Comparing the Correlations Between Solar Cycle Parameters in the Northern and Southern Hemispheres

Abstract

The correlations between the parameters of Solar Cycles 12 – 24 for the smoothed monthly mean sunspot numbers of the total [$R_{\mathrm{T}}$], northern [$R_{\mathrm{N}}$], and southern [$R_{\mathrm{S}}$] hemispheres are compared using the newly reconstructed hemispheric sunspot numbers. The main conclusions are as follows: i) the maximum amplitude [$R_{\mathrm{max}}$] is inversely correlated [$r=-0.54$] with the rise time [$T_{\mathrm{a}}$] of the cycle in the southern hemisphere [SH], while in the northern hemisphere [NH], they are positively correlated [$r=0.36$], not satisfying the Waldmeier effect; ii) the positive correlation between $R_{\mathrm{max}}$ and the preceding cycle minimum [$R_{\mathrm{min}}$] in the SH [$r=0.51$] is much stronger than that in the NH [$r=0.21$]; iii) the decay time [$T_{\mathrm{d}}$] is found to be strongly anti-correlated with $T_{\mathrm{a}}$ in the NH [$r=-0.83$], and this correlation is weaker in the SH [$r=-0.50$]; iv) the negative correlation between $R_{\mathrm{max}}$ and the cycle length [$P=T_{\mathrm{a}}+T_{\mathrm{d}}$] in the NH [$r=-0.51$] is much stronger than that in the SH [$r=-0.18$]; and v) the correlation in even-numbered cycles tends to be much stronger than in odd-numbered ones. These seem to imply that the solar activity in the northern hemisphere evolves partially differently from that in the southern hemisphere. These results might provide constraints on dynamo models in both hemispheres. However, the correlations depend on the timings of solar minima and maxima, which are related to the smoothing method.