Climate Dynamics

, Volume 39, Issue 12, pp 3057–3073 | Cite as

The impact of resolution on the adjustment and decadal variability of the Atlantic meridional overturning circulation in a coupled climate model

  • Daniel L. R. Hodson
  • Rowan T. Sutton


Variations in the Atlantic meridional overturning circulation (MOC) exert an important influence on climate, particularly on decadal time scales. Simulation of the MOC in coupled climate models is compromised, to a degree that is unknown, by their lack of fidelity in resolving some of the key processes involved. There is an overarching need to increase the resolution and fidelity of climate models, but also to assess how increases in resolution influence the simulation of key phenomena such as the MOC. In this study we investigate the impact of significantly increasing the (ocean and atmosphere) resolution of a coupled climate model on the simulation of MOC variability by comparing high and low resolution versions of the same model. In both versions, decadal variability of the MOC is closely linked to density anomalies that propagate from the Labrador Sea southward along the deep western boundary. We demonstrate that the MOC adjustment proceeds more rapidly in the higher resolution model due the increased speed of western boundary waves. However, the response of the Atlantic sea surface temperatures to MOC variations is relatively robust—in pattern if not in magnitude—across the two resolutions. The MOC also excites a coupled ocean-atmosphere response in the tropical Atlantic in both model versions. In the higher resolution model, but not the lower resolution model, there is evidence of a significant response in the extratropical atmosphere over the North Atlantic 6 years after a maximum in the MOC. In both models there is evidence of a weak negative feedback on deep density anomalies in the Labrador Sea, and hence on the MOC (with a time scale of approximately ten years). Our results highlight the need for further work to understand the decadal variability of the MOC and its simulation in climate models.


Atlantic MOC Decadal 



The Authors would like to thank Len Shaffrey and the HiGEM project for use of the HiGEM and HadGEM data in this study and two anonymous Reviewers for their valuable comments which notably improved the manuscript. This work was funded by the UK National Environment Research Council (NERC) Grant no. NE/F018533/1 and by the NERC NCAS-Climate programme.


  1. Balan Sarojini B, Gregory JM, Tailleux R, Bigg GR, Blaker AT, Cameron D, Edwards NR, Megann AP, Shaffrey LC, Sinha B (2011) High frequency variability of the Atlantic meridional overturning circulation. Ocean Sci Discussions 8(1):219–246. doi: 10.5194/osd-8-219-2011 CrossRefGoogle Scholar
  2. Böning CW, Bryan FO, Holland WR, Döscher R (1996) Deep-water formation and meridional overturning in a high-resolution model of the North Atlantic. J Phys Oceanogr 26(7):1142–1164. doi: 10.1175/1520-0485(1996)026%3C1142:DWFAMO%3E2.0.CO;2 CrossRefGoogle Scholar
  3. Beckmann A, Böning CW, Köberle C, Willebrand J (1994) Effects of increased horizontal resolution in a simulation of the North Atlantic Ocean. J Phys Oceanogr 24(2):326–344. doi: 10.1175/1520-0485(1994)024%3C0326:EOIHRI%3E2.0.CO;2 CrossRefGoogle Scholar
  4. Bentsen M, Drange H, Furevik T, Zhou T (2004) Simulated variability of the Atlantic meridional overturning circulation. Clim Dyn 22(6):701–720. doi: 10.1007/s00382-004-0397-x CrossRefGoogle Scholar
  5. Biastoch A, Böning CW, Getzlaff J, Molines JM, Madec G (2008) Causes of interannual decadal variability in the meridional overturning circulation of the midlatitude North Atlantic Ocean. J Clim 21(24):6599–6615. doi: 10.1175/2008JCLI2404.1 CrossRefGoogle Scholar
  6. Bower AS, Lozier SM, Gary SF, Boning CW (2009) Interior pathways of the North Atlantic meridional overturning circulation. Nature 459(7244):243–247. doi: 10.1038/nature07979 CrossRefGoogle Scholar
  7. de Boyer Montégut C (2004) Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J Geophys Res 109(C12). doi: 10.1029/2004JC002378
  8. Broccoli AJ, Dahl KA, Stouffer RJ (2006) Response of the ITCZ to Northern Hemisphere cooling. Geophys Res Lett 33(1):L01,702+. doi: 10.1029/2005GL024546 CrossRefGoogle Scholar
  9. Broecker W, Bond G, Klas M, Clark E, McManus J (1992) Origin of the northern Atlantic’s Heinrich events. Clim Dyn 6(3):265–273. doi: 10.1007/BF00193540 CrossRefGoogle Scholar
  10. Bryan K (1969) A numerical method for the study of the circulation of the world ocean. J Compu Phys 4(3):347–376. doi: 10.1016/0021-9991(69)90004-7 CrossRefGoogle Scholar
  11. Bryden HL, Mujahid A, Cunningham SA, Kanzow T (2009) Adjustment of the basin-scale circulation at 26 N to variations in Gulf Stream, deep western boundary current and Ekman transports as observed by the rapid array. Ocean Sci Discussions 6(1):871–908CrossRefGoogle Scholar
  12. Cassou C et al (2004) Summer sea surface temperature conditions in the north atlantic and their impact upon the atmospheric circulation in early winter. J Clim 17:3349–3363CrossRefGoogle Scholar
  13. Chang P, Ji L, Li H (1997) A decadal climate variation in the tropical Atlantic Ocean from thermodynamic air-sea interactions. Nature 385(6616):516–518. doi: 10.1038/385516a0 CrossRefGoogle Scholar
  14. Chelton DB, deSzoeke RA, Schlax MG, El Naggar K, Siwertz N (1998) Geographical variability of the first Baroclinic Rossby radius of deformation. J Phys Oceanogr 28(3):433–460. doi: 10.1175/1520-0485(1998)028%3C0433:GVOTFB%3E2.0.CO;2 CrossRefGoogle Scholar
  15. Conkright ME, Locarnini RA, Garcia HE, O’Brien TD, Boyer TP, Stephen C, Antonov JI (2002) World ocean atlas 2001: objective analyses, data statistics, and figures, CD-ROM documentation. Nat Oceanogr Data Center, Internal Rep (17)Google Scholar
  16. Cox MD (1984) A primitive equation, three dimensional model of the ocean. Tech. rep., GFDL, PrincetonGoogle Scholar
  17. Cunningham SA, Kanzow T, Rayner D, Baringer MO, Johns WE, Marotzke J, Longworth HR, Grant EM, Hirschi JJM, Beal LM, Meinen CS, Bryden HL (2007) Temporal variability of the atlantic meridional overturning circulation at 26.5degreesn. Science 317(5840):935–938. doi: 10.1126/science.1141304 CrossRefGoogle Scholar
  18. Curry RG, McCartney MS, Joyce TM (1998) Oceanic transport of subpolar climate signals to mid-depth subtropical waters. Nature 391(6667):575–577. doi: 10.1038/35356 CrossRefGoogle Scholar
  19. Döscher R, Böning CW, Herrmann P (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(11):2306–2320. doi: 10.1175/1520-0485(1994)024%3C2306:ROCAHT%3E2.0.CO;2 CrossRefGoogle Scholar
  20. Davey MK, Hsieh WW, Wajsowicz RC (1983) The free Kelvin wave with lateral and vertical viscosity. J Phys Oceanogr 13(12):2182–2191. doi: 10.1175/1520-0485(1983)013%3C2182:TFKWWL%3E2.0.CO;2 CrossRefGoogle Scholar
  21. Dickson R, Lazier J, Meincke J, Rhines P, Swift J (1996) Long-term coordinated changes in the convective activity of the North Atlantic. Prog Oceanogr 38(3):241–295. doi: 10.1016/S0079-6611(97)00002-5 CrossRefGoogle Scholar
  22. Dong B, Sutton RT (2005) Mechanism of interdecadal thermohaline circulation variability in a coupled ocean– atmosphere GCM. J Clim 18(8):1117–1135. doi: 10.1175/JCLI3328.1 CrossRefGoogle Scholar
  23. Dréevillon M, Cassou C, Terray L (2003) Model study of the North Atlantic region atmospheric response to autumn tropical Atlantic sea-surface-temperature anomalies. QJR Meteorol Soc 129(593):2591–2611. doi: 10.1256/qj.02.17 CrossRefGoogle Scholar
  24. Eden C, Willebrand J (2001) Mechanism of interannual to decadal variability of the North Atlantic circulation. J Clim 14(10):2266–2280. doi: 10.1175/1520-0442(2001)014%3C2266:MOITDV%3E2.0.CO;2 CrossRefGoogle Scholar
  25. Eden C, Willebrand J (2001) Mechanism of interannual to decadal variability of the north atlantic circulation. J Clim 14(10):2266–2280CrossRefGoogle Scholar
  26. Fanning AF, Weaver AJ (1998) Thermohaline variability: the effects of horizontal resolution and diffusion. J Clim 11(4):709–715. doi: 10.1175/1520-0442(1998)011%3C0709:TVTEOH%3E2.0.CO;2 CrossRefGoogle Scholar
  27. Frankignoul C, Deshayes J, Curry R (2009) The role of salinity in the decadal variability of the North Atlantic meridional overturning circulation. Clim Dyn 33(6):777–793. doi: 10.1007/s00382-008-0523-2 CrossRefGoogle Scholar
  28. Gent PR, Mcwilliams JC (1990) Isopycnal mixing in ocean circulation models. J Phys Oceanogr 20(1):150–155. doi: 10.1175/1520-0485(1990)020%3C0150:IMIOCM%3E2.0.CO;2 CrossRefGoogle Scholar
  29. Gerdes R, Köberle C (1995) On the influence of DSOW in a numerical model of the North Atlantic general circulation. J Phys Oceanogr 25(11):2624–2642. doi: 10.1175/1520-0485(1995)025%3C2624:OTIODI%3E2.0.CO;2 CrossRefGoogle Scholar
  30. Getzlaff J, Böning CW, Eden C, Biastoch A (2005) Signal propagation related to the North Atlantic overturning. Geophys Res Lett 21Google Scholar
  31. Goldenberg SB, Landsea CW, Mestas-Nuñez AM, Gray WM (2001) The recent increase in Atlantic Hurricane activity: causes and implications. Science 293(5529):474–479. doi: 10.1126/science.1060040 CrossRefGoogle Scholar
  32. Guemas V, Salas-Mélia D (2008) Simulation of the Atlantic meridional overturning circulation in an atmosphereocean global coupled model. Part I: a mechanism governing the variability of ocean convection in a preindustrial experiment. Clim Dyn 31(1):29–48. doi: 10.1007/s00382-007-0336-8 CrossRefGoogle Scholar
  33. Hawkins E, Sutton R (2008) Potential predictability of rapid changes in the Atlantic meridional overturning circulation. Geophys Res Lett 35(11):L11,603+. doi: 10.1029/2008GL034059 CrossRefGoogle Scholar
  34. Hirschi J, Marotzke J (2007) Reconstructing the meridional overturning circulation from boundary densities and the zonal wind stress. J Phys Oceanogr 37(3):743–763. doi: 10.1175/JPO3019.1 CrossRefGoogle Scholar
  35. Hirschi J, Stocker TF (2002) Rapid changes of the oceanic circulation in a hierarchy of ocean models. Tellus A 54(3):273–287. doi: 10.1034/j.1600-0870.2002.00323.x CrossRefGoogle Scholar
  36. Hirschi J, Baehr J, Marotzke J, Stark J, Cunningham S, Beismann JO (2003) A monitoring design for the Atlantic meridional overturning circulation. Geophys Res Lett 30(7):1413+,603+. doi: 10.1029/2002GL016776 CrossRefGoogle Scholar
  37. Hodson DLR, Sutton RT, Cassou C, Keenlyside N, Okumura Y, Zhou T (2009) Climate impacts of recent multidecadal changes in Atlantic Ocean Sea surface temperature: a multimodel comparison. Clim Dyn 34(7–8):1041–1058. doi: 10.1007/s00382-009-0571-2 Google Scholar
  38. Hsieh WW, Davey MK, Wajsowicz RC (1983) The free Kelvin wave in finite-difference numerical models. J Phys Oceanogr 13(8):1383–1397. doi: 10.1175/1520-0485(1983)013%3C1383:TFKWIF%3E2.0.CO;2 CrossRefGoogle Scholar
  39. Jochum M, Danabasoglu G, Holland M, Kwon YO, Large WG (2008) Ocean viscosity and climate. J Geophys Res 113(C6):C06,017+. doi: 10.1029/2007JC004515 CrossRefGoogle Scholar
  40. Johns TC, Durman CF, Banks HT, Roberts MJ, McLaren AJ, Ridley JK, Senior CA, Williams KD, Jones A, Rickard GJ, Cusack S, Ingram WJ, Crucifix M, Sexton DMH, Joshi MM, Dong BW, Spencer H, Hill RSR, Gregory JM, Keen AB, Pardaens AK, Lowe JA, Bodas-Salcedo A, Stark S, Searl Y (2006) The New Hadley Centre Climate Model (HadGEM1): evaluation of coupled simulations. J Clim 19(7):1327–1353. doi: 10.1175/JCLI3712.1 CrossRefGoogle Scholar
  41. Johnson HL, Marshall DP (2002) A theory for the surface atlantic response to thermohaline variability. J Phys Oceanogr 32(4):1121–1132. doi: 10.1175/1520-0485(2002)032%3C1121:ATFTSA%3E2.0.CO;2 CrossRefGoogle Scholar
  42. Köhl A (2005) Anomalies of Meridional Overturning: Mechanisms in the North Atlantic. J Phys Oceanogr 35(8):1455–1472. doi: 10.1175/JPO2767.1 CrossRefGoogle Scholar
  43. Kang SM, Frierson DMW, Held IM (2009) The tropical response to extratropical thermal forcing in an idealized GCM: the importance of radiative feedbacks and convective parameterization. J Atmospheric Sci 66:2812–2827CrossRefGoogle Scholar
  44. Kawase M (1987) Establishment of deep ocean circulation driven by deep-water production. J Phys Oceanogr 17(12):2294–2317. doi: 10.1175/1520-0485(1987)017%3C2294:EODOCD%3E2.0.CO;2 CrossRefGoogle Scholar
  45. Keenlyside NS, Latif M, Jungclaus J, Kornblueh L, Roeckner E (2008) Advancing decadal-scale climate prediction in the North Atlantic sector. Nature 453(7191):84–88. doi: 10.1038/nature06921 CrossRefGoogle Scholar
  46. 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(20):L20,708+. doi: 10.1029/2005GL024233 CrossRefGoogle Scholar
  47. Knight JR, Folland CK, Scaife AA (2006) Climate impacts of the Atlantic multidecadal oscillation. Geophys Res Lett 33(17):L17,706+. doi: 10.1029/2006GL026242 CrossRefGoogle Scholar
  48. Marshall J, Schott F (1999) Open-ocean convection: observations, theory, and models. Rev Geophys 37(1):1–64. doi: 10.1029/98RG02739 CrossRefGoogle Scholar
  49. Palter JB, Lozier MS, Lavender KL (2008) How does Labrador Sea water enter the deep western boundary current?. J Phys Oceanogr 38(5):968–983. doi: 10.1175/2007JPO3807.1 CrossRefGoogle Scholar
  50. 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(14):3926–3938. doi: 10.1175/2009JCLI2535.1 CrossRefGoogle Scholar
  51. Robson J, Sutton R, Lohmann K, Smith D, Palmer M (2011) Causes of the rapid warming of the north atlantic ocean in the mid 1990s. J Clim. doi: 10.1175/JCLI-D-11-00443.1
  52. Roussenov VM, Williams RG, Hughes CW, Bingham RJ (2008) Boundary wave communication of bottom pressure and overturning changes for the North Atlantic. J Geophys Res 113:C08, 042+. doi: 10.1029/2007JC004501 CrossRefGoogle Scholar
  53. Schwab D (1998) Propagation of Kelvin waves along irregular coastlines in finite-difference models. Adv Water Resour 22(3):239–245. doi: 10.1016/S0309-1708(98)00015-3 CrossRefGoogle Scholar
  54. Shaffrey LC, Stevens I, Norton WA, Roberts MJ, Vidale PL, Harle JD, Jrrar A, Stevens DP, Woodage MJ, Demory ME, Donners J, Clark DB, Clayton A, Cole JW, Wilson SS, Connolley WM, Davies TM, Iwi AM, Johns TC, King JC, New AL, Slingo JM, Slingo A, Steenman-Clark L, Martin GM (2009) U.K. HiGEM: the new U. K. high-resolution global environment model description and basic evaluation. J Clim 22(8):1861–1896. doi: 10.1175/2008JCLI2508.1 CrossRefGoogle Scholar
  55. Shaw PT, Csanady GT (1983) Self-advection of density perturbations on a sloping continental shelf. J Phys Oceanogr 13(5):769–782. doi: 10.1175/1520-0485(1983)013%3C0769:SAODPO%3E2.0.CO;2 CrossRefGoogle Scholar
  56. Smith DM, Cusack S, Colman AW, Folland CK, Harris GR, Murphy JM (2007) Improved surface temperature prediction for the coming decade from a global climate model. Science 317(5839):796–799. doi: 10.1126/science.1139540 CrossRefGoogle Scholar
  57. Smith RS, Gregory JM (2009) A study of the sensitivity of ocean overturning circulation and climate to freshwater input in different regions of the North Atlantic. Geophys Res Lett 36(15):L15, 701+. doi: 10.1029/2009GL038607 CrossRefGoogle Scholar
  58. Sutton R, Hodson D (2005) Atlantic ocean forcing of North American and European summer climate. Science 309:115–118. doi: 10.1126/science.1109496 CrossRefGoogle Scholar
  59. Sutton R, Hodson D (2007) Climate response to a multidecadal warming and cooling of the north atlantic ocean. J Clim 20(5):891–907. doi: 10.1175/JCLI4038.1 CrossRefGoogle Scholar
  60. Sutton R, Jewson S, Rowell D (2000) The elements of climate variability in the tropical atlantic region. J Clim 13:3261–3284CrossRefGoogle Scholar
  61. Terray L, Cassou C (2002) Tropical atlantic sea surface temperature forcing of quasi-decadal climate variability over the north Atlantic-Europe region. J Clim 15(22):3170–3187CrossRefGoogle Scholar
  62. Trenberth KE, Caron JM (2001) Estimates of meridional atmosphere and ocean heat transports. J Clim 14(16):3433–3443. doi: 10.1175/1520-0442(2001)014%3C3433:EOMAAO%3E2.0.CO;2 CrossRefGoogle Scholar
  63. Vellinga M, Wu P (2004) Low-latitude freshwater influence on centennial variability of the Atlantic thermohaline circulation. J Clim 17(23):4498–4511CrossRefGoogle Scholar
  64. Vellinga M, Wood RA, Gregory JM (2002) Processes governing the recovery of a perturbed thermohaline circulation in HadCM3. J Clim 15(7):764–780. doi: 10.1175/1520-0442(2002)015%3C0764:PGTROA%3E2.0.CO;2 CrossRefGoogle Scholar
  65. Wunsch C, Heimbach P (2006) Estimated decadal changes in the North Atlantic meridional overturning circulation and heat flux 1993–2004. J Phys Oceanogr 36(11):2012–2024. doi: 10.1175/JPO2957.1 CrossRefGoogle Scholar
  66. Zhang D, Msadek R, McPhaden MJ, Delworth T (2011) Multidecadal variability of the North Brazil current and its connection to the Atlantic meridional overturning circulation. J Geophys Res 116(C4):C04,012+. doi: 10.1029/2010JC006812 CrossRefGoogle Scholar
  67. Zhang R (2008) Coherent surface-subsurface fingerprint of the Atlantic meridional overturning circulation. Geophysical Research Letters 35:L20,705+. doi: 10.1029/2008GL035463 Google Scholar
  68. Zhang Z, Kang SM, Held IM (2010) Sensitivity of climate change induced by the weakening of the Atlantic meridional overturning circulation to cloud feedback. J Clim 23:378–389CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.NCAS-Climate, Department of MeteorologyUniversity of ReadingReadingUK

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