Intergyre transport in a wind-driven, quasigeostrophic double gyre: An application of lobe dynamics

Coulliette, Chad; Wiggins, Stephen

doi:10.5194/npg-8-69-2001

Cited by 66 publications

(88 citation statements)

References 19 publications

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“…Within a realistic range, the effect is still moderate and probably counterbalanced by the presence of total or partial slip at the western boundary (JJG), which tends to concentrate and reinforce the recirculation dipole. For high Reynolds numbers (Berloff and McWilliams, 1999;Simonnet et al, 2003bSimonnet et al, , 2005, the role of eddy diffusion (Berloff and McWilliams, 2002a, 2003 may be comparable to, or greater than, that of chaotic mixing (Yang and Liu, 1994;Yang, 1996;Coulliette and Wiggins, 2000). Thus localized sub-and superdiffusive mixing could be present in different parts of the flow domain; see also Huber et al (2001) for a discussion of these topics in the atmosphere.…”

Section: Discussionmentioning

confidence: 99%

Spatio‐temporal variability in a mid‐latitude ocean basin subject to periodic wind forcing

2007

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The mid-latitude ocean's response to time-dependent zonal wind-stress forcing is studied using a reduced-gravity, 1.5-layer, shallow-water IntroductionThe wind-driven, basin-scale circulation in the mid-latitude upper ocean exhibits variability on different time scales. This variability could be due to changes in the external atmospheric forcing or to the system's intrinsic instability and nonlinearity. The latter explanation was first put forward by Veronis (1963Veronis ( , 1966, but the former has enjoyed greater popularity in the oceanographic community until fairly recently. A systematic application of the methods of dynamical systems theory to the wind-driven circulation problem has yielded several physical mechanisms for the observed lowfrequency variability, on the time scale of several months to several years . This circulation has been studied in the last decade with a hierarchy of models that include rectangular-basin, as well as more realistic configurations. Pedlosky (1996) reviewed work that used time-independent, single-gyre forcing. Single-gyre results of particular interest since then include Berloff's (1997a, 1997b) work that emphasizes the role of basin size in this problem, and Sheremet et al.'s (1997) classification of instabilities for the single gyre. Chang et al. (2001) reviewed double-gyre results and compared the physical mechanisms for intrinsic variability found in this case with those obtained in the single-gyre problem. We only review here, therefore, the results that are most relevant to the present work. These emphasize the double-gyre problem. Jiang et al. (1995; JJG hereafter) studied the double-gyre wind-driven circulation in a mid-latitude rectangular basin on a β-plane using a 1.5-layer, reduced-gravity, shallow-water (SW) model. They used a time-constant zonal-wind profile, symmetric about the basin's mid-latitude axis. Their results showed that when non-linear processes come into play, multiple steady state solutions satisfying identical boundary conditions can arise for sufficiently strong wind-stress forcing. Two stable solutions were found to co-exist over a certain range of parameters. One had a stronger subpolar gyre and the other a stronger subtropical gyre, with overshooting of the western boundary currents to the north and south of the symmetry axis, respectively. Their periodic solutions had periods of several years and several weeks. Following JJG, Speich et al. (1995) analyzed the dependence of the stationary solutions on the SW model's nondimensional parameters such as the amplitude of the forcing, the Ekman number, the Rossby number, the non-dimensional β parameter, and the bottom drag coefficient. Using pseudo-

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Section: Discussionmentioning

confidence: 99%

Spatio‐temporal variability in a mid‐latitude ocean basin subject to periodic wind forcing

2007

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“…(A.8) can be recast in the form of a functional equation 9) which shows that, if exists, a solution of (A.8) is a fixed point of the map F. We want to argue that F indeed admits a fixed point (unique for fixed z s and t s ) when viewed as a map on an appropriate function space. Using the norm…”

Section: A4 Existence Of W Smentioning

confidence: 99%

“…A large body of literature has been developed on the statistical evaluation of Lagrangian dynamics from two-dimensional velocity data (see [37] for a survey). More recently, several numerical studies have been aimed at understanding the geometry of Lagrangian coherent structures in specific two-dimensional data sets (see, e.g., [9,30,35,34]). A theoretical approach to finite-time invariant manifolds (material lines) has been developed in [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Distinguished material surfaces and coherent structures in three-dimensional fluid flows

Haller

2001

Physica D: Nonlinear Phenomena

745

587

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We prove analytic criteria for the existence of finite-time attracting and repelling material surfaces and lines in threedimensional unsteady flows. The longest lived such structures define coherent structures in a Lagrangian sense. Our existence criteria involve the invariants of the velocity gradient tensor along fluid trajectories. An alternative approach to coherent structures is shown to lead to their characterization as local maximizers of the largest finite-time Lyapunov exponent field computed directly from particle paths. Both approaches provide effective tools for extracting distinguished Lagrangian structures from three-dimensional velocity data. We illustrate the results on steady and unsteady ABC-type flows.

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“…This observation inspires us to understand and predict different evolution patterns of a fluid parcel, depending on its initial location and time of release. Such patterns are known to be delineated by repelling material lines or finite-time stable manifolds [16,17,18,19,20,21]. Here we shall use a recently developed nonlinear technique, Direct Lyapunov Exponent [6] (DLE) analysis, which identifies repelling or attracting material lines in velocity data as local maximizing curves of material stretching.…”

Section: Numerical Experimentsmentioning

confidence: 99%

Lagrangian Structures in Very High-Frequency Radar Data and Optimal Pollution Timing

Lekien¹

2003

AIP Conference Proceedings

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Abstract. Very High-frequency (VHF) radar technology produces detailed surface velocity maps near the surface of coastal waters. The use of measured velocity data in environmental prediction, however, has remained unexplored. In this paper, we uncover a striking flow structure in coastal radar observations along the coast of Florida. This structure governs the spread of organic contaminants or passive drifters released in the area. We compute the Lyapunov exponents of the VHF radar data to determine optimal release windows in which contaminants are advected efficiently away from the coast and we show that a VHF radar-based pollution release scheme using the hidden flow structure reduces the effect of industrial pollution in the coastal environment.

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Intergyre transport in a wind-driven, quasigeostrophic double gyre: An application of lobe dynamics

Cited by 66 publications

References 19 publications

Spatio‐temporal variability in a mid‐latitude ocean basin subject to periodic wind forcing

Spatio‐temporal variability in a mid‐latitude ocean basin subject to periodic wind forcing

Distinguished material surfaces and coherent structures in three-dimensional fluid flows

Lagrangian Structures in Very High-Frequency Radar Data and Optimal Pollution Timing

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