Fluid Dynamics in Earth and Planetary Sciences (FDEPS) Second FDEPS Workshop Dec 04 - Dec 08, 2000 Graduate School of Mathematical Sciences, University of Tokyo
Various aspects of "eddy" parameterization in ocean general circulation
HASUMI, Hiroyasu (Center for Climate System Research, University of Tokyo)
In ocean general circulation modeling, where numerical models are applied to simulate the world ocean circulation, the current achievable resolution to integrate the model for the time scale of the oceanic thermal response is about 1 degree in horizontal and 100 meters in vertical. Transport and mixing processes associated with the unresolved "eddy" motions must be parameterized in some way, if they play significant roles in forming the ocean general circulation. The "eddy" motions to be parameterized, such as mesoscale eddies and gravity waves, span broad spectra in time and space, and different approaches have to be taken for different aspects of the "eddy" processes, such as the sea surface mixed layer, the bottom boundary layer, or the interior region mixing. In addition, since there's virtually no heat source associated with radiation, phase transition, or chemical reaction in the oceanic interior, it is not too much to say that the quality of the modeling depends on how to parameterize the "eddy" motions. This talk provides a brief review of the methods adopted in the present-day ocean general circulation models and discuss the problems and future developments of the parameterizations.