LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Watson, Andrew J.; Garabato, Alberto C. Naverira (2011)
Publisher: Tellus B
Journal: Tellus B
Languages: English
Types: Article
Subjects:
Decreased ventilation of the Southern Ocean in glacial time is implicated in most explanations of lower glacial atmospheric CO2. Today, the deep (>2000 m) ocean south of the Polar Front is rapidly ventilated from below, with the interaction of deep currents with topography driving high mixing rates well up into the water column. We show from a buoyancy budget that mixing rates are high in all the deep waters of the Southern Ocean. Between the surface and ∼2000 m depth, water is upwelled by a residual meridional overturning that is directly linked to buoyancy fluxes through the ocean surface. Combined with the rapid deep mixing, this upwelling serves to return deep water to the surface on a short time scale.We propose two new mechanisms by which, in glacial time, the deep Southern Ocean may have been more isolated from the surface. Firstly, the deep ocean appears to have been more stratified because of denser bottom water resulting from intense sea ice formation near Antarctica. The greater stratification would have slowed the deep mixing. Secondly, subzero atmospheric temperatures may have meant that the present-day buoyancy flux from the atmosphere to the ocean surface was reduced or reversed. This in turn would have reduced or eliminated the upwelling (contrary to a common assumption, upwelling is not solely a function of the wind stress but is coupled to the air–sea buoyancy flux too). The observed very close link between Antarctic temperatures and atmospheric CO2 could then be explained as a natural consequence of the connection between the air–sea buoyancy flux and upwelling in the Southern Ocean, if slower ventilation of the Southern Ocean led to lower atmospheric CO2. Here we use a box model, similar to those of previous authors, to show that weaker mixing and reduced upwelling in the Southern Ocean can explain the low glacial atmospheric CO2 in such a formulation.DOI: 10.1111/j.1600-0889.2005.00167.x
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • Adkins, J. F., McIntyre, K. and Schrag, D. P. 2002. The salinity, temperature, and delta O-18 of the glacial deep ocean. Science 298, 1769- 1773.
    • Anderson, D. M. and Archer, D. 2002. Glacial-interglacial stability of ocean pH inferred from foraminifera dissolution rates. Nature 416, 70-73.
    • Archer, D., Winguth, A., Lea, D. and Mahowald, N. 2000a. What caused the glacial/interglacial atmospheric pCO2 cycles? Rev. Geophys. 38, 159-189.
    • Archer, D. E., Eshel, G., Winguth, A., Broecker, W., Pierrehumbert, R., Tobis, M. and Jacob, R. 2000b. Atmospheric pCO2 sensitivity to the biological pump in the ocean. Global Biogeochem. Cyc. 14, 1219- 1230.
    • Bopp, L., Kohfeld, K. E., Le Quere´, C. and Aumont, O. 2003. Dust impact on marine biota and atmospheric CO2 during glacial periods. Paleoceanogr. 18, art. no.-1046.
    • Broecker, W., Lynch-Stieglitz, J., Archer, D., Hofmann, M., MaierReimer, E., Marchal, O., Stocker, T. and Gruber, N. 1999. How strong is the Harvardton-Bear constraint? Global Biogeochem. Cyc. 13, 817- 820.
    • Bryden, H. L. and Cunningham, S. A. 2003. How wind-forcing and airsea heat exchange determine the meridional temperature gradient and stratification for the Antarctic Circumpolar Current. J. Geophys. Res. - Oceans 108, 10.1029,2001JC0011296.
    • Crosta, X., Pichon, J. J. and Burckle, L. H. 1998a. Application of modern analog technique to marine Antarctic diatoms: reconstruction of maximum sea-ice extent at the Last Glacial Maximum. Paleoceanogr. 13, 284-297.
    • Crosta, X., Pichon, J. J. and Burckle, L. H. 1998b. Reappraisal of Antarctic seasonal sea ice at the Last Glacial Maximum, Geophys. Res. Lett. 25, 2703-2706.
    • Egbert, G. D., Ray, R. D. and Bills, B. G. 2004. Numerical modeling of the global semidiurnal tide in the present day and in the last glacial maximum. J. Geophys. Res. 109, C03003, doi: 10.1029/2003JC001973.
    • Ganachaud, A. and Wunsch, C. 2000. Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. Nature 408, 453-457.
    • Gent, P. R., Large, W. G. and Bryan, F. O. 2001. What sets the mean transport through Drake Passage? J. Geophys. Res. - Oceans 106, 2693-2712.
    • Gersonde, R. and Zielinski, U. 2000. The reconstruction of late Quaternary Antarctic sea ice distribution - the use of diatoms as a proxy for sea ice. Paleogeogr., Paleoclim., Paleoecol., 162, 263-286.
    • Gersonde, R., Crosta, X., Abelmann, A. and Armand, L. 2005. Sea surface termparature and sea ice distribution of the Southern Ocean at the EPILOG Last Glacial Maximum - a circum-Antarctic view based on siliceous microfossil records. Quat. Sci. Rev. 24, 869-896.
    • Gill, A. E. 1982. Atmosphere and ocean dynamics. Cambridge University Press.
    • Goldson, L. E. 2004. Determining vertical mixing rates in the nearsurface Southern Ocean using SF6 releases. PhD thesis, School of Environmental Sciences, U. East Anglia.
    • Haine, T. W. N., Watson, A. J., Liddicoat, M. I. and Dickson, R. R. 1998. The flow of Antarctic bottom water to the southwest Indian Ocean estimated using CFCs. J. Geophys. Res. - Oceans 103, 27637-27653.
    • Heywood, K. J., Naveira Garabato, A. C. and Stevens, D. P. 2002. High mixing rates in the abyssal Southern Ocean. Nature 415, 1011- 1014.
    • Karsten, R. H. and Marshall, J. 2002. Constructing the residual circulation of the ACC from observations. J. Phys. Oceanogr. 32, 3315-3327.
    • Keeling, R. F. 2002. On the freshwater forcing of the thermohaline circulation in the limit of low diapycnal mixing. J. Geophys. Res. - Oceans 107, 10.1029/2000JC000685.
    • Keeling, R. F. and Stephens, B. B. 2001. Antarctic sea ice and the control of Pleistocene climate instability. Paleoceanogr. 16, 112-131.
    • Keeling, R. and Visbeck, M. 2001. Palaeoceanography - Antarctic stratification and glacial CO2. Nature 412, 605-606.
    • Knox, F. and McElroy, M. B. 1984. Changes in atmospheric CO2 - Influence of the marine biota at high-latitude. J. Geophys. Res. - Atmos. 89, 4629-4637.
    • Law, C. S., Abraham, E. R., Watson, A. J. and Liddicoat, M. I. 2003. Vertical eddy diffusion and nutrient supply to the surface mixed layer of the Antarctic Circumpolar Current. J. Geophys. Res. - Oceans 108, 10.1029/2002JC001604.
    • Ledwell, J. R., Watson, A. J. and Law, C. S. 1998. Mixing of a tracer in the pycnocline. J. Geophys. Res. - Oceans 103, 21 499-21 529.
    • Ledwell, J. R., Montgomery, E. T., Polzin, K. L., St. Laurent, L. C., Schmitt, R. W. and Toole, J. M. 2000. Evidence for enhanced mixing over rough topography in the abyssal ocean. Nature 403, 179-182.
    • Mantyla, A. W. and Reid, J. L. 1983. Abyssal characteristics of the World Ocean waters. Deep-Sea Res. A 30, 805-833.
    • Marshall, D. 1997. Subduction of water masses in an eddying ocean. J. Mar. Res. 55, 201-222.
    • McCulloch, R. D., Bentley, M. J., Purves, R. S., Hulton, N. R. J., Sugden, D. E. and Clapperton, C. M. 2000. Climatic inferences from glacial and palaeoecological evidence at the last glacial termination, southern South America. J. Quat. Sci. 15, 409-417.
    • Monnin, E., Indermuhle, A., Dallenbach, A., Fluckiger, J., Stauffer, B., Stocker, T. F., Raynaud, D. and Barnola, J. M. 2001. Atmospheric CO2 concentrations over the last glacial termination. Science 291, 112-114.
    • Munk, W. H. 1966. Abyssal recipes. Deep-Sea Res. 13, 707-730.
    • Munk, W. and Wunsch, C. 1998. Abyssal recipes II: energetics of tidal and wind mixing. Deep-Sea Res. I, 45, 1977-2010.
    • Naveira Garabato, A. C., Polzin, K. L., King, B. A., Heywood, K. J. and Visbeck, M. 2004. Widespread intense turbulent mixing in the Southern Ocean. Science 303, 210-213.
    • Nilsson, J., Brostro¨m, G. and Walin, G. 2003. The thermohaline circulation and vertical mixing: does weaker density stratification give stronger overturning? J. Phys. Oceanogr. 33, 2781-2795.
    • Nilsson, J., Brostro¨m, G. and Walin, G. 2004. On the spontaneous transition to asymmetric thermohaline circulation. Tellus 56A, 68-78.
    • Olbers, D., Borowski, D., Vo¨lker, C. and Wolff, J.-O. 2004. The dynamical balance, circulation and transport of the Antarctic Circumpolar Current. Antarct. Sci. 16, 439-470.
    • Orsi, A. H., Johnson, G. C. and Bullister, J. L. 1999. Circulation, mixing, and production of Antarctic Bottom Water. Progr. Oceanogr. 43, 55- 109.
    • Polzin, K. L., Toole, J. M., Ledwell, J. R. and Schmitt, R. W. 1997. Spatial variability of turbulent mixing in the abyssal ocean. Science 276, 93-96.
    • Redi, M. 1982. Oceanic isopycnal mixing by co-ordinate rotation. J. Phys. Oceanogr. 12, 1154-1157.
    • Rintoul, S. R. 1998. On the origin and influence of Ade´lie Land Bottom Water. In: Ocean, ice and atmosphere: Interactions at the Antarctic continental margin. Antarctic Research Series (eds. S. S. Jacobs and R. F. Weiss), 151-171.
    • Robinson, R. S., Brunelle, B. G. and Sigman, D. M. 2004. Revisiting nutrient utilization in the glacial Antarctic: evidence from a new method for diatom-bound N isotopic analysis. Paleoceanogr. 19, 10.1029/2003PA000996.
    • Sarmiento, J. L. and Toggweiler, J. R. 1984. A new model for the role of the oceans in determining atmospheric pCO2. Nature 308, 621-624.
    • Shemesh, A., Hodell, D., Crosta, X., Kanfoush, S., Charles, C. and Guilderson, T. 2002. Sequence of events during the last deglaciation in Southern Ocean sediments and Antarctic ice cores. Paleoceanogr. 17, 10.1029/2000PA000599.
    • Siegenthaler, U. and Wenk, T. 1984. Rapid atmospheric CO2 variations and ocean circulation. Nature 308, 624-626.
    • Sigman, D. M. and Boyle, E. A. 2000. Glacial/interglacial variations in atmospheric carbon dioxide. Nature 407, 859-869.
    • Sloyan, B. M. and Rintoul, S. R. 2001. Circulation, renewal, and modification of Antarctic mode and intermediate water. J. Phys. Oceanogr. 31, 1005-1030.
    • Speer, K., Guilyardi, E. and Madec, G. 2000. Southern Ocean transformation in a coupled model with and without eddy mass fluxes. Tellus 52A, 554-565.
    • Stephens, B. B. and Keeling, R. F. 2000. The influence of Antarctic sea ice on glacial-interglacial CO2 variations. Nature 404, 171-174.
    • Talley, L. D. 1999. Some aspects of ocean heat transport by the shallow, intermediate and deep overturning circulations. In: Mechanisms of global climate change at millenial time scales (eds.P. U. Clark, R. S. Webb and L. D. Keigwin). American Geophysical Union, Washington DC, 1-22.
    • Toggweiler, J. R. 1999. Variation of atmospheric CO2 by ventilation of the ocean's deepest water, Paleoceanogr. 14, 571-588.
    • Toggweiler, J. R. and Samuels, B. 1995. Effect of Drake Passage on the global thermohaline circulation. Deep-Sea Res. I 42, 477-500.
    • Toggweiler, J. R. and Samuels, B. 1998. On the ocean's large-scale circulation near the limit of no vertical mixing. J. Phys. Oceanogr. 28, 1832-1852.
    • Toggweiler, J. R., Gnanadesikan, A., Carson, S., Murnane, R. and Sarmiento, J. L. 2003a. Representation of the carbon cycle in box models and GCMs: 1. Solubility pump. Global Biogeochem. Cyc. 17, 10.1029/2001GB001401.
    • Toggweiler, J. R., Murnane, R., Carson, S., Gnanadesikan, A. and Sarmiento, J. L. 2003b. Representation of the carbon cycle in box models and GCMs - 2. Organic pump. Global Biogeochem. Cyc. 17, 10.1029/2001GB001401.
    • Toole, J. M., Polzin, K. L. and Schmitt, R. W. 1994. Estimates of diapycnal mixing in the abyssal ocean. Science 264, 1120-1123.
    • Walin, G. 1982. On the relation between sea-surface heatflow and thermal circulation in the ocean. Tellus 34, 187- 195.
    • Watson, A. J., Bakker, D. C. E., Ridgwell, A. J., Boyd, P. W. and Law, C. S. 2000. Effect of iron supply on Southern Ocean CO2 uptake and implications for glacial atmospheric CO2. Nature 407, 730- 733.
    • Webb, D. J. and Suginohara, N. 2001. Oceanography - Vertical mixing in the ocean. Nature 409, 37-37.
    • Whitworth, T., Nowlin, W. D., Orsi, A. H., Locarnini, R. A. and Smith, S. G. 1994. Weddell Sea Shelf Water in the Bransfield Strait and Weddell-Scotia Confluence. Deep-Sea Res. I 41, 629- 641.
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article

Collected from