The dependence of flares on the magnetic classification of the source regions in solar cycles 22-23

Using 28 years of solar X-ray flares and sunspot-group records supplied by the National Geophysical Data Center, we carried a statistical study on the dependence of flares on the magnetic classification of the sunspot groups, and investigated the relationship with the phase in the 22nd and 23rd solar cycles. We found that (1) there are 83.34 per cent X-class flares, 62.35 per cent M-class flares, 43.18 per cent C-class flares, and 25.47 per cent B-class flares occurred in beta gamma delta sunspot groups. (2) The occurrence of X-class flares in different sunspot groups shows clear periodic characteristics in phase with the solar cycle: near the two solar maximums, X-class flares occurred in various sunspot groups, but still most X-flares occurred in the beta gamma delta sunspot groups. For the other phases, all X-class flare occurred in beta gamma delta sunspot groups except 1998. The occurrence of M-class flares in different sunspot groups shows some periodic features in phase with the solar cycle. The occurrence of C-class and B-class flares in different sunspot groups shows weak periodic features with the phase of the solar cycle.