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.

ХП-I r / r Ш j U -ЗШ и - m X - . в H i : го j L Pig. 4. Distribution of the IMP in the aolar-magnetosphere coordinate The appropriate relationship is also valid for the IMP B^M and B^M compon ents. That peculiarity is naturally reflected in geophysical effects. The diagramms in Pig.5 represent the frequency of magnetic disturbance occurence depending of the IMP orien tation in the solar-magnetosphere coordinate system (Kotikov et al., 1986b). This analysis was carried out on the basis of hourly values of the IMP parameters and AU, AL indices for 1966-1979. There are examined only magnetlo disturbances with AE > 150 nT with thair division on the following ranks: a) prevalence of the eastward electro jet, AU - | A L | ^ 25 nTj b) equivalence of the eastward and westward eleotrojets, -25 «|AL| - AU.£ 25 nT! c) prevalence of the westward electro- jet, 2 5 < |AL| - AU < 100 nT; d) dominance of the westward electro jet, 100 nT S |AL| - AU. The disturbances with the prevalence of the eastward electrojet (mode "a") were studied by Kotikov et al.(1986a) who marked their relation to the IMP By component. The mode "b" is identical with D P ^^ disturbances of .. .1. (1974) (Pig.6) or DPg disturbances in classification of Bauajohann (1983) and corresponds to the convection bays (Sergeev, 1977; Pytte et el. ,1978). The mode "d" is identical with D P ^ or DP1 disturbances (Troshichev et al.,1974; Baumjohann,1983) and corresponds to the explosive phase of aubstorms. The mode "o'1 is intermediate between "b" and "d" modes and corresponds to the most typical geophysical situations. The diagramms in Pig.5 show the following peculiarities: 1) Wh e n В < 0 the evident seasonal changes are seen in distribution of z the magnetic disturbance occurence frequency: in case of summer and winter seasons the picture, is more or less symmetrical, but in spring the disturbances occur aost commonly under B y< 0 and in autumn under By 7 0. Similar results were obtained earlier by Saito (1972), Burch (1973), Mishin et al.(1973), Murayama end Hakamada (1975), Murayama et al.(1980), Danilov (1981),Metlyaev et al.(1982). Their studies show that the magnetic activity is higher in negative sector (B < 0 ) for a period from March to June and in the positive sector (B > 0) for the second half of the year. The comparison of Figure 4 and 5 makes it obvious that such seasonal dependence is artificial. It is conditioned by the R u s s e l l -McPherron mechanism but not related to geophysical effecte of В oomponent itself. Prom here the well known results on the high efficiency of the sector border (+, -) in spring and the border (-, +) in II9