North–south asymmetry in solar activity: predicting the amplitude of the next solar cycle

Abstract

Abstract Using Greenwich and Solar Optical Observing Network sunspot group data obtained during the period 1874–2005, we find that the sums of the areas of the sunspot groups in the 0°–10° latitude-interval of the Sun's northern hemisphere and in the time-interval of −1.35 yr to +2.15 yr from the time of the preceding minimum – and in the same latitude interval of the southern hemisphere but +1.0 yr to +1.75 yr from the time of the maximum – of a sunspot cycle correlate well with the amplitude (maximum of the smoothed monthly sunspot number) of its immediate following cycle. Using this relationship it is possible to predict the amplitude of a sunspot cycle about 9–13 yr in advance. We predicted 74 ± 10 for the amplitude of the upcoming cycle 24. Variations in solar meridional flows during solar cycles and 9–16 yr variations in solar equatorial rotations may be responsible for the aforementioned relationship, which seems to be related to the 22-yr solar magnetic cycle.