Effect of wave‐current interaction on wind‐driven circulation in narrow, shallow embayments

Abstract

The effect of wind waves on the steady wind‐driven circulation in a narrow, shallow bay is investigated with a two‐dimensional ( y , z ) circulation model and the Grant and Madsen [1979] bottom‐boundary layer model, which includes wave‐current interaction. A constant wind stress is applied in the along‐channel x direction to a channel with a constant cross‐sectional profile h ( y ). The wind‐induced flushing of shallow bays is shown to be sensitive to both the shape of the cross section and the effects of surface waves. The flushing increases with increasing , where h ′ is the standard deviation of cross‐channel depth and is the mean depth. This is consistent with the findings of Hearn et al. [1987]. The flushing decreases, however, with the inclusion of surface wave effects which act to increase the bottom drag felt by the currents. Increasing effective bottom friction reduces the strength of the circulation, while the along‐bay surface slope, bottom stress and the structure of current profiles remain nearly unchanged. An implication of the circulation dependence on wave‐current interaction is that low‐frequency oscillatory winds may drive a mean circulation when the wave field changes with wind direction.