Cycle Dependence of Hemispheric Activity

Data of daily hemispheric Sunspot numbers are analyzed including the time span 1975-2001. The study of north-south asymmetries concerning solar activity and rotational behaviors is in particular relevant, as it is related to the solar dynamo and the generation of magnetic fields. As diagnostic tools we use wavelets and autocorrelation functions in combination with statistical significance tests that are applied separately for the to the northern and southern hemisphere. Pronounced differences between the northern hemisphere shows a rigid rotation of ~27 days which can be followed up to 15 periods in the autocorrelation function. The signal of the southern hemisphere is strongly attenuated after 3 recurrences showing variable periods in the range ~26-28.5 days. The presence of these periods is not permanent during a cycle suggesting activity pulses in each hemisphere. For the northern hemisphere strong relations to the motion of deeper lying convective structures building up long-living 'active zones' are suggested.