The Response of an Idealized Continental Shelf to Atmospheric Forcing
The response of continental shelf water to cooling and wind stress is investigated using a two-dimensional numerical model. The topography of the east coast continental shelf was idealized by connecting a shallow (50 m) rectangular nearshore basin to a deeper (100 m) rectangular offshore basin. Numerous cases were examined using a wide range of values for both the air•sea temperature difference and the Wind speed, although the direction of the wind was always perpendicular to the coast. The model predicts large excursions of shelf water offshore, and the subsequent surfacing of lower waters. Upwelling velocities of close to five meters per day at the shelf break were predicted by the model, but only for strong Winds which persisted for four days. Thus the results cf the model indicated that strong upwelling on the continental shelf, and at the break, can occur, but that it is both rare and intermittant. From an analysis of both the response and decay times, as well as the actual frequency of cyclonic disturbances on the east coast shelf, it is concluded that, during the winter, the continental shelf circulation is almost always in a transient state. Therefore, steady state, or close to fully developed flow, does not exist on the continental shelf most of the time.
Territorial waters, Atmospheric forcing, Continental shelf, Upwelling, Oceanography
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