Wind-driven barotropic gyre I: Circulation control by eddy vorticity fluxes to an enhanced removal region
نویسنده
چکیده
It is well known that the barotropic, wind-driven, single-gyre ocean model reaches an inertiallydominated equilibriumwith unrealistic circulation strength when the explicit viscosity is reduced to realistically low values. It is shown here that the overall circulation strength can be controlled nonlocally by retaining thin regions of enhanced viscosity parameterizing the effects of increased mixing and topographic interaction near the boundaries. The control is possible even when the inertial boundary layer width is larger than the enhanced viscosity region, as eddy uxes of vorticity from the interior transportvorticity across the mean streamlinesof the inertial boundary current to the frictional region. In relatively inviscid calculations the eddies are the major means of ux across interiormean streamlines.
منابع مشابه
Eddy-mean-flow interaction in a barotropic ocean model
The role of eddies in the maintenance of idealized, antisymmetrically forced double gyres is studied using a barotropic ocean circulation model. A diagnosis in terms of q , the quasi-conserved absolute vorticity , enables an understanding of the effect of the eddies on the time-mean flow. The unstable model Gulf Stream, partitioning counter-rotating gyres, is the confluence region where q conto...
متن کاملBarotropic Impacts of Surface Friction on Eddy Kinetic Energy and Momentum Fluxes: An Alternative to the Barotropic Governor
As the surface drag is increased in a comprehensive general circulation model (GCM), the upper-level zonal winds decrease and eddy momentum flux convergence into the jet core increases. Globally averaged eddy kinetic energy decreases, a response that is inconsistent with the conventional barotropic governor mechanism whereby decreased barotropic shears encourage baroclinic wave growth. As the c...
متن کاملDispersive–Dissipative Eddy Parameterization in a Barotropic Model
Recently a new class of coarse-grained equations, known as a models, have been proposed for the mean motion of an ideal incompressible fluid. The use of one such model to represent the time-mean component of a turbulent b-plane circulation characterized by potential vorticity mixing is considered. In particular, the focus is on the wind-driven circulation in a shallow ocean basin, a problem wel...
متن کاملAn Idealized Model of Weddell Gyre Export Variability
Recent observations suggest that the export of Antarctic Bottom Water (AABW) from the Weddell Sea has a seasonal cycle in its temperature and salinity that is correlated with annual wind stress variations. This variability has been attributed to annual vertical excursions of the isopycnals in theWeddell Gyre, modifying the water properties at the depth of the Orkney Passage. Recent studies attr...
متن کاملIsentropic Slopes, Downgradient Eddy Fluxes, and the Extratropical Atmospheric Circulation Response to Tropical Tropospheric Heating
Climate change experiments run on Intergovernmental Panel on Climate Change (IPCC)–class numerical models consistently suggest that increasing concentrations of greenhouse gases will lead to a poleward shift of the midlatitude jets and their associated eddy fluxes of heat and potential vorticity (PV). Experiments run on idealized models suggest that the poleward contraction of the jets can be t...
متن کامل