SCALE-RELATED ASPECTS OF NESTED FINITE-DIFFERENCE OCEAN MODELS

We describe a fully nonlinear wind-forced nested ocean model. The mode l has been configured for both the Greenland-Iceland-Norwegian (GW) Se a, an open ocean basin, and the Mediterranean Sea, a semienclosed basi n. Prescribed nested boundary conditions are corrected with a mixed Or lanski/Flather-type radiation of the difference between the two numeri cal solutions. A second correction can then be made to restore conserv ation of desired properties across the grid interface. The nested expe riments have produced multiyear simulations in good agreement with the basin-wide model. The differences between the basin-wide and the limi ted-area solutions are related, in part, to the different scales prese nt in the respective numerical solutions. We attribute our ability to produce realistic year long limited-area nested simulations to a reduc tion of these scale-related modeling differences, including reducing t he effects of aliasing between the two grids.