On the Role of Eddy Mixing in the Subtropical Ocean Circulation

Liu, Tongya; Ou, Hsien-Wang; Liu, Xiaohui; Chen, Dake

doi:10.1002/essoar.10506284.1

Cited by 3 publications

(9 citation statements)

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“…For the computational evidence, eddy-resolving numerical calculations have shown palpable homogenization of the PV in the subtropics [4]. For a quantitative assessment, we show in Figure 2 the warm-layer PV profiles adapted from our paper [5] for coarsegrid (1 degree, thick dashed line) and fine-grid (1/32 degree, solid line) calculations representing the laminar and eddying regimes, respectively (the thin dashed lines mark the outcrops). It is seen that the PV range in the eddying regime is reduced to about 20% of its laminar counterpart, which is consistent with the above estimate of the ratio of the basin-mixing to the basin-transit time.…”

Section: Model Configurationmentioning

confidence: 99%

“…While coarse-grained numerical calculations have validated the Sverdrup dynamics, they provide poor simulations of the observed GOC [53]. The simulations are much improved when the eddies are resolved [54], which however are at the expense of a shrinking Sverdrup domain [5,55]; and then the laminar dynamics has difficulty in accommodating a subtropical front to produce a closed circulation [56]. These deficiencies suggest that although the Sverdrup balance may hold locally, it falls short as an organization principle of the GOC.…”

Section: Sverdrup Perspectivementioning

confidence: 99%

“…Significantly, this shortfall is removed when eddies are resolved, which suggests that the mid-latitude front is the outcome of an eddying ocean, regardless of the wind force [3]. The second deficiency concerns the laminar vorticity balance, which is seen to be strongly perturbed when eddies are resolved in numerical calculations [4,5]. Specifically, because of the material conservation of the microscopic potential vorticity (PV), eddy mixing acts to homogenize the macroscopic PV, thus impairing the laminar vorticity balance, as discussed in Section 2.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2. Meridional profiles of the warm-layer PV from the coarse-grain (thick dashed) and finegrain (solid) numerical calculations (adapted from[5]), the thin dashed lines mark the outcrops. The eddy mixing has reduced the PV range to 20% of its laminar range.…”

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confidence: 99%

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Upper-Bound General Circulation of the Ocean: A Theoretical Exposition

2021

JMSE

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This paper considers the general ocean circulation (GOC) within the thermodynamical closure of our climate theory, which aims to deduce the generic climate state from first principles. The preceding papers of this theory have reduced planetary fluids to warm/cold masses and determined their bulk properties, which provide prior constraints for the derivation of the upper-bound circulation when the potential vorticity (PV) is homogenized in moving masses. In a companion paper on the general atmosphere circulation (GAC), this upper bound is seen to reproduce the observed prevailing wind, therefore forsaking discordant explanations of the easterly trade winds and the polar jet stream. In this paper on the ocean, we again show that this upper bound may replicate broad features of the observed circulation, including a western-intensified subtropical gyre and a counter-rotating tropical gyre feeding the equatorial undercurrent. Since PV homogenization has short-circuited the wind curl, the Sverdrup dynamics does not need to be the sole progenitor of the western intensification, as commonly perceived. Together with GAC, we posit that PV homogenization provides a unifying dynamical principle of the large-scale planetary circulation, which may be interpreted as the maximum macroscopic motion extractable by microscopic stirring, within the confines of thermal differentiation.

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Section: Model Configurationmentioning

confidence: 99%

Section: Sverdrup Perspectivementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Upper-Bound General Circulation of the Ocean: A Theoretical Exposition

2021

JMSE

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“…Significantly, this shortfall is removed when eddies are resolved, which suggests that the midlatitude front is the outcome of an eddying ocean ---regardless the wind forcing [3]. The second deficiency concerns the laminar vorticity balance, which is seen to be strongly perturbed when eddies are resolved in numerical calculations [4,5]. Specifically, because of the material conservation of the microscopic potential vorticity (PV), eddy mixing acts to homogenize the macroscopic PV, thus impairing the laminar vorticity balance, as discussed in Section 2.…”

Section: Introductionmentioning

confidence: 99%

Upper-Bound General Circulation of the Ocean: a Theoretical Exposition

Ou¹

2021

Preprint

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This paper considers the general ocean circulation within the thermodynamical closure of our climate theory, which aims to deduce the generic climate state from first principles. The preceding papers of the theory have reduced planetary fluids to warm/cold masses and determined their bulk thermal properties, which provide prior constraints for the derivation of the upper-bound circulation when the potential vorticity is homogenized in moving masses. In a companion paper on the atmosphere, this upper bound is seen to reproduce the prevailing wind, forsaking therefore previous discordant explanations of the easterly trade and the polar jet stream. In this paper on the ocean, we again show that this upper bound may replicate broad features of the observed circulation, including a western-intensified subtropical gyre and a counter-rotating tropical gyre feeding the equatorial undercurrent. Together, we posit that PV homogenization may provide a unifying dynamical principle of the large-scale planetary circulation, which may be interpreted as the maximum macroscopic motion extractable by microscopic stirring --- within the confine of the thermal differentiation.

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Linkage of tropical glaciation to supercontinents: a thermodynamic closure model

2023

Preprint

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Abstract. Precambrian tropical glaciations pose a significant challenge to our understanding of Earth’s climate. A popular explanation invokes runaway ice-albedo feedback leading to “iceball earth”, an extreme state conflicting however with the sedimentary evidence of an open ocean and active hydrological cycle. We point out flawed physics of the runaway scenario, which overlooks potency of the ocean heat transport in deterring the perennial sea ice. Nor is frozen ocean needed for tropical glaciation as the latter requires only that the tropical land be cooled to below the marking temperature of the glacial margin, which is necessarily above the freezing point to counter the yearly accumulation. Since tropical glaciations generally coincide with Precambrian supercontinents, we posit that it is their blockage of the brighter tropical sun that causes the required cooling. To test this hypothesis, we formulate a minimal two-box model, which is nonetheless thermodynamically closed and yields lowering tropical/polar temperatures with increasing tropical land, whose crossings of the glacial marking temperature would divide non/polar/pan-glacial regimes—the last being characterized by tropical glaciation abutting an open ocean. Given the observed chronology of paleogeography, our theory may provide a unified account of the faint-young-sun paradox, Precambrian tropical glaciations and glacio-epochs through Earth’s history.

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On the Role of Eddy Mixing in the Subtropical Ocean Circulation

Cited by 3 publications

References 0 publications

Upper-Bound General Circulation of the Ocean: A Theoretical Exposition

Upper-Bound General Circulation of the Ocean: A Theoretical Exposition

Upper-Bound General Circulation of the Ocean: a Theoretical Exposition

Linkage of tropical glaciation to supercontinents: a thermodynamic closure model

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