Полярные геомагнитные возмущения и связанные с ними явления : материалы международного симпозиума «Полярные геомагнитные явления», 25-31 мая 1986 г., Суздаль / Междунар. геодез. и геофиз. союз, междунар. ассоциация геомагнетизма и аэрономии, АН СССР, КНЦ, ПГИ. – Апатиты : [б. и.], 1989.

a peculiar magneto-corpuscular eclipse limited b y the n o n r egular fields. The r e g i o n of this eclipse is mu c h larger than the optical one and does not coincide wi t h it at all. The effect of the m a g n e tocorpusoular eclipse (if such exists) could be observed more often than the optical one as it would influence the Earth w h e n the optical umbra did not re a c h it. The preliminary a n alysis of the so selected periods f o r all ne w Moons f r o m 1970 to 1980 showed that in a number of cases at comparatively quiet v alues of the solar w i n d on the zero day or o n the + first, second,... day moderate increase of geomagnetic £ K p-index are obtained during one day, w h i c h is i n no case a magnetic storm but e v e ntually c a n be a we a k influence of a lunar wake on the magnetosphere. Several cases of this kind are shown i n Fig.1 w i t h effects on the zero day - the day of the n e w M o o n (in February 1970 and in May 1970) an d on the first day a f t e r the n e w Mo o n (in December 1976). However, these oases are not isolated a n d have a c omparatively h i g h frequency. The analysis of 114 ne w M o o n periods (-4, +4 days) during the period 1970-1980 showed that there are 102 su ch days o f’ the Z K p - i n d e x increase. These weak increases of лЕКр»5-10 against the b a c kground of the compar a tively quiet (even abating i n time) course of the solar w i n d c a n be c aused by the disturbing effect of the m a g n e t o h ydrodynamical wake of the Moon a p p earing o n account of the process of flo w - a r o u n d the M o o n fr o m the solar w i n d with a superalfvenic velocity. The analysis of the periods (-1, +1 day) w h e n a m aximal effect can be expected of the lunar plasma wake on the S u n - M o o n -magnetosphere line showed I K , 30 n 20 10 DECEMBER 1976 FEBRUARY 1977 V km/s 500 -400 - 3 00 500 400 L 300 Pig. 1. Ex a m p l e s of geomagnetic in d e x increases by n e w Mo o n at quiet va l u e s of the v e locity of the solar wind. 102 such in c reases were observed out of 114 i n v e s tigated periods, i.e. 89 per cent of the cases. I--- 1--- 1--- 1--- 1--- 1--- 1--- 1--- 1 -4 -3 -2 И 0 1 2 3 4 103