The latitude distributions of sunspots and its North-South asymmetry

The temporal variations observed in the monthly mean latitudes of sunspot groups are studied over 1874–2010 using the data of the Greenwich Catalog and its NOAA-USEF extension. The 11-year cycle is quite clear in the temporal variations of the monthly mean latitudes of sunspot groups (i.e., of the centers of spotting) in both the northern and southern hemispheres. The North-South (N-S) asymmetry in the latitudes of sunspot groups defined as the difference between the absolute values of sunspot latitudes observed in the N and S hemispheres is compared with the N-S asymmetry in the total area of sunspot groups determined on the scales of 11 years and longer. The N-S asymmetry is interpreted as an imbalance in the hemispheres’ powers (asymmetry in the total area of sunspot groups) and as spatial imbalance (asymmetry in the latitudes of the centers of spotting). This imbalance is most clearly seen at the solar minima, i.e., in the gradual transition from one cycle to the other, when the absolute values of the asymmetries observed both in the total sunspot area and in the sunspot latitudes reach their maxima. The results obtained here can be helpful for analyses of the solar dynamo.