Secular cycle of the north-south solar asymmetry
  The North-South asymmetry of solar activity has been recognized for different solar phenomena. Following Waldmeier, it is now assumed that solar activity dominates in the Northern solar hemisphere during the ascending part of the secular solar cycle, in the Southern one during the descending part, and in epochs of secular minima and maxima the asymmetry is small. The episodes when this rule does not hold (the Maunder minimum in the end of the 17th century, and 19th and 20th solar cycles in the 20th century secular maximum) are considered as "anomalies". Analyzing solar activity influence on climate, we come to the conclusion that the asymmetry differs not in the ascending and descending parts of the secular solar cycles, but in consecutive secular cycles. This hypothesis is in agreement with all available data and leaves no anomalies. 
K.Georgieva, B.Kirov