Climate Dynamics

, Volume 42, Issue 1–2, pp 171–188 | Cite as

Equatorial Atlantic variability and its relation to mean state biases in CMIP5

  • Ingo Richter
  • Shang-Ping Xie
  • Swadhin K. Behera
  • Takeshi Doi
  • Yukio Masumoto


Coupled general circulation model (GCM) simulations participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) are analyzed with respect to their performance in the equatorial Atlantic. In terms of the mean state, 29 out of 33 models examined continue to suffer from serious biases including an annual mean zonal equatorial SST gradient whose sign is opposite to observations. Westerly surface wind biases in boreal spring play an important role in the reversed SST gradient by deepening the thermocline in the eastern equatorial Atlantic and thus reducing upwelling efficiency and SST cooling in the following months. Both magnitude and seasonal evolution of the biases are very similar to what was found previously for CMIP3 models, indicating that improvements have only been modest. The weaker than observed equatorial easterlies are also simulated by atmospheric GCMs forced with observed SST. They are related to both continental convection and the latitudinal position of the intertropical convergence zone (ITCZ). Particularly the latter has a strong influence on equatorial zonal winds in both the seasonal cycle and interannual variability. The dependence of equatorial easterlies on ITCZ latitude shows a marked asymmetry. From the equator to 15°N, the equatorial easterlies intensify approximately linearly with ITCZ latitude. When the ITCZ is south of the equator, on the other hand, the equatorial easterlies are uniformly weak. Despite serious mean state biases, several models are able to capture some aspects of the equatorial mode of interannual SST variability, including amplitude, pattern, phase locking to boreal summer, and duration of events. The latitudinal position of the boreal spring ITCZ, through its influence on equatorial surface winds, appears to play an important role in initiating warm events.


Equatorial Atlantic GCM biases Interannual variability Double ITCZ CMIP5 Bjerknes feedback Surface winds Equatorial Kelvin waves 



We thank the anonymous reviewers for their helpful comments. We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison which provides coordinating support and led development of software infrastructure for CMIP, and the climate modeling groups for making available their model output. SPX is supported by NOAA.


  1. Adler RF, Huffman GJ, Chang A, Ferraro R, Xie P, Janowiak J, Rudolf B, Schneider U, Curtis S, Bolvin D, Gruber A, Susskind J, Arkin P (2003) The version 2 global precipitation climatology project (GPCP) monthly precipitation analysis (1979-present). J Hydrometeor 4:1147–1167CrossRefGoogle Scholar
  2. Bellucci A, Gualdi S, Navarra A (2010) The double-ITCZ syndrome in coupled general circulation models: the role of large-scale vertical circulation regimes. J Clim 23:1127–1145CrossRefGoogle Scholar
  3. Biasutti M, Sobel AH, Kushnir Y (2006) AGCM precipitation biases in the tropical Atlantic. J Clim 19:935–958CrossRefGoogle Scholar
  4. Breugem WP, Hazeleger W, Haarsma RJ (2006) Multimodel study of tropical Atlantic variability and change. Geophys Res Lett 33. doi: 10.1029/2006GL027831
  5. Caniaux G, Giordani H, Redelsperger J-L, Guichard F, Key E, Wade M (2011) Coupling between the Atlantic cold tongue and the West African monsoon in boreal spring and summer. J Geophys Res 116. doi: 10.1029/2010JC00657
  6. Carton JA, Huang B (1994) Warm events in the tropical Atlantic. J Phys Oceanogr 24:888–903CrossRefGoogle Scholar
  7. Carton JA, Chepurin G, Cao X, Giese BS (2000) A simple ocean data assimilation analysis of the global upper ocean 1950–95. Part I: methodology. J Phys Oceanogr 30:311–326CrossRefGoogle Scholar
  8. Chang P, Ji L, Li H (1997) A decadal climate variation in the tropical Atlantic Ocean from thermodynamic air-sea interactions. Nature 385:516–518CrossRefGoogle Scholar
  9. Chang P et al (2006) Climate fluctuations of tropical coupled systems—the role of ocean dynamics. J Clim 19:5122–5174CrossRefGoogle Scholar
  10. Chang CY, Carton JA, Grodsky SA, Nigam S (2007) Seasonal climate of the tropical Atlantic sector in the NCAR community climate system model 3: error structure and probable causes of errors. J Clim 20:1053–1070CrossRefGoogle Scholar
  11. Chang CY, Nigam S, Carton JA (2008) Origin of the springtime westerly bias in equatorial Atlantic surface winds in the community atmosphere model version 3 (CAM3) simulation. J Clim 21:4766–4778CrossRefGoogle Scholar
  12. Davey MK et al (2002) STOIC: a study of coupled model climatology and variability in topical ocean regions. Clim Dyn 18:403–420CrossRefGoogle Scholar
  13. de Szoeke SP, Xie S-P (2008) The tropical eastern Pacific seasonal cycle: assessment of errors and mechanisms in IPCC AR4 coupled ocean–atmosphere general circulation models. J Clim 21:2573–2590CrossRefGoogle Scholar
  14. Dee DP et al (2011) The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Quart J R Meteorol Soc 137:553–597CrossRefGoogle Scholar
  15. Ding H, Keenlyside NS, Latif M (2010) Equatorial Atlantic interannual variability: the role of heat content. J Geophys Res 115. doi: 10.1029/2010JC006304
  16. Doi T, Tozuka T, Sasaki H, Masumoto Y, Yamagata T (2007) Seasonal and interannual variations of oceanic conditions in the Angola Dome. J Phys Oceanogr 37:2698–2713CrossRefGoogle Scholar
  17. Doi T, Vecchi G, Rosati A, Delworth T (2012) Biases in the Atlantic ITCZ in seasonal-interannual variations for a coarse- and a high-resolution coupled climate model. J Clim 25:5494–5511CrossRefGoogle Scholar
  18. Du Penhoat Y, Treguier A-M (1985) The seasonal linear response of the Atlantic Ocean. J Phys Oceanogr 15:316–329CrossRefGoogle Scholar
  19. Florenchie, P, Lutjeharms JRE, Reason CJC, Masson S, Rouault M (2003) The source of Bengula Niños in the South Atlantic Ocean. Geophys Res Lett 30. doi: 10.1029/2003GL017,172
  20. Folland CK, Palmer TN, Parker DE (1986) Sahel rainfall and world-wide sea temperatures. Nature 320:602–607CrossRefGoogle Scholar
  21. Franca C, Wainer I, De Mesquita AR, Goni GJ (2003) Planetary equatorial trapped waves in the Atlantic Ocean from TOPEX/POSEIDON altimetry. In: Goni GJ, Malanotte-Rizzoli P (eds) Interhemispheric water exchange in the Atlantic Ocean, Elsevier Oceanogr, vol 68. Elsevier, New York, pp 213–232CrossRefGoogle Scholar
  22. Guiavarc’h C, Treguier AM, Vangriesheim A (2008) Remotely forced biweekly deep oscillations on the continental slope of the Gulf of Guinea. J Geophys Res 113. doi: 10.1029/2007JC004471
  23. Hastenrath S, Heller L (1977) Dynamics of climate hazards in Northeast Brazil. Q J R Meteorol Soc 103:77–92CrossRefGoogle Scholar
  24. Hisard P, Henin C, Houghton R, Piton B, Rual P (1986) Oceanic conditions in the tropical Atlantic during 1983 and 1984. Nature 322:243–245CrossRefGoogle Scholar
  25. Hormann V, Brandt P (2009) Upper equatorial Atlantic variability during 2002 and 2005 associated with equatorial Kelvin waves. J Geophys Res 114(C03007). doi: 10.1029/2008JC005101
  26. Illig S, Dewitte B, Ayoub N, du Penhoat Y, Reverdin G, De Mey P, Bonjean F, Lagerloef GSE (2004) Interannual long equatorial waves in the tropical Atlantic from a high-resolution ocean general circulation model experiment in 1981–2000. J Geophys Res 109(C02022). doi: 10.1029/2003JC001771
  27. Jin F–F (1997) An equatorial ocean recharge paradigm for ENSO. Part I: conceptual model. J Atmos Sci 54:811–829CrossRefGoogle Scholar
  28. Kalnay E et al (1996) The NCEP/NCAR 40-year reanalysis project. Bull Amer Meteor Soc 77:437–471CrossRefGoogle Scholar
  29. Katz EJ (1997) Waves along the equator in the Atlantic. J Phys Oceanogr 27:2536–2544CrossRefGoogle Scholar
  30. Keenlyside NS, Latif M (2007) Understanding equatorial Atlantic interannual variability. J Clim 20:131–142CrossRefGoogle Scholar
  31. Li G, Xie S-P (2012) Origins of tropical-wide SST biases in CMIP multi-model ensembles. Geophys Res Lett 39 (in press). doi: 10.1029/2012GL053777
  32. Lin JL (2007) The double-ITCZ problem in IPCC AR4 coupled GCMs: ocean–atmosphere feedback analysis. J Clim 20:4497–4525CrossRefGoogle Scholar
  33. Locarnini RA, Mishonov AV, Antonov JI, Boyer TP, Garcia HE (2006) World ocean Atlas 2005, volume 1: temperature. In: Levitus S (ed) NOAA Atlas NESDIS 61, U.S. Government Printing Office, Washington, DCGoogle Scholar
  34. Luo J–J, Masson S, Behera S, Yamagata T (2008) Extended ENSO predictions using a fully coupled ocean-atmosphere model. J Clim 21:84–93CrossRefGoogle Scholar
  35. Lübbecke JF, Böning CW, Keenlyside NS, Xie S-P (2010) On the connection between Benguela and equatorial Niños and the role of the South Atlantic anticyclone. J Geophys Res 115. doi: 10.1029/2009JC005964
  36. Mechoso CR et al (1995) The seasonal cycle over tropical Pacific in coupled ocean–atmosphere general circulation models. Mon Weather Rev 123:2825–2838CrossRefGoogle Scholar
  37. Mitchell T, Wallace JM (1992) The annual cycle in equatorial convection and sea surface temperature. J Clim 5:1140–1156CrossRefGoogle Scholar
  38. Nobre P, Shukla J (1996) Variations of sea surface temperature, wind stress, and rainfall over the tropical Atlantic and South America. J Clim 9:2464–2479CrossRefGoogle Scholar
  39. Ogata T, Xie S-P (2011) Semiannual cycle in zonal wind over the equatorial Indian Ocean. J Clim 24:6471–6485Google Scholar
  40. Okumura Y, Xie S-P (2004) Interaction of the Atlantic equatorial cold tongue and African monsoon. J Clim 17:3588–3601CrossRefGoogle Scholar
  41. Okumura Y, Xie S-P (2006) Some overlooked features of tropical Atlantic climate leading to a new Nino-like phenomenon. J Clim 19:5859–5874CrossRefGoogle Scholar
  42. Philander SGH (1986) Unusual conditions in the tropical Atlantic Ocean in 1984. Nature 322:236–238CrossRefGoogle Scholar
  43. Philander SGH (1990) El Niño, La Niña, and the Southern Oscillation, Int Geophys Ser 46 293 pp, Academic, New YorkGoogle Scholar
  44. Philander SGH, Pacanowski RC (1981) The oceanic response to cross-equatorial winds (with application to coastal upwelling in low latitudes). Tellus 33:201–210CrossRefGoogle Scholar
  45. Polo I, Lazar A, Rodriguez-Fonseca B, Arnault S (2008) Oceanic Kelvin waves and tropical Atlantic intraseasonal variability: 1. Kelvin wave characterization. J Geophys Res 113(C07009). doi: 10.1029/2007JC004495
  46. Rayner NA, Parker DE, Horton EB, Folland CK, Alexander LV, Rowell DP, Kent EC, Kaplan A (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J Geophys Res 108 (D14, 4407). doi: 10.1029/2002JD002670
  47. Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Clim 15:1609–1625CrossRefGoogle Scholar
  48. Richter I, Xie S-P (2008) On the origin of equatorial Atlantic biases in coupled general circulation models. Clim Dyn 31:587–598CrossRefGoogle Scholar
  49. Richter I, Behera SK, Masumoto Y, Taguchi B, Komori N, Yamagata T (2010) On the triggering of Benguela Niños: Remote equatorial versus local influences. Geophys Res Lett 37(L20604). doi: 10.1029/2010GL044461
  50. Richter I, Xie S-P, Wittenberg AT, Masumoto Y (2012a) Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation. Clim Dyn 38:985–1001. doi: 10.1007/s00382-011-1038-9 CrossRefGoogle Scholar
  51. Richter I, Behera SK, Masumoto Y, Taguchi B, Sasaki H, Yamagata T (2012b) Multiple causes of interannual sea surface temperature variability in the equatorial Atlantic Ocean. Nature Geosci (in press)Google Scholar
  52. Ruiz-Barradas A, Carton JA, Nigam S (2000) Structure of interannual-to-decadal variability in the tropical Atlantic sector. J Clim 13:3285–3297CrossRefGoogle Scholar
  53. Servain J, Picaut J, Merle J (1982) Evidence of remote forcing in the equatorial Atlantic Ocean. J Phys Oceanogr 12:457–463CrossRefGoogle Scholar
  54. Servain J, Wainer I, McCreary JP, Dessier A (1999) Relationship between the equatorial and meridional modes of climatic variability in the tropical Atlantic. Geophys Res Lett 26:485–488CrossRefGoogle Scholar
  55. Servain J, Wainer I, Ayina HL, Roquet H (2000) The relationship between the simulated climatic variability modes of the tropical Atlantic. Int J Climatol 20:939–953CrossRefGoogle Scholar
  56. Shannon LV, Boyd AJ, Bundrit GB, Taunton-Clark J (1986) On the existence of an El Niño–type phenomenon in the Benguela system. J Mar Sci 44:495–520Google Scholar
  57. Stockdale TN, Balmaseda MA, Vidard A (2006) Tropical Atlantic SST prediction with coupled ocean-atmosphere GCMs. J Clim 19:6047–6061CrossRefGoogle Scholar
  58. Tokinaga H, Xie S-P (2011) Wave and anemometer-based sea-surface wind (WASWind) for climate change analysis. J Clim 24:267–285CrossRefGoogle Scholar
  59. Tozuka T, Doi T, Miyasaka T, Keenlyside N, Yamagata T (2011) Key factors in simulating the equatorial Atlantic zonal sea surface temperature gradient in a coupled general circulation model. J Geophys Res 116(C06010). doi: 10.1029/2010JC006717
  60. Uppala SM et al (2005) The ERA-40 re-analysis. Quart J R Meteorol Soc 131:2961–3012. doi: 10.1256/qj.04.176 CrossRefGoogle Scholar
  61. Vauclair F, du Penhoat Y (2001) Interannual variability of the upper layer of the tropical Atlantic from in situ data between 1979 and 1999. Clim Dyn 17:527–546CrossRefGoogle Scholar
  62. Wahl S, Latif M, Park W, Keenlyside N (2011) On the tropical atlantic SST warm bias in the Kiel climate model. Clim Dyn 36:891–906Google Scholar
  63. Woodruff SD et al (2011) ICOADS Release 2.5: extensions and enhancements to the surface marine meteorological archive. Int J Climatol 31:951–967CrossRefGoogle Scholar
  64. Xie S-P, Carton JA (2004) Tropical Atlantic variability: patterns, mechanisms, and impacts. In: Wang C, Xie S-P, Carton JA (eds) Earth climate: the ocean-atmosphere interaction. Geophysical Monograph, 147, AGU, Washington D.C, pp 121–142CrossRefGoogle Scholar
  65. Xie S-P, Philander SGH (1994) A coupled ocean-atmosphere model of relevance to the ITCZ in the eastern Pacific. Tellus 46A:340–350CrossRefGoogle Scholar
  66. Zebiak SE (1993) Air–sea interaction in the equatorial Atlantic region. J Clim 6:1567–1586CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Ingo Richter
    • 1
    • 2
  • Shang-Ping Xie
    • 3
    • 4
    • 5
  • Swadhin K. Behera
    • 1
    • 2
  • Takeshi Doi
    • 1
    • 2
  • Yukio Masumoto
    • 1
  1. 1.Research Institute for Global ChangeJAMSTECYokohamaJapan
  2. 2.Application LaboratoryJAMSTECYokohamaJapan
  3. 3.International Pacific Research CenterUniversity of Hawaii at ManoaHonoluluUSA
  4. 4.Department of MeteorologyUniversity of Hawaii at ManoaHonoluluUSA
  5. 5.Scripps Institution of OceanographyUniversity of California at San DiegoLa JollaUSA

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