Methods for Determining the Statistical Significance of the Observed North-South Asymmetry of the Active Regions

Abstract

Statistical studies of 2046 active regions (ARs) of the solar cycle 23 and 1507 ARs of the solar cycle 24 were carried out using the catalog of magneto-morphological classes of ARs CrAO (https://sun.crao.ru/databases/catalog-mmc-ars). All ARs, except for unipolar spots, were divided into regular (obeying the Hale's polarity law, the Joy's law and the rule of the leading sunspot dominance) and irregular ARs (all others). The study of cyclic variations showed that the ARs of each type form peaks in two maxima of the cycle in different hemispheres not simultaneously (they reach maxima sometimes in-phase, and sometimes outof-phase with a total number of sunspots). We used the normal approximation to a binomial distribution and the Pearson's χ-square test to determine the level of statistical significance of the results obtained relatively north-south asymmetry of ARs for each of the two maxima of each of the cycles for each type of ARs. In four of the eight cases studied, we found a high level of statistical significance of the observed north-south asymmetry, in one -a marginal level, which allows us to confirm the statistical significance of the observed phenomenon as a whole.