Velocity structures from sunspot statistics in cycles 10 to 22 I. Rotational velocity

Data from the whole era of modern sunspot observations (1853-1996) from four different sources is considered. We find that rotation is continuously changing, not only in the course of a cycle but also in a longer time period. We also find strong fluctuations in the equatorial rotation in the course of a sunspot cycle which can be connected with the observed north/south asymmetry of rotation. The importance of age dependence on rotation is emphasized, both for non-recurrent and recurrent sunspots as the slowing down of rotation along with the age is confirmed.