Positive and Negative Photospheric Fields in Solar Cycles 21–24
The distribution of positive and negative photospheric fields is considered based on the synoptic maps of the photospheric magnetic field from the National Solar Observatory/Kitt Peak (NSO Kitt Peak) for 1976–2016. The analysis took into account only the sign of the field regardless of its strength, which underlined the role of the fields with medium and weak magnitudes. We considered the time variations in positive and negative magnetic fields, as well as their imbalances, for two hemispheres, for high latitudes, and for the sunspot zone. The distributions of the fields of different polarity are mainly conditioned by the high-latitude fields and vary with a 22-year cycle. The imbalance of polarities within a separate hemisphere is closely associated with the variations in the dipole moment g10. The high-latitude imbalance for two hemispheres varies with a 22-year period; its sign coincides with the polar field in the southern hemisphere and with the quadrupole moment g20. For the fields in the sunspot zone, the relation of the magnetic field imbalance to the quadrupole moment (–g20) and to the sign of the polar field in the northern hemisphere is observed ~75% of the time. The results show the evidence for cyclic variations in the imbalance of polarities.
The NSO/Kitt Peak data used here are produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL. This work utilizes the SOLIS data obtained by the NSO Integrated Synoptic Program (NISP), managed by the National Solar Observatory. The Wilcox Solar Observatory data used in this study were obtained via the website http://wso.stanford.edu courtesy of J.T. Hoeksema.
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