Magnetic fluxes of solar active regions of different magneto-morphological classes - I. Cyclic variations

Data for 3046 solar active regions (ARs) observed since 1996 May 12 to 2021 December 27 were utilized to explore how the magnetic fluxes from ARs of different complexity follow the solar cycle. Magnetograms from the Michelson Doppler Imager instrument on the Solar and Heliospheric Observatory and from the Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory were utilized. Each AR was classified as a regular bipolar AR (classes A1 or A2), or as an irregular bipolar AR (class B1), or as a multipolar AR (classes B2 or B3). Unipolar ARs were segregated into a specific class U. We found the following results. Unsigned magnetic fluxes from ARs of different classes evolve synchronously following the cycle, the correlation coefficient between the flux curves varies in a range of 0.70-0.99. The deepest solar minimum is observed simultaneously for all classes. Only the most simple ARs were observed during a deepest minimum: A1- and B1-class ARs. The overall shape of a cycle is governed by the regular ARs, whereas the fine structure of a solar maximum is determined by the most complex irregular ARs. Approximately equal amount of flux (45-50 per cent of the total flux) is contributed by the A-class and B-class ARs during a solar maximum. Thus, observations allow us to conclude that the appearance of ARs with the magnetic flux above 10(21) Mx is caused by the solar dynamo that operates as a unique process displaying the properties of a non-linear dynamical dissipative system with a cyclic behaviour and unavoidable fluctuations.

Automated summary

Data from 3046 solar active regions observed over a period of 25 years were used to study the magnetic fluxes of regions with different complexity during the solar cycle. The study found that the fluxes from different classes of regions evolve synchronously and correlate strongly with each other. The deepest solar minimum occurs simultaneously for all classes, and only the simplest regions are observed during this period. The overall shape of the solar cycle is determined by regular regions, while the fine structures of the solar maximum are influenced by the most complex irregular regions. Approximately equal amounts of flux are contributed by A-class and B-class regions during the solar maximum.