On the thermodynamics of the oceanic general circulation: entropy
                        increase rate of an open dissipative system and its surroundings

Shimokawa, Shinya; Ozawa, Hisashi

doi:10.3402/tellusa.v53i2.12185

Cited by 21 publications

(22 citation statements)

References 22 publications

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“…Comparing our case 1 estimate of 0.799 mW·m −2 ·K −1 with other estimates based solely on surface heat fluxes reveals that our estimate agrees well with the observationally based estimate of 1 mW·m −2 ·K −1 by Tailleux (), is about third of the model‐based estimate of 2.5 mW·m −2 ·K −1 of Shimokawa and Ozawa (), and is almost 3 orders of magnitude smaller than the estimates of Yan et al () and Huang (), the latter difference reflecting the differences in entropic temperature for shortwave radiation. Comparing cases 1 and 2, the addition of the wind/tidal input produces a large increase in entropy production.…”

Section: Ocean Heat‐engine Analysissupporting

confidence: 86%

“…Summarizing the literature on ocean heat engine and entropy production analyses, we find no rigorous estimation of the heat‐engine efficiency and only one study (model‐based) that directly computes the ocean's entropy production (Pascale et al, ). The four indirect estimates of entropy production (Huang, ; Shimokawa & Ozawa, ; Tailleux, ; Yan et al, ) all assume a steady state, and only one is both based on observations and considers correlations between the surface heat flux and surface temperature (Tailleux, ). Further, only one study estimates surface entropy fluxes associated with fresh water, and that study relies on an idealized numerical model (Shimokawa & Ozawa, ).…”

Section: Introductionmentioning

confidence: 99%

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Heat‐Engine and Entropy‐Production Analyses of the World Ocean

Bannon

Najjar

2018

JGR Oceans

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A heat‐engine analysis is performed in order to determine the ocean's Carnot efficiency, the maximum thermal energy (i.e., the Carnot work) available to drive the ocean circulation, and the ocean's irreversible entropy production. The analysis is based on a 36‐year monthly climatology of the surface heat flux; estimates of geothermal input, mechanical energy input, and heat storage; and a detailed treatment of freshwater fluxes. The ocean's Carnot efficiency is estimated to be 0.86%. The Carnot work is equal to 110 TW, which exceeds the mechanical energy input by the winds and tides. The net entropy flux from the ocean to its surroundings is found to be 0.617 TW/K, in good agreement with an independent estimate of the irreversible entropy production from viscous dissipation, thermal mixing, and haline mixing, demonstrating a balanced entropy budget of the ocean. Thermal mixing accounts for 56% of this entropy production, with most of the remaining production due to viscous dissipation and only small contributions from haline mixing and sea ice melting. Two thirds of the thermal entropy production is due to isopycnal mixing. The effect of thermal diffusion is to reduce the Carnot work significantly. The actual reduction is proportional to the amplitude of the (poorly known) eddy thermal diffusivity.

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Section: Ocean Heat‐engine Analysissupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Heat‐Engine and Entropy‐Production Analyses of the World Ocean

Bannon

Najjar

2018

JGR Oceans

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“…The horizontal grid spacing is 4 degree. The depth of the ocean is 4500 m with 12 vertical levels [ Shimokawa and Ozawa , 2001]. A series of multiple steady states of thermohaline circulation under the same set of mixed boundary conditions (four southern sinking circulations: S1–S4; and three northern sinking circulations: N1–N3, see Figure 1) are obtained by repeating two procedures: integrations under mixed boundary conditions with a high‐latitude salinity perturbation for 500 years and without perturbation for 1000 years.…”

Section: Methodsmentioning

confidence: 99%

“…The ocean system has been known to possesses multiple steady states of circulation under the same boundary conditions [ Stommel , 1961; Marotzke and Willebrand , 1991]. Our recent numerical simulations suggest that MEP is also valid for transitions of the circulation among these multiple steady states [ Shimokawa and Ozawa , 2001, 2002, 2005]. Hence it would seem that this MEP principle can stand for a universal principle for time evolution of non‐equilibrium systems [ Lorenz , 2003; Whitfield , 2005; Kleidon and Lorenz , 2005; Martyushev and Seleznev , 2006].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of irreversible transitions in the oceanic general circulation

Shimokawa

Ozawa

2007

Geophysical Research Letters

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In this study, we investigate a transition process among multiple steady states of oceanic circulation under the same set of boundary conditions, and clarify the relationship between entropy production and the strength and direction of fresh water perturbations. Our results are found to be consistent with “the principle of maximum entropy production (MEP)” in non‐equilibrium thermodynamics, and can be understood in a consistent manner by a concept of “dynamic potential” that regards the rate of entropy production as a kind of thermodynamic potential. MEP could be a general thermodynamic principle that determines the behavior of oceanic circulation in response to external perturbations, leading to a better understanding of abrupt climate changes such as the Younger Dryas event and Dansgaard–Oeschger oscillations.

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“…Here, the radiation effect has been included in the energy balance equation so as to extend our previous study Shimokawa and Ozawa, 2001). The surface integral in eq.…”

Section: Appendix Amentioning

confidence: 99%

Thermodynamics of a tropical cyclone: generation and dissipation of mechanical energy in a self-driven convection system

Ozawa

Shimokawa

2015

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C TThe formation process of circulatory motion of a tropical cyclone is investigated from a thermodynamic viewpoint. The generation rate of mechanical energy by a fluid motion under diabatic heating and cooling, and the dissipation rate of this energy due to irreversible processes are formulated from the first and second laws of thermodynamics. This formulation is applied to a tropical cyclone, and the formation process of the circulatory motion is examined from a balance between the generation and dissipation rates of mechanical energy in the fluid system. We find from this formulation and data analysis that the thermodynamic efficiency of tropical cyclones is about 40% lower than the Carnot maximum efficiency because of the presence of thermal dissipation due to irreversible transport of sensible and latent heat in the atmosphere. We show that a tropical cyclone tends to develop within a few days through a feedback supply of mechanical energy when the sea surface temperature is higher than 300 K, and when the horizontal scale of circulation becomes larger than the vertical height of the troposphere. This result is consistent with the critical radius of 50 km and the corresponding central pressure of about 995 hPa found in statistical properties of typhoons observed in the western North Pacific.

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On the thermodynamics of the oceanic general circulation: entropy increase rate of an open dissipative system and its surroundings

Cited by 21 publications

References 22 publications

Heat‐Engine and Entropy‐Production Analyses of the World Ocean

Heat‐Engine and Entropy‐Production Analyses of the World Ocean

Thermodynamics of irreversible transitions in the oceanic general circulation

Thermodynamics of a tropical cyclone: generation and dissipation of mechanical energy in a self-driven convection system

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