Parameterization of Quasigeostrophic Eddies in Primitive Equation Ocean Models

Tréguier, Anne‐Marie; Held, Isaac M.; Larichev, Vitaly D.

doi:10.1175/1520-0485(1997)027<0567:poqeip>2.0.co;2

Cited by 234 publications

(267 citation statements)

References 32 publications

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“…constrained to transport horizontally, horizontal diffusion is more physical and should be applied (Treguier et al, 1997). This idea has been commonly taken in ocean climate model practice (e.g.…”

Section: Diabatic Boundary Layermentioning

confidence: 99%

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

et al. 2014

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Abstract. The Finite Element Sea Ice-Ocean Model (FE-SOM) is the first global ocean general circulation model based on unstructured-mesh methods that has been developed for the purpose of climate research. The advantage of unstructured-mesh models is their flexible multi-resolution modelling functionality. In this study, an overview of the main features of FESOM will be given; based on sensitivity experiments a number of specific parameter choices will be explained; and directions of future developments will be outlined. It is argued that FESOM is sufficiently mature to explore the benefits of multi-resolution climate modelling and that its applications will provide information useful for the advancement of climate modelling on unstructured meshes.

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Section: Diabatic Boundary Layermentioning

confidence: 99%

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

et al. 2014

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“…Lateral mixing is computed along isopycnal surfaces, supplemented with the Gent and Williams (1990) eddy-induced velocity parameterization (Lazar et al, 1999). The mixing coefficient of the latter depends on the baroclinic instability growth rate (Treguier et al, 1997). The upper boundary of the model is a linear free surface (Roullet and Madec, 2000).…”

Section: The Opa Modelmentioning

confidence: 99%

Geothermal heating, diapycnal mixing and the abyssal circulation

Emile‐Geay

Madec

2009

Ocean Sci.

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Abstract. The dynamical role of geothermal heating in abyssal circulation is reconsidered using three independent arguments. First, we show that a uniform geothermal heat flux close to the observed average (86.4 mW m −2 ) supplies as much heat to near-bottom water as a diapycnal mixing rate of ∼10 −4 m 2 s −1 -the canonical value thought to be responsible for the magnitude of the present-day abyssal circulation. This parity raises the possibility that geothermal heating could have a dynamical impact of the same order. Second, we estimate the magnitude of geothermally-induced circulation with the density-binning method (Walin, 1982), applied to the observed thermohaline structure of Levitus (1998). The method also allows to investigate the effect of realistic spatial variations of the flux obtained from heatflow measurements and classical theories of lithospheric cooling. It is found that a uniform heatflow forces a transformation of ∼6 Sv at σ 4 =45.90, which is of the same order as current best estimates of AABW circulation. This transformation can be thought of as the geothermal circulation in the absence of mixing and is very similar for a realistic heatflow, albeit shifted towards slightly lighter density classes. Third, we use a general ocean circulation model in global configuration to perform three sets of experiments: (1) a thermally homogenous abyssal ocean with and without uniform geothermal heating; (2) a more stratified abyssal ocean subject to (i) no geothermal heating, (ii) a constant heat flux of 86.4 mW m −2 , (iii) a realistic, spatially varying heat flux of identical global average; (3) experiments (i) and (iii) with enhanced vertical mixing at depth. Geothermal heating and diapycnal mixing are found to interact non-linearly through the density field, with geothermal heating eroding the deep stratification supporting a downward diffusive flux, while diapycnal mixing acts to map near-surface temperature gradientsCorrespondence to: J. Emile-Geay (julieneg@usc.edu) onto the bottom, thereby altering the density structure that supports a geothermal circulation. For strong vertical mixing rates, geothermal heating enhances the AABW cell by about 15% (2.5 Sv) and heats up the last 2000 m by ∼0.15 • C, reaching a maximum of by 0.3 • C in the deep North Pacific. Prescribing a realistic spatial distribution of the heat flux acts to enhance this temperature rise at mid-depth and reduce it at great depth, producing a more modest increase in overturning than in the uniform case. In all cases, however, poleward heat transport increases by ∼10% in the Southern Ocean. The three approaches converge to the conclusion that geothermal heating is an important actor of abyssal dynamics, and should no longer be neglected in oceanographic studies.

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“…However, we note that the contribution from the vertical convergence of the vertical eddy potential density flux has been found to be small in previous studies (Roberts and Marshall, 2000), and this result can be expected on theoretical grounds if the eddies are quasi-geostrophic (Treguier et al, 1997). Any errors in this approximation are then absorbed into the mean buoyancy forcing, B, evaluated as a residual of the diagnosed terms in the time-mean potential density equation.…”

Section: Evaluation Of Potential Vorticity Fluxesmentioning

confidence: 55%

Overturning cells in the Southern Ocean and subtropical gyres

Polton

Marshall

2007

Ocean Sci.

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Abstract. The circulation of the subtropical gyres can be decomposed into a horizontal recirculation along contours of constant Bernoulli potential and an overturning circulation across these contours. While the geometry and topology of Bernoulli contours is more complicated in the subtropical gyres than in the Southern Ocean, these subtropical overturning circulations are very much analogous to the overturning cell found in the Southern Ocean. This analogy is formalised through an exact integral constraint, including the rectified effects of transient eddies. The constraint can be interpreted either in terms of vertical fluxes of potential vorticity, or equivalently as an integral buoyancy budget for an imaginary fluid parcel recirculating around a closed Bernoulli contour. Under conditions of vanishing buoyancy and mechanical forcing, the constraint reduces to a generalised nonacceleration condition, under which the Eulerian-mean and eddy-induced overturning circulations exactly compensate. The terms in the integral constraint are diagnosed in an eddypermitting ocean model in both the North Pacific subtropical gyre and the Southern Ocean. The extent to which the Eulerian-mean and eddy-induced overturning circulations compensate is discussed in each case.

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Parameterization of Quasigeostrophic Eddies in Primitive Equation Ocean Models

Cited by 234 publications

References 32 publications

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

Geothermal heating, diapycnal mixing and the abyssal circulation

Overturning cells in the Southern Ocean and subtropical gyres

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