Cyclic Variations of Large-Scale Solar Magnetic Fields

抄録

The global magnetic field is divided into a basic and an anomalous components. The dates when these components intersect in each solar cycle are called “equilibrium points”. It is stated that the equilibrium points determine the natural scale of magnetic cycles. The odd-zonal potential part of the field at the poles and at the equator is considered. It is shown that the anomalous part is much larger than the basic one. It is commonly believed that magnetic coupling between the solar hemispheres exists only at the minimum of the cycle. However the analysis of experimental data has shown that the coupling between the hemispheres in the epochs of maximum is as close as in the epochs of minimum. Characteristics of large-scale fields in the Sun can be determined by using the main reference points of the solar cycle. The phase of minimum of the solar cycle can be determined more precisely by using the magnetic field recurrence index and the two-dimensional correlation of the large-scale solar field. One can use indirect information on the polarity of large-scale fields to reveal a quasi- 17-year cycle. One can go further and calculate the source surface field using Ha observations. The obtained field structure proves to agree amazingly well with the characteristics obtained from Stanford magnetic measurements.