Abyssal recipes II: energetics of tidal and wind mixing

Munk, Walter; Wunsch, Carl

doi:10.1016/s0967-0637(98)00070-3

Cited by 1,844 publications

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“…Simple box models of the ocean circulation (which impose circulation and exchange fluxes between a handful of well-mixed water masses in the ocean and allow for gas exchange with the atmosphere) have been used to develop a theory called the "high-latitude outcrop model" for the interaction of CO2 between the ocean and the atmosphere [ [Ledwell et al, 1993] find low rates of diffusion, similar to the thermocline diffusivity used in the isopycnic model [Hu, 1996]. However, the density stratification of the thermocline and deep sea [Munk and Wunsch, 1998] and various geochemical measurements near the sea surface (such as oxygen [Spitzer and Jenkins, 1989] and helium concentrations [Jenkins, 1988] …”

Section: Most Of the Carbon On Earth Is Incorporated Intomentioning

confidence: 99%

What caused the glacial/interglacial atmospheric pCO₂ cycles?

Archer

Winguth²,

Lea

et al. 2000

Reviews of Geophysics

455

472

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Abstract. Fifteen years after the discovery of major glacial/interglacial cycles in the CO2 concentration of the atmosphere, it seems that all of the simple mechanisms for lowering pCO 2 have been eliminated. We use a model of ocean and sediment geochemistry, which includes new developments of iron limitation of biological production at the sea surface and anoxic diagenesis and its effect on CaCO 3 preservation in the sediments, to evaluate the current proposals for explaining the glacial/ interglacial pCO 2 cycles within the context of the ocean carbon cycle. After equilibration with CaCO 3 the model is unable to generate glacial pCO 2 by increasing ocean NO•-but predicts that a doubling of ocean H4SiO 4 might suffice. However, the model is unable to generate a doubling of ocean H4SiO 4 by any reasonable changes in SiO 2 weathering or production. Our conclusions force us to challenge one or more of the assumptions at the foundations of chemical oceanography. We can abandon the stability of the "Redfield ratio" of nitrogen to phosphorus in living marine phytoplankton and the ultimate limitation of marine photosynthesis by phosphorus. We can challenge the idea that the pH of the deep ocean is held relatively invariant by equilibrium with CaCO 3. A third possibility, which challenges physical oceanographers, is that diapycnal mixing in ocean circulation models exceeds the rate of mixing in the real ocean, diminishing the model pCO 2 sensitivity to biological carbon uptake. The ice age cycles underwent a midlife transition

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Section: Most Of the Carbon On Earth Is Incorporated Intomentioning

confidence: 99%

What caused the glacial/interglacial atmospheric pCO₂ cycles?

Archer

Winguth²,

Lea

et al. 2000

Reviews of Geophysics

455

472

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“…Correspondence and requests for information should be addressed to K. One of the greatest hazards associated with oceanic volcanoes is not volcanic in nature, but lies with the potential for catastrophic ank failure 1,2 . Such¯ank failure can result in devastating tsunamis and threaten not only the immediate vicinity, but coastal cities along the entire rim of an ocean basin 3 .…”

Section: Acknowledgementsmentioning

confidence: 99%

“…Taking the median thickness of the LWDSW layer to be 423 6 20 m, to mix the LWSDW into the overlying waters implies an energy dissipation of 1:8 6 0:5 3 10 9 W: small in comparison with the global requirements of 2:1 3 10 12 W (ref. 2) or 0:6 3 10 12 W (ref. 20), and not disproportionate with the area over which the mixing is occurring.…”

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confidence: 99%

High mixing rates in the abyssal Southern Ocean

Heywood

Garabato

Stevens

2002

Nature

104

107

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Mixing of water masses from the deep ocean to the layers above can be estimated from considerations of continuity in the global ocean overturning circulation. But averaged over ocean basins, diffusivity has been observed to be too small to account for the global upward flux of water, and high mixing intensities have only been found in the restricted areas close to sills and narrow gaps. Here we present observations from the Scotia Sea, a deep ocean basin between the Antarctic peninsula and the tip of South America, showing a high intensity of mixing that is unprecedented over such a large area. Using a budget calculation over the whole basin, we find a diffusivity of (39 +/_ 10) x 104 m2 s-1, averaged over an area of 7 x 105 km2. The Scotia Sea is a basin with a rough topography, situated just east of the Drake passage where the strong flow of the Antarctic Circumpolar Current is constricted in width. The high basin-wide mixing intensity in this area of the Southern Ocean may help resolve the question of where the abyssal water masses are mixed towards the surface

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“…Estimates from microscale profiling [Gregg, 1989] and tracer release experi•nents [Ledwell et al, 1993[Ledwell et al, , 1998] indicate that it is less than 1 x 10 -s m2/s at tile thermocline depths. On the other hand, vertical balance of heat, salt, and chemical tracers suggests that vertical dif[klsivity below the thermocline is 1 x 10 -4 •n2/s or larger [Munk, 1966: Munk andWunsch, 1998]. …”

Section: Introductionmentioning

confidence: 99%

Effects of locally enhanced vertical diffusivity over rough bathymetry on the world ocean circulation

Hasumi¹,

Suginohara²

1999

J. Geophys. Res.

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Abstract.Observations indicate that vertical diffusivity in the deep ocean is considerably enhanced over rough bathymetry and is very small elsewhere. Here we investigate effects of locally enhanced vertical diffusivity over rough bottom topography on the world ocean circulation by use of a coarse resolution ocean general circulation model. Vertical diffusivity is enhanced in the model, taking into account effects of internal tide breaking. For comparison, two cases of an experiment are carried out, where vertical diffusivity increases with depth without horizontal inhomogeneity. Horizontal distribution of deep upwelling is qualitatively different, depending on whether or not vertical diffusivity is horizontally inhomogeneous. Upwelling of Circumpolar Deep Water in the Pacific and Antarctic Bottom Water in the Atlantic is confined where vertical diffusivity is enhanced in the case of horizontally inhomogeneous vertical diffusivity, whereas it is horizontally uniform in the other cases. This difference leads to different three-dimensional structure of the deep circulation.

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Abyssal recipes II: energetics of tidal and wind mixing

Cited by 1,844 publications

References 0 publications

What caused the glacial/interglacial atmospheric pCO₂ cycles?

What caused the glacial/interglacial atmospheric pCO₂ cycles?

High mixing rates in the abyssal Southern Ocean

Effects of locally enhanced vertical diffusivity over rough bathymetry on the world ocean circulation

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Abyssal recipes II: energetics of tidal and wind mixing

Cited by 1,844 publications

References 0 publications

What caused the glacial/interglacial atmospheric pCO2 cycles?

What caused the glacial/interglacial atmospheric pCO2 cycles?

High mixing rates in the abyssal Southern Ocean

Effects of locally enhanced vertical diffusivity over rough bathymetry on the world ocean circulation

Contact Info

Product

Resources

About

What caused the glacial/interglacial atmospheric pCO₂ cycles?

What caused the glacial/interglacial atmospheric pCO₂ cycles?