Wind-Induced Circulation in Semienclosed Homogeneous, Rotating Basins

Abstract

The wind-induced circulation over laterally varying bathymetry was investigated in homogeneous systems using the three-dimensional Regional Ocean Model System (ROMS). The investigation focused on the influence of the earth?s rotation on the lateral distribution of the flow, with particular emphasis on the transverse circulation. Along-basin wind stress with no rotation caused a circulation dominated by an axially symmetric transverse structure consisting of downwind flow over the shoals and upwind flow in the channel along the whole domain. Transverse circulation was important only at the head of the system where the water sank and reversed direction to move toward the mouth. The wind-induced flow pattern under the effects of the earth?s rotation depended on the ratio of the maximum basin?s depth h to the Ekman depth d. The solution tended to that described in a nonrotating system as h/d remained equal to or below 1. For higher values of h/d, the longitudinal flow was axially asymmetric. Maximum downwind flow was located over the right shoal (in the Northern Hemisphere, looking downwind). The transverse component of velocity described three gyres. The main gyre was clockwise (looking downwind) and occupied the entire basin cross section, as expected from the earth?s rotation and the presence of channel walls. The other two gyres were small and localized and were linked to the lateral distribution of the along-channel velocity component, which in turn was dictated by bathymetry. These results compared favorably with a limited set of observations and are expected to motivate future measurements.