AOGCM: Ocean

The ocean component of the GEOS-5 AOGCM is the Modular Ocean Model version 4 (MOM4p1) developed at Geophysical Fluid Dynamics Laboratory (Griffies et al. 2005). It is a hydrostatic primitive equations model with a staggered Arakawa B-grid or C-grid (Mesinger and Arakawa 1976) and vertical coordinate based on depth or pressure. A tripolar grid is used to resolve the Arctic Ocean without polar filtering (Murray 1996). The model uses three level or two level time stepping scheme. The ocean surface boundary is computed as an explicit free surface with real fresh water forcing. The topography is represented as a partial bottom step to better represent topographically influenced advective and wave processes. Vertical mixing follows non-local K-profile parametrization of Large et al. (1994) and includes parametrization of tidal mixing on continental shelves. Horizontal mixing uses the isoneutral method developed by Gent and McWilliams (1990). The horizontal viscosity can use anisotropic scheme of Large et al. (2001) for better representation of equatorial currents. The exchange with marginal sea is parametrized under coarse resolution as discussed in Griffies et al (2004).