Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

I. M. Podgomy, and A. I. Podgomy However, the expected increasing of solar activity after minimum activity predicted in 2007 is not occurs. In the next 3 years the active regions have not appeared on the solar disk. The dependence o f sunspot number according to Belgium Solar Influence Center is shown in fig. la. The deep minimum after cycle 23 and cycle 24 delay is seen. In fig. lb the cycle 20 is overlapped on cycle 23. These cycles have the same magnitude. Tremendous sunspots difference in 2010 is seen. The figure shows that if 11 year cycle period is conserved, the solar activity in 2010 у should be very high. But instead of all predictions the solar activity is still very low. This unexpected situation has initiated conclusions that instead of a global warming, the global cooling similar to a little boulder period in the Mouder solar activity minimum is expected [1]. The situation shows that for solar activity prediction, it is necessary to understand all link of the chain of phenomena responsible for flare generation. Here we consider one of the links, namely, association of magnetic field dynamic in the active regions and solar flare creation. In our previous Apatity seminar reports we have considered the mechanism of energy accumulation for a flare in the current sheet magnetic field and the possibility of explosive release o f this energy [2, 3]. The association of the active region magnetic field and flares has been investigated many years. The necessity of the big magnetic flux in an active region for flare production has been pointed out by Ishkov [4]. The main topic of investigation is slow evolution of an active region that initiates a flare and a possible fast change o f the magnetic field on the photosphere during a flare. The review of such investigation has been published by Wang [5]. Most of the flares appear above active regions after slow magnetic field increasing. The results of detection o f fast magnetic disturbances are rather conflicting. Several flares usually are produced during a strong active region moves across the solar disk. The flare class of elementary flares in the set can change in three orders o f magnitude. During the set o f flares the magnetic field configuration in an active region slowly changes and magnetic field fluctuations occurs in some points of the active region. The SOHO MDI photospheric magnetic maps o f the component directed along the line of sight are published every 1.5 hours in http://soi.stanford.edu/magnetic/index5.html. Each SOHO magnetic map possesses its peculiarities, but main elements o f active regions are conserved several hours. Sometimes short time magnetic field fluctuations occur. The problem arises about association o f active region magnetic field change and flares appearing. Some researches [5] report about different photospheric magnetic field behavior at flares, but there are no certain opinion about such effects. The most outstanding local magnetic disturbances in the active region have been reported in [5]. Drops of the magnetic field o f the order o f 100 Гаусс are observed during the flare 20.01.2005 in active region AR10720. Field decreasing is starting at ~2 hours before this flare. The work [5] contains many references that reported active region disturbance during flares, but there are no agreements between these data. There are many attempts to find a correlation between situations on the photosphere and flare appearance. According to theoretical data [ 6 - 8 ] and results of RHESSI measurements [9, 10] the primary energy release occurs in the corona above an active region. The active region can be considered as local solar magnetosphere with magnetic field of several thousand Gauss. The energy for a flare is accumulated in a current sheet appeared above active region. This energy release occurs due to current sheet explosive decay. Such solar flare scenario is similar to substorm development in the Earth magnetosphere. Change of photospheric magnetic field cannot produce strong influence on flare dynamics. The similar manner, Earth magnetic field does not influence on substorm development The authors of [5] suppose that observed effect is associated with a magnetic rope, which influences on current sheet instability. It is necessary to emphasize that measurements in [4] has been carried out in the rather complicated conditions, at the active region AR 10720 location near the Western limb (N12 W56). The line o f sight angel with solar surface has been too little and the results of measurements untangled by combining intuitive geometric analysis and a transformation of the magnetogram into the heliographic coordination system”. The aim of the present work is analysis of the normal magnetic field in active region and search for possible connection the photospheric magnetic field with flare generation. The SOHO MDI measurements o f the line-of-sight magnetic component are used. But the line-of-sight magnetic field component is strongly depends on the active region position on the disk. The first task of investigation is calculation of the normal to the solar surface magnetic component from SOHO data. Flares in the active region 10486 AR 10486 has been observed in October-November 2003 y. It produces several powerful flares, including four X- class flares. Two other X-class flares have been observed near Eastern and Westcrn limbs (23 1 0 2003 v s a ci qpsc и 4.11.2003 X306 S18W88), their location does not permit to get a magnetic map containing all active region Magnetic field dynamic is determined by development o f SOHO MDI date ( http://soi.stanford.edu/magnetic/index5.html) . The time interval between the measurements is 1 5 hours The measured magnetic distribution in a region near solar disk centre almost coincides with the distribution of the normal magnetic component. However such distributions are considerably different for an active region displaced from the семге The normal magnet,с field distributions are obtained from potential field distribution above the active region. The potential field is calculated by solving Laplace equation with the oblique derivative as the