S. Danilov, S. Juricke, A. Kutsenko, and M. Oliver
Toward consistent subgrid momentum closures in ocean models,
in: C. Eden and A. Iske, eds.,
"Energy Transfers in Atmosphere and Ocean", pp. 145-192, Springer-Verlag, 2019.
Abstract:
State-of-the-art global ocean circulation models used in
climate studies are only passing the edge of becoming "eddy
permitting" or barely eddy resolving. Such models commonly suffer
from over-dissipation of mesoscale eddies by routinely used subgrid
dissipation (viscosity) operators and a resulting depletion of energy
in the large-scale structures which are crucial for draining available
potential energy into kinetic energy. More broadly, subgrid momentum
closures may lead to both overdissipation or pile up of eddy kinetic
energy and enstrophy of the smallest resolvable scales.
The aim of this chapter is two-fold. First, it reviews the theory of
two-dimensional and geostrophic turbulence. To a large part, this is
textbook material with particular emphasis, however, on issues
relevant to modeling the global ocean in the eddy permitting regime.
Second, we discuss several recent parameterizations of subgrid
dynamics, including simplified backscatter schemes by Jansen and Held,
stochastic superparameterizations by Grooms and Majda, and an
empirical backscatter scheme by Mana and Zanna.
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