Abstract. In the present work, the dominant hemisphere of solar activity in each of solar cycles 12 to 22 has been clarified by calculating the actual probability of the hemispheric distribution of several solar activity phenomena using long-term observational records. An attempt is made to demonstrate that a long characteristic time scale, about 12-cycle length, is inferred to occur in solar activity.

The data of the polar faculae observed by the National Astronomical Observatory of Japan from the year 1951 through 1991 and the Mount Wilson Observatory from 1906 to 1990 were analysed. We found that the polar facula cycle is in complete antiphase with the sunspot cycle, and highly correlated with the sunspot cycle with a time shift of 51 months into the following sunspot cycle. We also made a quantitative analysis of the hemispheric distribution of polar faculae, and found that hemispheric asymmetry exists, as in solar activity at low latitude. However, the hemispheric asymmetry of polar faculae seems to have little relationship with the asymmetry of solar activity at low latitude.

In the present work, the north–south asymmetry of solar activity was examined by analyzing statistically the hemispheric distribution of annual numbers of sunspot groups, using the Royal Greenwich Observatory data set from the year 1874 through 2000. An interesting phenomenon is found that the solar activity of a cycle usually has the same beginning and end times, but different maximum amplitudes at different maximum times in the hemispheres. Some characteristics of the asymmetry of solar activity were investigated and explained. For solar cycle 23, a dominance of solar activity is predicted to occur in the southern hemisphere in several forthcoming years.

Abstract. In this paper, we investigate the prospect of using previously occurring sunspot cycle signatures to determine future behavior in an ongoing cycle, with specific application to cycle 23, the current sunspot cycle. We find that the gross level of solar activity (i.e., the sum of the total number of sunspots over the course of a sunspot cycle) associated with cycle 23, based on a comparison of its first several years of activity against similar periods of preceding cycles, is such that cycle 23 best compares to cycle 2. Compared to cycles 2 and 22, respectively, cycle 23 appears 1.08 times larger and 0.75 times as large. Because cycle 2 was of shorter period, we infer that cycle 23 also might be of shorter length (period less than 11 years), ending sometime in late 2006 or early 2007.

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