Physics of auroral phenomena : proceedings of the 37th Annual seminar, Apatity, 25 - 28 February, 2014 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Изд-во Кольского научного центра РАН, 2014. - 125 с. : ил., табл.

Geomagnetic activity o f magnetic clouds considering season o fyear sources of geomagnetic storms in 80% of cases in the period’s solstice and 100% o f the equinoxes was become. The study that the geomagnetic activity during the equinoxes increases due to the different orientation of the clouds and clouds especially with small values of axis cloud inclination to ecliptic plane are shows. These clouds most often near the Earth due to the particular conditions of their Solar sources (input and output (tail) spots), mostly parallel to the equator of the Solar disk is recorded [Bothmer and Schwenn, 1998; Vitinsky, 1983]. 4. Testing the hypothesis by comparing geomagnetic effectiveness o f magnetic clouds similar orientation According to the proposed hypothesis of magnetic clouds with a similar orientation and magnetic field magnitude must be different geomagnetic effectiveness in different seasons are recognized. To verify this assertion a pair of magnetic clouds similar orientation and with similar values interplanetary magnetic field Bz component, recorded in different seasons of the year (Table 1), were considered. As a measure of the intensity o f the geomagnetic activity Dst- index examined. A comparison o f Dst-index corresponding to the considered pairs of magnetic clouds with small values of the axis inclination angle to the ecliptic plane with a similar orientation and similar values geoeffectiveness Bz component o f the interplanetary magnetic field has shown that in equinox times its value to 1.4-2.7 times higher . Consequently, the magnetic clouds with small values of the axis inclination angle to the ecliptic plane are more geoeffective structures around the equinoxes. 5. Conclusions Seasonal variation of geomagnetic activity, depending on the magnetic cloud orientation of Solar wind have investigated. It is shown that changes in the level of geomagnetic activity during the year the presence o f a magnetic cloud particular orientation in space, unlike other plasma flows is manifested. In solstice periods magnetic clouds with small angles to the axis of ecliptic plane to the geomagnetic activity due to reduced projections of their axial magnetic field on the Earth's magnetic dipole does not contribute. In equinox periods contribution to geomagnetic activity magnetic clouds give any orientation. Analysis of the latitude solar sources distribution of geoeffective magnetic clouds, registered in the vicinity of the Earth, the presence of a shift in the zone of active regions (royal latitudes) during equinox and symmetrical distribution during solstice periods was revealed. The resulting latitude distribution an increase in geomagnetic activity during the equinoxes as a result increases the probability of Earth's magnetosphere meeting with magnetic clouds are manifested. Comparison of geomagnetic activity pairs of magnetic clouds with small values of the axis inclination angle to the ecliptic plane with similar orientations and close values of geoeffectiveness Bz component of IMF are shows that in equinox times intensity of the generated magnetic storms above. Thus, studies that in equinox periods geomagnetic activity increases due to magnetic clouds with axial magnetic fields oriented along the ecliptic plane was show. Clouds with such an orientation in the near-Earth due to the particular conditions of their Solar sources in the form as master and slave systems o f sunspots most often recorded. In solstice periods such clouds are not geoeffective due to decrease the value of the projection of the axis magnetic field of clouds on the Earth's magnetic dipole in these intervals. This in the reduction of geomagnetic activity in the summer and winter is reflected. Acknowledgements. RFBR grant 12-05-00425 and the program of the Ministry o f Education and Science «Development of Scientific Potential of Higher Education, 2014-2016» supported this work. References Vitinsky Y. Solar activity. - Moscow: Nauka, Main Editorial physical and mathematical literature, 1983. -192 p. Cortie A.L. Sunspots and terrestrial magnetic phenomena, 1898-1911: the cause of the annual variation in magnetic disturbances / /Monthly Notices of the Royal Astronomical Society. 1912. V.73. P.52. Chapman, S., and J. Bartels // Geomagnetism, chap. 11. Oxford University Press. New York. 1940. Boiler, B. R., and H. L. Stolov. Kelvin-Helmholtz instability and the semiannual variation of geomagnetic activity // J Geonhvs Res. 1970. V.75. P. 6073-7084. 3 ' v 3 ' Bothmer V., Schwenn R. The structure and origin of magnetic clouds in the solar wind // Ann. Geophysicae. 1998. V. 16. P. 1-24. Russell C.T., McPherron R.L. Semiannual variation of geomagnetic activity // J. Geophys. Res. 1973. V.78. P.24. Table 1 01.07.96 17.02.97 30.09.01 01.11.01 14.01.07 29.10.09 Angle 8,° -8 -7 8 8 -4 -1 Bz, nT -7,8 -7,7 -10 -10 -6 -5 Dst, nT -20 -54 -148 -106 -18 -40 80