Wind-driven barotropic gyre I: Circulation control by eddy vorticity fluxes to an enhanced removal region

Fox‐Kemper, Baylor; Pedlosky, Joseph

doi:10.1357/002224004774201681

Cited by 34 publications

(50 citation statements)

References 25 publications

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“…This is consistent with the barotropic single-gyre solutions (Fox-Kemper and Pedlosky 2004), which have no thickness fluxes. The thickness flux recirculates in the form of the large-scale, cyclonic gyre that covers the WBC/EJ region.…”

Section: Vorticity-type Componentssupporting

confidence: 89%

“…The flux maintains the global PV budget (17) by transporting PV from the boundaries into the basin interior and from one gyre to the other. In the first mechanism, PV generated on the boundary is fluxed through the viscous boundary layer by the diffusion, then it is picked up and fluxed farther away by the eddies (Fox-Kemper and Pedlosky 2004). The boundary source of PV is large when the relative vorticity has large horizontal gradient in the off-boundary direction, as it occurs here in the western basin.…”

Section: Full Time-mean Eddy Fluxesmentioning

confidence: 97%

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On dynamically consistent eddy fluxes

Berloff

2005

Dynamics of Atmospheres and Oceans

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The role of mesoscale oceanic eddies in driving the large-scale currents is studied in an eddy-resolving, double-gyre ocean model. The new diagnostic method is proposed, which is based on dynamical decomposition of the flow into the large-scale and eddy components. The method yields the time history of the eddy forcing, which can be used as additional, external forcing in the corresponding non-eddy-resolving model of the gyres. The main strength of this approach is in its dynamical consistency: the non-eddy-resolving solution driven by the eddy forcing history correctly approximates the original large-scale flow component. It is shown that statistical decompositions, which are based on space-time filtering diagnostics, are dynamically inconsistent. The diagnostics algorithm is formulated and tested, and the diagnosed eddies are analysed, both statistically and dynamically. It is argued that the main dynamic role of the eddies is to maintain the eastward-jet extension of the subtropical western boundary current. This is done largely by both the time-mean isopycnal-thickness flux and the relativevorticity eddy flux fluctuations. The fluctuations drive large-scale flow through the nonlinear rectification mechanism. The relative-vorticity flux contributes mostly to the eastward jet meandering. Finally, eddy fluxes driven by both the eddies and the large-scale flow are found to be important. The latter is typically neglected in the analysis, but here it corresponds to important large-scale feedback on the eddies. i

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Section: Vorticity-type Componentssupporting

confidence: 89%

Section: Full Time-mean Eddy Fluxesmentioning

confidence: 97%

On dynamically consistent eddy fluxes

Berloff

2005

Dynamics of Atmospheres and Oceans

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“…a viscous sublayer), as eddies flux PV into the high friction boundary layer, where it can be dissipated more effectively. Fox-Kemper and Pedlosky (2004) illustrate that inertia and friction can co-exist effectively in a balanced gyre circulation, and that friction is necessary even in a strongly inertial system.…”

Section: Introductionmentioning

confidence: 89%

“…As discussed in Fox- Kemper and Pedlosky (2004), in ocean models with constant viscosity, if the inertial boundary layer is larger than the frictional boundary layer, i.e. the advection of PV is stronger than the dissipation of PV, the inertial boundary layer expands until it fills the entire domain.…”

Section: Introductionmentioning

confidence: 99%

“…the advection of PV is stronger than the dissipation of PV, the inertial boundary layer expands until it fills the entire domain. Fox-Kemper and Pedlosky (2004) overcame this "inertial runaway" solution by increasing the viscosity at the western boundary, to represent unresolved boundary dissipation and interaction with topography. In their model, realistic barotropic gyre strengths can be achieved even when the viscous boundary layer is smaller than the inertial boundary layer (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of North Atlantic western boundary currents

Bras¹,

Isabela²

2017

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The Gulf Stream and Deep Western Boundary Current (DWBC) shape the distribution of heat and carbon in the North Atlantic, with consequences for global climate. This thesis employs a combination of theory, observations and models to probe the dynamics of these two western boundary currents.First, to diagnose the dynamical balance of the Gulf Stream, a depth-averaged vorticity budget framework is developed. This framework is applied to observations and a state estimate in the subtropical North Atlantic. Budget terms indicate a primary balance of vorticity between wind stress forcing and dissipation, and that the Gulf Stream has a significant inertial component.The next chapter weighs in on an ongoing debate over how the deep ocean is filled with water from high latitude sources. Measurements of the DWBC at Line W, on the continental slope southeast of New England, reveal water mass changes that are consistent with changes in the Labrador Sea, one of the sources of deep water thousands of kilometers upstream. Coherent patterns of change are also found along the path of the DWBC. These changes are consistent with an advective-diffusive model, which is used to quantify transit time distributions between the Labrador Sea and Line W. Advection and stirring are both found to play leading order roles in the propagation of water mass anomalies in the DWBC.The final study brings the two currents together in a quasi-geostrophic process model, focusing on the interaction between the Gulf Stream's northern recirculation gyre and the continental slope along which the DWBC travels. We demonstrate that the continental slope restricts the extent of the recirculation gyre and alters its forcing mechanisms. The recirculation gyre can also merge with the DWBC at depth, and its adjustment is associated with eddy fluxes that stir the DWBC with the interior. This thesis provides a quantitative description of the structure of the overturning circulation in the western North Atlantic, which is an important step towards understanding its role in the climate system.

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Adaptive volume penalization for ocean modeling

2012

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The development of various volume penalization techniques for use in modeling topographical features in the ocean is the focus of this paper. Due to the complicated geometry inherent in ocean boundaries, the stair-step representation used in the majority of current global ocean circulation models causes accuracy and numerical stability problems. Brinkman penalization is the basis for the methods developed here and is a numerical technique used to enforce no-slip boundary conditions through the addition of a term to the governing equations. The second aspect to this proposed approach is that all governing equations are solved on a nonuniform, adaptive grid through the use of the adaptive wavelet collocation method. This method solves the governing equations on temporally and spatially varying meshes, which allows higher effective resolution to be obtained with less computational cost. When penalization methods are coupled with the adaptive wavelet collocation method, the flow near the boundary can be well-resolved. It is especially useful for simulations of boundary currents and tsunamis, where flow near the boundary is important. This paper will give a thorough analysis of these methods applied to the shallow water equations, as well as some preliminary work applying these methods to volume penalization for bathymetry representation for use in either the nonhydrostatic or hydrostatic primitive equations.

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Wind-driven barotropic gyre I: Circulation control by eddy vorticity fluxes to an enhanced removal region

Cited by 34 publications

References 25 publications

On dynamically consistent eddy fluxes

On dynamically consistent eddy fluxes

Dynamics of North Atlantic western boundary currents

Adaptive volume penalization for ocean modeling

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