Magnetic field evolution leading to solar flares II. Cases with high magnetic shear and flare-related shear change

Following Paper I in which we considered five solar flares: we have selecte d another three solar flares greater than GOES X-ray class M/H alpha import ance 1. The three active regions discussed here are characterized by high m agnetic shear. We investigated the spatial relationships among Her flare ri bbons, soft X-ray (SXR) hare loops, and magnetic configurations for the thr ee flares produced in these active regions. Our results show that only one of these three flares satisfies the sufficient conditions for a flare to oc cur proposed by Hagyard (1990, AAA 052.075.047). We also discuss the magnet ic shear changes around the flaring time only along the neutral lines assoc iated with the studied flares and over the whole flaring area. The flare-re lated changes on the neutral line are small (2 degrees-4 degrees) and the a ssociation of these changes with the hares is not conclusive. The average s hear in the flaring areas of the flares associated with high shear decrease s significantly after the flares and it may be a better parameter to charac terize the hare-related shear changes in such cases.