tokens: In contrast, for cycle 22, the south dominates over the north for small sunspots, but gradually the difference minimizes as we reach toward larger sunspots. Though, we must emphasize that there are cycles for which we do not see any large change in the two hemispheres for any sunspot size range. Cycles 16, 17, and 23 are examples of such cases. In order to quantify the asymmetry between the two hemispheres, we use the “north–south asymmetry index” ( A ns ) as ( S an - S as )/( S an + S as ), where S an and S as are the yearly averaged sunspot area values for the northern and the southern hemispheres, respectively. We plot the time variation of A ns for different sunspot sizes in different panels of Figure 4 . At a first glance, we notice that the variation of A ns is very smooth for the smallest sunspot sizes (Figure 4 (b)), as compared to any other size range (Figures 4 (c)–(f)). This can be understood from the definition of A ns , which varies between ±1, depending upon the presence of at least one single sunspot in any of the hemispheres and absence of any spot in the other hemisphere. Since the smaller sunspots occur more frequently at the time of solar minima compared to the appearance of a large sunspot, the variation of A ns is relatively smoother in the former case. We also notice (from Figure 4 (a)) that at the maximum phase of cycle 21, A ns , has values very close to zero as in the case of cycle 23. However, at the cycle 22 maximum, A ns attains a maximum value of ≈−0.5. This is consistent with the results as obtained by Javaraiah ( 2005 ). This scenario changes a little as we move from small to large sunspot sizes. There is a hint of long-term variation in the asymmetry index. For the largest-sized sunspots (Figure 4 (f)), the northern hemisphere dominates in the cycle minima until cycle 20, after which the southern hemisphere dominates. This trend is also visible in Figure 4 (e). Figure 4. Time evolution of the asymmetry index, A ns , for corresponding sunspot sizes. 3.3.1. Periodicities in the N–S Asymmetry Since the solar cycle has a dominant period of 11 years, it is expected that the N–S asymmetry index will also have some periodicity. There has been a lot of work done in order to probe this periodicity (Carbonell et al. 1993 ; Ballester et al. 2005 ; Chang 2009 ; Javaraiah 2015 ; Ravindra Javaraiah 2015 ). Here, we revisit the periodicity in the N–S asymmetry for different sunspot sizes. We use the A ns curves, shown in different panels in Figure 4 , and the wavelet analysis in order to obtain the periodicities in A ns . Results of the wavelet analysis on the different A ns curves is shown in Figure 5 . The global wavelet power (time-averaged power as shown in the “wavelet power spectrum panel”) is calculated along with a significance level of 90%. This significance level is obtained for the white noise (Torrence Compo 1998 ), and contours are overplotted on top of the wavelet spectrum in order to highlight the region
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