Amplitude variations of the 11 year cycle and the current solar maximum 23

We examined the conditions for violations of the Gnevyshev-Ohl rule, which states that the even-numbered 11 yr solar cycles have been followed by high er in amplitude odd-numbered ones. This regularity has been valid for the l ast 150 years, but it is very likely to be broken in the current 11 yr cycl e 23. We used the Schove series, which includes the main macrocharacteristi cs of the 11 yr cycles and is continuous since the end of the third century . The reliability of these data has been discussed. A total of 152 cycles w ere investigated, the last one being cycle 21 in the International Sunspot Number series. We showed that there is a well-outlined group of even-number ed 11 yr cycles that are very likely to be followed by weaker odd-numbered ones. These are the most powerful even cycles, characterized by maximum mon thly smoothed Wolf numbers exceeding 125 and decay times of 6 yr or more. T he main factor for violations of the Gnevyshev-Ohl rule is a very high maxi mum of the even-numbered ii yr cycle. Applied to the present Hale cycle, wh ich consists of ii yr cycles 22 and 23, our analysis implies a high probabi lity for violation of the Gnevyshev-Ohl rule. The development of 11 yr cycl e 23 confirms this conclusion. We argue that the present 11 yr cycle should not be qualified as "abnormal" when referring to the fact that it breaks a regularity that has lasted for 150 yr. The 11 yr cycle 23 might reveal a f eature in the dynamics of the Hale cycle that the strongest even-numbered 1 1 yr cycles are likely to be followed by lower amplitude odd-numbered ones. We briefly discuss the relation between the long-term solar variability an d the current violation of the Gnevyshev-Ohl rule.