Giant longitude zones on the sun

Regularities in the longitudinal distribution of high-flare-activity active regions during 1964–1979 have been examined. The Fourier spectrum for each 30°-wide longitude strip in northern and southern hemispheres has been obtained. It is seen that there exist two giant longitude zones in each hemisphere and solar activity remains concentrated in one of the giant zones. It also appears that the leading edge of a giant zone is more active as compared to its following edge.