The change of the solar cyclicity mode

Abstract

Our analysis of groups of sunspots since the year 1610 till indicates that the Gnevyshev–Ohl rule (GO) displays cycles of inversion with the period of 200years. The latest inversion occurred in the Hale double cycle 22–23. Due to that, in several subsequent double cycles the odd cycles should be weaker than their preceding even cycles. Gleissberg cycles with the period of about 100years and variations with the period of 200years are manifested in variations of physical parameters of sunspots and are interconnected. We suggested that the secular minima of the solar activity occur in the vicinity of the extreme points of the 200-year cycles of inversion of the GO rule. The peak of the next secular minimum is expected between the years 2025÷2035. We studied the variations of the physical parameters of sunspots in a Gleissberg cycle. At the maximum phase of the Gleissberg cycle, the average area of groups and the average number of spots in a group reach their maximum. According to our forecast, the amplitude of the 25th solar activity cycle will be somewhat lower than that of the 24th.