levelled off in statistical treatment if the probability of occurence of fixed field В had been the same for differ- ent angles S where 9-is an angle between В and Z axis. However Kotikov et al.(1986b)have shown that a normal distribution for the interplanetary field in SE coordinate system is | 2 nT and|ByE j « 3 nT and as a result of it the Russell-McPherron effect will not vanish in averaging of a considerable body of data. This fact is the cause of an artificial interrelation between the IMP Bz and B y components (or more exactly the interrelation between B z and the sector structure. Pig.4 (from Kotikov et al.,1986b) shows the distrib ution of the IMP By and B z components in the solar-magnetosphere coordinate system: in summer and winter seasons these components are distributed symmet rically relative to Y and Z axes, while the ocourence of the southward B 311 component is most likely when B^M ^ 0 in spring and when B S M > 0 in autumn. J у 118