Climate Dynamics

, Volume 38, Issue 3–4, pp 513–525 | Cite as

AMOC variations in 1979–2008 simulated by NCEP operational ocean data assimilation system

  • Boyin Huang
  • Yan Xue
  • Arun Kumar
  • David W. Behringer
Article

Abstract

Variations in the Atlantic meridional overturning circulation (AMOC) between 1979 and 2008 are documented using the operational ocean analysis, the Global Ocean Data Assimilation System (GODAS), at the National Centers for Climate Prediction (NCEP). The maximum AMOC at 40°N is about 16 Sv in average with peak-to-peak variability of 3–4 Sv. The AMOC variations are dominated by an upward trend from 1980 to 1995, and a downward trend from 1995 to 2008. The maximum AMOC at 26.5°N is slightly weaker than hydrographic estimates and observations from mooring array. The dominant variability of the AMOC in 20°–65°N (the first EOF, 51% variance) is highly correlated with that in the subsurface temperature (the first EOF, 33% variance), and therefore, with density (the first EOF, 25% variance) in the North Atlantic, and is consistent with the observational estimates based on the World Ocean Database 2005. The dominant variabilities of AMOC and subsurface temperature are also analyzed in the context of possible links with the net surface heat flux, deep convection, western boundary current, and subpolar gyre. Variation in the net surface heat flux is further linked to the North Atlantic Oscillation (NAO) index which is found to lead AMOC variations by about 5 years. Our results indicate that AMOC variations can be documented based on an ocean analysis system such as GODAS.

Keywords

Atlantic meridional overturning circulation AMOC Global ocean data assimilation system GODAS North Atlantic oscillation NAO National centers for environmental prediction NCEP 

Notes

Acknowledgments

Authors thank Tim Boyer of National Oceanographic Data Center for providing us objectively analyzed salinity and temperature data of the World Ocean Database 2005. Comments from two anonymous reviewers have greatly improved our manuscript.

References

  1. Balmaseda MA et al (2007) Historical reconstruction of the Atlantic meridional overturning circulation from the ECMWF operational ocean reanalysis. Geophys Res Lett 34:L23515. doi: 10.1029/2007GL031645 Google Scholar
  2. Behringer DW (2007) The global ocean data assimilation system (GODAS) at NCEP. Preprints, 11th symp. on integrated observing and assimilation systems for atmosphere, oceans, and land surface, San Antonio, TX, Amer. Meteor. Soc., 3.3. Available online at http://ams.confex.com/ams/87ANNUAL/techprogram/paper_119541.htm
  3. Behringer DW, Ji M, Leetma A (1998) An improved coupled model for ENSO prediction and implication for ocean initialization. Part I: the ocean data assimilation system. Mon Wea Rev 126:1013–1021Google Scholar
  4. Behringer DW, Xue Y (2004) Evaluation of the global ocean data assimilation system at NCEP: the Pacific ocean. Eighth symposium on integrated observing and assimilation system for atmosphere, ocean, and land surface, AMS 84th annual meeting, Washington State Convention and Trade Center, Seattle, Washington, pp 11–15Google Scholar
  5. Bentsen M et al (2004) Simulated variability of the Atlantic meridional overturning circulation. Clim Dyn 22:701–720CrossRefGoogle Scholar
  6. Bingham RJ et al (2007) Meridional coherence of the North Atlantic meridional overturning circulation. Geophys Res Lett 34:L23606. doi: 10.1029/2007GL031731 CrossRefGoogle Scholar
  7. Böning CW et al (2006) Decadal variability of subpolar gyre transport and its reverberation in the North Atlantic overturning. Geophys Res Lett 33:L21S01. doi: 10.1029/2006GL026906
  8. Boyer TP et al (2006) World Ocean database 2005. In: Levitus S (ed) NOAA atlas NESDIS, vol 60. U.S. Government Print Office, Washington, DC, 190 ppGoogle Scholar
  9. Bryden HL et al (2005) Slowing of the Atlantic meridional overturning circulation at 25 N. Nature 438. doi: 10.1038/nature04385
  10. Bugnion V et al (2006) An adjoint analysis of the meridional overturning circulation in an ocean model. J Clim 19:3732–3750CrossRefGoogle Scholar
  11. Cunningham SA, Kanzow T, Rayner D, Baringer MO, Johns WE, Marotzke J, Longworth HR, Grant EM, Hirschi JJ-M, Beal LM, Meinen CS, Bryden HL (2007) Temporal variability of the Atlantic meridional overturning circulation at 26.5°N. Science 317:935–938. doi: 10.1126/science.1141304 Google Scholar
  12. Danabasoglu G (2008) On multidecadal variability of the Atlantic meridional overturning circulation in the community climate system model version 3. J Clim 21:5524–5544CrossRefGoogle Scholar
  13. Delworth TL, Mann ME (2000) Observed and simulated multi-decadal variability in the Northern Hemisphere. Clim Dyn 16:661–676CrossRefGoogle Scholar
  14. Eden C, Willebrand J (2001) Mechanism of interannual to decadal variability of the North Atlantic circulation. J Clim 14:2266–2280CrossRefGoogle Scholar
  15. Frankignoul C, Deshayes J, Curry R (2009) The role of salinity in the decadal variability of the North Atlantic meridional overturning circulation. Clim Dyn. doi: 10.1007/s00382-008-0523-2
  16. Gill AE (1982) Atmosphere-ocean dynamics. Academic Press, CambridgeGoogle Scholar
  17. Grist JP, Marsh R, Josey SA (2009) On the relationship between the North Atlantic meridional overturning circulation and the surface-forced overturning stream function. J Clim 22:4989–5002CrossRefGoogle Scholar
  18. Häkkinen S, Rhines PB (2004) During the 1990s decline of subpolar North Atlantic circulation. Science 304. doi: 10.1126/science.1094917
  19. Held IM et al (2005) Simulation of Sahel drought in the 20th and 21st centuries. PNAS 102:17891–17896. doi: 10.1073/pnas.0509057102 CrossRefGoogle Scholar
  20. Huang B, Stone PH, Hill C (2003) Sensitivities of deep-ocean heat content to surface fluxes and subgrid-scale parameters in an ocean general circulation model. J Geophys Res 108. doi: 10.1029/2001JC001044
  21. Huang B, Xue Y, Behringer DW (2008) Impacts of Argo salinity in NCEP global ocean data assimilation system: the tropical Indian ocean. J Geophys Res 113:C08002. doi: 10.1029/2007JC004388 CrossRefGoogle Scholar
  22. Josey SA, Grist JP, Marsh R (2009) Estimates of meridional overturning circulation variability in the North Atlantic from surface density flux fields. J Geophys Res 114:C09022. doi: 10.1029/2008JC005230 CrossRefGoogle Scholar
  23. Jungclaus JH, Haak H, Latif M, Mikolajewicz U (2005) Arctic North Atlantic interactions and multidecadal variability of the meridional overturning circulation. J Clim 18:4013–4031CrossRefGoogle Scholar
  24. Kalnay E et al (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteor Soc 77:437–470CrossRefGoogle Scholar
  25. Kanamitsu M, Ebisuzaki W, Woolen J, Yang S-K, Hnilo JJ, Fiorino M, Potter GL (2002) NCEP-DOE AMIP-II reanalysis (R-2). Bull Am Meteor Soc 83:1631–1643CrossRefGoogle Scholar
  26. Kanzow T et al (2010) Seasonal variability of the Atlantic meridional overturning circulation at 26.5°N. J Clim 23:5678–5698Google Scholar
  27. Keenlyside NS et al (2008) Advancing decadal-scale climate prediction in the North Atlantic sector. Nature 453:84–88. doi: 10.1038/nature06921 CrossRefGoogle Scholar
  28. Kerr RA (2000) A North Atlantic climate pacemaker for the centuries. Science 288:1984–1985CrossRefGoogle Scholar
  29. Knight JR, Allan RJ, Folland CK, Vellinga M, Mann ME (2005) A signature of persistent natural thermohaline circulation cycles in observed climate. Geophys Res Lett 32:L20708. doi: 10.1029/2005GL024233 CrossRefGoogle Scholar
  30. Köhl A, Stammer D (2007) Variability of the meridional overturning in the North Atlantic from the 50 years GECCO state estimation. Rep. 43, Institut fur Meereskunde, University of Hamburg, 38 ppGoogle Scholar
  31. Kuhlbrodt K et al (2007) On the driving processes of the Atlantic meridional overturning circulation. Rev Geophys 45: RG2001. doi: 10.1029/2004RG000166
  32. Meehl GA et al (2009) Decadal prediction. Bull Am Metrol Soc 90:1467–1485CrossRefGoogle Scholar
  33. Msadek R, Frankignoul C (2009) Atlantic multidecadal oceanic variability and its influence on the atmosphere in a climate model. Clim Dyn 33:45–62. doi: 10.1007/s00382-008-0452-0 CrossRefGoogle Scholar
  34. Pohlmann H, Jungclaus JH, Köhl A, Stammer D, Marotzke J (2009) Initializing decadal climate predictions with the GECCO oceanic synthesis: effects on the North Atlantic. J Clim 22:3926–3938CrossRefGoogle Scholar
  35. Rahmstorf S (1996) On the freshwater forcing and transport of the Atlantic thermohaline circulation. Clim Dyn 12:799–811CrossRefGoogle Scholar
  36. Smith DM et al (2007) Improved surface temperature prediction for the coming decade from a global climate model. Science 317. doi: 10.1126/science.1139540
  37. Stommel H (1961) Thermohaline convection with two stable regimes of flow. Tellus 13B:224–230CrossRefGoogle Scholar
  38. Vellinga M (1996) Instability of two-dimensional thermohaline circulation. J Phys Oceanogr 26:305–319CrossRefGoogle Scholar
  39. Wang C et al (2009) Seawater density variations in the North Atlantic and the Atlantic meridional overturning circulation. Clim Dyn 33. doi: 10.1007/s00382-009-0560-5
  40. Wunsch C (2005) Thermohaline loops, Stommel box models, and the Sandstrom theorem. Tellus 57A:84–99Google Scholar
  41. Wunsch C, Heimbach P (2006) Estimated decadal changes in the North Atlantic meridional overturning circulation and heat flux 1993–2004. J Phys Oceanogr 36:2012–2024CrossRefGoogle Scholar
  42. Zhang R (2008) Coherent surface subsurface fingerprint of the Atlantic meridional overturning circulation. Geophys Res Lett 35:L20705. doi: 10.1029/2008GL035463 CrossRefGoogle Scholar
  43. Zhang S, Rosati A, Harrison MJ (2009) Detection of multidecadal oceanic variability by ocean data assimilation in the context of a “perfect” coupled model. J Geophys Res 114: C12018. doi: 10.1029/2008JC005261

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Boyin Huang
    • 1
    • 3
  • Yan Xue
    • 1
  • Arun Kumar
    • 1
  • David W. Behringer
    • 2
  1. 1.Climate Prediction Center, NOAACamp SpringsUSA
  2. 2.Environmental Modeling Center, NOAACamp SpringsUSA
  3. 3.AshevilleUSA

Personalised recommendations