Abstract
Assuming that the barotropic vorticity equation ∂ξ/∂t+V•∇(f+ξ)=0 is valid at the non-divergent level, the author discusses the displacement of a circular model perturbation superimposed on a basic motion and gives a generalized formula of Rossby's long wave theory.
This theory is applied to the displacement of typhoon in the subtropical zone and the author proposes a graphical forecasting method of typhoon movement.