Physics of auroral phenomena : proceedings of the 39th annual seminar, Apatity, 29 February-4 March, 2016 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2016. - 167 с. : ил., табл.

Comparison of llie "expanded" and “polar" substorms behavior during the 23 and 24 solar cycles In the Table 1, there are presented also the averaged values of the PC-index before the onsets o f the “polar” and “expanded” substorms for these considered year periods. It is seen that: 1) The PC-index values are about 2.6- 3 times lower for the “polar” substorms than for “expanded” substorms. 2) For all substorms, the PC-index values were 1.3 times lower during the solar cycle minima than solar cycles maxima. 3) For all substorms, the PC-index values were lower during the 24-th solar cycle than the 23th solar cycle. We considered also some solar wind parameters before the substorm onsets. Namely, we calculated the 1.5 hour averaged components of IMF, Ey component of the interplanetary electric field, temperature, density and dynamic pressure. It is shown that there are no significant differences in the distributions of the solar wind parameters before the substorm onsets observed during the different periods of solar activity (the picture not presented here). Summary 1. The summer minima and autumns and spring maxima of the substorm occurrence were observed during both cycles. But the substorm number is higher in the 23th solar cycle than in the 24lh solar cycle. 2. The seasonal variations of the “polar” substorms behavior was mainly opposite to the “expanded” substorms behavior. 3. The PC-index values are about 2.6- 3 times lower for the “polar” substorms than for “expanded” ones. 4. The PC-index values for substorms observed during the 24-th solar cycle are lower than for substorms during the 23-th solar cycle 5. The PC-index values for substorms during solar cycle minima (1995-1996 and 2008-2009) are ~ 1.3 times lower than for substorms during the solar cycle maxima (1999-2000 and 2012-2013). 6. There were no significant differences of the solar wind parameters before the substorms in the different solar cycle periods. Conclusions The comparative analysis of the space weather conditions for “expanded” and “polar” substorm observed at almost identical high geomagnetic latitudes during 23 and 24 solar cycles demonstrated that in both cycles, they appear under different solar wind conditions and IMF parameters. The “polar” substorms behavior was opposite to the “expanded” substorms behavior, so we can suppose that they reflect different sources. But this question is open yet. A ckn ow led gm en ts. This study was supported by Program No 7 of the Presidium of RAS. The study is part o f a joint Russian - Bulgarian Project “The influence of solar activity and solar wind streams on the magnetospheric disturbances, particle precipitations and auroral emissions” of PGI RAS and IKIT-BAS under the Fundamental Space Research Program between RAS and BAS. We are grateful to J. N. King and N. Papitashvili at AdnetSystems, NASA GSFC and CDAweb for providing the OMNI data. References 1. Feldstein Y.L. G.V. Starkov (1967), Dynamics of auroral belt and geomagnetic disturbances. Planet. Space Sci 15 209- 229. 2. Akasofu S-I, P.D. Perreault, F. Yasuhara, C.-I. Meng (1973). Auroral substorms and the interplanetary magnetic field. J Geophys Res. 78, 7490-7508. 3. Lui ATY, C.D. Anger, S.-I. Akasofu (1975) The equatorward boundary o f the diffuse aurora and auroral substorms as seen by the Isis 2 auroral scanning photometer. J. Geophys Res, 80, 3603-3614. 4. McPherron R.L. C.T. Russell, M.G. Kivelson, P.J. Jr Coleman (1973) Substorms in space: The correlation between ground and satellite observations of the magnetic field. Radio Science, 8. 1059-1076. 5. Kamide Y, S.-I. Akasofu, S.E. DeForest, J.L. Kisabeth (1975) Weak and intense substorms, Planet Space Sci., 23, 579-587 6. Petrukovich A.A., W. Baumjohann, R. Nakamura, T. Mukai, O.A. Troshichev (2000) Small substorms: Solar wind input and magnetotail dynamics. J Geophys Res, 105, 21109-21118. 7. Sergeev V.A., A.G. Yakhnin, N.P. Dmitrieva (1979) Substorms in the polar cap - the effect o f high-velocity streams o f the solar wind. Geomag Aeron (in Russian), 19, 1121-1122. 8. Despirak I V ., A.A. Lyubchich, Kh.K. Bimat, A.G. Yakhnin (2008), Poleward expansion o f the westward electrojet depending on the solar wind and IMF parameters. Geomagn. Aeron., 48. no. 3, 284-292. 9. Kleimenova N.G., E.E. Antonova, O.V. Kozyreva, L.M. Malysheva, T.A. Kornilova. I.A. Kornilov, W ave structure of magnetic substorms in polar latitudes (2012), Geomagn. Aeron., 52, no. 6, 785-793. 10. Despirak I.V.. A.A. Lyubchich, N.G. Kleimenova (2014), Polar and high latitude substorms and solar wind cnnHirinnc Geomagn. Aeron., 54, no. 5, 619-626. conumons. 10