The Sun’s Magnetic Power Spectra over Two Solar Cycles. II. Cycle Dependence of Active Regions, a Magnetic Network, and Their Relation

Abstract

The multiscaled solar magnetic field consists of two major components: active regions (ARs) and magnetic network. Unraveling the cycle-dependent properties and interrelations of these components is crucial for understanding the evolution of the solar magnetic field. In this study, we investigate these components using magnetic power spectra derived from high-resolution and continuous synoptic magnetograms since cycle 23 onward. Our results show that the size of the magnetic network ranges from 26 to 41 Mm without dependence on the solar cycle. The power of the network field (P NW) accounts for approximately 20% of the total power during any phase of solar cycles. In contrast to the AR power (P AR), P NW displays a weaker cycle dependence, as described by the relationship P NW ≈ 0.6* P AR + 40. The power-law index between AR sizes and magnetic network sizes presents a strong anticorrelation with the activity level. Additionally, our study indicates that in the absence of sunspots on the solar disc, the magnetic power spectra remain time-independent, consistently exhibiting similarity in both shape and power. This study introduces a new method to investigate the properties of the magnetic network and provides magnetic power spectra for high-resolution simulations of the solar magnetic field at the surface at various phases of solar cycles.