Investigating the associations between solar flares and magnetic complexity of active regions

Abstract

It is generally believed that solar activities are closely linked with magnetic fields on the solar surface. To learn more about how solar flares are produced in relation to solar magnetic configurations, we examined a total of 37,741 soft-X ray solar flare events observed by a series of GOES satellites. The flare and sunspot data catalogued by NOAA were obtained from 1996 July through 2018 December, covering solar cycles 23 and 24. The investigated flares database consists of 38.26% B-, 55.52% C-, 5.78%M- and 0.44% X-class. In accordance with the Hale magnetic complexity categorisation system, a total of 33,562 sunspot groups comprised of 30.65% α -, 57.7% β-, 8.69% βγ, and 2.96% -βγδ-type active regions were counted based on their daily appearances, from the same source and period. The Multi-Taper and cross-correlations analyses were adopted in carrying out the investigation using their daily numbers. Our findings reveal that B-flares are negatively correlated with all the sunspot groups, in contrast to other flare classes that are positively correlated and synchronous. The β-sunspot and C-flares are found to exhibit the typical 11-year solar cycle, including the double-peaks feature during solar maximum. Correspondingly, the measured daily occurrence rates of β-sunspot and C-flares were the highest during the studied two solar cycles. Meanwhile, a total of 22,121 flare events were observed to be occurring concurrently with sunspot groups, out of which 10,019 flare events were found associated with β-sunspot, from which 5,378 happened to be C-class, the highest number obtained, followed by 4,164 with B-class. The X-flares recorded 2 events with α- sunspot group, the least recorded in the studied period. We also confirm that the βγδ-group is more likely to produce any class of flare. However, constrained by their formation rates, resulting in the β-group producing the most flares by number. Periodicities of 9.9, 10.67, and 9.9 years were obtained for α-, β-, and complex (βγ-and-βγδ) respectively while 4.1-6.5, 10.67, 11.2 and 10.64 years were obtained for B-, C-, M-and-X flares.