Modeling the distribution of circular polarization degree of microwave emission along the flare loops in event July 19, 2012

The distribution of the degree of circular polarization of microwave emission along the solar flare loops during the event on July 19, 2012, was analyzed with the use of data from the Nobeyama Radioheliograph (NoRH). It was found that the polarization degree in the loop footpoints remains negative (R–L < 0) during the entire burst. At the upper part of the flare loop, the polarization is inverse with respect to the footpoints (R–L > 0 ) and also does not change over time. In the northern and southern legs of the loop, the polarization degree sign changes over time. The proposed explanation of this effect is based on modeling the kinetics of nonthermal electrons and the calculation of their gyrosynchrotron (GS) emission for the model loop located on the solar limb. It was shown that the observed change in the polarization sign in the event on July 19, 2012, can be caused by the presence of longitudinal anisotropy of energy electrons at the upper part of the flare loop