Positive and Negative Photospheric Fields in Solar Cycles 21–24

Abstract

Distribution of the positive and negative photospheric fields is studied on the base of synoptic maps of the photospheric magnetic field produced by the National Solar Observatory Kitt Peak (NSO Kitt Peak) for 1976-2016. In the analysis only the sign of the field irrespective of its strength is taken into account, emphasizing the role of the fields with average and weak strengths. Time changes in the positive and negative magnetic fields for two hemispheres, for the high latitudes and for the sunspot zone as well as their imbalances are considered. Distributions of fields of opposite polarities, which are defined mostly by the fields of the high latitudes, change with a 22-year cycle. The polarity imbalance in each hemisphere is closely connected with the dipole moment $g_{10}$. The imbalance of high latitudes for two hemispheres changes with the 22-year period and coincides with the sign of both the polar field in the southern hemisphere, and the quadrupole moment $g_{20}$. For the magnetic fields of the sunspot zone during ~75% of time a connection of the magnetic field imbalance with the quadrupole moment taken with the reversed sign $- g_{20}$ and with the sign of the polar field in the northern hemisphere is observed. The received results testify to cyclic changes in the polarity imbalance.