MOM-3 - The Ocean model


The oceanic component of CLIMBER-3α is the MOM 3 ocean model developed at the Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton (Pacanowski and Griffies, 1999), to which a number of new parameterisations and numerical schemes have been added (Hofmann and Morales-Maqueda, 2004).  It is a primitive equation three-dimensional oceanic general circulation model (OGCM).  It employs a staggered Arakawa B-grid (Arakawa, 1966; Bryan, 1969) with a horizontal resolution of 3.75° × 3.75° and a z-coordinate vertical discretisation with 24 variably spaced levels, ranging from 25 m thickness at the surface to ca. 500 m at depth, allowing for partial cells.

The topography is based on the 1/12° ETOPO5 dataset (National Geophysical Data Center, 1988).

One main difference with respect to previous MOM versions is the fact that MOM-3 includes a nonlinear, explicit free surface such that the ocean volume changes directly via explicit freshwater fluxes, and changes in ocean volume are directly incorporated into the tracer equations. This allows accounting for the effect of freshwater fluxes on  the ocean's buoyancy field (Griffies et al., 2000).

The penetration of shortwave radiation into the water column is taken into account as a source term for the ocean temperature following an exponential law.