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Article
Article Type:
Research Article

Mechanism of Interdecadal Thermohaline Circulation Variability in a Coupled Ocean–Atmosphere GCM

Buwen Dong Hadley Centre for Climate Prediction and Research, Met Office, Exeter, United Kingdom

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Rowan T. Sutton Centre for Global Atmospheric Modelling, Department of Meteorology, University of Reading, Reading, United Kingdom

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Print Publication:
15 Apr 2005
DOI:
https://doi.org/10.1175/JCLI3328.1
Page(s):
1117–1135
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Abstract

Interdecadal variability of the Atlantic thermohaline circulation (THC) is studied in the third version of the Hadley Centre global coupled atmosphere–ocean sea-ice general circulation model (HadCM3). A diagnostic approach is used to elucidate the mechanism that governs the variability and its impacts on climate. An irregular and heavily damped THC oscillation with a period around 25 yr is identified. The oscillation appears to be forced by the atmosphere but the ocean is responsible for setting the time scale. Following a minimum in the THC, the mechanism for phase reversal involves the accumulation of cold water in the subpolar gyre, leading to an acceleration of the gyre circulation and the North Atlantic Current. This acceleration increases the transport of saline waters into the regions of active deep convection, raising the upper-ocean density and leading, after adjustment, to acceleration of the THC. The atmosphere stimulates this THC variability in two ways: 1) by forcing the subpolar gyre through (North Atlantic Oscillation) NAO-related wind stress curl and heat flux anomalies; and 2) by direct forcing of the region of active deep convection, also through wind stress curl and heat flux anomalies. The latter is not closely related to the NAO. The mechanism for phase reversal has many similarities to that found in a previous study with a much lower resolution coupled model, suggesting that this mechanism may be quite robust. However the time scale, and details of the atmospheric forcing, differ.

The THC variability in HadCM3 has significant impacts on the atmosphere not just in the Atlantic region but also more widely, throughout the global Tropics. The mechanism involves modulation by the THC of the cross-equator SST gradient in the tropical Atlantic. The SST anomalies induce a displacement of the ITCZ in the Atlantic basin with knock-on effects over the other ocean basins. These findings highlight the potential importance of the Atlantic THC as a cause of interdecadal climate variability on a global scale.

Corresponding author address: Dr. Buwen Dong, Hadley Centre for Climate Prediction and Research, Met Office, FitzRoy Road, Exeter EX1 3PB, United Kingdom. Email: buwen.dong@metoffice.gov.uk

Abstract

Interdecadal variability of the Atlantic thermohaline circulation (THC) is studied in the third version of the Hadley Centre global coupled atmosphere–ocean sea-ice general circulation model (HadCM3). A diagnostic approach is used to elucidate the mechanism that governs the variability and its impacts on climate. An irregular and heavily damped THC oscillation with a period around 25 yr is identified. The oscillation appears to be forced by the atmosphere but the ocean is responsible for setting the time scale. Following a minimum in the THC, the mechanism for phase reversal involves the accumulation of cold water in the subpolar gyre, leading to an acceleration of the gyre circulation and the North Atlantic Current. This acceleration increases the transport of saline waters into the regions of active deep convection, raising the upper-ocean density and leading, after adjustment, to acceleration of the THC. The atmosphere stimulates this THC variability in two ways: 1) by forcing the subpolar gyre through (North Atlantic Oscillation) NAO-related wind stress curl and heat flux anomalies; and 2) by direct forcing of the region of active deep convection, also through wind stress curl and heat flux anomalies. The latter is not closely related to the NAO. The mechanism for phase reversal has many similarities to that found in a previous study with a much lower resolution coupled model, suggesting that this mechanism may be quite robust. However the time scale, and details of the atmospheric forcing, differ.

The THC variability in HadCM3 has significant impacts on the atmosphere not just in the Atlantic region but also more widely, throughout the global Tropics. The mechanism involves modulation by the THC of the cross-equator SST gradient in the tropical Atlantic. The SST anomalies induce a displacement of the ITCZ in the Atlantic basin with knock-on effects over the other ocean basins. These findings highlight the potential importance of the Atlantic THC as a cause of interdecadal climate variability on a global scale.

Corresponding author address: Dr. Buwen Dong, Hadley Centre for Climate Prediction and Research, Met Office, FitzRoy Road, Exeter EX1 3PB, United Kingdom. Email: buwen.dong@metoffice.gov.uk

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  • Anderson, D., and Coauthors, 1998: Climate variability and predictability research in Europe, 1999–2004. Euroclivar recommendations. KNMI, De Bilt, Netherlands, xxiv + 120 pp.

  • Bentsen, M., H. Drange, T. Furevik, and T. Zhou, 2004: Variability of the Atlantic meridional overturning circulation in an isopycnic coordinate OGCM. Climate Dyn., 22 , 701–720.

    • Search Google Scholar
    • Export Citation

  • Bjerknes, J., 1964: Atlantic air-sea interaction. Advance in Geophysics,, Vol. 10, Academic Press,. 1–82.

  • Broecker, W. S., 1991: The great ocean conveyor. Oceanography, 4 , 79–89.

  • Cappellini, V., 1978: Digital Filters and Their Applications. Academic Press, 393 pp.

  • Cheng, W., R. Bleck, and C. Rooth, 2004: Multi-decadal thermohaline variability in an ocean-atmosphere general circulation model. Climate Dyn., 22 , 573–590.

    • Search Google Scholar
    • Export Citation

  • Christoph, M., U. Ulbrich, J. M. Oberhuber, and E. Roeckner, 2000: The role of ocean dynamics for low-frequency fluctuations of the NAO in a coupled ocean–atmosphere GCM. J. Climate, 13 , 2536–2549.

    • Search Google Scholar
    • Export Citation

  • CLIVAR, 1998: CLIVAR initial implementation plan. WCRP No. 102, 314 pp.

  • Cox, M. D., 1984: A primitive equation. 3: Dimensional model of the ocean. GFDL Ocean Group Tech. Rep. 1, Princeton, NJ, 143 pp.

  • Cox, P. M., R. A. Betts, C. Bunton, R. L. H. Essery, P. R. Rowntree, and J. Smith, 1999: The impact of new land surface physics on the GCM simulation of climate and climate sensitivity. Climate Dyn., 15 , 183–203.

    • Search Google Scholar
    • Export Citation

  • Curry, R. G., and M. S. McCartney, 2001: Ocean gyre circulation changes associated with the North Atlantic Oscillation. J. Phys. Oceanogr., 31 , 3374–3400.

    • Search Google Scholar
    • Export Citation

  • Delworth, T. L., and R. J. Greatbatch, 2000: Multidecadal thermohaline circulation variability driven by atmospheric surface flux forcing. J. Climate, 13 , 1481–1495.

    • Search Google Scholar
    • Export Citation

  • Delworth, T. L., and M. E. Mann, 2000: Observed and simulated multidecadal variability in the Northern Hemisphere. Climate Dyn., 16 , 661–676.

    • Search Google Scholar
    • Export Citation

  • Delworth, T. L., S. Manabe, and R. J. Stouffer, 1993: Interdecadal variations of the thermohaline circulation in a coupled ocean–atmosphere model. J. Climate, 6 , 1993–2011.

    • Search Google Scholar
    • Export Citation

  • Deser, C., and M. L. Blackman, 1993: Surface climate variations over the North Atlantic Ocean during winter 1900–89. J. Climate, 6 , 1743–1753.

    • Search Google Scholar
    • Export Citation

  • Dong, B-W., and R. Sutton, 2001: The dominant mechanisms of variability in Atlantic Ocean heat transport in a coupled ocean-atmosphere GCM. Geophys. Res. Lett., 28 , 2445–2448.

    • Search Google Scholar
    • Export Citation

  • Dong, B-W., and R. Sutton, 2002a: Adjustment of the coupled ocean-atmosphere system to a sudden change in the Thermohaline Circulation. Geophys. Res. Lett., 29 .1728, doi:10.1029/2002GL015229.

    • Search Google Scholar
    • Export Citation

  • Dong, B-W., and R. Sutton, 2002b: Variability in North Atlantic heat content and heat transport in a coupled ocean-atmosphere GCM. Climate Dyn., 19 , 485–497.

    • Search Google Scholar
    • Export Citation

  • Doscher, R. C., W. Boning, and P. Harmony, 1994: Response of circulation and heat transport in the North Atlantic to changes in thermohaline forcing in Northern latitudes: A model study. J. Phys. Oceanogr., 24 , 2306–2320.

    • Search Google Scholar
    • Export Citation

  • Eden, C., and T. Jung, 2001: North Atlantic interdecadal variability: Oceanic response to the North Atlantic Oscillation (1865–1997). J. Climate, 14 , 676–691.

    • Search Google Scholar
    • Export Citation

  • Eden, C., and J. Willebrand, 2001: Mechanism of interannual to decadal variability of the North Atlantic circulation. J. Climate, 14 , 2266–2280.

    • Search Google Scholar
    • Export Citation

  • Edwards, J. M., and A. Slingo, 1996: Studies with a flexible new radiation code. I: Choosing a configuration for a large scale model. Quart. J. Roy. Meteor. Soc., 122 , 689–719.

    • Search Google Scholar
    • Export Citation

  • Folland, C. K., A. W. Colman, D. P. Rowell, and M. K. Davey, 2001: Predictability of northeast Brazil rainfall and real-time forecast skill, 1987–98. J. Climate, 14 , 1937–1958.

    • Search Google Scholar
    • Export Citation

  • Ganachaud, A., and C. Wunsch, 2000: Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. Nature, 408 , 453–457.

    • Search Google Scholar
    • Export Citation

  • Gordon, C., C. Cooper, C. A. Senior, H. Banks, J. M. Gregory, T. C. Johns, J. F. B. Mitchell, and R. A. Wood, 2000: The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments. Climate Dyn., 16 , 147–168.

    • Search Google Scholar
    • Export Citation

  • Grotzner, A., M. Latif, and T. P. Barnett, 1998: A decadal climate cycle in the North Atlantic Ocean as simulated by the ECHO coupled GCM. J. Climate, 11 , 831–847.

    • Search Google Scholar
    • Export Citation

  • Halliwell, G. R., 1997: Decadal and multidecadal North Atlantic SST anomalies driven by standing and propagating basin-scale atmospheric anomalies. J. Climate, 10 , 2405–2411.

    • Search Google Scholar
    • Export Citation

  • Halliwell, G. R., 1998: Simulation of North Atlantic decadal/multidecadal winter SST anomalies driven by basin-scale atmospheric circulation anomalies. J. Phys. Oceanogr., 28 , 5–21.

    • Search Google Scholar
    • Export Citation

  • Hoerling, M. P., J. W. Hurrell, and T. Xu, 2001: Tropical origins for recent North Atlantic climate change. Science, 292 , 90–92.

  • Holland, M. M., C. M. Bitz, M. Eby, and A. J. Weaver, 2001: The role of ice–ocean interactions in the variability of the North Atlantic thermohaline circulation. J. Climate, 14 , 656–676.

    • Search Google Scholar
    • Export Citation

  • Hurrell, J. W., 1995: Decadal trends in the North Atlantic oscillation: Regional temperatures and precipitation. Science, 269 , 676–679.

    • Search Google Scholar
    • Export Citation

  • Johannssen, O. M., and Coauthors, 2004: Arctic climate change: Observed and modelled temperature and sea-ice variability. Tellus, 56 , 328–341.

    • Search Google Scholar
    • Export Citation

  • Johnson, H. L., and D. P. Marshall, 2002: A theory for the surface Atlantic response to thermohaline variability. J. Phys. Oceanogr., 32 , 1121–1132.

    • Search Google Scholar
    • Export Citation

  • Josey, S. A., E. C. Kent, and P. K. Taylor, 2002: On the wind stress forcing of the ocean in the SOC climatology: Comparisons with the NCEP–NCAR, ECMWF, UWM/COADS, and Hellerman and Rosenstein datasets. J. Phys. Oceanogr., 32 , 1993–2019.

    • Search Google Scholar
    • Export Citation

  • Kawase, M., 1987: Establishment of deep ocean circulation driven by deep-water production. J. Phys. Oceanogr., 17 , 2294–2317.

  • Killworth, P. D., 1983: Deep convection in the world ocean. Rev. Geophys. Space Phys., 21 , 1–26.

  • Kushnir, Y., 1994: Interdecadal variations in North Atlantic sea surface temperature and associated atmospheric conditions. J. Climate, 7 , 141–157.

    • Search Google Scholar
    • Export Citation

  • Latif, M., K. Arpe, and E. Roecker, 2000: Oceanic control of decadal North Atlantic sea level pressure variability in winter. Geophys. Res. Lett., 27 , 727–730.

    • Search Google Scholar
    • Export Citation

  • Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Paper 13, 173 pp. and 17 microfiche.

  • Manabe, S., and R. J. Stouffer, 1999: The role of thermohaline circulation in climate. Tellus, 51 , 91–109.

  • Mauritzen, C., and S. Hakkinen, 1999: On the relationship between dense water formation and the “Meridional Overturning Cell” in the North Atlatin Ocean. Deep-Sea Res., 46 , 877–894.

    • Search Google Scholar
    • Export Citation

  • Mehta, V. M., M. J. Suarez, J. V. Manganello, and T. L. Delworth, 2000: Oceanic influence on the North Atlantic Oscillation and associated Northern Hemisphere climate variations: 1959–1993. Geophys. Res. Lett., 27 , 121–124.

    • Search Google Scholar
    • Export Citation

  • Moura, A. D., and J. Shukla, 1981: On the dynamics of droughts in Northeast Brazil: Observations, theory, and numerical experiments with a general circulation model. J. Atmos. Sci., 38 , 2653–2675.

    • Search Google Scholar
    • Export Citation

  • Pope, V. D., M. L. Gallani, R. R. Rowntree, and R. A. Stratton, 2000: The impact of new physical parameterizations in the Hadley Centre climate model—HadAM3. Climate Dyn., 16 , 123–146.

    • Search Google Scholar
    • Export Citation

  • Power, S., T. Casey, C. K. Folland, A. Colman, and V. Mehta, 1999: Inter-decadal modulation of the impact of ENSO on Australia. Climate Dyn., 15 , 319–323.

    • Search Google Scholar
    • Export Citation

  • Rahmstorf, S., 1995: Multiple convection patterns and thermohaline flow in an idealized OGCM. J. Climate, 8 , 3028–3039.

  • Rodwell, M. J., D. P. Rowell, and C. K. Folland, 1999: Oceanic forcing of the winter North Atlantic Oscillation and European climate. Nature, 398 , 320–323.

    • Search Google Scholar
    • Export Citation

  • Seager, R., Y. Kushnir, M. Visbeck, N. Naik, J. Miller, G. Krahmann, and H. Cullen, 2000: Cause of Atlantic Ocean climate variability between 1958 and 1998. J. Climate, 13 , 2845–2862.

    • Search Google Scholar
    • Export Citation

  • Sutton, R. T., S. P. Jewson, and D. P. Rowell, 2000: The elements of climate variability in the tropical Atlantic region. J. Climate, 13 , 3261–3284.

    • Search Google Scholar
    • Export Citation

  • Timmermann, A., M. Latif, R. Voss, and A. Groetzner, 1998: Northern Hemispheric interdecadal variability: A coupled air–sea mode. J. Climate, 11 , 1906–1931.

    • Search Google Scholar
    • Export Citation

  • Vellinga, M., and R. A. Wood, 2002: Global climatic impacts of a collapse of the Atlantic thermohaline circulation. Climate Change, 54 , 251–267.

    • Search Google Scholar
    • Export Citation

  • Vellinga, M., and P-L. Wu, 2004: Low-latitude freshwater influence on centennial variability of the Atlantic thermohaline circulation. J. Climate, 17 , 4498–4511.

    • Search Google Scholar
    • Export Citation

  • Visbeck, M., H. Cullen, G. Krahmann, and N. Naik, 1998: An ocean model’s response to North Atlantic Oscillation-like wind forcing. Geophys. Res. Lett., 25 , 4521–4524.

    • Search Google Scholar
    • Export Citation

  • Watanabe, M., M. Kimoto, T. Nitta, and M. Kachi, 1999: A comparison of decadal climate oscillations in the North Atlantic detected in observations and a coupled GCM. J. Climate, 12 , 2920–2940.

    • Search Google Scholar
    • Export Citation

  • Weaver, A. J., C. M. Bitz, A. F. Fanning, and M. M. Holland, 1999: Thermohaline circulation: High latitude phenomena and the difference between the Pacific and Atlantic. Annu. Rev. Earth Planet. Sci., 27 , 231–285.

    • Search Google Scholar
    • Export Citation

  • Wood, R. A., A. B. Keen, J. F. B. Mitchell, and J. M. Gregory, 1999: Changing spatial structure of the thermohaline circulation in response to atmospheric CO2 forcing in a climate model. Nature, 399 , 572–575.

    • Search Google Scholar
    • Export Citation

  • Wu, P-L., and C. Gordon, 2002: Oceanic influence on North Atlantic climate variability. J. Climate, 15 , 1911–1925.

  • Yang, J., 1999: A linkage between decadal climate variations in the Labrador Sea and the tropical Atlantic Ocean. Geophys. Res. Lett., 26 , 1023–1026.

    • Search Google Scholar
    • Export Citation
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