A statistical study on solar soft X-ray flare and the sources

We surveyed 28 year of Solar X-ray flares and sunspot group records supplied by the National Geophysical Data Center (NGDC) to study the dependence of different class Xray flares on the magnetic structure of sunspot groups statistically. It is found that 82.5% X-class flare, 51.4% M-class flare, 26.3% C-class flare, and 10.1% B-class flare occurred in the sunspot group with βγδ structure. There are 6.6% X-class flares, 17.5% M-class flare, 39.1% C-class flare, and 60.4% B-class flare occurred out of sunspot group.