A study of the north-south asymmetry of solar photospheric magnetic flux

Statistical characteristics of the variation of the North-South asymmetry of solar photospheric magnetic flux in 1978-2002 are systematically studied, and they are found to be related to the cycle of solar activity. The degree of the asymmetry during the minimum of solar activity is obviously higher than that during the maximum of solar activity. Moreover, the change of magnetic flux is always accompanied by a gradual shift of dominance from the northern hemisphere in the ascending phase to the southern hemisphere in the descending phase. A wavelet transform is used to make a detailed probe of possible periodicities in the variation of the North-South asymmetry.