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E.A. Revunova at al. ТаЫеЗ. The parameters of analyzed clouds determined on initial measurements magnetic o f field components. Data registration magnetic cloud H Bo, n T R o , R e (3, deg 6 , deg b, R e V, km-s ' 1 L , h Percent data on which parameters are established 1 6 .04 .1 9 9 9 -1 -2 2 1888 6 0 80 9 7 4 4 5 0 15 2 8 2 1 .0 2 .2 0 0 0 +1 23 1500 180 1 40 1252 3 5 0 2 0 4 8 2 8 .1 0 .2 0 0 0 -1 -2 2 3 0 5 2 80 -4 0 9 7 4 4 5 0 15 3 9 5. Conclusions The analysis of influence o f large-scale magnetic cloud parameters on geoefficiency has allowed establishing the ranges of their values responsible for development o f various intensity geomagnetic storms. It is received, that extreme storms are generated clouds with great values o f polar angel and strong negative magnetic field on cloud axis. For development o f strong geomagnetic storms enough high values o f magnetic field on cloud axes. Weak geomagnetic storms are caused mainly by clouds with small polar angel and almost all value ranges o f axis field. On real events the technique o f short-term forecasting o f geomagnetic storms intensity expected at interaction of clouds with Earth’s magnetosphere is developed and checked up. It is received high (-80% ) conformity o f intensity classes of the geomagnetic storms, caused real by magnetic clouds and expected from modeling events. Divergences in classes of real and expected geomagnetic storms it is observed for magnetic clouds at which the cloud sheath or combination of sheath and leading field is geoeffective. However such events make only ~20%, therefore the suggested technique can be used for short-term forecast of geomagnetic storms intensity caused by clouds. A cknow ledgm en ts. Work is executed at partial support under grant o f the RFBR 09-05-00495, and also program Ministry of Education and Science «Development o f higher school scientific potential (2009 - 2010, project N 1623)». References Barkhatov N. A., Kalinina E. A. and Levitin A.E. Manifestation o f configurations magnetic clouds o f the solar wind in geomagnetic activity // Kosmicheskie Issledovaniya (RAS). V. 47, No 4. P. 300 - 310. 2009. Barkhatov N. A. and Kalinina E. A. Determination of magnetic cloud parameters and prediction o f magnetic storm intensity // Geomagnetism and Aeronomy. V. 50. No.4. P. 477 —485. 2010. Bothmer V. and Schwenn R. The structure and origin of magnetic clouds in the solar wind // Arm. Geophys V 16 P. 1 - 2 4 . 1998. Burlaga L., Sittler E., Mariani F. and Schwenn N. Magnetic loop behind an interplanetary shock: Voyager, Helios and IMP 8 observations // J. Geophys. Res. V. 8 6 . P. 6673 - 6684. 1981. Echer E., and Gonzalez W. Geoeffectiveness o f interplanetary shocks, magnetic clouds, sector boundary crossings and their combined occurrence // Geophys. Res. Let. V. 31. L09808. doi:10.1029/2003GL019199. 2004. Gonzalez W.D., Joselyn J.A., Kamide Y., Kroehl H.W.. Rostoker G.. Tsurutani B.T. and Vasyliunas V.M. What is a geomagnetic storm? // J. Geophys. Res. V.99. No. A4. P. 5771 - 5792. 1994. Lepping R., Jones J., and Burlaga L. Magnetic field structure of interplanetary magnetic clouds at 1 AU // J. Geophys. Res. V. 95. P. 11,957-11,965. 1990. Lynch B., Zurbuchen Т., Fisk L. and Antiochos S. Internal structure o f magnetic clouds: Plasma and composition // J. Geophys. Res. V. 108. No A 6 . P. 1239. doi:10.1029/2002JA009591. 2003. Romashets, E. P. and Vandas V. Dynamics o f a toroidal magnetic clouds in the solar wind // J Geophvs Res V 106.No.A6. P. 10,615- 10,624. 2001. ' Vandas, М., Odstrcil, D. and Watari S. Three-dimensional MHD simulation o f a loop-like magnetic cloud in the solar w ind// J. Geophys. Res. V. 107. No. A9. P. 1236. doi:10.1029/2001JA005068. 2002. Hidalgo, M. A , Nieves-Chinchilla, T. and Cid C. Elliptical cross-section model for the magnetic topology of magnetic clouds // Geophys. Res. Letters. V. 29. No. 13. P. 1637. doi:10.1029/2001GL013875. 2002. Hidalgo, M. A., Vinas, A. F., and Sequeiros J. A non-force-free approach to the topology o f magnetic clouds in the solar w ind// J. Geophys. Res. V. 106. No. A l. P. 1002. doi:10.1029/2001JA900100. 2002 Wu C. and Lepping R. Effects of magnetic clouds on the occurrence o f geomagnetic storms- The first 4 years of W ind/ / J. Geophys. Res. V. 107. No. A10. P. 1314. doi: 10.1029/2001JA000161 2002 Zhang J., Liemohn M„ Kozyra J„ Lynch B. and Zurbuchen T. A statistical study o f the geoeffectiveness o f magnetic clouds during high solar activity year // J. Geophys. Res. V. 109. No. A09101. doi-10 1029/2004JA010410 2004 94