Time variations of the mean magnetic flux in active regions of different magneto-morphological classes

TL;DR

This study analyzes the time variations of magnetic flux in different classes of solar active regions, revealing that irregular regions dominate flux and exhibit intermittent behavior, indicating turbulence involvement in solar dynamo processes.

Contribution

It provides the first observational evidence linking turbulence in the convection zone to the formation of different active region classes in the solar dynamo.

Findings

B-class active regions dominate flux except during deep minima.

B-class flux profiles are highly intermittent, unlike the smooth A-class profiles.

Regular ARs are produced at a steady rate, while irregular ARs are produced intermittently.

Abstract

Using a recently suggested magneto-morphological classification (MMC, Abramenko, 2021, MNRAS Vol 507) of solar active regions (ARs), we explored 3048 ARs, observed from12 May 1996 to 27 December 2021. Magnetograms were acquired with the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) and with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). ARs were separated between three classes: class A - regular ARs (bipoles which follow the empirical rules compatible with the mean field dynamo theory); class B - irregular ARs (``wrong'' bipoles and multipolars); class U - unipolar sunspots. An aim of the present study is to explore time variations of a typical unsigned magnetic flux of ARs of different classes. The typical flux was acquired as the mean flux over all ARs of a given class observed during one solar rotation. The time profiles of the mean fluxes for different classes were compared. We found that, except for periods of deep solar minima, the mean flux of B-class ARs always dominate that of A-class ARs, and, what is the most important, the time profile of B-class ARs is highly intermittent versus the rather smooth and quazi-constant A-class profile. Intermittency implies a direct involvement of turbulence. We conclude that, through the entire active phase, the Sun is capable of producing regular moderate ARs at a quazi-constant rate along with the production of large and complex irregular ARs in the very intermittent manner. The result is the first observational evidence for the long-standing speculative assumption on the involvement of the convection zone turbulence into the regular global dynamo-process on a stage of the active regions formation.