Abstract Unraveling the origins of the quiet Sun’s magnetic fields remains a key challenge. Using observations from Heliospheric Magnetic Imager on board Solar Dynamics Observatory, we identified over 86 million quiet region (QR) structures in daily full-disk magnetograms spanning 2010–2025, a period covering nearly the entire Solar Cycle 24 and half of Cycle 25. By analyzing the cyclic variations, our key findings are as follows. (1) The area coverage and total magnetic flux of QRs closely follow sunspot cycles, indicating that Cycle 25 is stronger than Cycle 24. Throughout Cycle 24, the QR flux surpasses active region (AR) flux for almost the entire cycle. In the first 5.5 yr of Cycle 25, the QR flux remains greater than AR flux except for nine isolated months. (2) From the detection limit to the large-scale end, both the flux and number of QR structures exhibit a sequential pattern of anticorrelation and positive correlation with sunspots. Notably, anticorrelated structures constitute more than 95% of QR structures at any given time, and dominate the QR flux during solar minimum. (3) We develop an empirical model for QR magnetic sources based on long-term flux variations, revealing that the flux contribution of ARs remnants to QRs varies in the solar cycle. During solar maximum, most of the QR flux and positive-correlated QR flux originate from ARs, while roughly 30% of the anticorrelated flux is suppressed by ARs. These findings suggest that the solar cycle should be characterized by the magnetic fields in both ARs and their associated QRs.
Jin et al. (Sun,) studied this question.