Response of a two-layer ocean with a baroclinic current to a moving storm, part II - Non-geostrophic baroclinic mode

Abstract

A circular storm moves with a constant speed c along a geostrophic flow similar to a western boundary current in the upper layer of a two-layer ocean with the motionless lower layer. The linear inertia terms are retained. Effects of the current becomes more conspicuous for smaller c and insignificant for c above 10 m s-1. The inertia effects are manifested in cellular patterns of the interface perturbations with cell lengths of π(c-vf-1 in a wake of the storm with a radius of an order of 100 km, where v is the current velocity. On the left hand edge where the flow has a strong shear, the interface displacements have large amplitudes which increase with a distance along the path in a wake of the storm. These disturbances propagate to the left of the edge within an angle of cot-1 (c2/gεH0-1), where gε is the reduced gravity and H0 is the depth of the interface at the edge of the current. Comparison with the observations during Typhoon Trix in 1971 south of Japan suggests that fluctuations of the daily mean sea level with several days' periods observed along the southern coast of Japan may be due to the stationary oscillations of the Kuroshio caused by the inertia undulations along its left edge or due to the propagating perturbations to the left. © 1977 Oceanographical Society of Japan.