Olga Burtseva, Gordon Petrie
We perform a statistical study of permanent changes in longitudinal fields associated with solar flares by tracking magnetic features. The YAFTA feature tracking algorithm is applied to GONG++ one-minute magnetograms for 77 X- and M-class flares to analyze the evolution and interaction of the magnetic features and to estimate the amount of cancelled flux. We find significantly more magnetic flux decreases than increases occurred during the flares, consistent with collapsing loop structure. Correlations of both unsigned and signed flux changes with GOES peak X-ray flux are dominated by X-class flares in limb locations. The flux changes were accompanied in most cases by significant cancellation, most of which occurred during the flares. We find that the field strength and complexity at the polarity inversion line are approximately equally important in the flux cancellation processes accompanied flares. We do not find correlation between the flux cancellation events and the stepwise changes in the features' fluxes.
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http://arxiv.org/abs/1210.4200
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