Numerical Study of Shallow-Water Island Wake

Changming Dong and James McWilliams
IGPP, University of California at Los Angeles

In terms of the vorticity generation mechanisms, there are two types of island wakes: deep-water and shallow-water. In the former one, the lateral friction boundary is the source of the vorticity and for the latter, the bottom friction is the primary source of the vorticity. We extend our previous study on the stratified and rotating deep water wake to the shallow-water one. With the existence of the shelf slope, internal Froude number is the controlling non-dimensional parameter determining if the current flows over or around the island shelf, which leads to different effective island diameters. In the basic experiment, the vorticity generation in the shallow water wake is analyzed. A series of numerical experiments are performed to test the sensitivity of shallow-water island wake to non-dimensional parameters, such as Ekman number, Burger number and Rossby number. The studies are applied to the real island wakes in the Southern California Bight.