A Study of the Periodic Variations of Solar Magnetic Fields During Maxima and Minima of Solar Activity

By using the solar magnetic field data of Wilcox Observatory from 1975 to 2010, the short-time periodicities of solar mean magnetic fields during solar maximum and minimum years are analyzed. The results reveal that the solar magnetic fields mainly exhibit the approximate periods of 9 d, 13 d, and 27 d. During maximal solar activity the period about 27 d is most conspicuous, while during minimal solar activity the most evident period is approximately 13.5 d (except the solar minimum in the years 1984-1986). These results imply that solar active regions exhibit evidently different distributions in the periods of maxima and minima of solar activity.