North-south asymmetry in solar activity: Predicting the amplitude of the next solar cycle

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. © 2007 The Author. Journal compilation © 2007 RAS.