Cyclic Variations of the Polarity of the Photospheric Magnetic Field

The distribution of magnetic fields of positive and negative polarities over the Sun's surface has been studied. Synoptic maps of the photospheric magnetic field (NSO Kitt Peak, 1978-2016) were used as the initial data. The latitude-time diagram for weak magnetic fields (B <= 5 G) clearly shows tilted bands, which indicate the alternate dominance of magnetic fields with positive or negative polarity drifting towards the Sun's poles. The analysis of the latitude-time diagram using the method of empirical orthogonal functions (EOFs) made it possible to reveal a cyclic variation of the polarity of magnetic field fluxes with a period of 1-3 years, which indicates a possible relation to quasi-biennial oscillations. Similar values of the periods were obtained by latitudinal averaging of the latitude-time diagram.