22-year Periodicity in the Solar Differential Rotation

Abstract

Using the data on sunspot groups compiled during 1879- 1975, we determined variations in the differential rotation coefficients A and Β during the solar cycle. The variation in the equatorial rotation rate A is found to be significant only in the odd numbered cycles, with an ampli tude ~ 0.01 μrads–1. There exists a good anticorrelation between the variations of the differential rotation rate Β derived from the odd and even numbered cycles, suggesting existence of a '22-year' periodicity in B. The amplitude of the variation of Β is ~ 0.05 μ rad s–1.