The north-south asymmetry of filaments in solar cycles 16-21

In the present study, the north-south asymmetry of filaments in solar cycles 16-21 is investigated with the use of the solar filaments observed at the Observatoire de Paris, Section de Meudon from March 1919 to December 1989. Filament activity is found regularly dominated in each of cycles 16-21 in the same hemisphere as that inferred by sunspot activity, and it is found to run in a different asymmetrical behavior at different latitudinal bands, suggesting that the north-south asymmetry of filament activity should be a function of latitudes. The regularity on the north-south asymmetry of sunspot activity given by Li et al. (2002b) is demonstrated by filament activity. The periods in the north-south asymmetry of solar filament activity are 9.13, and 12.8 years without the solar cycle found.