On a Wind-Driven, Double-Gyre, Quasi-Geostrophic Ocean Model: Numerical Simulations and Structural Analysis

Shen, Jie; Medjo, T. Tachim; Wang, S.

doi:10.1006/jcph.1999.6344

Cited by 26 publications

(14 citation statements)

References 30 publications

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“…Along a similar line of research, Maddison et al [14] used refined numerical grids to investigate the effect of potential vorticity fluxes on the dynamics of the double-gyre system by decomposing eddy potential vorticity fluxes into divergent and rotational components. Another example of highfidelity simulations for the double-gyre problem can be found in [15] which applied highorder spectral elements for numerical accuracy.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Fast spectral solutions of the double-gyre problem in a turbulent flow regime

Naghibi

Karabasov

Jalali

et al. 2019

Applied Mathematical Modelling

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Several semi-analytical models are considered for a double-gyre problem in a turbulent flow regime for which a reference fully numerical eddy-resolving solution is obtained. The semianalytical models correspond to solving the depth-averaged Navier-Stokes equations using the spectral Galerkin approach. The robustness of the linear and Smagorinsky eddy-viscosity models for turbulent diffusion approximation is investigated. To capture essential properties of the double-gyre configuration, such as the integral kinetic energy, the integral angular momentum, and the jet mean-flow distribution, an improved semi-analytical model is suggested that is inspired by the idea of scale decomposition between the jet and the surrounding flow.

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Section: Accepted Manuscriptmentioning

confidence: 99%

Fast spectral solutions of the double-gyre problem in a turbulent flow regime

Naghibi

Karabasov

Jalali

et al. 2019

Applied Mathematical Modelling

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“…Although forced by a steady wind, such a model configuration is not stationary for this viscosity value, as circulation is characterized by an oscillating behavior with formation of smaller scale vortices and shifting of main current patterns. In fact, DG circulation shows a bifurcation (Shen et al, 1999), identified by a critical value of the Reynolds number: for values lower than it, the flow converges quickly to an unique steady state solution, which is 10 structurally stable, while above that value, instabilities occur and the symmetry of the structure between sub-polar and sub-tropical cells is broken. The vertical turbulent mixing is parameterized by coefficients of vertical viscosity and diffusion of 1 m 2 /s; a linear bottom friction is introduced with a coefficient of bottom drag of 8x10 -7 m/s.…”

Section: The Twin Model Experimentsmentioning

confidence: 99%

Sampling strategies based on the Singular Value Decomposition for ocean analysis and forecast

Fattorini

Brandini

2018

Preprint

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Abstract. In this article we discuss some possible optimal sampling strategies for a simplified ocean model, used as a preliminary tool to understand the observation needs for real analysis and forecasting systems. Indeed, observations are mostly useful for improving the reliability of forecasting models, which require upstream an analysis model in which Data Assimilation techniques are used. In addition, observation networks and in particular in-situ networks are expensive and require careful positioning of a limited number of observation instruments. As in other literature studies, the Singular Value Decomposition has been adopted, which has many advantages, especially when we dispose of a variational assimilation method like the 4D-Var, also because the calculation of Singular Vectors and Singular Values is linked to the availability of tangent linear and adjoint models. SVD has been adopted here as a method for identifying areas where maximum error growth occurs, within which sampling gives particular advantages. However, a SVD-based sampling strategy may not be unique, and we need to introduce other criteria, based on the correlation between points, since the information observed on neighbouring points can be redundant. The criteria adopted are easily replicable in practical applications, and require rather standard studies to obtain prior information (for example, climatological and correlation studies), to be carried out in order to properly design observation networks.

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“…[20]) with an implicit treatment of the rotational term to avoid stability constraint by the strong rotation, one need to solve, at each time step, the following system of two secondorder equations:…”

Section: Problems With Variable Coefficients In One Directionmentioning

confidence: 99%