Estimates of Area-Averaged Diapycnal Fluxes from Basin-Scale Budgets

Bernadette M. Sloyan Antarctic Cooperative Research Centre, and Institute of Antarctic and Southern Ocean Studies, University of Tasmania, Hobart, Tasmania, Australia

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Stephen R. Rintoul Antarctic Cooperative Research Centre, University of Tasmania, and CSIRO Division of Marine Research, Hobart, Tasmania, Australia

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Abstract

Estimates of area-averaged diapycnal fluxes for the southern oceans are derived from basin-scale budgets of mass, heat, and salt using a box inverse model. The diapycnal fluxes are found to be significant terms in the isopycnal budgets of mass, heat, and salt. Dense water entering the subtropical Indian and Pacific basins from the south is returned below the thermocline as less dense deep water. In the Southern Ocean deep water is converted to denser deep and bottom water. Water properties at intermediate depth are substantially modified by diapycnal fluxes of heat and salt, but the modification of intermediate water is not solely driven by interior mixing. The inferred fluxes help explain the changes in temperature–salinity curves observed across each basin, and they are consistent with our understanding of the overall three-dimensional circulation of the Southern Ocean.

The fact that area-averaged diapycnal fluxes can be determined from basin-scale budgets using a suitably designed inverse model is encouraging: similar methods applied to the high-quality measurements collected during the World Ocean Circulation Experiment promise to provide the first global maps of diapycnal fluxes derived from ocean observations.

Corresponding author address: Dr. Bernadette Sloyan, NOAA/PMEL/OCRD, 7600 Sand Point Way NE, Building 3, Seattle, WA 98115-0070.

sloyan&commat±el.noaa.gov

Abstract

Estimates of area-averaged diapycnal fluxes for the southern oceans are derived from basin-scale budgets of mass, heat, and salt using a box inverse model. The diapycnal fluxes are found to be significant terms in the isopycnal budgets of mass, heat, and salt. Dense water entering the subtropical Indian and Pacific basins from the south is returned below the thermocline as less dense deep water. In the Southern Ocean deep water is converted to denser deep and bottom water. Water properties at intermediate depth are substantially modified by diapycnal fluxes of heat and salt, but the modification of intermediate water is not solely driven by interior mixing. The inferred fluxes help explain the changes in temperature–salinity curves observed across each basin, and they are consistent with our understanding of the overall three-dimensional circulation of the Southern Ocean.

The fact that area-averaged diapycnal fluxes can be determined from basin-scale budgets using a suitably designed inverse model is encouraging: similar methods applied to the high-quality measurements collected during the World Ocean Circulation Experiment promise to provide the first global maps of diapycnal fluxes derived from ocean observations.

Corresponding author address: Dr. Bernadette Sloyan, NOAA/PMEL/OCRD, 7600 Sand Point Way NE, Building 3, Seattle, WA 98115-0070.

sloyan&commat±el.noaa.gov

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  • Armi, L., 1978: Some evidence for boundary mixing in the deep ocean. J. Geophys. Res.,83, 1971–1979.

  • Budd, W. F., P. A. Reid, and L. J. Minty, 1995: Antarctic moisture flux and net accumulation from global atmospheric analyses. Ann. Glaciol.,21, 149–156.

  • Carmack, E. C., 1990: Large scale physical oceanography of polar oceans. Polar Oceanography Part A: Physical Science, W. O. Smith Jr., Ed., Academic Press, 171–222.

  • Coachman, L., and K. Aagaard, 1988: Transport through Bering Strait: Annual and interannual variability. J. Geophys. Res.,93, 15535–15539.

  • Cresswell, G. R., A. Frische, J. Peterson, and D. Quadfasel, 1993: Circulation in the Timor Sea. J. Geophys. Res.,98, 14379– 14389.

  • da Silva, A. M., C. C. Young, and S. Levitus, 1994: Atlas of Surface Marine Data 1994. Vol. 1: Algorithms and Procedures, NOAA NESDIS Tech. Rep. 6, U.S. Department of Commerce, 83 pp.

  • Dickson, R. R., and J. Brown, 1994: The production of North Atlantic Deep Water: Sources, rates and pathways. Geophys. Res.,99, 12319–12341.

  • Döös, K., and A. Coward, 1997: The Southern Ocean as the major upwelling zone of North Atlantic Deep Water. Int. WOCE Newslett.,27, 3–4.

  • Fahrbach, E., G. Rohardt, M. Schröder, and V. Strass, 1994: Transport and structure of the Weddell Sea. Ann. Geophys.,12, 840–855.

  • Fu, L.-L., 1986: Mass, heat and freshwater fluxes in the south Indian Ocean. J. Phys. Oceanogr.,16, 1683–1693.

  • Gordon, A. L., 1986: Interocean exchange of thermocline water. J. Geophys. Res.,91, 5037–5046.

  • ——, and B. A. Huber, 1990: Southern Ocean winter mixed layer. J. Geophys. Res.,95, 11655–11672.

  • ——, R. F. Weiss, W. M. Smethie Jr., and M. J. Warner, 1992: Thermocline and intermediate water communication between the South Atlantic and Indian Oceans. J. Geophys. Res.,97, 7223– 7240.

  • Hellerman, S., and M. Rosenstein, 1983: Normal monthly wind stress over the world ocean with error estimates. J. Phys. Oceanogr.,13, 1093–1104.

  • Hogg, N., 1987: A least-squares fit of the advective–diffusive equations to Levitus atlas data. J. Mar. Res.,45, 347–375.

  • ——, P. Biscaye, W. Gardner, and W. J. Schmitz Jr., 1982: On the transport and modification of Antarctic Bottom Water in the Vema Channel. J. Mar. Res.,40, 231–263.

  • Jackett, D., and T. J. McDougall, 1997: A neutral density variable for the world’s oceans. J. Phys. Oceanogr.,27, 237–263.

  • Jacobs, S. S., R. G. Fairbanks, and Y. Horibe, 1985: Origin and evolution of water masses near the Antarctic continental margin. Oceanology of the Antarctic Continental Shelf, S. S. Jacob, Ed., Vol. 43, Antarctic Research Series, Amer. Geophys. Union, 59– 85.

  • Lanczos, C., 1961: Linear Differential Operators. Van Nostrand, 564 pp.

  • Levitus, S., and T. Boyer, 1994: World Ocean Atlas 1994. NOAA Tech. Rep. Atlas NESDIS 4, 117 pp.

  • Macdonald, A., 1991: Mass, heat, oxygen and nutrient fluxes at 30°S and their implication for the Pacific–Indian through flow and the global heat budget. M.S. thesis, Woods Hole Oceanographic Institute, Massachusetts Institute of Technology, 183 pp. [Available from Woods Hole Oceanographic Institute, Woods Hole, MA 02543.].

  • ——, 1998: The global ocean circulation: a hydrographic estimate and regional analysis. Progress in Oceanography, Vol. 41, Pergamon, 281–382.

  • McCartney, M. S., 1977: Subantarctic Mode Water. Deep-Sea Res.,24, 103–119.

  • ——, 1993: Crossing of the equator by the deep western boundary current in the western Atlantic Ocean. J. Phys. Oceanogr.,23, 1953–1974.

  • McIntosh, P. C., and S. R. Rintoul, 1997: Do box inverse models work? J. Phys. Oceanogr.,27, 291–208.

  • Meyers, G., R. J. Bailey, and A. P. Worby, 1995: Geostrophic transport of Indonesian throughflow. Deep-Sea Res.,42, 1163–1174.

  • Peterson, R., 1992: The boundary currents in the western Argentine basin. Deep-Sea Res.,39, 623–644.

  • ——, and T. Whitworth III., 1989: The Subantarctic and Polar fronts in relation to deep water masses through the southwestern Atlantic. J. Geophys. Res.,94, 10817–10838.

  • ——, and L. Stramma, 1991: Upper-level circulation in the South Atlantic Ocean. Progress in Oceanography, Vol. 26, Pergamon, 1–73.

  • Polzin, K. L., J. M. Toole, J. R. Ledwell, and R. W. Schmitt, 1997: Spatial variability of turbulent mixing in the abyssal ocean. Science,276, 93–96.

  • Reid, J. L., 1989: On the total geostrophic circulation of the South Atlantic Ocean: Flow patterns, tracers and transports. Progress in Oceanography, Vol. 23, Pergamon, 149–244.

  • Rintoul, S. R., 1991: South Atlantic interbasin exchange. J. Geophys. Res.,96, 2675–2692.

  • ——, 1998: On the origin and influence of Adélie Land bottom water. Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin, S. Jacobs, and R. Wiess, Eds., Vol. 75, Antarctic Research Series, Amer. Geophys. Union, 151–171.

  • ——, and C. Wunsch, 1990: Mass, heat, salt and nutrient fluxes and budgets in the North Atlantic Ocean. Deep-Sea Res.,38, 355– 377.

  • Robbins, P. E., and J. M. Toole, 1997: The dissolved silica budget as a constraint on the meridional overturning circulation of the Indian Ocean. Deep-Sea Res.,44, 879–906.

  • Roemmich, D., and T. McCallister, 1989: Large scale circulation of the North Pacific Ocean. Progress in Oceanography, Vol. 22, Pergamon, 171–204.

  • Roether, W., R. Schlitzer, A. Putzka, P. Beining, K. Bulsiewicz, G. Rohardt, and F. Delahoyde, 1993: A chlorofluoromethane and hydrographic section across Drake Passage: Deep water ventilation and meridional property transport. J. Geophys. Res.,98, 14423–14435.

  • Rosenberg, M., R. Eriksen, S. Bell, and S. Rintoul, 1997: Aurora Australis Marine Science Cruise AU9404—Oceanographic field measurements and analysis. Tech. Rep. 8, Cooperative Research Centre for Antarctic and Southern Ocean Environments (ANTARCTIC CRC), 53 pp. [Available from Antarctic CRC, GPO Box 252-80, Hobart, Tasmania 7001, Australia.].

  • Saunders, P. M., and B. R. King, 1995: Oceanic fluxes on the WOCE A11 section. J. Phys. Oceanogr.,25, 1942–1957.

  • SAVE, 1992a: South Atlantic Ventilation Experiment (SAVE), chemistry, physical and CTD data: Legs 1, 2 and 3. Tech. Rep. 92-9, 729 pp. [Available from Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0224.].

  • ——, 1992b: South Atlantic Ventilation Experiment (SAVE), chemistry, physical and CTD data: Legs 4 and 5. Tech. Rep 92-10, 625 pp. [Available from Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0224.].

  • Schlitzer, R., 1987: Renewal rates of east Atlanitc deep water estimated by inversion of 14C. J. Geophys. Res.,92, 2953–2969.

  • Schmitz, W. J., Jr., 1995: On the interbasin-scale thermohaline circulation. Rev. Geophys.,33, 151–173.

  • ——, 1996: On the World Ocean circulation. Vol. II: The Pacific and Indian Oceans/A global update. Tech. Rep. WHOI-96-08, 237 pp. [Available from Woods Hole Oceanographic Institute, Woods Hole, MA 02543.].

  • Sloyan, B. M., 1997: The circulation of the Southern Ocean and the adjacent ocean basins determined by inverse methods. Ph.D. thesis, Institute of Antarctic and Southern Ocean Studies, University of Tasmania, 479 pp. [Available from IASOS, University of Tasmania, GPO Box 252-77, Hobart, Tasmania 7001, Australia.].

  • ——, and S. R. Rintoul, 2000: The Southern Ocean limb of the global deep overturning circulation. J. Phys. Oceanogr., in press.

  • Speer, K., and E. Tziperman, 1992: Rates of water mass formation in the North Atlantic Ocean. J. Phys. Oceanogr.,22, 93–104.

  • ——, and W. Zenk, 1993: The flow of Antarctic Bottom Water into the Brazil Basin. J. Phys. Oceanogr.,23, 2667–2682.

  • Stommel, H., and A. B. Arons, 1960: On the abyssal circulation of the world’s ocean—ii: An idealized model of circulation pattern and amplitude in oceanic basins. Deep-Sea Res.,6, 140–154.

  • Stramma, L., and R. G. Peterson, 1990: The South Atlantic Current. J. Phys. Oceanogr.,20, 846–859.

  • Talley, L. D., 1996: Antarctic Intermediate Water in the South Atlantic. The South Atlantic: Present and Past Circulation, G. Wefer, W. H. Berger, G. Siedler, and D. J. Webb, Eds., Springer-Verlag, 219–238.

  • Toggweiler, J. R., and B. Samuels, 1993: New radiocarbon constraints on the upwelling of abyssal water to the ocean’s surface. The Global Carbon Cycle. NATO ASI Series I: Global Enviornmental Change, Vol. 15, M. Heimann, Ed., Springer-Verlag, 333– 363.

  • ——, and ——, 1998: On the ocean’s large-scale circulation near limit of no vertical mixing. J. Phys. Oceanogr.,28, 1832–1852.

  • Toole, J. M., and B. A. Warren, 1993: A hydrographic section across the Subtropical South Indian Ocean. Deep-Sea Res.,40, 1973– 2019.

  • Tr&egraveθer, P., D. M. Nelson, A. J. Van Bennekorn, D. J. DeMaster, A. Leynaert, and B. Qu&egraveθiner, 1995: The silica balance in the world ocean: A reestimate. Science,268, 375–379.

  • Tsimplis, M. N., S. Bacon, and H. L. Bryden, 1998: The circulation of the subtropical South Pacific derived from hydrographic data. J. Geophys. Res.,103, 21443–21468.

  • Tziperman, E., and A. Hecht, 1988: Circulation in the eastern Levantine Basin determined by inverse methods. J. Phys. Oceanogr.,18, 506–518.

  • Walin, G., 1982: On the relation between sea-surface heat flow and thermal circulation in the ocean. Tellus,34, 187–195.

  • Warren, B., 1981a: Transindian hydrographic section at lat. 18°S: Property distribution and circulation in the South Indian Ocean. Deep-Sea Res.,28, 759–788.

  • ——, 1981b: Deep circulation of the World Ocean. Evolution of Physical Oceanography, B. A. Warren and C. Wunsch, Eds., The MIT Press, 6–41.

  • ——, and K. G. Speer, 1991: Deep circulation in the eastern South Atlantic Ocean. Deep-Sea Res.,38, S281–S322.

  • Whitworth, T., III, and W. D. Nowlin Jr., 1987: Water masses and currents of the Southern Ocean at the Greenwich Meridian. J. Geophys. Res.,92, 6462–6476.

  • ——, ——, R. D. Pillsbury, and R. F. Weiss, 1991: Observations of the Antarctic Circumpolar Current and deep boundary current in the Southwest Atlantic. J. Geophys. Res.,96, 15105–15118.

  • ——, B. A. Warren, W. D. Nowlin Jr., R. D. Pillsbury, and M. I. Moore, 1999: On the deep western-boundary current in the southwest Pacific Basin. Progress in Oceanography, Vol. 43, Pergamon, 1–54.

  • Wong, A. P. S., N. L. Bindoff, and A. Forbes, 1998: Ocean–e shelf interactions and possible bottom water formation in Prydz Bay, Antarctica. Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin. S. Jacobs and R. Wiess, Eds., Vol. 75, Antarctic Research Series, Amer. Geophys. Union, 173–187.

  • Wunsch, C., 1970: On oceanic boundary mixing. Deep-Sea Res.,17, 293–301.

  • ——, 1978: The North Atlantic general circulation west of 50°W determined by inverse methods. Rev. Geophys. Space Phys.,16 (4), 583–620.

  • ——, 1984: An eclectic Atlantic Ocean circulation model. I: The meridonal flux of heat. J. Phys. Oceanogr.,14, 1712–1732.

  • ——, 1996: The Ocean Circulation Inverse Problem. Cambridge University Press, 441 pp.

  • ——, D. Hu, and B. Grant, 1983: Mass, heat, salt and nutrient fluxes in the South Pacific Ocean. J. Phys. Oceanogr.,13, 725–753.

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