22-year cycle or 11-year cycle in the latitude drift of sunspot groups?

Abstract

Some earlier investigations seem to indicate that sunspots show an average drift in latitude which varies sinusoidally with the period of the double sunspot cycle (about 22 years), while the same investigations do not show similar variability with the period of the single sunspot cycle (about 11 years). Other studies, however, show that the drift of sunspots varies with the period of the single sunspot cycle. There seems to be a discrepancy between the two results. The problem is reinvestigated on the basis of long-lived sunspot groups, but treating the material in a way different from that used before. This procedure, which uses central values of the proper motions of the groups instead of their average values, gives an additional proof of the reality of the ll-year period of the drift. It also seems to produce the 22-year period, but there is such a difference between the variabilities of the drift found on the basis of the two methods that the 22-year cycle of the drift is made doubtful.

The Sunspot Cycle and Solar Magnetic Fields. I. The Mechanism as Inferred from Observation

“…The accuracy of measurement is not great, but the order of magnitude is the same from 10° to 50° in latitude. This is much greater than the cyclic variations in meridional sunspot motion reported by Tuominen (1941Tuominen ( , 1976 and Richardson and Schwarzschild (1953), which can be ignored by comparison. While these measurements were made at sunspot minimum, similar results have been obtained (T. L. Duvall, personal communication) through the recent solar maximum, so that the phenomenon appears to be independent of the phase of the cycle.…”