Climate Dynamics

, Volume 48, Issue 3–4, pp 1353–1373 | Cite as

West African monsoon dynamics and precipitation: the competition between global SST warming and CO2 increase in CMIP5 idealized simulations

  • Marco Gaetani
  • Cyrille Flamant
  • Sophie Bastin
  • Serge Janicot
  • Christophe Lavaysse
  • Frederic Hourdin
  • Pascale Braconnot
  • Sandrine Bony
Article

Abstract

Climate variability associated with the West African monsoon (WAM) has important environmental and socio-economic impacts in the region. However, state-of-the-art climate models still struggle in producing reliable climate predictions. An important cause of this low predictive skill is the sensitivity of climate models to different forcings. In this study, the mechanisms linking the WAM dynamics to the CO2 forcing are investigated, by comparing the effect of the CO2 direct radiative effect with its indirect effect mediated by the global sea surface warming. The July-to-September WAM variability is studied in climate simulations extracted from the Coupled Model Intercomparison Project Phase 5 archive, driven by prescribed sea surface temperature (SST). The individual roles of global SST warming and CO2 atmospheric concentration increase are investigated through idealized experiments simulating a 4 K warmer SST and a quadrupled CO2 concentration, respectively. Results show opposite and competing responses in the WAM dynamics and precipitation. A dry response (−0.6 mm/day) to the SST warming is simulated in the Sahel, with dryer conditions over western Sahel (−0.8 mm/day). Conversely, the CO2 increase produces wet conditions (+0.5 mm/day) in the Sahel, with the strongest response over central-eastern Sahel (+0.7 mm/day). The associated responses in the atmospheric dynamics are also analysed, showing that the SST warming affects the Sahelian precipitation through modifications in the global tropical atmospheric dynamics, reducing the importance of the regional drivers, while the CO2 increase reinforces the coupling between precipitation and regional dynamics. A general agreement in model responses demonstrates the robustness of the identified mechanisms linking the WAM dynamics to the CO2 direct and indirect forcing, and indicates that these primary mechanisms are captured by climate models. Results also suggest that the spread in future projections may be caused by unbalanced model responses to the CO2 direct and indirect forcing.

Keywords

West Africa Sahel Monsoon Precipitation Sahara CO2 SST Global warming Climate modelling CMIP5 

Supplementary material

382_2016_3146_MOESM1_ESM.pdf (1.3 mb)
Supplementary material 1 (PDF 1326 kb)

References

  1. Adler RF et al (2003) The version-2 global precipitation climatology project (GPCP) monthly precipitation analysis (1979–present). J Hydrometeorol 4:1147–1167. doi:10.1175/1525-7541(2003)004<1147:TVGPCP>2.0.CO;2 CrossRefGoogle Scholar
  2. Bader J, Latif M (2003) The impact of decadal-scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic Oscillation. Geophys Res Lett 30:1–4. doi:10.1029/2003GL018426 CrossRefGoogle Scholar
  3. Biasutti M (2013) Forced Sahel rainfall trends in the CMIP5 archive. J Geophys Res Atmos 118:1613–1623. doi:10.1002/jgrd.50206 CrossRefGoogle Scholar
  4. Biasutti M, Sobel AH, Camargo SJ (2009) The role of the Sahara low in summertime Sahel rainfall variability and change in the CMIP3 models. J Clim 22:5755–5771. doi:10.1175/2009JCLI2969.1 CrossRefGoogle Scholar
  5. Bony S, Bellon G, Klocke D, Sherwood S, Fermepin S, Denvil S (2013) Robust direct effect of carbon dioxide on tropical circulation and regional precipitation. Nat Geosci 6:447–451. doi:10.1038/ngeo1799 CrossRefGoogle Scholar
  6. Caminade C, Terray L (2010) Twentieth century sahel rainfall variability as simulated by the ARPEGE AGCM, and future changes. Clim Dyn 35:75–94. doi:10.1007/s00382-009-0545-4 CrossRefGoogle Scholar
  7. Chauvin F, Roehrig R, Lafore JP (2010) Intraseasonal variability of the Saharan heat low and its link with midlatitudes. J Clim 23:2544–2561. doi:10.1175/2010JCLI3093.1 CrossRefGoogle Scholar
  8. Chen TC (2005) Maintenance of the midtropospheric North African summer circulation; Saharan high and African easterly jet. J Clim 18:2943–2962. doi:10.1175/JCLI3446.1 CrossRefGoogle Scholar
  9. Cook KH (1999) Generation of the African easterly jet and its role in determining West African precipitation. J Clim 12:1165–1184. doi:10.1175/1520-0442(1999)012<1165:GOTAEJ>2.0.CO;2 CrossRefGoogle Scholar
  10. Cook KH, Vizy EK (2006) Coupled model simulations of the West African monsoon system: twentieth- and twenty-first-century simulations. J Clim 19:3681–3703. doi:10.1175/JCLI3814.1 CrossRefGoogle Scholar
  11. Diedhiou A, Janicot S, Viltard A, De Felice P, Laurent H (1999) Easterly wave regimes and associated convection over West Africa and tropical Atlantic: results from the NCEP/NCAR and ECMWF reanalyses. Clim Dyn 15:795–822. doi:10.1007/s003820050316 CrossRefGoogle Scholar
  12. Evan AT, Flamant C, Lavaysse C, Kocha C, Saci A (2015) Water vapor-forced greenhouse warming over the Sahara desert and the recent recovery from the Sahelian drought. J Clim 28:108–123. doi:10.1175/JCLI-D-14-00039.1 CrossRefGoogle Scholar
  13. Fink AH, Reiner A (2003) Spatiotemporal variability of the relation between African Easterly Waves and West African Squall Lines in 1998 and 1999. J Geophys Res 108:1–17. doi:10.1029/2002JD002816 CrossRefGoogle Scholar
  14. Fontaine B, Philippon N (2000) Seasonal evolution of boundary layer heat content in the West African Monsoon from the Ncep/Ncar. Int J Climatol 20:1777–1790CrossRefGoogle Scholar
  15. Fontaine B, Janicot S, Moron V (1995) Rainfall anomaly patterns and wind field signals over West Africa in August (1958–1989). J Clim 8:1503–1510CrossRefGoogle Scholar
  16. Fontaine B, Garcia-Serrano J, Roucou P, Rodriguez-Fonseca B, Losada T, Chauvin F, Gervois S, Sijikumar S, Ruti P, Janicot S (2010) 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 35:95–114. doi:10.1007/s00382-009-0599-3 CrossRefGoogle Scholar
  17. Fontaine B, Gaetani M, Ullmann A, Roucou P (2011) Time evolution of observed July–September sea surface temperature-Sahel climate teleconnection with removed quasi-global effect (1900–2008). J Geophys Res Atmos 116:1–17. doi:10.1029/2010JD014843 Google Scholar
  18. Gaetani M, Fontaine B, Roucou P, Baldi M (2010) Influence of the Mediterranean Sea on the West African monsoon: intraseasonal variability in numerical simulations. J Geophys Res 115:1–17. doi:10.1029/2010JD014436 CrossRefGoogle Scholar
  19. Garric G, Douville H, Déqué M (2002) Prospects for improved seasonal predictions of monsoon precipitation over Sahel. Int J Climatol 22:331–345. doi:10.1002/joc.736 CrossRefGoogle Scholar
  20. Giannini A (2010) Mechanisms of climate change in the Semiarid African Sahel: the local view. J Clim 23:743–756. doi:10.1175/2009JCLI3123.1 CrossRefGoogle Scholar
  21. Giannini A, Saravanan R, Chang P (2003) Oceanic forcing of Sahel rainfall on interannual to interdecadal time scales. Science 302:1027–1030. doi:10.1126/science.1089357 CrossRefGoogle Scholar
  22. Haarsma RJ, Selten FM, Weber SL, Kliphuis M (2005) Sahel rainfall variability and response to greenhouse warming. Geophys Res Lett 32:1–4. doi:10.1029/2005GL023232 CrossRefGoogle Scholar
  23. Held IM, Delworth TL, Lu J, Findell KL, Knutson TR (2005) Simulation of Sahel drought in the 20th and 21st centuries. Proc Natl Acad Sci USA 102:17891–17896. doi:10.1073/pnas.0509057102 CrossRefGoogle Scholar
  24. Hoerling M, Hurrell J, Eischeid J, Phillips A (2006) Detection and attribution of twentieth-century northern and southern African rainfall change. J Clim 19:3989–4008. doi:10.1175/JCLI3842.1 CrossRefGoogle Scholar
  25. IPCC (2014) Climate change 2014: synthesis report. In: Core Writing Team, Pachauri RK, Meyer LA (eds) Contribution of working groups I, II and III to the fifth assessment report of the intergovernmental panel on climate change. IPCC, Geneva, SwitzerlandGoogle Scholar
  26. Issa Lélé M, Lamb PJ (2010) Variability of the intertropical front (ITF) and rainfall over the West African Sudan-Sahel Zone. J Clim 23:3984–4004. doi:10.1175/2010JCLI3277.1 CrossRefGoogle Scholar
  27. Kandji ST, Verchot L, Mackensen J (2006) Climate change and variability in the Sahel region : impacts and adaptation strategies in the agricultural sector. UNEP & ICRAFGoogle Scholar
  28. Lavaysse C, Flamant C, Janicot S, Parker DJ, Lafore JP, Sultan B, Pelon J (2009) Seasonal evolution of the West African heat low: a climatological perspective. Clim Dyn 33:313–330. doi:10.1007/s00382-009-0553-4 CrossRefGoogle Scholar
  29. Lavaysse C, Flamant C, Janicot S, Knippertz P (2010a) Links between African easterly waves, midlatitude circulation and intraseasonal pulsations of the West African heat low. Q J R Meteorol Soc 136:141–158. doi:10.1002/qj.555 CrossRefGoogle Scholar
  30. Lavaysse C, Flamant C, Janicot S (2010b) Regional-scale convection patterns during strong and weak phases of the Saharan heat low. Atmos Sci Lett 11:255–264. doi:10.1002/asl.284 CrossRefGoogle Scholar
  31. Lavaysse C, Chaboureau JP, Flamant C (2011) Dust impact on the west african heat low in summertime. Q J R Meteorol Soc 137:1227–1240. doi:10.1002/qj.844 CrossRefGoogle Scholar
  32. Losada T, Rodríguez-Fonseca B, Janicot S, Gervois S, Chauvin F, Ruti P (2010) A multi-model approach to the Atlantic Equatorial mode: impact on the West African monsoon. Clim Dyn 35:29–43. doi:10.1007/s00382-009-0625-5 CrossRefGoogle Scholar
  33. Lu J, Delworth TL (2005) Oceanic forcing of the late 20th century Sahel drought. Geophys Res Lett 32:L22706. doi:10.1029/2005GL023316 CrossRefGoogle Scholar
  34. Meehl GA, Covey C, Taylor KE, Delworth T, Stouffer RJ, Latif M, McAvaney B, Mitchell JFB (2007) THE WCRP CMIP3 multimodel dataset: a new era in climate change research. Bull Am Meteorol Soc 88:1383–1394. doi:10.1175/BAMS-88-9-1383 CrossRefGoogle Scholar
  35. Mohino E, Janicot S, Bader J (2011) Sahel rainfall and decadal to multi-decadal sea surface temperature variability. Clim Dyn 37:419–440. doi:10.1007/s00382-010-0867-2 CrossRefGoogle Scholar
  36. Monerie PA, Fontaine B, Roucou P (2012) Expected future changes in the African monsoon between 2030 and 2070 using some CMIP3 and CMIP5 models under a medium-low RCP scenario. J Geophys Res Atmos 117:1–12. doi:10.1029/2012JD017510 CrossRefGoogle Scholar
  37. Monerie P-A, Roucou P, Fontaine B (2013) Mid-century effects of climate change on African monsoon dynamics using the A1B emission scenario. Int J Climatol 33:881–896. doi:10.1002/joc.3476 CrossRefGoogle Scholar
  38. Nicholson SE (2013) The West African Sahel: a review of recent studies on the rainfall regime and its interannual variability. ISRN Meteorol 2013:32. doi:10.1155/2013/453521 CrossRefGoogle Scholar
  39. Nicholson SE, Some B, McCollum J, Nelkin E, Klotter D, Berte Y, Diallo BM, Gaye I, Kpabeba G, Ndiaye O, Noukpozounkou JN, Tanu MM, Thiam A, Toure AA, Traore AK (2003) Validation of TRMM and other rainfall estimates with a high-density gauge dataset for West Africa. Part I: validation of GPCC rainfall product and pre-TRMM satellite and blended products. J Appl Meteorol 42:1337–1354. doi:10.1175/1520-0450(2003)042<1337:VOTAOR>2.0.CO;2 CrossRefGoogle Scholar
  40. Panthou G, Vischel T, Lebel T (2014) Recent trends in the regime of extreme rainfall in the Central Sahel. Int J Climatol 34:3998–4006. doi:10.1002/joc.3984 CrossRefGoogle Scholar
  41. Riahi K, Rao S, Krey V, Cho C, Chirkov V, Fischer G, Kindermann G, Nakicenovic N, Rafaj P (2011) RCP 8.5-A scenario of comparatively high greenhouse gas emissions. Clim Change 109:33–57. doi:10.1007/s10584-011-0149-y CrossRefGoogle Scholar
  42. Rodríguez-Fonseca B, Mohino E, Mechoso CR, Caminade C, Biasutti M, Gaetani M, Garcia-Serrano J, Vizy EK, Cook K, Xue Y, Polo I, Losada T, Druyan L, Fontaine B, Bader J, Doblas-Reyes FJ, Goddard L, Janicot S, Arribas A, Lau W, Colman A, Vellinga M, Rowell DP, Kucharski F, Voldoire A (2015) Variability and predictability of West African droughts: a review on the role of sea surface temperature anomalies. J Clim 28:4034–4060. doi:10.1175/JCLI-D-14-00130.1 CrossRefGoogle Scholar
  43. Roehrig R, Bouniol D, Guichard F, Hourdin FD, Redelsperger JL (2013) The present and future of the west african monsoon: a process-oriented assessment of CMIP5 simulations along the AMMA transect. J Clim 26:6471–6505. doi:10.1175/JCLI-D-12-00505.1 CrossRefGoogle Scholar
  44. Rowell DP (2001) Teleconnections between the tropical Pacific and the Sahel. Q J R Meteorol Soc 127:1683–1706. doi:10.1002/qj.49712757512 CrossRefGoogle Scholar
  45. Rowell DP (2013) Simulating SST teleconnections to Africa: what is the state of the art? J Clim 26:5397–5418. doi:10.1175/JCLI-D-12-00761.1 CrossRefGoogle Scholar
  46. Santer BD, Taylor KE, Gleckler PJ, Bonfils C, Barnett TP, Pierce DW, Wigley TML, Mears C, Wentz FJ, Bruggemann W, Gillett NP, Klein SA, Solomon S, Stott PA, Wehner MF (2009) Incorporating model quality information in climate change detection and attribution studies. Proc Natl Acad Sci USA 106:14778–14783. doi:10.1073/pnas.0901736106 CrossRefGoogle Scholar
  47. Skinner CB, Ashfaq M, Diffenbaugh NS (2012) Influence of twenty-first-century atmospheric and sea surface temperature forcing on West African climate. J Clim 25:527–542. doi:10.1175/2011JCLI4183.1 CrossRefGoogle Scholar
  48. Tanaka HL, Ishizaki N, Kitoh A (2004) Trend and interannual variability of Walker, monsoon and Hadley circulations defined by velocity potential in the upper troposphere. Tellus Ser A Dyn Meteorol Oceanogr 56:250–269. doi:10.1111/j.1600-0870.2004.00049.x CrossRefGoogle Scholar
  49. Taylor KE, Stouffer RJ, Meehl GA (2012) An overview of CMIP5 and the experiment design. Bull Am Meteorol Soc 93:485–498. doi:10.1175/BAMS-D-11-00094.1 CrossRefGoogle Scholar
  50. Thorncroft CD, Blackburn M (1999) Maintenance of the African easterly jet. Q J R Meteorol Soc 125:763–786. doi:10.1002/qj.49712555502 Google Scholar
  51. Ting M, Kushnir Y, Seager R, Li C (2009) Forced and internal twentieth-century SST trends in the North Atlantic. J Clim 22:1469–1481. doi:10.1175/2008JCLI2561.1 CrossRefGoogle Scholar
  52. 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
  53. Villamayor J, Mohino E (2015) Robust Sahel drought due to the Interdecadal Pacific Oscillation in CMIP5 simulations. Geophys Res Lett 42:1214–1222. doi:10.1002/2014GL062473 CrossRefGoogle Scholar
  54. Vizy EK, Cook KH (2009) A mechanism for African monsoon breaks: mediterranean cold air surges. J Geophys Res Atmos 114:1–19. doi:10.1029/2008JD010654 CrossRefGoogle Scholar
  55. Xue Y et al (2010) Intercomparison and analyses of the climatology of the West African Monsoon in the West African Monsoon Modeling and Evaluation project (WAMME) first model intercomparison experiment. Clim Dyn 35:3–27. doi:10.1007/s00382-010-0778-2 CrossRefGoogle Scholar
  56. Zhang R, Delworth TL (2006) Impact of Atlantic multidecadal oscillations on India/Sahel rainfall and Atlantic hurricanes. Geophys Res Lett 33:L17712. doi:10.1029/2006GL026267 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Marco Gaetani
    • 1
    • 2
  • Cyrille Flamant
    • 1
  • Sophie Bastin
    • 1
  • Serge Janicot
    • 3
  • Christophe Lavaysse
    • 4
  • Frederic Hourdin
    • 2
  • Pascale Braconnot
    • 5
  • Sandrine Bony
    • 2
  1. 1.Laboratoire Atmosphères, Milieux, Observations Spatiales, LATMOS-IPSLUPMC Univ. Paris 06 Sorbonne Universités, UVSQ, CNRSParisFrance
  2. 2.Laboratoire de Météorologie Dynamique, LMD-IPSLUPMC Univ. Paris 06 Sorbonne Universités, Ecole Normale Supérieur, Ecole Polytechnique, CNRSParisFrance
  3. 3.Laboratoire d’Océanographie et du Climat: Expérimentation et Approches Numériques, LOCEAN-IPSLUPMC Univ. Paris 06 Sorbonne Universités, IRD, MNHM, CNRSParisFrance
  4. 4.Joint Research CentreEuropean CommissionIspraItaly
  5. 5.Laboratoire des Sciences du Climat et de l’Environnement, LSCE-IPSLUVSQ, CEA, CNRSGif-Sur-YvetteFrance

Personalised recommendations