Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

Role o f tilt orientation o f BMRs and meridional circulation in the polar magneticfield reversal on the Sun suggest that strong surges are resulted primarily of enhanced activity (powerful sunspot impulses). Weak sunspot impulses and small tilt angle of BMRs at low latitudes reduce surges, which could not even reach the poles during the declining phase of solar cycles. We suggest that effect of the meridional flow is smaller in comparison influence of strength of sunspot impulses on magnitude of the polar field. с р Ш П щ ж т ш Time, year Fig. 3 (a) Sunspot impulses are constructed for average window dl*dt = 0 . 6 x 1 and iteration step /=20. (b) Reconstructed surges, (c) Smoothed northern and southern dimensionless values 5'Resui 1 (/,f) at latitudes 80° and -80°. Blue denotes the northern hemisphere and red - the southern hemisphere. Used parameters: Ad = 10° and l’o = 13 m s ' 1 at latitude 45°. (d) The same for Ad = 10° and "o = 13 m s ' 1 at latitude 13.3°. (e) For Ad = 8 ° and l"« = 13 m s ' 1 at latitude 45°. Conclusions In this paper, we performed parameter study o f tilt angle (latitudinal segregation) of BMRs and meridional flow profile on poleward magnetic field surges. In our model polar large-scale magnetic fields are closely related to small-scale bipolar magnetic regions at low latitudes. Variations in latitudinal profile of the meridional flow result in variations of simulated poleward surges. However further investigations are required due to dependence of findings on size mesh grid. The latitudinal profile o f tilt angle o f BMPRs also determines the strength o f the polar field. The polar field reversals are intimately related to the sunspot impulses. Their behavior exhibits long­ term dynamical evolution. We suggest that weakening o f the polar fields during the recent minimum is more associated with decrease in the field strength o f sunspots (Livingston and Penn, 2009) and nominal sunspot counts (decrease of intensity o f sunspot impulses) along the cycle 23 with respect to the cycles 2 1 and 2 2 . A ckn ow led g em en ts. The work is supported by grant of the Russian Foundation for Basic Research 12-02-31108 mol_a. References A ntalova, A ., G n evyshev, M . N ., (1983). C ontributions o f the A stronom ical O b serv ato ry S kalnate Pleso, 11, 63 B ishop, С. M . (2006). P attern R ecognition and M achine L earning, S pringer, N ew Y ork, 738 D eV ore, C .R ., S heeley, N .. Jr. (1987). S o lar Phys., 108, 47 D ikpati, М ., G ilm an, P .A ., U lrich , R .K . (2010). A strophys. J., 722, 774 G leissberg, W . (1 9 6 7 ). S o lar P h y s., 2, 231 G nevyshev, M .N . (1 96 3 ). S o v iet A stronom y-A J, 7, 3 G nevyshev, M .N . (1 96 7 ). S o lar P hys., 1, 107 H athaw ay, D .H . (2 0 1 0 ). L iv in g R eview s in S olar P hysics 7, 1 H athaw ay, D .H ., R ig h tm ire, L. (2011). A strophys. J., 729, 80 Jiang, J., C am eron, R .H ., S chm itt, D ., S chussler, M . (2011). S pace Sci. R ev., 136 L ivingston, W „ P en n , M „ (2009). E O ST r, 9 0 ,2 5 7 N andy, D ., M u n o z-Jaram illo , A ., M artens, P. С. H. (2011). N ature, 471, 80 S chrijver, C. J., L iu , Y . (2008). S olar P hys., 252, 19 S chrijver, C .J., T itle, A .M . (2001). A strophys. J., 551, 1099 Sheeley, N . R „ Jr. (2 0 1 0 ), SO H O -23: U nderstanding a P eculiar S o lar M in im um , 4 2 8 , 3 van B allegooijen, A .A ., C artledge, N .P ., Priest, E. R. (1998). A stro ph y s. J., 501, 866 W aldm eier, M . (1 93 5 ). A stron. M itt. E idgen. Sternw . Z urich, 14, 105 W ang, Y .-M ., L ean , J., Sheeley, N .R ., Jr. (2002a). A strophys. J., 5 7 7 , L53 W ang, Y .-M ., N ash , A .G ., S heeley, N .R ., Jr. (1989). A strophys. J. 3 4 7 , 529 W ang Y .-M ., R o b b rech t E „ S h eeley N . R ., Jr. (2009). A strophys. J., 7 0 7 , 1372 W ang, Y .-M ., S heeley, N .R ., Jr., L ean, J. (2002b), A strophys. J., 580, 1188 Z olotova, N .V ., P o n y av in , D .I. (2008). IAUS 286: C om parative M ag n etic M inim a: C haracterizing quiet tim es in th e S un and stars, 88 Z olotova, N .V ., P o n y av in , D .I. (2012a). A stronom y R eports, 56, 250 Z olotova N .V ., P o n y av in D .I. (2012b), P u lk ov o annual solar physics co n feren ce S o lar and Solar-T errestrial p h y sic s- 2 0 1 2 , 47 Z olotova N .V ., P o n y av in D .I. (2013), G eom agnetism and A eronom y, in press. 132