Climate Dynamics

, Volume 37, Issue 3–4, pp 419–440 | Cite as

Sahel rainfall and decadal to multi-decadal sea surface temperature variability

  • Elsa Mohino
  • Serge Janicot
  • Juergen Bader


Decadal Sahelian rainfall variability was mainly driven by sea surface temperatures (SSTs) during the twentieth century. At the same time SSTs showed a marked long-term global warming (GW) trend. Superimposed on this long-term trend decadal and multi-decadal variability patterns are observed like the Atlantic Multidecadal Oscillation (AMO) and the inter-decadal Pacific Oscillation (IPO). Using an atmospheric general circulation model we investigate the relative contribution of each component to the Sahelian precipitation variability. To take into account the uncertainty related to the use of different SST data sets, we perform the experiments using HadISST1 and ERSSTv3 reconstructed sets. The simulations show that all three SST signals have a significant impact over West Africa: the positive phases of the GW and the IPO lead to drought over the Sahel, while a positive AMO enhances Sahel rainfall. The tropical SST warming is the main cause for the GW impact on Sahel rainfall. Regarding the AMO, the pattern of anomalous precipitation is established by the SSTs in the Atlantic and Mediterranean basins. In turn, the tropical SST anomalies control the impact of the IPO component on West Africa. Our results suggest that the low-frequency evolution of Sahel rainfall can be interpreted as the competition of three factors: the effect of the GW, the AMO and the IPO. Following this interpretation, our results show that 50% of the SST-driven Sahel drought in the 1980s is explained by the change to a negative phase of the AMO, and that the GW contribution was 10%. In addition, the partial recovery of Sahel rainfall in recent years was mainly driven by the AMO.


Decadal variability Sea surface temperatures West African Monsoon Atmospheric general circulation models 



We would like to thank the anonymous reviewers for their helpful comments, which greatly helped to improve the manuscript. This work was supported by the POSDEXT-MEC programme of the Spanish Ministry for Science and Innovation and by the COMPAS and DecCen project funded by the research council of Norway. Additional support was provided by the Spanish projects: MICINN CGL2009-10285 and MARM MOVAC 200800050084028. This work was carried out in the framework of the AMMA-EU project. Based on French initiative, AMMA was built by an international scientific group and is currently funded by a large number of agencies, especially form France, UK, US and Africa. It has been beneficiary of a major financial contribution from the European Community's Sixth Framework Research Programme. Detailed information on scientific coordination and funding is available on the AMMA International website


  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 Hydrometeorol 4:1147–1167CrossRefGoogle Scholar
  2. Ashok K, Chan WL, Motoi T, Yamagata T (2004) Decadal variability of the Indian Ocean dipole. Geophys Res Lett 31:L24207. doi: 10.1029/2004GL021345 CrossRefGoogle Scholar
  3. Bader J, Latif M (2003) The impact of decadal scale Indian Ocean SST anomalies on Sahelian rainfall and the North Atlantic Oscillation. Geophys Res Lett 30:2169. doi: 10.1029/2003GL018426 CrossRefGoogle Scholar
  4. Baines PG, Folland CK (2007) Evidence for a rapid global climate shift across the late 1960s. J Clim 20:2721–2744. doi: 10.1175/JCLI4177.1 CrossRefGoogle Scholar
  5. Barnett TP, Pierce DW, AchutaRao KM, Gleckler PJ, Santer BD, Gregory JM, Washington WM (2005) Penetration of human-induced warming into the world’s oceans. Science 309:284–287CrossRefGoogle Scholar
  6. Biasutti M, Giannini A (2006) Robust Sahel drying in response to late 20th century forcings. Geophys Res Lett 33:L11706. doi: 10.1029/2006GL026067 CrossRefGoogle Scholar
  7. Biasutti M, Held IM, Sobel AH, Giannini A (2008) SST forcings and Sahel rainfall variability in simulations of the twentieth and twenty-first centuries. J Clim 21:3471–3486CrossRefGoogle Scholar
  8. Bony S, Emanuel JL (2001) A parameterization of the cloudiness associated with cumulus convection; evaluation using TOGA COARE data. J Atmos Sci 58:3158–3183CrossRefGoogle Scholar
  9. Bretherton CS, Widmann M, Dymnikov VP, Wallace JM, Bladé I (1999) The effective number of spatial degrees of freedom of a time-varying field. J Clim 12:1990–2009CrossRefGoogle Scholar
  10. Cai W, Whetton PH (2001) Modes of SST variability and the fluctuation of global mean temperature. Clim Dyn 17:889–901CrossRefGoogle Scholar
  11. Caminade C, Terray L (2009) Twentieth century Sahel rainfall variability as simulated by the ARPEGE AGCM, and future changes. Clim Dyn. doi: 10.1007/s00382-009-0545-4
  12. Cole JE, Dunbar RB, McClanahan TR, Muthiga NA (2000) Tropical Pacific forcing of decadal SST variability in the western Indian Ocean over the past two centuries. Science 287:617–619CrossRefGoogle Scholar
  13. Crowley TJ (2000) Causes of climate change over the past 1000 years. Science 289:270–277CrossRefGoogle Scholar
  14. Crueger T, Zinke J, Pfeiffer M (2009) Patterns of Pacific decadal variability recorded by Indian Ocean corals. Int J Earth Sci 98:41–52CrossRefGoogle Scholar
  15. Desser C, Phillips AS, Hurrel JW (2004) Pacific interdecadal climate variability: linkages between the Tropics and the North Pacific during boreal winter since 1900. J Clim 17:3109–3124CrossRefGoogle Scholar
  16. Dima M, Lohmann G (2007) A hemispheric mechanism for the Atlantic Multidecadal Oscillation. J Clim 20:2706–2719. doi: 10.1175/JCLI4174.1 CrossRefGoogle Scholar
  17. Emanuel KA (1991) A scheme for representing cumulus convection in large-scale models. J Atmos Sci 48:2313–2335CrossRefGoogle Scholar
  18. Emanuel KA (1993) A cumulus representation based on the episodic mixing model; the importance of mixing and microphysics in predicting humidity. AMS Meteorol Monogr 24:185–192Google Scholar
  19. Falvey M, Garreaud RD (2009) Regional cooling in a warming world: recent temperature trends in the southeast Pacific and along the west coast of subtropical South America (1979–2006). J Geophys Res 114. doi: 10.1029/2008JD010519
  20. Folland CK, Parker DE (1995) Corrections of instrumental biases in historical sea surface temperature data. Q J R Meteorol Soc 121:319–367CrossRefGoogle Scholar
  21. Folland CK, Palmer TN, Parker DE (1986) Sahel rainfall and worldwide sea temperatures, 1901–85. Nature 320:602–607. doi: 10.1038/320602a0 CrossRefGoogle Scholar
  22. Fontaine B, Trzaska S, Janicot S (1998) Evolution of the relationship between near global and Atlantic SST modes and the rainy season in West Africa: statistical analyses and sensitivity experiments. Clim Dyn 14:353–368CrossRefGoogle Scholar
  23. Fontaine B, Garcia-Serrano J, Roucou P, Rodriguez-Fonseca B, Losada T, Chauvin F, Gervois S, Sijikumar S, Ruti P, Janicot S (2009) Impacts of warm and cold situations in the Mediterranean basins on the West African monsoon: observed connection patterns (1979–2006) and climate simulations. Clim Dyn. doi: 10.1007/s00382-009-0599-3
  24. Giannini A (2009) Mechanisms of climate change in the semi-arid African Sahel: the local view. J Clim. doi: 10.1175/2009JCLI3123.1
  25. Giannini A, Saravannan R, Chang P (2003) Oceanic forcing of Sahel rainfall on interannual to interdecadal time scales. Science 302:1027–1030CrossRefGoogle Scholar
  26. Haarsma RJ, Selten FM, Weber SL, Kliphuis M (2005) Sahel rainfall variability and response to greenhouse warming. Geophys Res Lett 32:L17702. doi: 10.1029/2005GL023232 CrossRefGoogle Scholar
  27. Hagos S, Cook K (2008) Ocean warming and late-twentieth-century Sahel drought and recovery. J Clim 21:3797–3814. doi: 10.1175/2008JCLI2055.1 CrossRefGoogle Scholar
  28. Hansen J, Nazarenko L, Ruedy R, Sato M, Willis J, Del Genio A, Koch D, Lacis A, Lo K, Menon S, Novakov T, Perlwitz J, Russell G, Schmidt GA, Tausnev N (2005) Earth’s energy imbalance: confirmation and implications. Science 308:1431–1435CrossRefGoogle Scholar
  29. Hansen J, Sato M, Ruedy R, Lo K, Lea D, Medina-Elizade M (2006) Global temperature change. PNAS 103:14288–14293CrossRefGoogle Scholar
  30. Held IM, Delworth TL, Lu J, Findell KL, Knutson TR (2005) Simulation of Sahel drought in the 20th and 21st centuries. PNAS 102:17891–17896CrossRefGoogle Scholar
  31. 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. doi: 10.1007/s00382-009-0571-2
  32. Hoerling M, Hurrell JW, Eischeid J, Phillips AS (2006) Detection and attribution of twentieth-century northern and southern African rainfall change. J Clim 19:3989–4008CrossRefGoogle Scholar
  33. Hourdin F, Musat I, Bony S, Braconnot P, Codron F, Dufresne JL, Fairhead L, Filiberti MA, Friedlingstein P, Grandpeix JY, Krinner G, LeVan P, Li ZX, Lott F (2006) The LMDZ4 general circulation model: climate performance and sensitivity to parametrized physics with emphasis on tropical convection. Clim Dyn 27:787–813CrossRefGoogle Scholar
  34. Joly M (2008) Rôle des océans dans la variabilité climatique de la Mousson Africaine. Dissertation, Université Paris-EstGoogle Scholar
  35. Jung T, Ferranti L, Tompkins AM (2006) Response to the summer of 2003 Mediterranean SST anomalies over Europe and Africa. J Clim 19:5439–5454CrossRefGoogle Scholar
  36. Kerr RA (2000) A North Atlantic climate pacemaker for the centuries. Science 288:1984–1985CrossRefGoogle Scholar
  37. Knight JR (2009) The Atlantic multidecadal oscillation inferred from the forced climate response in coupled general circulation models. J Clim 22:1610–1625. doi: 10.1175/2008JCLI2628.1 CrossRefGoogle Scholar
  38. 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. doi: 10.1029/2005GL024233
  39. Knight JR, Folland CK, Scaife AA (2006) Climate impacts of the Atlantic multidecadal oscillation. Geophys Res Lett 33. doi: 10.1029/2006GL026242
  40. Koster R, Dirmeyer P, Cuo Z, Bonan C, Chan E, Cox P, Gordon C, Kanae S, Kowalczyk E, Lawrence D, Liu P, Lu C, Malyshev S, McAvaney B, Mitchell K, Mocko D, Oki T, Oleson K, Pitman A, Sud Y (2004) Regions of strong coupling between soil moisture and precipitation. Science 305(5687):1138–1140CrossRefGoogle Scholar
  41. Krishnan R, Sugi M (2003) Pacific decadal oscillation and variability of the Indian summer monsoon rainfall. Clim Dyn 21:233–242CrossRefGoogle Scholar
  42. Latif M, Keenlyside N, Bader J (2007) Tropical sea surface temperature, vertical wind shear, and hurricane development. Geophys Res Lett 34:L01710. doi: 10.1029/2006GL027969 CrossRefGoogle Scholar
  43. Lu J, Delworth TL (2005) Oceanic forcing of the late 20th century Sahel drought. Geophys Res Lett 32. doi: 10.1029/2005GL023316
  44. Lu R, Dong B (2008) Response of the Asian summer monsoon to weakening of Atlantic thermohaline circulation. Adv Atmos Sci 25:723–736CrossRefGoogle Scholar
  45. Mann ME (2004) On smoothing potentially non-stationary climate time series. Geophys Res Lett 31. doi: 10.1029/2004GL019569
  46. Mann ME (2008) Smoothing of climate time series revisited. Geophys Res Lett 35. doi: 10.1029/2008GL034716
  47. Mantua NJ, Hare SR (2002) The Pacific decadal oscillation. J Oceanogr 58:35–44CrossRefGoogle Scholar
  48. Mantua NJ, Hare SR, Zhang Y, Wallace JM, Francis RC (1997) A Pacific interdecadal climate oscillation with impacts on Salmon production. Bull Am Meteorol Soc 78:1069–1079CrossRefGoogle Scholar
  49. Meehl GA, Hu A (2006) Megadroughts in the Indian Monsoon region and southwest North America and a mechanism for associated multidecadal Pacific sea surface temperature anomalies. J Clim 19:1605–1623CrossRefGoogle Scholar
  50. Meehl GA, Washington WM, Ammann CM, Arblaster JM, Wigley TML, Tebaldi C (2004) Combinations of natural and anthropogenic forcings in twentieth-century climate. J Clim 17:3721–3727CrossRefGoogle Scholar
  51. Meehl GA, Stocker TF, Collins WD, Friedlingstein P, Gaye AT, Gregory JM, Kitoh A, Knutti R, Murphy JM, Noda A, Raper SCB, Watterson IG, Weaver AJ Zhao ZC (2007) Global climate projections. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Climate Change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, CambridgeGoogle Scholar
  52. Meehl GA, Hu A, Santer BD (2009) The mod-1970s climate shift in the Pacific and the relative roles of forced versus inherent decadal variability. J Clim 22:780–792CrossRefGoogle Scholar
  53. Miller AJ, Cayan DR, Barnett TP, Graham NE, Oberhuber JM (1994) The 1979–77 climate shift of the Pacific Ocean. Oceanography 7:21–26Google Scholar
  54. Mitchel TD, Jones PD (2005) An improved method of constructing a database of monthly climate observations and associated high-resolution grids. Int J Climatol 25:693–712. doi: 10.1002/joc.1181 CrossRefGoogle Scholar
  55. North GR, Bell TL, Cahalan RF (1982) Sampling errors in the estimation of empirical orthogonal functions. Mon Weather Rev 110:699–706CrossRefGoogle Scholar
  56. Palmer TN (1986) Influence of the Atlantic, Pacific, and Indian Oceans on Sahel rainfall. Nature 322:251–253CrossRefGoogle Scholar
  57. Polyakov IV, Alexeev A, Bhatt US, Polyakova EI, Zhang X (2009) North Atlantic warming: patterns of long-term trend and multidecadal variability. Clim Dyn. doi: 10.1007/s00382-008-0522-3
  58. Power S, Casey T, Folland C, Colman A, Mehta V (1999) Inter-decadal modulation of the impact of ENSO on Australia. Clim Dyn 15:319–324CrossRefGoogle Scholar
  59. Rayner NA, Parker DE, Horton EB, Folland CK, Alexander LV, Rowell DP (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the nineteenth century. J Geophys Res 108. doi: 10.1029/2002JD002670
  60. Rotstayn LD, Lohmann U (2002) Tropical rainfall trends and the indirect aerosol effect. J Clim 15:2103–2116CrossRefGoogle Scholar
  61. Rowell DP (2003) The impact of the Mediterranean SSTs on the Sahelian rainfall season. J Clim 16:849–862CrossRefGoogle Scholar
  62. Rowell DP, Folland CK, Maskell K, Owen JA, Ward NM (1992) Modelling the influence of global sea surface temperatures on the variability and predictability of seasonal Sahel rainfall. Geophys Res Lett 19:905–908CrossRefGoogle Scholar
  63. Rowell DP, Folland CK, Maskell K, Ward NM (1995) Variability of summer rainfall over tropical North Africa (1906–92): observations and modelling. Q J R Meteorol Soc 121:669–704Google Scholar
  64. Scott PA, Tett SFB, Jones GS, Allen MR, Mitchell JFB, Jenckins GJ (2000) External control of 20th century temperature by natural and anthropogenic forcings. Science 290:2133–2137CrossRefGoogle Scholar
  65. Shanahan TM, Overpeck JT, Anchukatis KJ, Beck JW, Cole JE, Dettman DL, Peck JA, Scholz CA, King JW (2009) Atlantic forcing of persistent drought in West Africa. Science 324:377–380CrossRefGoogle Scholar
  66. Smith TM, Reynolds RW (2002) Bias corrections for historical sea surface temperatures based on marine air temperatures. J Clim 15:73–87CrossRefGoogle Scholar
  67. Smith TM, Reynolds RW, Peterson TC, Lawrimore J (2008) Improvements to NOAA’s historical merged land-ocean surface temperature analysis (1880–2006). J Clim 21:2283–2296. doi: 10.1175/2007JCLI2100.1 CrossRefGoogle Scholar
  68. Sutton RT, Hodson DLR (2005) Atlantic Ocean forcing of North American and European summer climate. Science 309:115–118CrossRefGoogle Scholar
  69. Thompson DWJ, Kennedy JJ, Wallace JM, Jones PD (2008) A large discontinuity in the mid-twentieth century in observed global-mean surface temperature. Nature 453:646–649. doi: 10.1038/nature06982 CrossRefGoogle Scholar
  70. Ting M, Kushnir Y, Seager R, Cuihua Li (2009) Forced and internal 20th century SST trends in the North Atlantic. J Clim 22:1469–1481CrossRefGoogle Scholar
  71. Tippet MK, Giannini A (2006) Potentially predicable components of African summer rainfall in an SST-forced GCM simulation. J Clim 19:3133–3144CrossRefGoogle Scholar
  72. Trenberth KE, Shea DJ (2006) Atlantic hurricanes and natural variability in 2005. Geophys Res Lett 33. doi: 10.1029/2006GL026894
  73. Trenberth KE, Jones PD, Ambenje P, Bojariu R, Easterling D, Klein Tank A, Parker D, Rahimzadeh F, Renwick JA, Rusticucci M, Soden B, Zhai P (2007) Observations: surface and atmospheric climate change. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, CambridgeGoogle Scholar
  74. Vecchi GA, Clement A, Solden BJ (2008) Examining the tropical Pacific’s response to global warming. EOS 89(9):81–83CrossRefGoogle Scholar
  75. Worley SJ, Woodruff SD, Reynolds RW, Lubker SJ, Lott N (2005) ICOADS release 2.1 data and products. Int J Climatol 25:823–842CrossRefGoogle Scholar
  76. Yoshioka M, Mahowald NM, Conley AJ, Collins WD, Fillmore DW, Zender CS, Coleman DB (2007) Impact of desert dust radiative forcing on Sahel precipitation: relative importance of dust compared to sea surface temperature variations, vegetation changes and greenhouse gas warming. J Clim 20:1445–1467. doi: 10.1175/JCLI4056.1 CrossRefGoogle Scholar
  77. Zeng N, Neelin JD, Lau KM, Tucker CJ (1999) Enhancement of interdecadal climate variability in the Sahel by vegetation interaction. Science 286:1537–1540CrossRefGoogle Scholar
  78. Zhang R, Delworth TL (2006) Impact of Atlantic multidecadal oscillations on India/Sahel rainfall and Atlantic hurricanes. Geophys Res Lett 33. doi: 10.1029/2006GL026267
  79. Zhang Y, Wallace JM, Battisti DS (1997) ENSO-like interdecadal variability:1900–93. J Clim 10:1004–1020CrossRefGoogle Scholar
  80. Zhou T, Yu R, Li H, Wang B (2008) Ocean forcing to changes in global monsoon precipitation over the recent half-century. J Clim 21:3833–3852. doi: 10.1175/2008JCLI2067.1 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.LOCEAN/IPSL, CNRS, Université Pierre et Marie CurieParisFrance
  2. 2.Universidad de SevillaSevilleSpain
  3. 3.LOCEAN/IPSL, IRD, Université Pierre et Marie CurieParisFrance
  4. 4.Bjerknes Centre for Climate ResearchBergenNorway
  5. 5.Geophysical Institute, University of BergenBergenNorway

Personalised recommendations