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ISRN Meteorology
Volume 2013 (2013), Article ID 453521, 32 pages
http://dx.doi.org/10.1155/2013/453521
Review Article

The West African Sahel: A Review of Recent Studies on the Rainfall Regime and Its Interannual Variability

Earth, Ocean, and Atmospheric Sciences Department, Florida State University, Tallahassee, FL 32306, USA

Received 23 October 2012; Accepted 20 November 2012

Academic Editors: F. Acs, I. Bordi, and D.-Y. Wang

Copyright © 2013 Sharon E. Nicholson. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Linked References

  1. S. E. Nicholson and J. P. Grist, “The seasonal evolution of the atmospheric circulation over West Africa and equatorial Africa,” Journal of Climate, vol. 16, pp. 1013–1030, 2003.
  2. A. Ali and T. Lebel, “The Sahelian standardized rainfall index revisited,” International Journal of Climatology, vol. 29, no. 12, pp. 1705–1714, 2009. View at Publisher · View at Google Scholar · View at Scopus
  3. S. Nicholson, “On the question of the “recovery” of the rains in the West African Sahel,” Journal of Arid Environments, vol. 63, no. 3, pp. 615–641, 2005. View at Publisher · View at Google Scholar · View at Scopus
  4. P. J. Lamb, “Sub-Saharan rainfall update for 1982: continued drought,” Journal of Climatology, vol. 3, no. 4, pp. 419–422, 1983. View at Scopus
  5. P. J. Lamb and R. A. Peppler, “Further case studies of tropical Atlantic surface atmospheric and oceanic patterns associated with sub-Saharan drought,” Journal of Climate, vol. 5, pp. 476–488, 1992.
  6. S. E. Nicholson and I. M. Palao, “A re-evaluation of rainfall variability in the Sahel. Part I. Characteristics of rainfall fluctuations,” International Journal of Climatology, vol. 13, no. 4, pp. 371–389, 1993. View at Scopus
  7. S. E. Nicholson, “The nature of rainfall fluctuations in subtropical West Africa (Guinea Sahel Soudan),” Monthly Weather Review, vol. 108, no. 4, pp. 473–487, 1980. View at Scopus
  8. T. Lebel and A. Ali, “Recent trends in the Central and Western Sahel rainfall regime (1990–2007),” Journal of Hydrology, vol. 375, no. 1-2, pp. 52–64, 2009. View at Publisher · View at Google Scholar · View at Scopus
  9. S. Janicot, C. D. Thorncroft, A. Ali et al., “Large-scale overview of the summer monsoon over West Africa during the AMMA field experiment in 2006,” Annales Geophysicae, vol. 26, no. 9, pp. 2569–2595, 2008. View at Scopus
  10. J. L. Redelsperger, C. D. Thorncroft, A. Diedhiou, T. Lebel, D. J. Parker, and J. Polcher, “African Monsoon Multidisciplinary Analysis: an international research project and field campaign,” Bulletin of the American Meteorological Society, vol. 87, no. 12, pp. 1739–1746, 2006. View at Publisher · View at Google Scholar · View at Scopus
  11. A. Boone, P. De Rosnay, G. Balsamo et al., “The AMMA land surface model intercomparison project (ALMIP),” Bulletin of the American Meteorological Society, vol. 90, no. 12, pp. 1865–1880, 2009. View at Publisher · View at Google Scholar · View at Scopus
  12. T. Lebel, B. Cappelaere, S. Galle et al., “AMMA-CATCH studies in the Sahelian region of West-Africa: an overview,” Journal of Hydrology, vol. 375, no. 1-2, pp. 3–13, 2009. View at Publisher · View at Google Scholar · View at Scopus
  13. C. D. Thorncroft, D. J. Parker, and R. R. Burton, “The JET2000 project—aircraft observations of the African easterly jet and African easterly waves,” Bulletin of the American Meteorological Society, vol. 84, pp. 337–351, 2003.
  14. J. F. Griffiths, World Survey of Climatology, vol. 10, Elsevier, 1972.
  15. C. Zhang, P. Woodworth, and G. Gu, “The seasonal cycle in the lower troposphere over West Africa from sounding observations,” Quarterly Journal of the Royal Meteorological Society, vol. 132, no. 621, pp. 2559–2582, 2006. View at Publisher · View at Google Scholar · View at Scopus
  16. B. J. Mason, “The GARP Atlantic tropical experiment,” Nature, vol. 255, no. 5503, pp. 17–20, 1975. View at Publisher · View at Google Scholar · View at Scopus
  17. Y. Y. Yan, “Intertropical Convergence Zone (ITCZ),” in Encyclopedia of World Climatology, J. E. Oliver, Ed., pp. 429–432, 2005.
  18. R. L. Miller, “The intertropical convergence zone,” in Encyclopedia of Climate and Weather, S. H. Schneider, Ed., vol. 1, pp. 445–448, 1996.
  19. J. R. Holton, J. M. Wallace, and J. A. Young, “On boundary layer dynamics and the ITCZ,” Journal of the Atmospheric Sciences, vol. 28, pp. 275–280, 1971.
  20. S. E. Nicholson, “A revised picture of the structure of the “monsoon” and land ITCZ over West Africa,” Climate Dynamics, vol. 32, no. 7-8, pp. 1155–1171, 2009. View at Publisher · View at Google Scholar · View at Scopus
  21. R. A. Tomas, J. R. Holton, and P. J. Webster, “The influence of cross-equatorial pressure gradients on the location of near-equatorial convection,” Quarterly Journal of the Royal Meteorological Society, vol. 125, no. 556, pp. 1107–1127, 1999. View at Scopus
  22. T. Lebel, A. Diedhiou, and H. Laurent, “Seasonal cycle and interannual variability of the Sahelian rainfall at hydrological scales,” Journal of Geophysical Research D, vol. 108, no. 8, pp. 14–11, 2003. View at Scopus
  23. S. W. Nesbitt and E. J. Zipser, “The diurnal cycle of rainfall and convective intensity according to three years of TRMM measurements,” Journal of Climate, vol. 16, no. 10, pp. 1456–1475, 2003. View at Scopus
  24. P. Peyrillé, J. P. Lafore, and J. L. Redelsperger, “An idealized two-dimensional framework to study the West African Monsoon—part I: validation and key controlling factors,” Journal of the Atmospheric Sciences, vol. 64, no. 8, pp. 2765–2782, 2007. View at Publisher · View at Google Scholar · View at Scopus
  25. C. D. Thorncroft, H. Nguyen, C. Zhang, and P. Peyrille, “Annual cycle of the West African monsoon: regional circulations and associated water vapour transport,” Quarterly Journal of the Royal Meteorological Society, vol. 137, no. 654, pp. 129–147, 2011. View at Publisher · View at Google Scholar · View at Scopus
  26. C. Lavaysse, C. Flamant, and S. Janicot, “Regional-scale convection patterns during strong and weak phases of the Saharan heat low,” Atmospheric Science Letters, vol. 11, no. 4, pp. 255–264, 2010. View at Publisher · View at Google Scholar · View at Scopus
  27. P. Peyrillé and J. P. Lafore, “An idealized two-dimensional framework to study the West African Monsoon—part II: large-scale advection and the diurnal cycle,” Journal of the Atmospheric Sciences, vol. 64, no. 8, pp. 2783–2803, 2007. View at Publisher · View at Google Scholar · View at Scopus
  28. G. J. Gu and R. F. Adler, “Seasonal evolution and variability associated with the West African monsoon system,” Journal of Climate, vol. 17, pp. 3364–3377, 2004.
  29. D. J. Parker, R. R. Burton, A. Diongue-Niang, et al., “The diurnal cycle of the West African monsoon circulation,” Quarterly Journal of the Royal Meteorological Society, vol. 131, pp. 2839–2860, 2005.
  30. J. P. Grist and E. Nicholson, “A study of the dynamic factors influencing the rainfall variability in the West African Sahel,” Journal of Climate, vol. 14, no. 7, pp. 1337–1359, 2001. View at Scopus
  31. C. D. Thorncroft and M. Blackburn, “Maintenance of the African easterly jet,” Quarterly Journal of the Royal Meteorological Society, vol. 125, no. 555, pp. 763–786, 1999. View at Scopus
  32. D. S. Nolan, C. Zhang, and S. H. Chen, “Dynamics of the shallow meridional circulation around intertropical convergence zones,” Journal of the Atmospheric Sciences, vol. 64, no. 7, pp. 2262–2285, 2007. View at Publisher · View at Google Scholar · View at Scopus
  33. C. Zhang, D. S. Nolan, C. D. Thorncroft, and H. Nguyen, “Shallow meridional circulations in the tropical atmosphere,” Journal of Climate, vol. 21, no. 14, pp. 3453–3470, 2008. View at Publisher · View at Google Scholar · View at Scopus
  34. F. Couvreux, F. Guichard, O. Bock, B. Campistron, J. P. Lafore, and J. L. Redelsperger, “Synoptic variability of the monsoon flux over West Africa prior to the onset,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 159–173, 2010. View at Publisher · View at Google Scholar · View at Scopus
  35. J. Cuesta, C. Lavaysse, C. Flamant, M. Mimouni, and P. Knippertz, “Northward bursts of the West African monsoon leading to rainfall over the Hoggar Massif, Algeria,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 174–189, 2010. View at Publisher · View at Google Scholar · View at Scopus
  36. S. E. Nicholson, “The intensity, location and structure of the tropical rainbelt over west Africa as factors in interannual variability,” International Journal of Climatology, vol. 28, no. 13, pp. 1775–1785, 2008. View at Publisher · View at Google Scholar · View at Scopus
  37. S. E. Nicholson, “On the factors modulating the intensity of the tropical rainbelt over West Africa,” International Journal of Climatology, vol. 29, no. 5, pp. 673–689, 2009. View at Publisher · View at Google Scholar · View at Scopus
  38. P. Laux, H. Kunstmann, and A. Bárdossy, “Predicting the regional onset of the rainy season in West Africa,” International Journal of Climatology, vol. 28, no. 3, pp. 329–342, 2008. View at Publisher · View at Google Scholar · View at Scopus
  39. B. Sultan and S. Janicot, “The West African monsoon dynamics. Part II: The“preonset” and “onset” of the summer monsoon,” Journal of Climate, vol. 16, pp. 3407–3427, 2003.
  40. R. Marteau, V. Moron, and N. Philippon, “Spatial coherence of Monsoon onset over Western and Central Sahel (1950–2000),” Journal of Climate, vol. 22, no. 5, pp. 1313–1324, 2009. View at Publisher · View at Google Scholar · View at Scopus
  41. B. Sultan and S. Janicot, “Abrupt shift of the ITCZ over West Africa and intra-seasonal variability,” Geophysical Research Letters, vol. 27, no. 20, pp. 3353–3356, 2000. View at Publisher · View at Google Scholar · View at Scopus
  42. P. Drobinski, S. Bastin, S. Janicot et al., “On the late northward propagation of the west African monsoon in summer 2006 in the region of Niger/Mali,” Journal of Geophysical Research D, vol. 114, no. 9, Article ID D09108, 2009. View at Publisher · View at Google Scholar · View at Scopus
  43. O. Dieng, P. Roucou, and S. Lovet, “Intra-seasonal variability of precipitation in Senegal (1951–1996),” Secheresse, vol. 19, pp. 87–93, 2008.
  44. G. A. Dalu, M. Gaetani, and M. Baldi, “A hydrological onset and withdrawal index for the West African monsoon,” Theoretical and Applied Climatology, vol. 96, no. 1-2, pp. 179–189, 2009. View at Publisher · View at Google Scholar · View at Scopus
  45. E. Flaounas, S. Janicot, S. Bastin, and R. Roca, “The West Africa monsoon onset in 2006: sensitivity to surface albedo, orography, SST and synoptic scale dry-air intrusions using WRF,” Climate Dynamics, vol. 38, pp. 685–708, 2012.
  46. E. Flaounas, S. Janicot, S. Bastin, R. Roca, and E. Mohino, “The role of the Indian monsoon onset in the West African monsoon onset: observations and AGCM nudged simulations,” Climate Dynamics, vol. 38, no. 5-6, pp. 965–983, 2011. View at Publisher · View at Google Scholar · View at Scopus
  47. P. Camberlin, B. Fontaine, S. Louvet, P. Oettli, and P. Valimba, “Climate adjustments over Africa accompanying the Indian monsoon onset,” Journal of Climate, vol. 23, no. 8, pp. 2047–2064, 2010. View at Publisher · View at Google Scholar · View at Scopus
  48. C. Schumacher and R. A. House, “Stratiform precipitation production over sub-Saharan Africa and the tropical East Atlantic as observed by TRMM,” Quarterly Journal of the Royal Meteorological Society, vol. 132, no. 620, pp. 2235–2255, 2006. View at Publisher · View at Google Scholar · View at Scopus
  49. L. Le Barbé, T. Lebel, and D. Tapsoba, “Rainfall variability in West Africa during the years 1950–90,” Journal of Climate, vol. 15, no. 2, pp. 187–202, 2002. View at Scopus
  50. B. Sultan, S. Janicot, and A. Diedhiou, “The West African monsoon dynamics. Part I: documentation of interaseasonal variability,” Journal of Climate, vol. 21, pp. 3389–3406, 2003.
  51. S. Sijikumar, P. Roucou, and B. Fontaine, “Monsoon onset over Sudan-Sahel: simulation by the regional scale model MM5,” Geophysical Research Letters, vol. 33, no. 3, Article ID L03814, 2006. View at Publisher · View at Google Scholar · View at Scopus
  52. R. Ramel, H. Gallé, and C. Messager, “On the northward shift of the West African monsoon,” Climate Dynamics, vol. 26, no. 4, pp. 429–440, 2006. View at Publisher · View at Google Scholar · View at Scopus
  53. Y. Okumura and S. P. Xie, “Interaction of the Atlantic equatorial cold tongue and the African monsoon,” Journal of Climate, vol. 17, pp. 3589–3602, 2004.
  54. S. M. Hagos and K. H. Cook, “Dynamics of the West African monsoon jump,” Journal of Climate, vol. 20, no. 21, pp. 5264–5284, 2007. View at Publisher · View at Google Scholar · View at Scopus
  55. A. Sealy, G. S. Jenkins, and S. C. Walford, “Seasonal/regional comparisons of rain rates and rain characteristics in West Africa using TRMM observations,” Journal of Geophysical Research D, vol. 108, no. 10, pp. 3–21, 2003. View at Scopus
  56. M. A. Bell and P. J. Lamb, “Integration of weather system variability to multidecadal regional climate change: the West African Sudan-Sahel zone, 1951–98,” Journal of Climate, vol. 19, no. 20, pp. 5343–5365, 2006. View at Publisher · View at Google Scholar · View at Scopus
  57. S. E. Nicholson, Dryland Climatology, Cambridge University Press, Cambridge, 2011.
  58. M. Le Lay and S. Galle, “Seasonal cycle and interannual variability of rainfall at hydrological scales. The West African monsoon in a Sudanese climate,” Hydrological Sciences Journal, vol. 50, no. 3, pp. 509–524, 2005. View at Publisher · View at Google Scholar · View at Scopus
  59. E. Mohino, S. Janicot, H. Douville, and L. Z. X. Li, “Impact of the Indian part of the summer MJO on West Africa using nudged climate simulations,” Climate Dynamics, vol. 38, pp. 2319–2334, 2012.
  60. S. Janicot, F. Mounier, N. M. J. Hall, S. Leroux, B. Sultan, and G. N. Kiladis, “Dynamics of the West African monsoon. Part IV: analysis of 25–90-day variability of convection and the role of the Indian monsoon,” Journal of Climate, vol. 22, no. 6, pp. 1541–1565, 2009. View at Publisher · View at Google Scholar · View at Scopus
  61. S. Janicot, F. Mounier, S. Gervois, B. Sultan, and G. N. Kiladis, “The dynamics of the West African monsoon—part V: the detection and role of the dominant modes of convectively coupled equatorial Rossby waves,” Journal of Climate, vol. 23, no. 14, pp. 4005–4024, 2010. View at Publisher · View at Google Scholar · View at Scopus
  62. G. Gu, R. F. Adler, G. J. Huffman, and S. Curtis, “African easterly waves and their association with precipitation,” Journal of Geophysical Research D, vol. 109, no. 4, Article ID D04101, 12 pages, 2004. View at Scopus
  63. S. L. Lavender and A. J. Matthews, “Response of the West African monsoon to the Madden-Julian oscillation,” Journal of Climate, vol. 22, no. 15, pp. 4097–4116, 2009. View at Publisher · View at Google Scholar · View at Scopus
  64. M. J. Ventrice, C. D. Thorncroft, and P. E. Roundy, “The madden-julian oscillation's influence on african easterly waves and downstream tropical cyclogenesis,” Monthly Weather Review, vol. 139, pp. 2704–2722, 2011.
  65. S. Janicot and B. Sultan, “Intra-seasonal modulation of convection in the West African monsoon,” Geophysical Research Letters, vol. 28, no. 3, pp. 523–526, 2001. View at Publisher · View at Google Scholar · View at Scopus
  66. F. Mounier, S. Janicot, and G. N. Kiladis, “The west African monsoon dynamics. Part III: the quasi-biweekly zonal dipole,” Journal of Climate, vol. 21, no. 9, pp. 1911–1928, 2008. View at Publisher · View at Google Scholar · View at Scopus
  67. E. D. Maloney and J. Shaman, “Intraseasonal variability of the West African monsoon and Atlantic ITCZ,” Journal of Climate, vol. 21, no. 12, pp. 2898–2918, 2008. View at Publisher · View at Google Scholar · View at Scopus
  68. S. Leroux, N. M. J. Hall, and G. N. Kiladis, “A climatological study of transient-mean-flow interactions over West Africa,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 397–410, 2010. View at Publisher · View at Google Scholar · View at Scopus
  69. C. D. Thorncroft, N. M. J. Hall, and G. N. Kiladis, “Three-dimensional structure and dynamics of African easterly waves. Part III: genesis,” Journal of the Atmospheric Sciences, vol. 65, no. 11, pp. 3596–3607, 2008. View at Publisher · View at Google Scholar · View at Scopus
  70. R. Roehrig, F. Chauvin, and J. P. Lafore, “10–25 day intraseasonal variability of convection over the Sahel: a role of the Saharan Heat Low and midlatitudes,” Journal of Climate, vol. 24, pp. 5863–5878, 2011.
  71. F. Chauvin, R. Roehrig, and J. P. Lafore, “Intraseasonal variability of the saharan heat low and its link with midlatitudes,” Journal of Climate, vol. 23, no. 10, pp. 2544–2561, 2010. View at Publisher · View at Google Scholar · View at Scopus
  72. E. K. Vizy and K. H. Cook, “A mechanism for African monsoon breaks: mediterranean cold air surges,” Journal of Geophysical Research D, vol. 114, no. 1, Article ID D01104, 2009. View at Publisher · View at Google Scholar · View at Scopus
  73. R. Roca, J. P. Lafore, C. Piriou, and J. L. Redelsperger, “Extratropical dry-air intrusions into the West African monsoon midtroposphere: an important factor for the convective activity over the Sahel,” Journal of the Atmospheric Sciences, vol. 62, no. 2, pp. 390–407, 2005. View at Publisher · View at Google Scholar · View at Scopus
  74. S. E. Nicholson, “The nature of rainfall variability in Africa south of the equator,” Journal of Climatology, vol. 6, no. 5, pp. 515–530, 1986. View at Scopus
  75. S. E. Nicholson, “Revised rainfall series for the West African subtropics,” Monthly Weather Review, vol. 107, no. 5, pp. 620–623, 1979. View at Scopus
  76. S. E. Nicholson, B. Some, and B. Kone, “An analysis of recent rainfall conditions in West Africa, including the rainy seasons of the 1997 El Nino and the 1998 La Nina years,” Journal of Climate, vol. 13, no. 14, pp. 2628–2640, 2000. View at Scopus
  77. M. D. Dennett, J. Elston, and J. A. Rodgers, “A reappraisal of rainfall trends in the Sahel,” Journal of Climatology, vol. 5, no. 4, pp. 353–361, 1985. View at Scopus
  78. S. E. Nicholson, “Climatic and environmental change in Africa during the last two centuries,” Climate Research, vol. 17, no. 2, pp. 123–144, 2001. View at Scopus
  79. Y. L'Hote, G. Mahe, and B. Some, “The 1990s rainfall in the Sahel: the third driest decade since the beginning of the century,” Hydrological Sciences Journal, vol. 48, no. 3, pp. 493–496, 2003. View at Publisher · View at Google Scholar · View at Scopus
  80. A. Dai, P. J. Lamb, K. E. Trenberth, M. Hulme, P. D. Jones, and P. Xie, “The recent Sahel drought is real,” International Journal of Climatology, vol. 24, no. 11, pp. 1323–1331, 2004. View at Publisher · View at Google Scholar · View at Scopus
  81. Y. L'Hôte, G. Mahé, B. Somé, and J. P. Triboulet, “Analysis of a Sahelian annual rainfall index from 1896 to 2000; the drought continues,” Hydrological Sciences Journal, vol. 47, no. 4, pp. 563–572, 2002. View at Scopus
  82. S. E. Nicholson, A. K. Dezfuli, and D. Klotter, “A two-century precipitation data set for the continent of Africa,” Bulletin of the American Meteorological Society, vol. 93, pp. 1219–1231, 2012.
  83. S. E. Nicholson, D. Klotter, and A. K. Dezfuli, “Spatial reconstruction of semi-quantitative precipitation fields over Africa during the nineteenth century from documentary evidence and gauge data,” Quaternary Research, vol. 78, pp. 13–23, 2012.
  84. H. Faure and J. Y. Gac, “Will the Sahelian drought end in 1985?” Nature, vol. 291, no. 5815, pp. 475–478, 1981. View at Publisher · View at Google Scholar · View at Scopus
  85. J. M. Prospero and T. N. Carlson, “Vertical and areal distribution of saharan dust over western equatorial north-atlantic ocean,” Journal of Geophysical Research, vol. 77, pp. 5255–5265, 1972.
  86. P. Ozer, M. Erpicum, G. Demarée, and M. Vandiepenbeeck, “The Sahelian drought may have ended during the 1990s,” Hydrological Sciences Journal, vol. 48, no. 3, pp. 489–492, 2003. View at Publisher · View at Google Scholar · View at Scopus
  87. S. Hastenrath and D. Polzin, “Long-term variations of circulation in the tropical Atlantic sector and Sahel rainfall,” International Journal of Climatology, vol. 31, no. 5, pp. 649–655, 2011. View at Publisher · View at Google Scholar · View at Scopus
  88. B. Fontaine, P. Roucou, M. Gaetani, and R. Marteau, “Recent changes in precipitation, ITCZ convection and northern tropical circulation over North Africa (1979–2007),” International Journal of Climatology, vol. 31, no. 5, pp. 633–648, 2011. View at Publisher · View at Google Scholar · View at Scopus
  89. G. Mahé and J. E. Paturel, “1896–2006 Sahelian annual rainfall variability and runoff increase of Sahelian Rivers,” Comptes Rendus, vol. 341, no. 7, pp. 538–546, 2009. View at Publisher · View at Google Scholar · View at Scopus
  90. L. Olsson, L. Eklundh, and J. Ardö, “A recent greening of the Sahel—trends, patterns and potential causes,” Journal of Arid Environments, vol. 63, no. 3, pp. 556–566, 2005. View at Publisher · View at Google Scholar · View at Scopus
  91. S. M. Herrmann and C. F. Hutchinson, “The changing contexts of the desertification debate,” Journal of Arid Environments, vol. 63, no. 3, pp. 538–555, 2005. View at Publisher · View at Google Scholar · View at Scopus
  92. S. M. Herrmann, A. Anyamba, and C. J. Tucker, “Recent trends in vegetation dynamics in the African Sahel and their relationship to climate,” Global Environmental Change, vol. 15, no. 4, pp. 394–404, 2005. View at Publisher · View at Google Scholar · View at Scopus
  93. J. W. Seaquist, L. Olsson, J. Ardö, and L. Eklundh, “Broad-scale increase in NPP quantified for the African Sahel, 1982–1999,” International Journal of Remote Sensing, vol. 27, no. 22, pp. 5115–5122, 2006. View at Publisher · View at Google Scholar · View at Scopus
  94. S. E. Nicholson, B. Some, J. McCollum et al., et al., “Validation of TRMM and other rainfall estimates with a high-density gauge dataset for West Africa—part II: validation of TRMM rainfall products,” Journal of Applied Meteorology, vol. 42, pp. 1355–1368, 2003.
  95. S. E. Nicholson and P. J. Webster, “A physical basis for the interannual variability of rainfall in the Sahel,” Quarterly Journal of the Royal Meteorological Society, vol. 133, no. 629, pp. 2065–2084, 2007. View at Publisher · View at Google Scholar · View at Scopus
  96. S. W. Nesbitt , et al., 2000.
  97. S. E. Nicholson, “Rainfall and atmospheric circulation during drought periods and wetter years in West Africa,” Monthly Weather Review, vol. 109, no. 10, pp. 2191–2208, 1981. View at Scopus
  98. H. Flohn, “Tropische zirkulationsformen im lichte der satellitenaufnahmen,” Bonner Meteorologishe Abhandlungen, vol. 21, 82 pages, 1975.
  99. M. Biasutti, I. M. Held, A. H. Sobel, and A. Giannini, “SST forcings and Sahel rainfall variability in simulations of the twentieth and twenty-first centuries,” Journal of Climate, vol. 21, no. 14, pp. 3471–3486, 2008. View at Publisher · View at Google Scholar · View at Scopus
  100. A. K. Dezfuli and S. E. Nicholson, “Re-examination of the relationship between the AMO and Sahel rainfall and the potential for long-term forecasting,” In press.
  101. N. A. Elagib and M. M. Elhag, “Major climate indicators of ongoing drought in Sudan,” Journal of Hydrology, vol. 409, pp. 612–625, 2011.
  102. S. Nicholson, “Land surface processes and Sahel climate,” Reviews of Geophysics, vol. 38, no. 1, pp. 117–139, 2000. View at Publisher · View at Google Scholar · View at Scopus
  103. S. E. Nicholson and J. P. Grist, “A conceptual model for understanding rainfall variability in the West African Sahel on interannual and interdecadal timescales,” International Journal of Climatology, vol. 21, no. 14, pp. 1733–1757, 2001. View at Publisher · View at Google Scholar · View at Scopus
  104. T. Losada, B. Rodríguez-Fonseca, E. Mohino, J. Bader, S. Janicot, and C. R. Mechoso, “Tropical SST and Sahel rainfall: a non-stationary relationship,” Geophysical Research Letters, vol. 39, Article ID L12705, 2012.
  105. M. I. Lélé and P. J. Lamb, “Variability of the Intertropical Front (ITF) and rainfall over the West African Sudan-Sahel zone,” Journal of Climate, vol. 23, no. 14, pp. 3984–4004, 2010. View at Publisher · View at Google Scholar · View at Scopus
  106. M. Balme, T. Lebel, and A. Amani, “Dry years and wet years in the Sahel: quo vadimus?” Hydrological Sciences Journal, vol. 51, no. 2, pp. 254–271, 2006. View at Publisher · View at Google Scholar · View at Scopus
  107. F. Frappart, P. Hiernaux, F. Guichard et al., “Rainfall regime across the Sahel band in the Gourma region, Mali,” Journal of Hydrology, vol. 375, no. 1-2, pp. 128–142, 2009. View at Publisher · View at Google Scholar · View at Scopus
  108. R. A. Bryson, “Drought in Sahelia. Who or what is to blame?” Ecologist, vol. 3, no. 10, pp. 366–371, 1973. View at Scopus
  109. E. B. Kraus, “Subtropical droughts and cross-equatorial energy transports,” Monthly Weather Review, vol. 105, pp. 1009–1018, 1977.
  110. M. K. Miles and C. K. Follard, “Changes in the latitude of the climatic zones of the Northern Hemisphere,” Nature, vol. 252, no. 5484, article 616, 1974. View at Publisher · View at Google Scholar · View at Scopus
  111. T. C. Chen, “Maintenance of the midtropospheric North African summer circulation; Saharan high and African easterly jet,” Journal of Climate, vol. 18, no. 15, pp. 2943–2962, 2005. View at Publisher · View at Google Scholar · View at Scopus
  112. R. J. Cornforth, B. J. Hoskins, and C. D. Thorncroft, “The impact of moist processes on the African Easterly Jet-African Easterly Wave system,” Quarterly Journal of the Royal Meteorological Society, vol. 135, no. 641, pp. 894–913, 2009. View at Publisher · View at Google Scholar · View at Scopus
  113. A. M. Tompkins, C. Cardinali, J. J. Morcrette, and M. Rodwell, “Influence of aerosol climatology on forecasts of the African Easterly Jet,” Geophysical Research Letters, vol. 32, no. 10, Article ID L10801, 2005. View at Publisher · View at Google Scholar · View at Scopus
  114. K. H. Cook, “Generation of the African easterly jet and its role in determining West African precipitation,” Journal of Climate, vol. 12, no. 5, pp. 1165–1184, 1999. View at Scopus
  115. M. C. R. Kalapureddy, M. Lothon, B. Campistron, F. Lohou, and F. Saïd, “Wind profiler analysis of the African Easterly Jet in relation with the boundary layer and the Saharan heat-low,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 77–91, 2010. View at Publisher · View at Google Scholar · View at Scopus
  116. R. W. Burpee, “Origin and structure of easterly waves in lower troposphere of North Africa,” Journal of the Atmospheric Sciences, vol. 29, pp. 77–90, 1972.
  117. J. S. Hsieh and K. H. Cook, “Generation of African easterly wave disturbances: relationship to the African easterly jet,” Monthly Weather Review, vol. 133, no. 5, pp. 1311–1327, 2005. View at Publisher · View at Google Scholar · View at Scopus
  118. J. S. Hsieh and K. H. Cook, “On the instability of the African easterly jet and the generation of African waves: reversals of the potential vorticity gradient,” Journal of the Atmospheric Sciences, vol. 65, no. 7, pp. 2130–2151, 2008. View at Publisher · View at Google Scholar · View at Scopus
  119. N. M. J. Hall, G. N. Kiladis, and C. D. Thorncroft, “Three-dimensional structure and dynamics of African easterly waves. Part II: dynamical modes,” Journal of the Atmospheric Sciences, vol. 63, no. 9, pp. 2231–2245, 2006. View at Publisher · View at Google Scholar · View at Scopus
  120. A. K. Dezfuli and S. E. Nicholson, “A note on long-term variations of the African easterly jet,” International Journal of Climatology, vol. 31, pp. 2049–2054, 2011.
  121. Z. Wang and R. L. Elsberry, “Modulation of the African easterly jet by a mesoscale convective system,” Atmospheric Science Letters, vol. 11, pp. 169–174, 2010.
  122. M. V. Ratnam, M. R. Raman, S. K. Mehta et al., “Sub-daily variations observed in Tropical Easterly Jet (TEJ) streams,” Journal of Atmospheric and Solar-Terrestrial Physics, vol. 73, no. 7-8, pp. 731–740, 2011. View at Publisher · View at Google Scholar · View at Scopus
  123. M. R. Raman, V. V. M. Jagannadha Rao, M. Venkat Ratnam et al., “Characteristics of the Tropical Easterly Jet: long-term trends and their features during active and break monsoon phases,” Journal of Geophysical Research D, vol. 114, no. 19, Article ID D19105, 2009. View at Publisher · View at Google Scholar · View at Scopus
  124. D. R. Pattanaik and V. Satyan, “Fluctuations of Tropical Easterly Jet during contrasting monsoons over India: a GCM study,” Meteorology and Atmospheric Physics, vol. 75, no. 1-2, pp. 51–60, 2000. View at Scopus
  125. V. Sathiyamoorthy, “Large scale reduction in the size of the Tropical Easterly Jet,” Geophysical Research Letters, vol. 32, no. 14, Article ID L14802, 2005. View at Publisher · View at Google Scholar · View at Scopus
  126. M. Hulme and N. Tosdevin, “The Tropical easterly Jet and Sudan rainfall: a review,” Theoretical and Applied Climatology, vol. 39, no. 4, pp. 179–187, 1989. View at Publisher · View at Google Scholar · View at Scopus
  127. Z. T. Segele, P. J. Lamb, and L. M. Leslie, “Large-scale atmospheric circulation and global sea surface temperature associations with horn of Africa June–September rainfall,” International Journal of Climatology, vol. 29, no. 8, pp. 1075–1100, 2009. View at Publisher · View at Google Scholar · View at Scopus
  128. B. R. Srinivasa Rao, D. V. Bhaskar Rao, and V. Brahmananda Rao, “Decreasing trend in the strength of Tropical Easterly Jet during the Asian summer monsoon season and the number of tropical cyclonic systems over Bay of Bengal,” Geophysical Research Letters, vol. 31, no. 14, pp. L141031–L141033, 2004. View at Publisher · View at Google Scholar
  129. H. Flohn, “The tropical easterly jet,” Bonner meteorologische Abhandlungen, vol. 4, pp. 1–69, 1964.
  130. H. Besler, “The Tropical Easterly Jet as a cause for intensified aridity in the Sahara,” Palaeoecology of Africa, vol. 16, pp. 163–172, 1984. View at Scopus
  131. P. J. Webster and J. Fasullo, “Monsoon: dynamical theory,” in Encyclopedia of Atmospheric Sciences, J. Holton and J. A. Curry, Eds., pp. 1370–1385, Academic Press, London, UK, 2003.
  132. T. C. Chen and H. van Loon, “Interannual variation of the tropical easterly jet,” Monthly Weather Review, vol. 115, no. 8, pp. 1739–1759, 1987. View at Scopus
  133. S. K. Mishra, “Nonlinear barotropic instability of upper-tropospheric tropical easterly jet on the sphere,” Journal of the Atmospheric Sciences, vol. 50, no. 21, pp. 3541–3552, 1993. View at Scopus
  134. S. K. Mishra and M. K. Tandon, “A combined barotropic-baroclinic instability study of the upper tropospheric tropical easterly jet,” Journal of the Atmospheric Sciences, vol. 40, no. 11, pp. 2708–2723, 1983. View at Scopus
  135. S. E. Nicholson, A. I. Barcilon, M. Challa, and J. Baum, “Wave activity on the tropical easterly jet,” Journal of the Atmospheric Sciences, vol. 64, no. 7, pp. 2756–2763, 2007. View at Publisher · View at Google Scholar · View at Scopus
  136. S. E. Nicholson, A. I. Barcilon, and M. Challa, “An analaysis of west African dynamics using a linearized GCM,” Journal of the Atmospheric Sciences, vol. 65, no. 4, pp. 1182–1203, 2008. View at Publisher · View at Google Scholar · View at Scopus
  137. R. Washington and M. C. Todd, “Atmospheric controls on mineral dust emission from the Bodélé Depression, Chad: the role of the low level jet,” Geophysical Research Letters, vol. 32, article 17701, 2005.
  138. R. Washington, M. C. Todd, S. Engelstaedter, S. Mbainayel, and F. Mitchell, “Dust and the low-level circulation over the Bodélé Depression, Chad: observations from BoDEx 2005,” Journal of Geophysical Research D, vol. 111, no. 3, Article ID D03201, 2006. View at Publisher · View at Google Scholar · View at Scopus
  139. R. Washington and M. C. Todd, “Atmospheric controls on mineral dust emission from the Bodélé Depression, Chad: the role of the low level jet,” Geophysical Research Letters, vol. 32, no. 17, Article ID L17701, pp. 1–5, 2005. View at Publisher · View at Google Scholar · View at Scopus
  140. M. C. Todd, R. Washington, S. Raghavan, G. Lizcano, and P. Knippertz, “Regional model simulations of the Bodélé low-level jet of Northern Chad during the Bodélé dust experiment (BoDEx 2005),” Journal of Climate, vol. 21, no. 5, pp. 995–1012, 2008. View at Publisher · View at Google Scholar · View at Scopus
  141. R. A. Tomas and P. J. Webster, “The role of inertial instability in determining the location and strength of near-equatorial convection,” Quarterly Journal of the Royal Meteorological Society, vol. 123, no. 542, pp. 1445–1482, 1997. View at Scopus
  142. S. A. Grodsky, J. A. Carton, and S. Nigam, “Near surface westerly wind jet in the Atlantic ITCZ,” Geophysical Research Letters, vol. 30, no. 19, pp. 1–4, 2003. View at Scopus
  143. B. Pu and K. H. Cook, “Dynamics of the West African westerly jet,” Journal of Climate, vol. 23, no. 23, pp. 6263–6276, 2010. View at Publisher · View at Google Scholar · View at Scopus
  144. J. P. Grist, S. E. Nicholson, and A. I. Barcilon, “Easterly waves over Africa. Part II: observed and modeled contrasts between wet and dry years,” Monthly Weather Review, vol. 130, no. 2, pp. 212–225, 2002. View at Scopus
  145. B. Pu and K. H. Cook, “Role of the West African Westerly Jet in Sahel rainfall variations,” Journal of Climate, vol. 25, pp. 2880–2896, 2012.
  146. K. Abdou, D. J. Parker, B. Brooks, N. Kalthoff, and T. Lebel, “The diurnal cycle of lower boundary-layer wind in the West African Monsoon,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 66–76, 2010. View at Publisher · View at Google Scholar · View at Scopus
  147. M. Lothon, F. Saïd, F. Lohou, and B. Campistron, “Observation of the diurnal cycle in the low troposphere of West Africa,” Monthly Weather Review, vol. 136, no. 9, pp. 3477–3500, 2008. View at Publisher · View at Google Scholar · View at Scopus
  148. B. Sultan, S. Janicot, and P. Drobinski, “Characterization of the diurnal cycle of the West African monsoon around the monsoon onset,” Journal of Climate, vol. 20, no. 15, pp. 4014–4032, 2007. View at Publisher · View at Google Scholar · View at Scopus
  149. C. L. Bain, D. J. Parker, C. M. Taylor, L. Kergoat, and F. Guichard, “Observations of the nocturnal boundary layer associated with the West African monsoon,” Monthly Weather Review, vol. 138, no. 8, pp. 3142–3156, 2010. View at Publisher · View at Google Scholar · View at Scopus
  150. P. Peyrille and J. Lafore, “An idealized two-dimensional framework to study the West African monsoon. Part II: large-scale advection and the diurnal cycle,” Journal of the Atmospheric Sciences, vol. 64, no. 8, pp. 2783–2803, 2007.
  151. J. M. Schrage and A. H. Fink, “Nocturnal continental low-level stratus over tropical West Africa: observations and possible mechanisms controlling its onset,” Monthly Weather Review, vol. 140, pp. 1794–1809, 2012.
  152. C. Lavaysse, C. Flamant, S. Janicot, and P. Knippertz, “Links between African easterly waves, midlatitude circulation and intraseasonal pulsations of the West African heat low,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 141–158, 2010. View at Publisher · View at Google Scholar · View at Scopus
  153. M. Biasutti, A. H. Sobel, and S. J. Camargo, “The role of the Sahara low in summertime Sahel rainfall variability and change in the CMIP3 models,” Journal of Climate, vol. 22, no. 21, pp. 5755–5771, 2009. View at Publisher · View at Google Scholar · View at Scopus
  154. C. Lavaysse, C. Flamant, S. Janicot et al., “Seasonal evolution of the West African heat low: a climatological perspective,” Climate Dynamics, vol. 33, no. 2-3, pp. 313–330, 2009. View at Publisher · View at Google Scholar · View at Scopus
  155. A. Mekonnen, C. D. Thorncroft, and A. R. Aiyyer, “Analysis of convection and its association with African easterly waves,” Journal of Climate, vol. 19, no. 20, pp. 5405–5421, 2006. View at Publisher · View at Google Scholar · View at Scopus
  156. L. Bounoua and T. N. Krishnamurti, “Thermodynamic budget of the five day wave over the Saharan desert during summer,” Meteorology and Atmospheric Physics, vol. 47, no. 1, pp. 1–25, 1991. View at Publisher · View at Google Scholar · View at Scopus
  157. C. Lavaysse, J. P. Chaboureau, and C. Flamant, “Dust impact on the west african heat low in summertime,” Quarterly Journal of the Royal Meteorological Society, vol. 137, no. 658, pp. 1227–1240, 2011. View at Publisher · View at Google Scholar · View at Scopus
  158. C. M. Grams, S. C. Jones, J. H. Marsham, D. J. Parker, J. M. Haywood, and V. Heuveline, “The atlantic inflow to the saharan heat low: observations and modelling,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 125–140, 2010. View at Publisher · View at Google Scholar · View at Scopus
  159. C. Messager, D. J. Parker, O. Reitebuch, A. Agusti-Panareda, C. M. Taylor, and J. Cuesta, “Structure and dynamics of the Saharan atmospheric boundary layer during the West African monsoon onset: observations and analyses from the research flights of 14 and 17 July 2006,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 107–124, 2010. View at Publisher · View at Google Scholar · View at Scopus
  160. J. M. Prospero, P. Ginoux, O. Torres, S. E. Nicholson, and T. E. Gill, “Environmental characterization of global sources of atmospheric soil dust identified with the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) absorbing aerosol product,” Reviews of Geophysics, vol. 40, no. 1, pp. 1–31, 2002. View at Scopus
  161. J. P. Dunion and C. S. Velden, “The impact of the Saharan Air Layer on Atlantic tropical cyclone activity,” Bulletin of the American Meteorological Society, vol. 85, no. 3, pp. 353–365, 2004. View at Publisher · View at Google Scholar · View at Scopus
  162. D. J. Parker, C. D. Thorncroft, R. R. Burton, and A. Diongue-Niang, “Analysis of the African easterly jet, using aircraft observations from the JET2000 experiment,” Quarterly Journal of the Royal Meteorological Society, vol. 131, no. 608, pp. 1461–1482, 2005. View at Publisher · View at Google Scholar · View at Scopus
  163. H. F. Diaz, T. N. Carlson, and J. M. Propsero, “A study of the structure and dynamics of the Saharan air layer over the northern equatorial Atlantic during BOMEX,” NOAA Technical Memorandum ERL WMPO-32, 1976.
  164. S. Wong, A. E. Dessler, N. M. Mahowald, P. Yang, and Q. Feng, “Maintenance of lower tropospheric temperature inversion in the Saharan air layer by dust and dry anomaly,” Journal of Climate, vol. 22, no. 19, pp. 5149–5162, 2009. View at Publisher · View at Google Scholar · View at Scopus
  165. V. M. Karyampudi, S. P. Palm, J. A. Reagen et al., “Validation of the Saharan dust plume conceptual model using lidar, Meteosat, and ECMWF data,” Bulletin of the American Meteorological Society, vol. 80, no. 6, pp. 1045–1075, 1999. View at Scopus
  166. F. Couvreux, C. Rio, F. Guichard, et al., “Initiation of daytime local convection in a semi-arid region analysed with high-resolution simulations and AMMA observations,” Quarterly Journal of the Royal Meteorological Society, vol. 138, pp. 56–71, 2012.
  167. S. W. Nesbitt, R. Cifelli, and S. A. Rutledge, “Storm morphology and rainfall characteristics of TRMM precipitation features,” Monthly Weather Review, vol. 134, no. 10, pp. 2702–2721, 2006. View at Publisher · View at Google Scholar · View at Scopus
  168. C. Schumacher and R. A. Houze Jr., “Stratiform rain in the tropics as seen by the TRMM precipitation radar,” Journal of Climate, vol. 16, no. 11, pp. 1739–1756, 2003.
  169. B. Jackson, S. E. Nicholson, and D. Klotter, “Mesoscale convective systems over western equatorial Africa and their relationship to large-scale circulation,” Monthly Weather Review, vol. 137, no. 4, pp. 1272–1294, 2009. View at Publisher · View at Google Scholar · View at Scopus
  170. L. Ricciardulli and P. D. Sardeshmukh, “Local time- and space scales of organized tropical deep convection,” Journal of Climate, vol. 15, no. 19, pp. 2775–2790, 2002. View at Scopus
  171. A. Gaye, A. Viltard, and P. de Félice, “Squall lines and rainfall over Western Africa during summer 1986 and 87,” Meteorology and Atmospheric Physics, vol. 90, no. 3-4, pp. 215–224, 2005. View at Publisher · View at Google Scholar · View at Scopus
  172. R. N. Ferreira, T. Rickenbach, N. Guy, and E. Williams, “Radar observations of convective system variability in relationship to african easterly waves during the 2006 AMMA special observing period,” Monthly Weather Review, vol. 137, no. 12, pp. 4136–4150, 2009. View at Publisher · View at Google Scholar · View at Scopus
  173. A. H. Fink and A. Reiner, “Spatiotemporal variability of the relation between African Easterly Waves and West African Squall Lines in 1998 and 1999,” Journal of Geophysical Research D, vol. 108, no. 11, article 4332, pp. 1–17, 2003. View at Scopus
  174. A. G. Laing, R. Carbone, V. Levizzani, and J. Tuttle, “The propagation and diurnal cycles of deep convection in northern tropical Africa,” Quarterly Journal of the Royal Meteorological Society, vol. 134, no. 630, pp. 93–109, 2008. View at Publisher · View at Google Scholar · View at Scopus
  175. K. I. Mohr and C. D. Thorncroft, “Intense convective systems in West Africa and their relationship to the African easterly jet,” Quarterly Journal of the Royal Meteorological Society, vol. 132, no. 614, pp. 163–176, 2006. View at Publisher · View at Google Scholar · View at Scopus
  176. S. D. Nicholls and K. I. Mohr, “An analysis of the environments of intense convective systems in West Africa in 2003,” Monthly Weather Review, vol. 138, pp. 3721–3739, 2010.
  177. P. Knippertz and J. E. Martin, “Tropical plumes and extreme precipitation in subtropical and tropical West Africa,” Quarterly Journal of the Royal Meteorological Society, vol. 131, no. 610, pp. 2337–2365, 2005. View at Publisher · View at Google Scholar · View at Scopus
  178. P. Knippertz, A. H. Fink, A. Reiner, and P. Speth, “Three late summer/early autumn cases of tropical-extratropical interactions causing precipitation in Northwest Africa,” Monthly Weather Review, vol. 131, no. 1, pp. 116–135, 2003. View at Scopus
  179. P. Knippertz and J. E. Martin, “The role of dynamic and diabatic processes in the generation of cut-off lows over Northwest Africa,” Meteorology and Atmospheric Physics, vol. 96, no. 1-2, pp. 3–19, 2007. View at Publisher · View at Google Scholar · View at Scopus
  180. F. Meier and P. Knippertz, “Dynamics and predictability of a heavy dry-season precipitation event over West Africa—sensitivity experiments with a global model,” Monthly Weather Review, vol. 137, no. 1, pp. 189–206, 2009. View at Publisher · View at Google Scholar · View at Scopus
  181. K. Schepanski and P. Knippertz, “Soudano-Saharan depressions and their importance for precipitation and dust: a new perspective on a classical synoptic concept,” Journal of Climate, vol. 137, pp. 1431–1445, 2011.
  182. P. Knippertz and A. H. Fink, “Dry-season precipitation in tropical West Africa and its relation to forcing from the extratropics,” Monthly Weather Review, vol. 136, no. 9, pp. 3579–3596, 2008. View at Publisher · View at Google Scholar · View at Scopus
  183. M. Geb, “Factors favouring precipitation in North Africa: seen from the viewpoint of present-day climatology,” Global and Planetary Change, vol. 26, no. 1–3, pp. 85–96, 2000. View at Publisher · View at Google Scholar · View at Scopus
  184. J. Zawislak and E. J. Zipser, “Observations of seven African easterly waves in the east Atlantic during 2006,” Journal of the Atmospheric Sciences, vol. 67, no. 1, pp. 26–43, 2010. View at Publisher · View at Google Scholar · View at Scopus
  185. A. Diedhiou, S. Janicot, A. Viltard, P. De Felice, and H. Laurent, “Easterly wave regimes and associated convection over West Africa and tropical Atlantic: results from the NCEP/NCAR and ECMWF reanalyses,” Climate Dynamics, vol. 15, no. 11, pp. 795–822, 1999. View at Publisher · View at Google Scholar · View at Scopus
  186. I. Pytharoulis and C. Thorncroft, “The low-level structure of African easterly waves in 1995,” Monthly Weather Review, vol. 127, no. 10, pp. 2266–2280, 1999. View at Scopus
  187. A. H. Fink, D. G. Vincent, P. M. Reiner, and P. Speth, “Mean state and wave disturbances during Phases I, II and III of GATE based on ERA-40,” Monthly Weather Review, vol. 132, pp. 1661–1683, 2004.
  188. C. Thorncroft and K. Hodges, “African easterly wave variability and its relationship to Atlantic tropical cyclone activity,” Journal of Climate, vol. 14, no. 6, pp. 1166–1179, 2001. View at Scopus
  189. T. C. Chen, “Characteristics of African easterly waves depicted by ECMWF reanalyses for 1991–2000,” Monthly Weather Review, vol. 134, no. 12, pp. 3539–3566, 2006. View at Publisher · View at Google Scholar · View at Scopus
  190. L. M. Druyan, M. Fulakeza, and P. Lonergan, “Mesoscale analyses of West African summer climate: focus on wave disturbances,” Climate Dynamics, vol. 27, no. 5, pp. 459–481, 2006. View at Publisher · View at Google Scholar · View at Scopus
  191. R. S. Ross and T. N. Krishnamurti, “Low-level African easterly wave activity and its relation to Atlantic tropical cyclogenesis in 2001,” Monthly Weather Review, vol. 135, no. 12, pp. 3950–3964, 2007. View at Publisher · View at Google Scholar
  192. G. J. Berry and C. Thorncroft, “Case study of an intense African easterly wave,” Monthly Weather Review, vol. 133, no. 4, pp. 752–766, 2005. View at Publisher · View at Google Scholar · View at Scopus
  193. S. Leroux and N. M. J. Hall, “On the relationship between African easterly waves and the African easterly jet,” Journal of the Atmospheric Sciences, vol. 66, no. 8, pp. 2303–2316, 2009. View at Publisher · View at Google Scholar · View at Scopus
  194. A. J. Matthews, “Intraseasonal variability over tropical Africa during northern summer,” Journal of Climate, vol. 17, pp. 2427–2440, 2004.
  195. G. J. Alaka and E. D. Maloney, “The influence of the MJO on upstream precursors to African Easterly Waves,” Journal of Climate, vol. 25, pp. 3219–3236, 2012.
  196. F. Mounier, G. N. Kiladis, and S. Janicot, “Analysis of the dominant mode of convectively coupled Kelvin waves in the West African monsoon,” Journal of Climate, vol. 20, no. 8, pp. 1487–1503, 2007. View at Publisher · View at Google Scholar · View at Scopus
  197. A. Mekonnen, C. D. Thorncroft, A. R. Aiyyer, and G. N. Kiladis, “Convectively coupled Kelvin waves over tropical Africa during the boreal summer: structure and variability,” Journal of Climate, vol. 21, no. 24, pp. 6649–6667, 2008. View at Publisher · View at Google Scholar · View at Scopus
  198. J. P. Grist, “Easterly waves over Africa. Part I: the seasonal cycle and contrasts between wet and dry years,” Monthly Weather Review, vol. 130, no. 2, pp. 197–211, 2002. View at Scopus
  199. E. H. Taleb and L. M. Druyan, “Relationships between rainfall and West African wave disturbances in station observations,” International Journal of Climatology, vol. 23, no. 3, pp. 305–313, 2003. View at Publisher · View at Google Scholar · View at Scopus
  200. G. N. Kiladis, C. D. Thorncroft, and N. M. J. Hall, “Three-dimensional structure and dynamics of African easterly waves. Part I: observations,” Journal of the Atmospheric Sciences, vol. 63, no. 9, pp. 2212–2230, 2006. View at Publisher · View at Google Scholar · View at Scopus
  201. C. L. Bain, D. J. Parker, N. Dixon et al., “Anatomy of an observed African easterly wave in July 2006,” Quarterly Journal of the Royal Meteorological Society, vol. 137, no. 657, pp. 923–933, 2011. View at Publisher · View at Google Scholar · View at Scopus
  202. D. Monkam, “The 6–9 day wave and rainfall modulation in northern Africa during summer 1981,” Journal of Geophysical Research D, vol. 108, no. 17, pp. 5–12, 2003. View at Scopus
  203. P. J. Lamb, “Case studies of tropical Atlantic surface circulation patterns during recent sub-Saharan weather anomalies: 1967 and 1968,” Monthly Weather Review, vol. 106, pp. 482–491, 1978.
  204. P. J. Lamb, “Large-scale tropical Atlantic surface circulation patterns associated with sub-Saharan weather anomalies,” Tellus, vol. 30, pp. 482–491, 1978.
  205. C. K. Folland, T. N. Palmer, and D. E. Parker, “Sahel rainfall and worldwide sea temperatures, 1901–1985,” Journal of Forecasting, vol. 1, pp. 21–56, 1986.
  206. A. Giannini, R. Saravanan, and P. Chang, “Oceanic forcing of sahel rainfall on interannual to interdecadal time scales,” Science, vol. 302, no. 5647, pp. 1027–1030, 2003. View at Publisher · View at Google Scholar · View at Scopus
  207. A. Giannini, R. Saravanan, and P. Chang, “Dynamics of the boreal summer African monsoon in the NSIPP1 atmospheric model,” Climate Dynamics, vol. 25, pp. 517–535, 2005.
  208. A. Giannini, M. Biasutti, and M. M. Verstraete, “A climate model-based review of drought in the Sahel: desertification, the re-greening and climate change,” Global and Planetary Change, vol. 64, no. 3-4, pp. 119–128, 2008. View at Publisher · View at Google Scholar · View at Scopus
  209. D. P. Rowell, “The impact of Mediterranean SSTs on the Sahelian rainfall season,” Journal of Climate, vol. 16, no. 5, pp. 849–862, 2003. View at Scopus
  210. K. M. Lau, S. S. P. Shen, K. M. Kim, and H. Wang, “A multimodel study of the twentieth-century simulations of Sahel drought from the 1970s to 1990s,” Journal of Geophysical Research D, vol. 111, no. 7, Article ID D07111, 2006. View at Publisher · View at Google Scholar · View at Scopus
  211. M. N. Ward, “Diagnosis and short-lead time prediction of summer rainfall in tropical North Africa at interannual and multidecadal timescales,” Journal of Climate, vol. 11, no. 12, pp. 3167–3191, 1998. View at Scopus
  212. M. Joly, A. Voldoire, H. Douville, P. Terray, and J. F. Royer, “African monsoon teleconnections with tropical SSTs: validation and evolution in a set of IPCC4 simulations,” Climate Dynamics, vol. 29, no. 1, pp. 1–20, 2007. View at Publisher · View at Google Scholar · View at Scopus
  213. M. Joly and A. Voldoire, “Role of the Gulf of Guinea in the inter-annual variability of the West African monsoon: what do we learn from CMIP3 coupled simulations?” International Journal of Climatology, vol. 30, no. 12, pp. 1843–1856, 2010. View at Publisher · View at Google Scholar · View at Scopus
  214. E. Mohino, B. Rodríguez-Fonseca, T. Losada, et al., “Changes in the interannual SST-forced signals on West African rainfall. AGCM intercomparison,” Climate Dynamics, vol. 37, no. 9-10, pp. 1707–1725, 2011. View at Publisher · View at Google Scholar
  215. K. M. Lau, K. M. Kim, Y. C. Sud, and G. K. Walker, “A GCM study of the response of the atmospheric water cycle of West Africa and the Atlantic to Saharan dust radiative forcing,” Annales Geophysicae, vol. 27, no. 10, pp. 4023–4037, 2009. View at Publisher · View at Google Scholar · View at Scopus
  216. A. Konare, A. S. Zakey, F. Solmon et al., “A regional climate modeling study of the effect of desert dust on the West African monsoon,” Journal of Geophysical Research D, vol. 113, no. 12, Article ID D12206, 2008. View at Publisher · View at Google Scholar · View at Scopus
  217. M. Yoshioka, N. M. Mahowald, A. J. Conley et al., “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,” Journal of Climate, vol. 20, no. 8, pp. 1445–1467, 2007. View at Publisher · View at Google Scholar · View at Scopus
  218. B. Rodríguez-Fonseca, S. Janicot, E. Mohino et al., et al., “Interannual and decadal SST-forced responses of the West African monsoon,” Atmospheric Science Letters, vol. 12, pp. 67–74, 2011.
  219. L. M. Druyan, “Studies of 21st-century precipitation trends over West Africa,” International Journal of Climatology, vol. 31, no. 10, pp. 1415–1424, 2011. View at Publisher · View at Google Scholar · View at Scopus
  220. H. Paeth and A. Hense, “SST versus climate change signals in West Africa n rainfall: 20th-century variations and future projections,” Climatic Change, vol. 65, no. 1-2, pp. 179–208, 2004. View at Publisher · View at Google Scholar · View at Scopus
  221. C. M. Patricola and K. H. Cook, “Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models,” Climate Dynamics, vol. 35, no. 1, pp. 193–212, 2010. View at Publisher · View at Google Scholar · View at Scopus
  222. F. Hourdin, I. Musat, F. Guichard et al., “Amma-Model intercomparison project,” Bulletin of the American Meteorological Society, vol. 91, no. 1, pp. 95–104, 2010. View at Publisher · View at Google Scholar · View at Scopus
  223. L. M. Druyan, J. Feng, K. H. Cook et al., “The WAMME regional model intercomparison study,” Climate Dynamics, vol. 35, no. 1, pp. 175–192, 2010. View at Publisher · View at Google Scholar · View at Scopus
  224. K. H. Cook, G. A. Meehl, and J. M. Arblaster, “Monsoon regimes and processes in CCSM4. Part II: african and American monsoon systems,” Journal of Climate, vol. 24, pp. 2609–2621, 2012.
  225. G. Nikulin, C. Jones, F. Giorgi, et al., “Precipitation climatology in an ensemble of CORDEX-Africa regional climate simulations,” Journal of Climate, vol. 25, pp. 6057–6078, 2012.
  226. P. M. Ruti, J. E. Williams, F. Hourdin et al., “The West African climate system: a review of the AMMA model inter-comparison initiatives,” Atmospheric Science Letters, vol. 12, no. 1, pp. 116–122, 2011. View at Publisher · View at Google Scholar · View at Scopus
  227. M. Hoerling, J. Hurrell, J. Eischeid, and A. Phillips, “Detection and attribution of twentieth-century northern and southern African rainfall change,” Journal of Climate, vol. 19, no. 16, pp. 3989–4008, 2006. View at Publisher · View at Google Scholar · View at Scopus
  228. T. Losada, B. Rodríguez-Fonseca, S. Janicot, S. Gervois, F. Chauvin, and P. Ruti, “A multi-model approach to the Atlantic Equatorial mode: impact on the West African monsoon,” Climate Dynamics, vol. 35, no. 1, pp. 29–43, 2010. View at Publisher · View at Google Scholar · View at Scopus
  229. J. Sun, H. Wang, and W. Yuan, “Linkage of the boreal spring antarctic oscillation to the west african summer monsoon,” Journal of the Meteorological Society of Japan, vol. 88, no. 1, pp. 15–28, 2010. View at Publisher · View at Google Scholar · View at Scopus
  230. I. Polo, A. Ullmann, P. Roucou, and B. Fontaine, “Weather regimes in the Euro-Atlantic and Mediterranean sector, and relationship with West African rainfall over the 1989–2008 period from a self-organizing maps approach,” Journal of Climate, vol. 24, no. 13, pp. 3423–3432, 2011. View at Publisher · View at Google Scholar · View at Scopus
  231. R. Zhang and T. L. Delworth, “Impact of Atlantic multidecadal oscillations on India/Sahel rainfall and Atlantic hurricanes,” Geophysical Research Letters, vol. 33, Article ID L17712, 2006. View at Publisher · View at Google Scholar
  232. T. L. Delworth, R. Zhang, and M. E. Mann, “Decadal to centennial variability of the Atlantic from observations and models. Ocean circulation: mechanisms and impacts,” Geophysical Monograph Series, vol. 173, pp. 121–148, 2007.
  233. M. F. Ting, Y. Kushnir, R. Seager, and C. H. Li, “Robust features ofg Atlantic multidecadal variability and its climate impacts,” Geophysical Research Letters, vol. 38, Article ID L17705, 2011.
  234. T. M. Shanahan, J. T. Overpeck, K. J. Anchukaitis et al., “Atlantic forcing of persistent drought in West Africa,” Science, vol. 324, no. 5925, pp. 377–380, 2009. View at Publisher · View at Google Scholar · View at Scopus
  235. D. L. R. Hodson, R. T. Sutton, C. Cassou, N. Keenlyside, Y. Okumura, and T. Zhou, “Climate impacts of recent multidecadal changes in Atlantic Ocean sea surface temperature: a multimodel comparison,” Climate Dynamics, vol. 34, no. 7, pp. 1041–1058, 2010. View at Publisher · View at Google Scholar · View at Scopus
  236. H. Paeth and P. Friederichs, “Seasonality and time scales in the relationship between global SST and African rainfall,” Climate Dynamics, vol. 23, no. 7-8, pp. 815–837, 2004. View at Publisher · View at Google Scholar · View at Scopus
  237. D. P. Rowell, “Teleconnections between the tropical Pacific and the Sahel,” Quarterly Journal of the Royal Meteorological Society, vol. 127, pp. 1683–1706, 2001.
  238. C. F. Ropelewski and M. S. Halpert, “Global and regional scale precipitation patterns associated with the El-Nino Southern oscillation,” Monthly Weather Review, vol. 115, pp. 1606–1626, 1987.
  239. C. F. Ropelewski and M. S. Halpert, “Precipitation patterns associated with the high index phase of the southern oscillation,” Journal of Climate, vol. 2, pp. 268–284, 1989.
  240. S. E. Nicholson and J. Kim, “The relationship of the El Nino Southern oscillation to African rainfall,” International Journal of Climatology, vol. 17, no. 2, pp. 117–135, 1997. View at Scopus
  241. J. Bader and M. Latif, “The impact of decadal-scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic Oscillation,” Geophysical Research Letters, vol. 30, no. 22, pp. 2169–2173, 2003. View at Scopus
  242. F. Raicich, N. Pinardi, and A. Navarra, “Teleconnections between Indian monsoon and Sahel rainfall and the Mediterranean,” International Journal of Climatology, vol. 23, no. 2, pp. 173–186, 2003. View at Publisher · View at Google Scholar · View at Scopus
  243. C. E. Chung and V. Ramanathan, “Weakening of north Indian SST gradients and the monsoon rainfall in India and the Sahel,” Journal of Climate, vol. 19, no. 10, pp. 2036–2045, 2006. View at Publisher · View at Google Scholar · View at Scopus
  244. J. Bader and M. Latif, “The 1983 drought in the West Sahel: a case study,” Climate Dynamics, vol. 36, no. 3, pp. 463–472, 2011. View at Publisher · View at Google Scholar · View at Scopus
  245. J. Lu and T. L. Delworth, “Oceanic forcing of the late 20th century Sahel drought,” Geophysical Research Letters, vol. 32, Article ID L22706, 2005.
  246. J. Lu, “The dynamics of the Indian Ocean sea surface temperature forcing of Sahel drought,” Climate Dynamics, vol. 33, no. 4, pp. 445–460, 2009. View at Publisher · View at Google Scholar · View at Scopus
  247. I. Polo, B. Rodríguez-Fonseca, T. Losada, and J. García-Serrano, “Tropical atlantic variability modes (1979–2002)—part I: time-evolving SST modes related to West African rainfall,” Journal of Climate, vol. 21, no. 24, pp. 6457–6475, 2008. View at Publisher · View at Google Scholar · View at Scopus
  248. T. Jung, L. Ferranti, and A. M. Tompkins, “Response to the summer of 2003 Mediterranean SST anomalies over Europe and Africa,” Journal of Climate, vol. 19, no. 20, pp. 5439–5454, 2006. View at Publisher · View at Google Scholar · View at Scopus
  249. M. Gaetani, B. Fontaine, P. Roucou, and M. Baldi, “Influence of the Mediterranean Sea on the West African monsoon: intraseasonal variability in numerical simulations,” Journal of Geophysical Research-Atmospheres, vol. 115, no. D24, 2010. View at Publisher · View at Google Scholar
  250. B. Fontaine, J. Garcia-Serrano, P. Roucou et al., “Impacts of warm and cold situations in the Mediterranean basins on the West African monsoon: observed connection patterns (1979–2006) and climate simulations,” Climate Dynamics, vol. 35, no. 1, pp. 95–114, 2010. View at Publisher · View at Google Scholar · View at Scopus
  251. J. G. Charney, “The dynamics of deserts and droughts,” Quarterly Journal of the Royal Meteorological Society, vol. 101, pp. 193–202, 1975.
  252. D. Entekhabi, “Recent advances in land-atmosphere interaction research,” Reviews of Geophysics, vol. 33, no. 2, pp. 995–1003, 1995. View at Scopus
  253. A. R. Lare and S. E. Nicholson, “Contrasting conditions of surface water balance in wet years and dry years as a possible land surface-atmosphere feedback mechanism in the West African Sahel,” Journal of Climate, vol. 7, no. 5, pp. 653–668, 1994. View at Scopus
  254. N. Zeng, J. D. Neelin, K. M. Lau, and C. J. Tucker, “Enhancement of interdecadal climate variability in the Sahel by vegetation interaction,” Science, vol. 286, no. 5444, pp. 1537–1540, 1999. View at Publisher · View at Google Scholar · View at Scopus
  255. C. M. Taylor, E. F. Lambin, N. Stephenne, R. J. Harding, and R. L. H. Essery, “The influence of land use change on climate in the Sahel,” Journal of Climate, vol. 15, no. 24, pp. 3615–3629, 2002. View at Scopus
  256. S. E. Nicholson, C. J. Tucker, and M. B. Ba, “Desertification, drought, and surface vegetation: an example from the West African Sahel,” Bulletin of the American Meteorological Society, vol. 79, no. 5, pp. 815–829, 1998. View at Scopus
  257. S. D. Prince, E. Brown De Colstoun, and L. L. Kravitz, “Evidence from rain-use efficiencies does not indicate extensive Sahelian desertification,” Global Change Biology, vol. 4, no. 4, pp. 359–374, 1998. View at Scopus
  258. J. F. Reynolds and D. M. Stafford Smith, Global Desertification: Do Humans Cause Deserts?Dahlem University Press, Berlin, Germany, 2002.
  259. S. D. Prince, “Spatial and temporal scales for detection of desertification,” in Global Desertification: Do Humans Cause Deserts? J. F. Reynolds and D. M. Stafford Smith, Eds., pp. 23–40, Dahlem University Press, Berlin, Germany, 2002.
  260. C. A. Alo and G. Wang, “Role of dynamic vegetation in regional climate predictions over Western Africa,” Climate Dynamics, vol. 35, no. 5, pp. 907–922, 2010. View at Publisher · View at Google Scholar · View at Scopus
  261. B. J. Abiodun, J. S. Pal, E. A. Afiesimama, W. J. Gutowski, and A. Adedoyin, “Simulation of West African monsoon using RegCM3 Part II: impacts of deforestation and desertification,” Theoretical and Applied Climatology, vol. 93, no. 3-4, pp. 245–261, 2008. View at Publisher · View at Google Scholar · View at Scopus
  262. X. Zeng, M. Barlage, C. Castro, and K. Fling, “Comparison of land-precipitation coupling strength using observations and models,” Journal of Hydrometeorology, vol. 11, no. 4, pp. 979–994, 2010. View at Publisher · View at Google Scholar · View at Scopus
  263. C. M. Taylor, P. P. Harrisa, and D. J. Parkerb, “Impact of soil moisture on the development of a sahelian mesoscale convective system: a case-study from the AMMA special observing period,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 456–470, 2010. View at Publisher · View at Google Scholar · View at Scopus
  264. M. Rietkerk, V. Brovkin, P. M. van Bodegom et al., “Local ecosystem feedbacks and critical transitions in the climate,” Ecological Complexity, vol. 8, no. 3, pp. 223–228, 2011. View at Publisher · View at Google Scholar · View at Scopus
  265. L. M. Druyan, M. Fulakeza, and P. Lonergan, “Land surface influences on the West African summer monsoon: implications for synoptic disturbances,” Meteorology and Atmospheric Physics, vol. 86, no. 3-4, pp. 261–273, 2004. View at Publisher · View at Google Scholar · View at Scopus
  266. A. L. Steiner, J. S. Pal, S. A. Rauscher et al., “Land surface coupling in regional climate simulations of the West African monsoon,” Climate Dynamics, vol. 33, no. 6, pp. 869–892, 2009. View at Publisher · View at Google Scholar · View at Scopus
  267. B. J. J. M. van den Hurk and E. van Meijgaard, “Diagnosing land-atmosphere interaction from a regional climate model simulation over West Africa,” Journal of Hydrometeorology, vol. 11, no. 2, pp. 467–481, 2010. View at Publisher · View at Google Scholar · View at Scopus
  268. D. B. Clark, C. M. Taylor, and A. J. Thorpe, “Feedback between the land surface and rainfall at convective length scales,” Journal Hydrometeor, vol. 5, pp. 625–639, 2004.
  269. C. M. Taylor, D. J. Parker, C. R. Lloyd, and C. D. Thorncroft, “Observations of synoptic-scale land surface variability and its coupling with the atmosphere,” Quarterly Journal of the Royal Meteorological Society, vol. 131, no. 607, pp. 913–937, 2005. View at Publisher · View at Google Scholar · View at Scopus
  270. C. M. Taylor, A. Gounou, F. Guichard et al., “Frequency of sahelian storm initiation enhanced over mesoscale soil-moisture patterns,” Nature Geoscience, vol. 4, no. 7, pp. 430–433, 2011. View at Publisher · View at Google Scholar · View at Scopus
  271. L. Gantner and N. Kalthoff, “Sensitivity of a modelled life cycle of a mesoscale convective system to soil conditions over West Africa,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 471–482, 2010. View at Publisher · View at Google Scholar · View at Scopus
  272. R. A. Anthes, “Enhancement of convective precipitation by mesoscale variations in vegetative covering in semiarid regions,” Journal of Climate & Applied Meteorology, vol. 23, no. 4, pp. 541–554, 1984. View at Scopus
  273. B. Adler, N. Kalthoff, and L. Gantner, “Initiation of deep convection caused by land-surface inhomogeneities in West Africa: a modelled case study,” Meteorology and Atmospheric Physics, vol. 112, no. 1-2, pp. 15–27, 2011. View at Publisher · View at Google Scholar · View at Scopus
  274. B. Adler, N. Kalthoff, and L. Gantner, “The impact of soil moisture inhomogeneities on the modification of a mesoscale convective system: an idealised model study,” Atmospheric Research, vol. 101, no. 1-2, pp. 354–372, 2011. View at Publisher · View at Google Scholar · View at Scopus
  275. K. I. Mohr, R. D. Baker, W. K. Tau, and J. S. Famiglietti, “The sensitivity of West African convective-line water budgets to land cover,” Journal of Hydrology, vol. 4, pp. 62–76, 2003.
  276. D. J. Parker, “A simple model of coupled synoptic waves in the land surface and atmosphere of the northern Sahel,” Quarterly Journal of the Royal Meteorological Society, vol. 134, no. 637, pp. 2173–2184, 2008. View at Publisher · View at Google Scholar · View at Scopus
  277. J. Schwendike, N. Kalthoff, and M. Kohler, “The impact of mesoscale convective systems on the surface and boundary-layer structure in West Africa: case-studies from the AMMA campaign 2006,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 648, pp. 566–582, 2010. View at Publisher · View at Google Scholar · View at Scopus
  278. C. M. Taylor, R. J. Harding, A. J. Thorpe, and P. Bessemoulin, “A mesoscale simulation of land surface heterogeneity from HAPEX-Sahel,” Journal of Hydrology, vol. 188-189, no. 1–4, pp. 1040–1066, 1997. View at Publisher · View at Google Scholar · View at Scopus
  279. C. M. Taylor and T. Lebel, “Observational evidence of persistent convective-scale rainfall patterns,” Monthly Weather Review, vol. 126, no. 6, pp. 1597–1607, 1998. View at Scopus
  280. J.-P. Goutorbe, T. Lebel, A. Tinga et al., et al., “Hapex-sahel—a large-scale study of land-atmosphere interactions in the semiarid tropics,” Annales Geophysicae-Atmospheres Hydrospheres and Space Sciences, vol. 12, pp. 53–64, 1994.
  281. C. M. Taylor, “Intraseasonal land-atmospheric coupling in the West African monsoon,” Journal of Climate, vol. 21, no. 24, pp. 6636–6648, 2008. View at Publisher · View at Google Scholar · View at Scopus
  282. C. M. Taylor and R. J. Ellis, “Satellite detection of soil moisture impacts on convection at the mesoscale,” Geophysical Research Letters, vol. 33, no. 3, Article ID L03404, 2006. View at Publisher · View at Google Scholar · View at Scopus
  283. V. Klupfel, N. Kalthoff, L. Gantner, and C. M. Taylor, “Convergence zones and their impact on the initiation of a mesoscale convective system in West Africa,” Quarterly Journal of the Royal Meteorological Society, vol. 138, pp. 950–963, 2012.
  284. D. Lauwaet, N. P. M. Lipzig, and K. Ridder, “The effect of vegetation changes on precipitation and Mesoscale Convective Systems in the Sahel,” Climate Dynamics, vol. 33, no. 4, pp. 521–534, 2009. View at Publisher · View at Google Scholar · View at Scopus
  285. D. Lauwaet, N. P. M. van Lipzig, N. Kalthoff, and K. de Ridder, “Impact of vegetation changes on a mesoscale convective system in West Africa,” Meteorology and Atmospheric Physics, vol. 107, no. 3, pp. 109–122, 2010. View at Publisher · View at Google Scholar · View at Scopus
  286. M. A. Gaertner, M. Domínguez, and M. Garvert, “A modelling case-study of soil moisture-atmosphere coupling,” Quarterly Journal of the Royal Meteorological Society, vol. 136, no. 1, pp. 483–495, 2010. View at Publisher · View at Google Scholar · View at Scopus
  287. W. Moufouma-Okia and D. P. Rowell, “Impact of soil moisture initialisation and lateral boundary conditions on regional climate model simulations of the West African Monsoon,” Climate Dynamics, vol. 35, no. 1, pp. 213–229, 2010. View at Publisher · View at Google Scholar · View at Scopus
  288. P. Knippertz and M. C. Todd, “The central west Saharan dust hot spot and its relation to African easterly waves and extratropical disturbances,” Journal of Geophysical Research D, vol. 115, no. 12, Article ID D12117, 2010. View at Publisher · View at Google Scholar · View at Scopus
  289. C. Jones, N. Mahowald, and C. Luo, “The role of easterly waves on African desert dust transport,” Journal of Climate, vol. 16, pp. 3617–3628, 2003.
  290. G. N'Tchayi Mbourou, J. J. Bertrand, and S. E. Nicholson, “The diurnal and seasonal cycles of wind-borne dust over africa north of the equator,” Journal of Applied Meteorology, vol. 36, no. 7, pp. 868–882, 1997. View at Scopus
  291. P. J. deMott, K. Sassen, M. R. Poellot, et al., “African dust aerosols as atmospheric ice nuclei,” Geophysical Research Letters, vol. 30, article 1732, 2003.
  292. W. J. Hui, B. I. Cook, S. Ravi, J. D. Fuentes, and P. D'Odorico, “Dust-rainfall feedbacks in the West African Sahel,” Water Resources Research, vol. 44, no. 5, Article ID W05202, 2008. View at Publisher · View at Google Scholar · View at Scopus
  293. A. Wiacek, T. Peter, and U. Lohmann, “The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds,” Atmospheric Chemistry and Physics, vol. 10, no. 18, pp. 8649–8667, 2010. View at Publisher · View at Google Scholar · View at Scopus
  294. J. Huang, C. Zhang, and J. M. Prospero, “African aerosol and large-scale precipitation variability over West Africa,” Environmental Research Letters, vol. 4, no. 1, Article ID 015006, 2009. View at Publisher · View at Google Scholar · View at Scopus
  295. O. Reale, K. M. Lau, and A. da Silva, “Impact of an interactive aerosol on the African Easterly Jet in the NASA GEOS-5 Global Forecasting System,” Weather and Forecasting, vol. 26, pp. 504–519, 2011.
  296. F. Solomon, N. Elguindi, and M. Mallet, “Radiative and climatic effects of dust over West Africa, as simulated by a regional climate model,” Climate Research, vol. 52, article 2012, 2012.
  297. L. Klüser and T. Holzer-Popp, “Relationships between mineral dust and cloud properties in the West African Sahel,” Atmospheric Chemistry and Physics, vol. 10, no. 14, pp. 6901–6915, 2010. View at Publisher · View at Google Scholar · View at Scopus
  298. C. M. Patricola and K. H. Cook, “Atmosphere/vegetation feedbacks: a mechanism for abrupt climate change over northern Africa,” Journal of Geophysical Research D, vol. 113, no. 18, Article ID D18102, 2008. View at Publisher · View at Google Scholar · View at Scopus
  299. P. Kabat, M. Claussen, P. A. Dirmeyer, et al., Vegetation, Water, Humans and the Climate: A New Perspective on an Interactive System, Springer, Berlin, Germany, 2004.
  300. P. Demenocal, J. Ortiz, T. Guilderson et al., “Abrupt onset and termination of the African Humid Period: rapid climate responses to gradual insolation forcing,” Quaternary Science Reviews, vol. 19, no. 1–5, pp. 347–361, 2000. View at Publisher · View at Google Scholar · View at Scopus
  301. S. Kroepelin, D. Verschuren, A.-M. Lézine, et al., “Climate-driven ecosystem succession in the Sahara: the past 6000 years,” Science, vol. 320, pp. 765–768, 2008.
  302. M. Claussen, “Modeling bio-geophysical feedback in the African and Indian monsoon region,” Climate Dynamics, vol. 13, no. 4, pp. 247–257, 1997. View at Scopus
  303. Z. Liu, Y. Wang, R. Gallimore et al., “Simulating the transient evolution and abrupt change of Northern Africa atmosphere-ocean-terrestrial ecosystem in the Holocene,” Quaternary Science Reviews, vol. 26, no. 13-14, pp. 1818–1837, 2007. View at Publisher · View at Google Scholar · View at Scopus
  304. M. Rietkerk, S. C. Dekker, P. C. De Ruiter, and J. Van De Koppel, “Self-organized patchiness and catastrophic shifts in ecosystems,” Science, vol. 305, no. 5692, pp. 1926–1929, 2004. View at Publisher · View at Google Scholar · View at Scopus
  305. O. Lejeune, M. Tlidi, and P. Couteron, “Localized vegetation patches: a self-organized response to resource scarcity,” Physical Review E, vol. 66, no. 1, Article ID 010901, 2002. View at Publisher · View at Google Scholar · View at Scopus
  306. M. Rietkerk and J. Van De Koppel, “Alternate stable states and threshold effects in semi-arid grazing systems,” Oikos, vol. 79, no. 1, pp. 69–76, 1997. View at Scopus
  307. R. H. H. Janssen, M. B. J. Meinders, E. H. van Nes, and M. Scheffer, “Microscale vegetation-soil feedback boosts hysteresis in a regional vegetation-climate system,” Global Change Biology, vol. 14, no. 5, pp. 1104–1112, 2008. View at Publisher · View at Google Scholar · View at Scopus
  308. R. D. Koster, P. A. Dirmeyer, Z. Guo et al., “Regions of strong coupling between soil moisture and precipitation,” Science, vol. 305, no. 5687, pp. 1138–1140, 2004. View at Publisher · View at Google Scholar · View at Scopus
  309. M. Scheffer, M. Holmgren, V. Brovkin, and M. Claussen, “Synergy between small—and large-scale feedbacks of vegetation on the water cycle,” Global Change Biology, vol. 11, no. 7, pp. 1003–1012, 2005. View at Publisher · View at Google Scholar · View at Scopus
  310. P. D'Odorico, K. Caylor, G. S. Okin, and T. M. Scanlon, “On soil moisture-vegetation feedbacks and their possible effects on the dynamics of dryland ecosystems,” Journal of Geophysical Research G, vol. 112, no. 4, Article ID G04010, 2007. View at Publisher · View at Google Scholar · View at Scopus
  311. S. C. Dekker, M. Rietkerk, and M. F. P. Bierkens, “Coupling microscale vegetation-soil water and macroscale vegetation-precipitation feedbacks in semiarid ecosystems,” Global Change Biology, vol. 13, no. 3, pp. 671–678, 2007. View at Publisher · View at Google Scholar · View at Scopus
  312. S. C. Dekker, H. J. De Boer, V. Brovkin, K. Fraedrich, M. J. Wassen, and M. Rietkerk, “Biogeophysical feedbacks trigger shifts in the modelled vegetation-atmosphere system at multiple scales,” Biogeosciences, vol. 7, no. 4, pp. 1237–1245, 2010. View at Scopus