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Acta Meteorologica Sinica

, Volume 25, Issue 3, pp 364–375 | Cite as

Simulated spatiotemporal response of ocean heat transport to freshwater enhancement in North Atlantic and associated mechanisms

  • Lei Yu (于 雷)
  • Yongqi Gao (郜永祺)Email author
Article
  • 587 Downloads

Abstract

The Atlantic Meridional Overturning Circulation (AMOC) transports a large amount of heat to northern high latitudes, playing an important role in the global climate change. Investigation of the freshwater perturbation in North Atlantic (NA) has become one of the hot topics in the recent years. In this study, the mechanism and pathway of meridional ocean heat transport (OHT) under the enhanced freshwater input to the northern high latitudes in the Atlantic are investigated by an ocean-sea ice-atmosphere coupled model. The results show that the anomalous OHT in the freshwater experiment (FW) is dominated by the meridional circulation kinetic and ocean thermal processes. In the FW, OHT drops down during the period of weakened AMOC while the upper tropical ocean turns warmer due to the retained NA warm currents. Conversely, OHT recovers as the AMOC recovers, and the mechanism can be generalized as: 1) increased ocean heat content in the tropical Southern Ocean during the early integration provides the thermal condition for the recovery of OHT in NA; 2) the OHT from the Southern Ocean enters the NA through the equator along the deep Ekman layer; 3) in NA, the recovery of OHT appears mainly along the isopycnic layers of 24.70–25.77 below the mixing layer. It is then transported into the mixing layer from the “outcropping points” in northern high latitudes, and finally released to the atmosphere by the ocean-atmosphere heat exchange.

Key words

the Atlantic meridional overturning circulation meridional ocean heat transport freshwater experiment 

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References

  1. Bleck, R., C. Rooth, D. Hu, et al., 1992: Salinitydriven therm Ohaline transient in a wind- and thermohaline-forced isopycnic coordinate model of the North Atlantic. J. Phys. Oeanogr., 22, 1486–1505.CrossRefGoogle Scholar
  2. Bond, G., W. Broecker, S. Johnsen, et al., 1993: Correlations between climate records from North Atlantic sediments and Greenland ice. Nature, 365, 143–147.CrossRefGoogle Scholar
  3. Broecker, W. S., 1991: The great ocean conveyor. Oceanography, 4, 79–89.Google Scholar
  4. Charles, C. D., and R. G. Fairbanks, 1992: Evidence from Southern Ocean sediments for the effect of North Atlantic deep-water flux on climate. Nature, 355, 416–419.CrossRefGoogle Scholar
  5. Clark, P. U., N. G. Pisias, T. F. Stocker, et al., 2002: The role of the thermohaline circulation in abrupt climate change. Nature, 415, 863–869.CrossRefGoogle Scholar
  6. Delworth, T. L., and R. J. Greatbatch, 2000: Multi-decadal thermohaline circulation variability driven by atmospheric surface flux forcing. J. Climate, 13, 1481–1495.CrossRefGoogle Scholar
  7. Déqué, M., C. Dreveton, A. Braun, et al., 1994: The ARPEGE/IFS atmosphere model: A contribution to the french community climate modeling. Climate Dyn., 10, 249–266.CrossRefGoogle Scholar
  8. Dong, B. W., and T. S. Rowan, 2003: Variability of Atlantic Ocean heat transport and its effects in the atmosphere. Annals of Geophysics, 46, 87–97.Google Scholar
  9. —, and R. T. Sutton, 2001: The dominant mechanisms of variability in Atlantic Ocean heat transport in a coupled model. Geo. Res. Lett., 28, 2445–2448.CrossRefGoogle Scholar
  10. Furevik, T., M. Bentsen, H. Drange, et al., 2003: Description and validation of the Bergen Climate Model: ARPEGE coupled with MICOM. Climate Dyn., 21, 27–51.CrossRefGoogle Scholar
  11. Ganachaud, A., and C. Wusch, 2000: Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. Nature, 408, 453–457.CrossRefGoogle Scholar
  12. Ganopolski, A., and S. Rahmstorf, 2001: Rapid changes of glacial climate simulated in a coupled climate model. Nature, 409, 153–158.CrossRefGoogle Scholar
  13. Gao, Y. Q., H. Drange, and M. Bentsen, 2003: Effects of diapycnal mixing and isopycnal mixing on the ventilation of CFCs in the North Atlantic in an isopycnal coordinate OGCM. Tellus, 55B, 837–854.Google Scholar
  14. Hall, M. M., and H. L. Bryden, 1982: Direct estimates and mechanisms of ocean heat transport. Deep-Sea Res., 29, 339–359.CrossRefGoogle Scholar
  15. Jayne, S. R., and J. Marotzke, 2001: The dynamics of ocean heat transport variability. Rev. Geophys., 39, 385–411.CrossRefGoogle Scholar
  16. Jia, Y. L., 2003: Ocean heat transport and its relationship to ocean circulation in the CMIP coupled models. Climate Dyn., 20, 153–174.Google Scholar
  17. Kobayashi, T., and N. Imasato, 1998: Seasonal variability of heat transport derived from hydrographic and wind stress data. J. Geophys. Res., 103, 663–674.CrossRefGoogle Scholar
  18. Lu, R., and B. Dong, 2009: Response of the Asian summer monsoon to weakening of Atlantic thermohaline circulation. Adv. Atmos. Sci., 25, 723–736.CrossRefGoogle Scholar
  19. Manabe, S., and R. J. Stouffer, 1997: Coupled ocean-atmosphere model response to freshwater input: Comparison to Younger Dryas event. Paleoceanography, 12, 321–336.CrossRefGoogle Scholar
  20. Mauritzen, C., 1996: Production of dense overflow waters feeding the North Atlantic across the Greenland-Scotland ridge. Part I: Evidence for a revised circulation scheme. Deep-Sea Res., 43, 769–806.CrossRefGoogle Scholar
  21. McManus, J. F., R. Francols, J. M. Gherardi, et al., 2004: Collapse and rapid resumption of Atlantic Meridional Circulation linked to deglacial climate changes. Nature, 428, 834–837.CrossRefGoogle Scholar
  22. Otterå, O. H., H. Drange, M. Bentsen, et al., 2004: Transient response of the Atlantic Meridional Overturning Circulation to enhanced freshwater input to the Nordic Seas-Arctic Ocean in the Bergen Climate Model. Tellus, 56, 342–361.CrossRefGoogle Scholar
  23. Rahmstorf, S., 1996: On the freshwater forcing and transport of the Atlantic thermohaline circulation. Clim. Dyn., 12, 799–811.CrossRefGoogle Scholar
  24. —, 2003: Thermohaline circulation: The current climate. Nature, 421, 699.CrossRefGoogle Scholar
  25. —, and A. Ganopolski, 1999: Long-term global warming scenarios computed with efficient coupled climate model. Climatic Changes, 43, 353–367.CrossRefGoogle Scholar
  26. Schweckendiek, U., and J. Willebrand, 2005: Mechanisms affecting the overturning response in global warming simulations. J. Climate, 4925–4936.Google Scholar
  27. Steven, R. J., and J. Marotzke, 2001: The dynamics of ocean heat transport variability. Rev. Geophys., 39, 385–411.CrossRefGoogle Scholar
  28. Stouffer, R. J., J. Yin, J. M. Gregory, et al., 2006: Investigating the causes of the response of the thermohaline circulation to past and future climate changes. J. Climate, 19, 1365–1387.CrossRefGoogle Scholar
  29. Terray, L., O. Thual, S. Belamari, et al., 1995: Climatology and interannual variability simulated by the ARPEGEOPA coupled model. Climate Dyn., 11, 487–505.CrossRefGoogle Scholar
  30. Trenberth, K. E., and J. M. Caron, 2001: Estimates of meridional atmosphere and ocean heat transports. J. Climate, 14, 3433–3443.CrossRefGoogle Scholar
  31. Tziperman, E., 2000: Proximity of the present day thermohaline circulation to an instability threshold. J. Phys. Oceanogr., 30, 90–104.CrossRefGoogle Scholar
  32. Weaver, A. J., and S. Valcke, 1998: On the variability of the thermohaline circulation in the GFDL coupled model. J. Climate, 11, 759–767.CrossRefGoogle Scholar
  33. Yu, L., Y. Q. Gao, H. J. Wang, et al., 2008: Revisiting effect of ocean diapycnal mixing on Atlantic Meridional Overturning Circulation recovery in a freshwater perturbation simulation. Adv. Atmos. Sci., 25, 597–609.CrossRefGoogle Scholar
  34. —,—,—, et al., 2009a: The responses of East Asian summer monsoon to the North Atlantic Meridional Overturning Circulation in an enhanced freshwater input simulation. Chinese Sci. Bull., 54, 4724–4732.CrossRefGoogle Scholar
  35. —,—,—, et al., 2009b: Transient response of the Atlantic Meridional Overturning Circulation to the enhanced freshwater forcing and its mechanism. Chinese J. Atmos. Sci., 3(1), 179–197. (in Chinese)Google Scholar
  36. Zhou, T. J., R. C. Yu, X. Y. Liu, et al., 2005: Weak response of the Atlantic thermohaline circulation to an increase of atmospheric carbon dioxide in IAP/LASG Climate System Model. Chinese Sci. Bull., 50, 592–598.Google Scholar

Copyright information

© The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Nansen-Zhu International Research Center, Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina
  2. 2.Nansen Environmental and Remote Sensing Center/Bjerknes Centre for Climate ResearchBergenNorway

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