Modelling Bottom Stress in Depth-Averaged Flows
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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The relationship between depth-averaged velocity and bottom stress for wind-driven flow in unstratified coastal waters is examined here. The adequacy of traditional linear and quadratic drag laws is addressed by comparison with a 2 12-D model. A 2 12-D model is one which a simplified 1-D depth-resolving model DRM is used to provide an estimate of the relationship between the flow and bottom stress at each grid point of a depth-averaged model DAM. Bottom stress information is passed from the DRM to the DAM in the form of drag tensor with two components one which scales the flow and one which rotates it. This eliminates the problem of traditional drag laws requiring the flow and bottom stress to be collinear. In addition, the drag tensor field is updated periodically so that the relationship between the velocity and bottom stress can be time-dependent. However, simplifications in the 2 12-D model that render it computationally efficient also impose restrictions on the time-scale of resolvable processes. Basically, they must be much longer than the vertical diffusion time scale. Keywords Theses Bottom stress Wind driven Circulation.
- Physical and Dynamic Oceanography