Numerical simulation of the ocean circulation

Environmental problems do not generally lend themselves to controlled experiments familiar in many laboratory sciences. In order to conduct controlled experiments in physical oceanography we frequently turn to numerical simulations of a hierarchy of complexities. With such a model we can look at the impact of changes in surface forcing, or the influence of alterations in the equations of motion. These models also find application as components in data assimilation and in coupled models.

General circulation models

These are models that solve the simplified Navier-Stokes equations (e.g. hydrostatic, Boussinesq, rigid lid, no metric terms, geologic deformation or self-gravitation) with simplified parameterizations for mixing and diffusion. Models in use at UMD include

· POSEIDON (www.scs.gmu.edu/climate/poseidon/)

· Micom/Hycom, (www.rsmas.miami.edu/groups/micom.html)

· LOAM (ocp.ldeo.columbia.edu/climategroup/loam/loam.html)

· MOM2 (www.gfdl.noaa.gov/~smg/MOM/MOM.html)

· POP1.3 (climate.lanl.gov/Models/POP/)

Simple models

A number of interesting simplifications of the equations used by GCMs are possible. These include the shallow water equations, valid for motion with fixed vertical structure and the quasi-geostrophic potential vorticity equations valid for motion that is nearly geostrophic.