Interaction of Binary Tropical Cyclones of the Western North Pacific Ocean

Fifteen years of typhoon data (1953–67) were evaluated to determine the general character of the “Fuji-whara effect” with respect to the separation distance between two interacting tropical cyclones. The results show that the rotation of the binary system is sharply dependent upon separation distance for distances <750 n mi. There appears also to be a slight attraction between the two vortex systems, which becomes well defined at separation distances <400 n mi. The results are compared with theoretical rotation rates for vortex systems with varying velocity profiles.