Reversals of Gnevyshev-Ohl rule

Abstract

This paper considers the changes of average number of sunspots groups per day, aggregated by activity cycles Gn within the period since 1610 till present time. The relation of parameter Gn of the preceding and the following activity cycles has a long-term variation with the period of about 20 activity cycles. There is a positive correlation between the parameter Gn in the current cycle and analogous parameter in the following cycle Gn+1. For cycles N 10-21 for a pair of even and odd cycles the relation of parameter Gn corresponds to Gnevyshev-Ohl rule Godd/Geven>1. But in previous epochs the odd cycles could be less than the preceding even cycles, and it only proves the reversal of Gnevyshev-Ohl rule.