Missing solar cycle hypothesis and basic statistical regularities of solar cycles

Abstract

The basic statistical properties of solar cycles, including the Gnevyshev-Ol’ rule, the Waldmeier effect, and the amplitude-period effect, are tested using data on the number of sunspot groups for 1700–1996, considering the hypothesis about a missing solar cycle in the late 18th century. The results show that the division of the long cycle of 1784–1800 into two short cycles—1784–1793 and 1793–1800—alters significantly the pattern of the solar cycles. The Gnevyshev-Ol’ cycle intensity effect becomes stronger, and almost all other statistical effects grow weaker. This change is due to the fact that the short and weak cycle of 1793–1800 is statistically very unusual and its features are very different from those of other solar cycles.