Polarity Imbalance of the Photospheric Magnetic Field

The polarity sign imbalance of the photospheric magnetic field is examined using synoptic maps produced by the Kitt Peak National Solar Observatory (NSO) (1976 - 2016). An imbalance of fluxes with opposite sign polarities is analyzed for a field strength B >50 G in the sunspot zone at latitudes 5^∘-40^∘ and for a field strength B <50 G at higher latitudes 40^∘-90^∘. A 22-year periodicity in the imbalance of positive and negative fluxes is found; this periodicity is maintained during four solar cycles. While for the sunspot zone the sign of the imbalance always agrees with the polarity sign of the northern hemisphere polar field, for the high latitudes the sign of the imbalance always agrees with the polarity sign of the southern hemisphere polar field. A good agreement of the imbalance of high-latitude fields with the quadrupole moment of the photospheric magnetic field g₂₀ is observed and also holds for the low-latitude fields, but with a reversed sign, i.e.−g₂₀. The polarity sign imbalance of the sunspot zone correlates with the Sun's mean magnetic field on the one hand, and with the sector structure of the heliospheric magnetic field on the other. The obtained results clearly show the interconnection of the magnetic fields in the activity zone with the Sun's polar magnetic field. The weakest fields B <5 G represent quite a special group, with the magnetic flux developing in antiphase to the fluxes of the stronger fields.