Climate Dynamics

, Volume 8, Issue 3, pp 103–116 | Cite as

Century-scale variability in a randomly forced, two-dimensional thermohaline ocean circulation model

  • L A Mysak
  • T F Stocker
  • F Huang


The response of a two-dimensional thermohaline ocean circulation model to a random freshwater flux superimposed on the usual mixed boundary conditions for temperature and salinity is considered. It is shown that for a wide range of vertical and horizontal diffusivities and a box geometry that approximates the Atlantic Ocean, 200–300 yr period oscillations exist in the basic-state, interhemispheric meridional overturning circulation with deep convection in the north. These fluctuations can also be described in terms of propagating salinity anomalies which travel in the direction of the thermohaline flow. For large horizontal (K h = 15 × 103 m2/s) and small vertical (K v = 0.5 × 10−4 m2/s) diffusivities, the random forcing also excites deca-millennial oscillations in the basic structure of the thermohaline circulation. In this case, the meridional circulation pattern slowly oscillates between three different stages: a large positive cell, with deep convection in the North Atlantic and upwelling in the south; a symmetric two-cell circulation, with deep convection in both polar regions and upwelling near the equator; and a large negative cell, with deep convection in the South Atlantic and upwelling in the north. Each state can persist for 0 (10 kyr).


Atlantic Ocean Basic Structure Polar Region Period Oscillation Circulation Pattern 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. Berger A, Melice JL, Hinnov L (1991) A strategy for frequency spectra of Quaternary climate records. Clim Dyn 5:227–240Google Scholar
  2. Boyle EA, Keigwin L (1987) North Atlantic thermohaline circulation during the past 20000 years linked to high-latitude surface temperature. Nature 330:35–40Google Scholar
  3. Broecker WS, Denton GH (1989) The role of ocean-atmosphere reorganizations in glacial cycles. Geochim Cosmochim Acta 53:2465–2501Google Scholar
  4. Broecker WS, Andree M, Wolfli W, Oeschger H, Bonani G, Kennett J, Peteet D (1988) The chronology of the last deglaciation: implications to the cause of the Younger Dryas event. Paleoceanogr 3:1–19Google Scholar
  5. Bryan F (1986) High-latitude salinity effects and interhemispheric thermohaline circulations. Nature 323:301–304Google Scholar
  6. Bryan F (1987) Parameter sensitivity of primitive equation ocean general circulation models. J Phys Oceanogr 17:970–985Google Scholar
  7. Dickson RR, Meinke J, Malmberg SA, Lee AJ (1988) The “Great Salinity Anomaly” in the northern North Atlantic, 1968–82. Prog Oceanogr 20:103–151Google Scholar
  8. Gordon AL (1986) Interocean exchange of thermocline water. J Geophys Res 91:5037–5046Google Scholar
  9. Levitus S (1982) Climatological atlas of the World Ocean. NOAA Prof Paper 13, 177 pGoogle Scholar
  10. Maier-Reimer E, Mikolajewicz U (1989) Experiments with an OGCM on the cause of the Younger Dryas. In: Ayala-Castañares A, Wooster W, Yáñez-Arancibia A (eds) Oceanography. UNAM Press 87–100Google Scholar
  11. Manabe S, Stouffer RJ (1988) Two stable equilibria of a coupled ocean-atmosphere model. J Climate 1:841–866Google Scholar
  12. Marotzke J, Welander P, Willebrand J (1988) Instability and multiple equilibria in a meridional-plane model of the thermohaline circulation. Tellus 40A:162–172Google Scholar
  13. Mikolajewicz U, Maier-Reimer E (1990) Internal secular variability in an ocean general circulation model. Clim Dyn 4:145–156Google Scholar
  14. Mitchell JM, Dzerdzeevskii B, Flohn H, Hofmeyr WL, Lamb HH, Rao KN, Wallén CC (1966) ‘Climatic Change’, World Meteorological Organization Technical Note 79, 79 ppGoogle Scholar
  15. Mysak LA, Manak DK (1989) Arctic sea-ice extent and anomalies, 1953–1984. Atmos-Ocean 27:376–405Google Scholar
  16. Mysak LA, Manak DK, Marsden RF (1990) Sea-ice anomalies observed in the Greenland and Labrador Seas during 1901–1984 and their relation to an interdecadal Arctic climate cycle. Clim Dyn 5:111–133Google Scholar
  17. Pestiaux P, van der Mersh I, Berger A, Duplessy JC (1988) Paleoclimatic variability at frequencies ranging from I cycle per 10000 years to 1 cycle per 1000 years: evidence for nonlinear behaviour of the climate system. Clim Change 12:9–37Google Scholar
  18. Priestley MB (1989) Spectral analysis and time series. Academic Press, San DiegoGoogle Scholar
  19. Roemmich D, Wunsch C (1985) Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean. Deep Sea Res 32:619–664Google Scholar
  20. Rooth C (1982) Hydrology and ocean circulation. Prog Oceanogr 11:131–149Google Scholar
  21. Saltzman B (1990) Three basic problems of paleoclimatic-modeling: a personal perspective and review. Clim Dyn 5:67–78Google Scholar
  22. Stocker TF, Mysak LA (1992) Climatic fluctuations on the century time scale: a review of high-resolution proxy data and possible mechanisms. Clim Change 20:227–250Google Scholar
  23. Stocker-TF, Wright DG (1991a) A zonally averaged ocean model for the thermohaline circulation. Part 11: Interocean circulation in the Pacific-Atlantic basin system. J Phys Oceanogr 21:1725–1739Google Scholar
  24. Stocker TF, Wright DG (1991b) Rapid transitions of the ocean's deep circulation induced by changes in surface water fluxes. Nature 251:729–732Google Scholar
  25. Stocker TF, Wright DG, Mysak LA (1992) A zonally averaged, coupled ocean-atmosphere model for paleoclimatic studies. J Climate 5 (in press)Google Scholar
  26. Stommel H (1961) Thermohaline convection with two stable regimes of flow. Tellus 13:224–230Google Scholar
  27. Weaver AJ, Sarachik ES (1991a) The role of mixed boundary conditions in numerical models of the ocean's climate. J Phys Oceanogr 21:1470–1493Google Scholar
  28. Weaver AJ, Sarachik ES (1991b) Evidence for decadal variability in an ocean general circulation model: an advective mechanism. Atmos Ocean 29:197–231Google Scholar
  29. Weaver AJ, Sarachik ES, Marotzke J (1991) Freshwater flux forcing of decadal and interdecadal oceanic variability. Nature 353:836–838Google Scholar
  30. Wright DG, Stocker TF (1991) A zonally averaged ocean model for the thermohaline circulation. Part 1: Model development and flow dynamics. J Phys Oceanogr 21:1713–1724Google Scholar
  31. Wright DG, Stocker TF (1992) Sensitivities of a zonally averaged global ocean circulation model. J Geophys Res 91 (in press)Google Scholar
  32. Yiou P, Genthon C, Ghil M, Jouzel J, Le Trent H, Barnola JM, Lorius C, Korotkevitch YN (1991) High-frequency paleovariability in climate and CO2 levels from Vostock ice core records. J Geophys Res 96:20365–20378Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • L A Mysak
    • 1
  • T F Stocker
    • 1
  • F Huang
    • 1
  1. 1.Department of Atmospheric and Oceanic Sciences and Centre for Climate and Global Change ResearchMcGill UniversityMontrealCanada

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