Abstract
This study systematically examines teleconnections between Atlantic sea surface temperature (SST) and the west–east distribution of Sahel rainfall throughout the twentieth century, taking nonstationarity into account. Sahel rainfall variability of six selected rain gauges displays three dominant time scales: multi-decadal (>20 years), quasi-decadal (8–18 years) and interannual (2–8 years). Regarding their patterns of low-frequency scales, three coherent Sahelian subregions can be identified: the Atlantic Coast (Dakar), western–central Sahel (Nioro and Mopti) and eastern Sahel (Niamey, Maradi, Maine-Soroa). Cross-analyses combining spectral and multivariate analyses of 20 station-based data and West-African gridded rainfall data statistically confirm dissimilarities between the western and eastern Sahel. Western and eastern Sahel rainfall data are correlated with SSTs from different regions of the Atlantic Ocean, especially in the North and tropical South Atlantic. As determined by wavelet coherence and phase, in-phase relationship with North Atlantic SSTs only occurs in wet periods and at the multi- and quasi-decadal scales. This teleconnection depends on the time period and the time scale, displaying a NW–SE pattern, which suggests nonuniform modulations of meridional displacements of the Intertropical Convergence Zone (ITCZ). Tropical South Atlantic SST variability is often related to opposite patterns between the Gulf of Guinean Coast (in phase) and Sahel region (out of phase).
Similar content being viewed by others
References
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 30:2169. doi:10.1029/2003GL018426
Christensen JH, Hewitson B, Busuioc A, Chen A, Gao X, Held I, Jones R, Kolli RK, Kwon WT, Laprise R, Mangaña Rueda V, Meams L, Menéndez CG, Räisänen J, Rinke A, Sarr A, Whetton P (2007) Regional 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 sciences basis. Contribution of Working Group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge
Dai A, Lamb PJ, Trenberth KE, Hulme M, Jones PD, Xie P (2004) The recent Sahel drought is real. Int J Climatol 24:1323–1331
Dieppois B, Diedhiou A, Durand A, Fournier M, Massei N, Sebag D, Xue Y, Fontaine B (2013) Quasi-decadal signals of Sahel rainfall and West African monsoon since the mid-twentieth century. J Geophys Res Atmos 118:12587–12599
Ebisuzaki W (1997) A method to estimate the statistical significance of a correlation when the data are serially correlated. J Clim 10:2147–2153
Enfield DB, Mestas-Nuñez AM, Mayer DA, Cid-Serrano L (1999) How ubiquitous is the dipole relationship in the tropical Atlantic sea surface temperatures? J Geophys Res 104:7841–7848
Folland CK, Palmer TN, Parker DE (1986) Sahel rainfall and worldwide sea temperatures, 1901-85. Nature 320:602–606
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 414:353–368
Fontaine B, Garcia-Serrano J, Roucou P, Rodriguez-Fonseca B, Losada T, Chauvin F, Gervois S, Sivarajan 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 35:95–114
Fontaine B, Roucou P, Gaetani M, Marteau R (2011a) Recent changes in precipitations, ITCZ convection and northern tropical circulation over North Africa (1979–2007). Int J Climatol 31:633–648
Fontaine B, Roucou P, Monerie PA (2011b) Changes in the African monsoon region at medium-term time horizon using 12 AR4 coupled models under the A1b emissions scenario. Atmos Sci Lett 12:83–88
Fontaine B, Monerie PA, Gaetani M, Roucou P (2011c) Climate adjustments over the African-Indian monsoon regions accompanying Mediterranean Sea thermal variability. J Geophys Res 116:D23122. doi:10.1029/2011JD016273
Fontaine B, Gaetani M, Ullmann A, Roucou P (2011d) Time evolution of observed July–September sea surface temperature-Sahel climate teleconnection with removed quasi-global effect (1900–2008). J Geophys Res 116:D04105. doi:10.1029/2010JD014843
Giannini A, Saravannan RP, Chang P (2003) Ocean forcing of Sahel rainfall on interannual to interdecadal time scales. Science 302:1027–1030
Hagos SM, Cook KH (2008) Ocean warming and late-twentieth-century sahel drought and recovery. J Clim 21:3797–3814
Hodson DLR, Sutton RT, Cassou C, Keenlyside N, Okumura Y, Zhou T (2010) Climate impact of recent multidecadal changes in Atlantic Ocean Sea Surface Temperature: a multimode comparison. Clim Dyn 34:1041–1058
Janicot S (1992) Spatio-temporal variability of West African rainfall. Part I: regionalizations and typings. J Clim 5:489–497
Janicot S, Trzaska S, Poccard I (2001) Summer Sahel-ENSO teleconnection and decadal time-scale SST variations. Clim Dyn 18:303–320
Joly M, Voldoire A (2010) Role of the Gulf of Guinea in the inter-annual variability of the West African monsoon: what do we learn from CMIP3 coupled simulations? Int J Climatol 30:1843–1856
Knight JR, Folland CK, Scaife AA (2006) Climate impacts of the Atlantic multidecadal oscillation. Geophys Res Lett 33:L17706. doi:10.1029/2006GL026242
Lamb PJ (1978) Case studies of tropical Atlantic surface circulation patterns during recent sub-Saharan weather anomalies: 1967 and 1968. Mon Weather Rev 106:482–491
Latif M, Grotzner A (2000) On the equatorial Atlantic oscillation and its response to ENSO. Clim Dyn 16:213–218
Le Barbé L, Lebel T, Tapsoba D (2002) Rainfall Variability in West Africa during the years 1950–90. J Clim 15:187–202
Lebel T, Ali A (2009) Recent trends in the Central and Western Sahel rainfall regime 1990–1997. J Hydrol 375:52–64
Lebel T, Delclaux F, Le Barbé L, Polcher J (2000) From MCG scales to hydrological scales: Rainfall variability in West Africa. Stoch Env Res Risk Ass 14:275–295
Losada T, Rodriguez-Fonseca B, Janicot S, Gervois S, Chauvin F, Ruti P (2010) A multimodel approach to the Atlantic equatorial mode. Impact on the West African monsoon. Clim Dyn 35:29–43
Lu J, Delworth TL (2005) Ocean forcing of the late 20th century Sahel drought. Geophys Res Lett 32:L22706. doi:10.1029/2005GL023316
Maraun D (2006) What can we learn from climate data? Methods for fluctuation time/scale and phase analysis. Universitât Postdam
Maraun D, Kurths J (2004) Cross wavelet analysis: significance testing and pitfalls. Nonlinear Process Geophys 11:505–514
Mohino E, Janicot S, Bader J (2011) Sahel rainfall and decadal to multi-decadal sea surface temperature variability. Clim Dyn 37:419–440
Monerie PA, Roucou P, Fontaine B (2012) Mid-century effects of Climate Change on African monsoon dynamics using A1B emission scenario. Int J Climatol 33:881–896
Moron V (1994) Guinean and Sahelian rainfall anomaly indices at annual and monthly time scales (1933-1990). Int J Climatol 14:325–341
Nicholson SE (2005) On the question of the ‘recovery’ of the rains in the West African Sahel. J Arid Environ 63:615–641
Nieto R, Gimeno L, Trigo R (2006) A Lagrangian identification of major sources of Sahel moisture. Geophys Res Lett 33:L18707. doi:10.1029/2006GL027232
Palmer TN (1986) The influence of the Atlantic, Pacific and Indian Oceans on Sahel rainfall. Nature 322:251–253
Polo I, Rodriguez-Fonseca B, Losada T, Garcia-Serrano J (2008) Tropical Atlantic variability modes (1979–2002). Part I: time-evolving SST modes related to West African rainfall. J Clim 21:6457–6475
Rodriguez-Fonseca B, Janicot S, Mohino E, Losada T, Bader J, Caminade C, Chauvin F, Fontaine B, Garcia-Serrano J, Gervois S, Joly M, Polo I, Ruti P, Roucou P, Voldoire A (2011) Interannual and decadal SST-forced responses of the West African monsoon. Atmos Sci Lett 12:67–74
Rouyer T, Fromentin JM, Stenseth NC, Cazelles B (2008) Analysing multiple time series and extending significance testing in wavelet analysis. Mar Ecol Prog Ser 359:11–23
Rowell DP, Folland CK, Maskell K, Ward MN (1995) Variability of summer rainfall over tropical North Africa (1906–1992): observations and modelling. Quart J Roy Met Soc 121:669–704
Servain J, Picaut J, Merle J (1982) Evidence of remote forcing in the equatorial Atlantic Ocean. J Phys Oceanogr 12:457–463
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
Sutton RT, Hodson DLR (2005) Atlantic Ocean forcing of North American European summer climate. Science 309:115–118
Torrence C, Compo GP (1998) A practical guide to wavelet analysis. B Am Soc Met Soc 79:61–78
Torrence C, Webster P (1999) Interdecadal Changes in the ENSO-Monsoon System. J Clim 12:2679–2690
van Oldenborgh GJ, te Raa LA, Dijkstra HA, Philip SY (2009) Frequency- or amplitude-dependent effects of the Atlantic meridional overturning on the tropical Pacific Ocean. Ocean Sci 5:293–301
Wang C, Kucharski F, Barimalala R, Bracco A (2009) Teleconnections of the Tropical Atlantic to the Tropical Indian and Pacific Oceans a review of recent findings. Spec Issue Meteorol Z 18:445–454
Ward NM (1998) Diagnosis and short-lead time prediction of summer rainfall in tropical North Africa at interannual and multidecadal timescales. J Clim 11:3167–3191
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
Acknowledgments
This study was conducted as part of the CORUS2 project entitled “Impact de la pression anthropique et du Changement Global sur les flux sédimentaires en zone sahélienne” (grant no. 6116) supported by the French Institute of Research for Development (Institut de Recherche pour le Développement, IRD). This topic has been a contribution of the AMEDE action (Analyse Multi-Echelle de la Dynamique Eolienne au Sahel) based on the FED 4116 SCALE (TEQQ project) supported by the Upper Normandy region (France). This study also contributes in the FRIEND-AOC research program (Flow Regimes from International Experimental and Network Data in Central and West Africa), which is a UNESCO initiative within its International Hydrological Programme (IHP).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Dieppois, B., Durand, A., Fournier, M. et al. Low-frequency variability and zonal contrast in Sahel rainfall and Atlantic sea surface temperature teleconnections during the last century. Theor Appl Climatol 121, 139–155 (2015). https://doi.org/10.1007/s00704-014-1229-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00704-014-1229-5