Barotropic disturbances caused by a point storm in aβ-plane ocean

Abstract

Barotropic equation for vorticity balance in theβ-plane is solved for a volume transport stream function with a northward moving wind stress torque concentrated at a point (tweak). Asymptotic techniques are applied to the solution expressed by Fourier type integrals. In the front zone (northern half from the tweak) the stream function behaves asO(¦X¦−5) whereX is a scaled eastward coordinate. In the wake, the stream function behaves asO(¦X¦−1/2) within a wedge bounded by the westward axis and a line directed SSE approximately, but behaves asO(¦X¦−5) in the rest of the half plane. On these boundaries it behaves asO(¦X¦−5/2) andO(¦X¦−1/3), respectively. East-west asymmetry is a result of asymmetry in zonal propagation of the planetary waves, which also cause the wavy pattern of the streamline in the western half of the wake. Friction is most effective in decreasing the stream function in the south to SSW sector and least effective to the west. Effect of divergence changes the wave pattern in the western half of the wake but does not change magnitude of the stream function. It is speculated that abnormal changes in daily mean sea levels observed in 1965 to 1971 along the south coast of Japan may be caused by the wake effect of moving typhoons east off Japan.