Abstract

An analysis of solar rotation as a function of heliographic latitude and time is made using daily radio maps of the Sun at the wavelength of 1.76 cm. Variations of the velocity as a function of the latitude during the period 1992-2001 have been studied. The mean synodical rotation rate of the intensity features is best fit by ω = 13.41 - 1.66\sin² θ -2.19 \sin⁴ θ (deg/day) where theta is the latitude. We have found alternating bands of faster and slower rotation. They travel from higher latitudes towards the equator during the current solar cycle. Radio observations with high accuracy and reliability thus confirm the reality of torsional oscillations in the higher levels of the solar atmosphere.