Solar Differential Rotation at the Moment of Polarity Reversal of the Solar Magnetic Field.

Variations in the solar differential rotation have been studied at the moment of the polarity reversal of the sun's general magnetic field in solar activity cycles 20 and 21. Data on Hα filaments obtained at the Abastumani Astrophysical Observatory and on compact magnetic features from an atlas of synoptic charts were used. Before and after a single polarity reversal of the solar magnetic field (cycle 21), a higher rotation rate was observed for compact magnetic features with the polarity of the circumpolar magnetic field than for the oppositely polarized features. In the case of a triple polarity reversal of the solar magnetic field (cycle 20), this pattern was disturbed. The variations in the rotation rate of compact magnetic features with both negative and positive polarities differ from the rotation rates of hydrogen filaments at times when the solar general magnetic field undergoes a polarity reversal. [ABSTRACT FROM AUTHOR]