We investigate the phase difference of the sunspot cycles in the two
hemispheres and compare it with the latitudinal sunspot distribution. If the
north-south phase difference exhibits a long-term tendency, it should not be
regarded as a stochastic phenomenon.
We use datasets of historical sunspot records and drawings made by
Staudacher, Hamilton, Gimingham, Carrington, Spouml;rer, and Greenwich
observers, as well as the sunspot activity during the Maunder minimum
reconstructed by Ribes and Nesme-Ribes.
We employ cross-recurrence plots to analyse north-south phase differences. We
show that during the last 300 years, the persistence of phase-leading in one of
the hemispheres exhibits a secular variation. Changes from one hemisphere to
the other leading in phase were registered near 1928 and 1968 as well as two
historical ones near 1783 and 1875.
A long-term anticorrelation between the hemispheric phase differences in the
sunspot cycles and the latitudinal distribution of sunspots was traced since
1750.Comment: 7 pages, 4 figure
