Physics of auroral phenomena : proceedings of the 34th Annual seminar, Apatity, 01 - 04 March, 2011 / [ed.: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 231 с. : ил.

О.M. Barkhatova etal. Fig. 1. Example spectrum 3. Ionospheric disturbances relationship with the Solar-geomagnetic activity CCF comparing with F10.7 and Kp*10 indices which characterize the level of Solar and geomagnetic activity in the given month shows that most cases have characteristic jumps of CCF variations with increasing index Kp*10. This suggests a connection between these variations and geomagnetic disturbances. It was also found markedly increasing of CCF variations amplitude during Solar maximum indicating a significant effect of Solar radiation on the variation. Fig. 2 shows examples of CCF amplitude increasing with extension of index Kp*10 values for the February 1975 and April 1982. Arrows indicate jumps in CCF variations and corresponding jumps in the index Kp*10. February, 1975 April, 1982 N 5 X s 0 LL О о -5 100 о т - Q . 50 X. 0 N 250 X 200 cn " E 150 1 100 50 * 4 1 1-- feb1 - i ; ....... - l - - i _ i__ : * + J----------- 1-------Z_J-----------L. N b x S. 0 LL О o 5 100 о.* 50 j \i ---- L i i I *j Г-»Н --------i----------i i ____ L-. ...... I i t j j Г 4 r ' f u V r 4 : ! ------ -1------- 100 200 300 400 500 600 700 Time’ h Time, h Fig. 2. Examples of CCF increasing amplitude with increasing values of index Kp*10 for the February 1975 and April 1982; arrows marks jumps in CCF variations and corresponding jumps in the index Kp*10. Thus, the study of CCF variations can give an overall picture of ionospheric state depending on the level of Solar activity and global geomagnetic disturbances. According to the results ionospheric state is directly characterized by the CCF deviation amplitudes from the zero average. However such variations using is difficult to analyze because they have short periods and very noisy background values. 4. Classification of ionospheric disturbances and ionospheric activity index IAI To characterize the ionospheric disturbances related to the direct influence of Solar and geomagnetic activity the ionospheric activity index (IAI) based on CCF variations is developed. In the first stage of index development were studied CCF deviations above average in the minimum and maximum Solar activity years taking into account the values of Dst index. It allows us to identify the main classes of ionospheric disturbances. January, 1975 2 10 a 10 E < -2 10 10 " 1 0 " 10 10 10 Frequency, Hz of "cleared" critical frequencies for the Moscow station in January 1975 126