Possibility of Diagnostics of the Beginning of Solar Cycle 25 Based on Its Precursors at Mid-Heliolatitudes

The potential to diagnose the beginning of the solar cycle based on the detection of small-scale magnetic formations, the magnetic nodes of ephemeral active regions in the zone of mid-heliolatitudes from 40° to 60°, has been studied. Magnetic nodes were detected at the stage of their emergence by the multifractal segmentation method, which was previously used to fix new magnetic fluxes of active regions in the zone of low heliolatitudes. Statistical estimates of the number of magnetic nodes recorded by this method were performed based on magnetograph data from the Synoptic Optical Long-term Investigations of the Sun of the National Solar Observatory (SOLIS NSO) for the 24th solar activity cycle, as well as for the beginning of the 25th activity cycle. A precursor of solar cycle 24 has been found in the form of a burst in the number of magnetic nodes in 2007-2008 that significantly exceeds the background value characteristic of the period 2011-2015. Two years later, the first active regions began to appear at latitudes of 30° ± 10°. A similar sequence of phases in the beginning of the cycle was found for cycle 25. Unlike the situation with solar cycle 24, the mass appearance of high-latitude active regions of cycle 25 occurred about 2.5 years after the burst in the number of nodes of ephemeral active regions.