Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

1. M. Podgomy and A. /. Podgomy Magnetogramms in Fig. 2, taken during the flare X2.2 15.02.2011 demonstrate also the high stability of the photospheric magnetic field just before the flare, throughout and after the flare. For more than two hours the magnetograms do not show any significant changes of the magnetic field, which can be attributed to the energy release of flares. These observations are fully consistent with the results of 3D MHD simulation that show the energy storage before the flare in the current sheet magnetic field high in the corona [3, 4], and the results of X-ray measurements, during the flare, which occurred on the limb. SDO data show that the primary flare energy release occurs in the corona. A similar situation was observed during the major flare of X I7, occurred over AR 10486 10.28.2003 (Fig. 3). Here also there is virtually unchanged magnetogram during the entire time of development and decay of the flare. The local field changes are not exceeding 1% - 2%. Such local micro changes has been observed in [9] in the flare X7.1 on January 20 2005. 11.02.2011 01:45:00 12.02.2011 01:45:00 13.02.2011 01:45:00 14.02.2011 01:45:00 15.02.2011 01:42:00 15.02.2011 01:50:15 NOAA 11158 2011 GOES Xray flux 1' X2.2 2' “ " ” I ; 3‘ i Л-i Й) ij i/ Л * vV о H Г Б l.Ai J i....l ..i l l . j M j i ...... — ^Л ____ О R H Ж. Ш 1Ш 1 Ш К Ж ' c 1 1 12 13 1 4 15 February U Fig. 1. Magnetograms NOAA 11158 show the development of the active region before the X2.2 flare 14.02.2011 and SDO measurements, showing an increase of flare activity. Fig. 2. NOAA 11158 magnetogram during the flare X2.2. Fig. 4 shows the northern and southern magnetic fluxes of NOAA 10720 and dynamics of solar activity in AR during it passages across the solar disk. As for AR 10365, 10486 and 11158 observed increase of the flare activity with increasing magnetic flux [ 6 , 7]. Flares of the X-class in NOAA 10720 also occur only at high magnetic flux order of 10 22 Mx. The considerable change of magnetic flux in during the flare time is not observed. In the three cases analyzed the dynamics of AR, there is a significant disbalance between the northern and southern magnetic fluxes after the maximum of their values. It is not clear whether such a behavior of magnetic flux a natural. The magnetic flux o f the active region NOAA 10720 before the X-type flare Investigations carried out for the flare in AR 10365 and 10486 have shown that powerful flares (X-type) begin to occur after increasing the magnetic flux of AR up to 10 22 Mx [ 6 , 7]. In this paper we studied AR 10720, that gave a series of X-type flares. We used measurements of the magnetic field component directed along the line-of-sight on the SDO. The magnitude of this component depends on the angle of view. To eliminate this dependence and FLARE Febrary 15, 2011 . X2.2 S20W10 Start 01:44:00 Peak 01:45:00 15.02.2011 01:42:00 01:45:00 01:46:30 SDO magnetograms NOAA 11158 89