Revealing flare productivity of solar active regions through magnetic field parameters and their evolution

Solar flares are one of the spectacular phenomena on the Sun. Solar active regions (ARs) are the main sources of flares, where stored magnetic energy in non-potential magnetic structures is released through magnetic reconnection. Many magnetic parameters, calculated using the photospheric magnetic field, are used to understand the non-potentiality and flare productivity of ARs. In this study, we address a particular question: what kind of ARs are capable of producing multiple intense flares that are likely to be a concern for space weather? We compared the evolution of twenty ARs; for each region, we analyzed six magnetic field parameters (total unsigned magnetic flux, net flux, current density, current helicity, neutralized current, length of strong-gradient polarity inversion line, and R-value). The average flare activity of ARs is compared on the basis of flare index (FI), a number calculated using the number and intensity of flares. Our analysis shows that the length of the strong-gradient polarity inversion line (sgPIL) has the highest correlation coefficient, but the unsigned total flux has the weakest correlation with respect to FI. Also, our analysis shows that most effective evolution in determining flare productivity is the interaction between opposite magnetic fluxes of non-conjugate pairs (not emerging simultaneously). Such regions are identified as having long sgPIL for a considerable long evolutionary period. Consistent magnetic flux cancellation and shearing motion along the sgPIL result in multiple intense flares from an AR.