A spectral filtering procedure for eddy-resolving simulations with a spectral element ocean model (Q1375507)

We introduce a filtering procedure designed to control the growth of nonlinear instabilities in the spectral element solution of nonlinear oceanic flows. The procedure involves two separate steps. First, a spectral filter is applied to the vorticity and divergence fields to damp oscillations in high-gradient regions and to restore spectral accuracy away from them. Second, the associated velocity field is computed from a set of Poisson equations, and its boundary conditions and interelement continuity are restored. The behavior of the filter is investigated numerically on the canonical problem of the double-gyre wind-driven cirulation in a rectangular basin using a spectral element shallow water model.