Formulation of an ocean model for global climate simulations

[摘要] This paper summarizes the formulation of the ocean component to theGeophysical Fluid Dynamics Laboratory's (GFDL) climate model used forthe 4th IPCC Assessment (AR4) of global climate change.Inparticular, it reviews the numerical schemes and physicalparameterizations that make up an ocean climate model and how theseschemes are pieced together for use in a state-of-the-art climatemodel.Features of the model described here include the following:(1) tripolar grid to resolve the Arctic Ocean without polar filtering,(2) partial bottom step representation of topography to betterrepresent topographically influenced advective and wave processes, (3)more accurate equation of state, (4) three-dimensional flux limitedtracer advection to reduce overshoots and undershoots, (5)incorporation of regional climatological variability in shortwavepenetration, (6) neutral physics parameterization for representationof the pathways of tracer transport, (7) staggered time stepping fortracer conservation and numerical efficiency, (8) anisotropichorizontal viscosities for representation of equatorial currents, (9)parameterization of exchange with marginal seas, (10) incorporation ofa free surface that accomodates a dynamic ice model and wavepropagation, (11) transport of water across the ocean free surface toeliminate unphysical ``virtual tracer flux" methods, (12)parameterization of tidal mixing on continental shelves. We alsopresent preliminary analyses of two particularly importantsensitivities isolated during the development process, namely thedetails of how parameterized subgridscale eddies transport momentumand tracers.

[学科分类] 海洋学与技术