Авроральные явления - 71 : материалы наблюдений Полярного геофизического института 1971 г. : [сборник] / Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т ; [редкол.: Б. Е. Брюнелли (отв. ред.) и др.]. - Апатиты : Кольский филиал АН СССР, 1975.

5 27 clay reccurence tendency. There exist three reccurence sequences of disturbed periods. These sequences began on 3-5.I, 18-21.1 and 27-29.1. Prom the calendar and Big.2 one can notice two equinox maxima . The spring maximum is higher than the autumn one. On the whole the activity in 1971 was some lower than in 1970 but still higher as compared with those for previous 9 years. The seasonal variation of pro bability of occurence of aurora has minimum in December (Fig.4). In general the seasonal course of aurora is like that of magnetic activity. The same is for the diurnal courses of aurora and magnetic activity - the main peculiarity of the both is the maximum near local midnight (Fig.3,Fig.5). It is interesting but difficult to understand that there no obvious correlation between the activity of aurora and mean К values. To describe the general behaviuor of activity during 1971 we take into account the next geophysical phenomeha and connections : 1. The behaviour of H component at Loparskaya (Pig.7) that is s usual or unusual appearance of negative and positi ve disturbances, the shape of more prominent bays , the appearance of significant pulsations, the activity interval and ite connection to those according the world wide data and etc. 2. The behaviour of the riometer absorption at Loparskaya that iss the appearance of the different types of the anomalous absorption: SCNA - sudden cosmic noise absorption, SCA - sudden commencement absorption, PCA - polar cap ab sorption and AA - auroral absorption. As the more typical anomalous absorption was the auroral one and we also describe the different types of auroral absorption: F- subtype - short burst of absorption near the local midnight, S-subtype - the slow increasing and decreasing absorption in the morning hours, P-absorption - the morning (as a rule) 5-10 min pulsations. These pulsations usually are laid on the S-bays of absorption. We also considered the connection of magnetic and absorption disturbances. 3. The behaviour of the local activity in Cola Peninsula region we tried to compare with the behaviour of variation of geomagnetic field that is to take into consi deration the different development the initial (DCF) and the main (DR) phases of the world-wide storms. Below we describe some prominent storms using the above-nentioned parameters. The great world-wide magnetic storm begin at 1243 (SC) April 14. The initial (DCF) and the main (DE) phases are rather well-developed. At the moment SC the rio meter shows SCA absorption. SC impulse is clear seen on record of H component. The appearance of SCA is not surprising because of the storm developes at the recovery phase of the previous world-wide storm. On the Loparskaya d a t a one can see t h a t during the following days there appears the shorting of the disturbed period and on the 19tJl of April we can observe only the single negative magnetic bay. As the activity increases the moment of passage of positive H variations to negative ones shifts to the earlier hours (14, 15 and 16 ^ 0f April). On the 1 5 ^ of April riometer shows the significant absorption pulsations whose amplitudes were up to 1.5 dB at 05 14 on the 2 0 ^ of April the stations at lower latitudes show SID and SCNA. Our rio meter also shows SCNA at the SC moment. The next SC world-wide storm considered began at 23 03 on 30^ of August( the maximum of amplitude of the initial phase occured after 24 00 so it is possible that the absorption at 01 15- 01 20 on 31st of August is SCNA one. The value of absorption is 1.2 dB. But we also can not exclude that the case of absorption discussed is the auroral absorption because of the appearance of the rather иеѵеіорьіі magnetic bay near 01 00. Tie main phase of the storm coar.inued up to evening of the 4th of September. At Cola region the ground appearance of the storm ended to the 2a<^ of September, that is earlier than the main phase of the storm end.