To the Question of North–South Asymmetry of Solar Activity in the 25th Schwabe–Wolf Cycle

Abstract

An analysis of the north–south asymmetry (NSA) of the groups of sunspots and flares location during the growth phase of the 25th Schwabe–Wolf cycle of solar activity was performed. During the first four years of the cycle’s development, sunspot activity increased quasi-synchronously in the northern and southern hemispheres; the absolute value of the NSA coefficient during this period decreased from 0.6 to 0.2. The longitudinal distribution of sunspots in the second half of 2023 was uneven and similar in both hemispheres; groups of sunspots appeared during this period mainly in the longitudinal intervals of 30°–100°, as well as 200°–280°, while at other longitudes activity was reduced both in the northern and in the southern hemispheres. The number of flares of all classes was 45% in the northern hemisphere, 42% in the southern hemisphere, and 13% were not identified. The flare index was distributed between the hemispheres in the ratio of 49.5 to 42, with 8.5% not identified. A comparison with the 24th cycle shows that NSA in the distribution of sunspots and flares between the northern and southern hemispheres in the current (25th) cycle is significantly lower than in the previous one. A high degree of symmetry of activity can ensure a greater height of the 25th cycle compared to the 24th, as well as the single-peaked nature of the 25th cycle. It is hypothesized that the 25th cycle exhibits a higher level of dipole parity of the global magnetic field compared to the 24th cycle.