Theoretical and Applied Climatology

, Volume 93, Issue 3–4, pp 245–261

Simulation of West African monsoon using RegCM3 Part II: impacts of deforestation and desertification

  • B. J. Abiodun
  • J. S. Pal
  • E. A. Afiesimama
  • W. J. Gutowski
  • A. Adedoyin
Article

Summary

In this study, we investigate the feedback mechanisms between land cover and the monsoon in West African using the International Centre for Theoretical Physics Regional Climate Model (RegCM3). A series of multi-year simulations are performed using reanalysis boundary conditions under three idealised vegetation states (potential, desertified and deforested). The study shows that both desertification and deforestation tend to increase the monsoon flow over the Guinean region, although the mechanisms for change are different in each case. Desertification increases the flow mainly by increasing the meridional temperature gradient. While this reduces rainfall over the desertification region, it increases rainfall to the south. On the other hand, deforestation increases the monsoon flow mainly due to the reduced surface friction experienced by the flow over the Guinean region. This reduces rainfall over the entire West African region.

The study further shows that desertification and deforestation also increase the speed and specific humidity of the mid-tropospheric easterly flow, to the south of the African easterly jet. Consequently, the flow transports more moisture away from the West Africa region at the expense of low-level moisture, resulting in less moisture available for rainfall over the region. Overall, this study suggests that the state of the biosphere in West Africa may play an important role in determining the characteristics of the monsoon and rainfall pattern.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Afiesimama, EA, Pal, J, Abiodun, BJ, Gutowski, WJ, Adedoyin, A 2006Simulation of West African Monsoon using the RegCM3. Part I: Model validation and interannual variabilityTheor Appl Climatol822338CrossRefGoogle Scholar
  2. Burke, EJ, Shuttleworth, WJ, Yang, ZL, Mullen, SL, Arain, MA 2000The impact of parameterization of heteorogenous vegetation on the modelled large-scale circulation in CCM3-BATSGeophys Res27397400Google Scholar
  3. Cadet, DL, Nnoli, NO 1987Water vapour transport over Africa and the Atlantic ocean during summer 1979Quart J Roy Meteor Soc113581602CrossRefGoogle Scholar
  4. Charney, JG 1975Dynamics of deserts and drought in the SahelQuart J Roy Meteor Soc101193202CrossRefGoogle Scholar
  5. Charney, JG, Quirk, WJ, Chow, S-H, Korfield, J 1977A comparative study of effect albedo change on drought in semi-arid regionsJ Atmos Sci3413661385CrossRefGoogle Scholar
  6. Clark, CB, Xue, Y, Harding, RJ, Valdes, PJ 2001Modeling the impact of land surface degradation on the climate or tropical north AfricaJ Climate1418091822CrossRefGoogle Scholar
  7. Cook, HK 1999Generation of the African easterly jet and its role in determining West African precipitationJ Climate1211651184CrossRefGoogle Scholar
  8. Dickinson RE, Henderson-Sellers A, Kennedy PJ (1993) Biosphere – atmosphere transfer scheme (BATS) version 1 as coupled to the NCAR Community Climate Model. NCAR Tech. Note NCAR\TN-3871STR, National Center for Atmospheric Research, Boulder, CO, 72 ppGoogle Scholar
  9. Eltahir, EAB, Gong, CL 1996Dynamics of wet and dry years in West AfricaJ Climate510301042CrossRefGoogle Scholar
  10. Folland, CK, Palmer, TN, Parker, DE 1986Sahel rainfall and worldwide sea temperature, 1901–1985Nature320602607CrossRefGoogle Scholar
  11. Fritsch, JM, Chappell, CF 1980Numerical prediction of convectively driven mesoscale pressure systems. Part 1: Convective parameterisationJ Atmos Sci3717221733CrossRefGoogle Scholar
  12. Giannini, A, Saravanan, R, Chang, PO 2003Oceanic forcing of Sahel rainfall on interannual to interdecadal time scalesScience30210271030CrossRefGoogle Scholar
  13. Grell, GA 1993Prognostic evaluation of assumptions used by cumulus parameterizationsMon Wea Rev121764787CrossRefGoogle Scholar
  14. Grist, JP, Nicholson, SE 2001A study of the dynamic factors influencing the rainfall variability in the West African SahelJ Climate1413371359CrossRefGoogle Scholar
  15. Hahmann, AN, Dickinson, R 2001A fine-mesh approach for general circulation model and its impact on regional climateJ Clim1416341964CrossRefGoogle Scholar
  16. Holtslag, AAM, De Bruijn, EIF, Pan, H-L 1990A high resolution air mass transformation model for short-range weather forecastingMon Wea Rev11815611575CrossRefGoogle Scholar
  17. Hulme, M 1992Rainfall changes in Africa. 1931–1960 to 1961–1990Int J Climatol12685699CrossRefGoogle Scholar
  18. Kalnay, E, Kanamitsu, M, Kistler, R, Collins, W, Deaven, D, Gandin, L, Iredell, M, Saha, S, White, G, Woollen, J, Zhu, Y, Chelliah, M, Ebisuzaki, W, Higgins, W, Janowiak, J, Mo, KC, Ropelewski, C, Wang, J, Leetma, A, Reynolds, R, Jenne, R, Joseph, D 1996The NCEP\NCAR 40-year reanalysis projectBull Amer Meteor Soc77437471CrossRefGoogle Scholar
  19. Kiehl JT, Hack JJ, Bonan GB, Boville BA, Breigleb BP, Williamson DL, Rasch PJ (1996) Description of the NCAR community climate Model (CCM3). NCAR Tech. Note, NCAR\TN-420+STR, 152 pp, Natl. Cent. for Atmos. Res; Boulder, ColoradoGoogle Scholar
  20. Lamb, PJ 1978Large scale tropical Atlantic surface circulations pattern associated with sub-Saharan weather anomaliesTellus30240251CrossRefGoogle Scholar
  21. Lamb PJ, Peppler RA (1991) West Africa. In: Glantz M, Kats RW, Nicholson N (eds) Teleconnections Linking Worldwide Climate Anomalies. Cambridge University Press, pp 121–189Google Scholar
  22. Lau, KM, Shen, SSP, Kim, K-M, Wang, H 2006A multimodel study of the twentieth-century simulations of Sahel drought from the 1970s to 1990sJ Geophys Res111D07111doi:10.1029\2005JD006281CrossRefGoogle Scholar
  23. Maynard, K, Royer, J-F 2004Sensitivity of a general circulation model to land surface parameters in African tropical deforestation experimentsClim Dynam22555572Google Scholar
  24. Nicholson, SE 1993An overview of Africa rainfall fluctuation of the last decadeJ Climate614631466CrossRefGoogle Scholar
  25. Omotosho, J, ‘Bayo, H 1985The separate contributions of squall lines, thunderstorms and the monsoon to the total rainfall in NigeriaJ Climatol5543552CrossRefGoogle Scholar
  26. Pal, JS, Small, EE, Eltahir, EAB 2000Simulation of regional-scale water and energy budgets: representation of subgrid cloud and precipitation processes within RegCMJ Geophys Res1052957929594CrossRefGoogle Scholar
  27. Pal JS, Giorgi F, Bi X, Elguindi N, Solmon F, Gao X, Rauscher SA, Ashfaq M, Francisco R, Bell J, Diffenbaugh N, Karmacharya J, Konaré11 A, Martinez D, da Rocha RP, Sloan LC, Steiner AL, Winter JM, Zakey A (2005) Regional Climate Modeling for the Developing World: The ICTP RegCM3 and RegCNET. In Press BAMSGoogle Scholar
  28. Peter, M, Tetzlaff, G 1988The structure of West African squall lines and their environmental moisture budgetMeteorol Atmos Phys397484CrossRefGoogle Scholar
  29. Reynolds, RW, Rayner, NA, Smith, TM, Stokes, DC, Wang, W 2002An improved in situ and satellite SST analysis for climateJ Climate1516091625CrossRefGoogle Scholar
  30. Rowell, DP, Folland, CK, Maskell, K, Ward, MN 1995Variability of summer rainfall over tropical North Africa (106–92): observation and modelingQuart J Roy Meteor Soc121669704Google Scholar
  31. Taylor, CM, Lambin, EF, Stephenne, N, Harding, RJ, Essery, RLH 2002The influence of land use change on climate in the SahelJ Climate1536153629CrossRefGoogle Scholar
  32. Wang, G, Eltahir, EAB, Foley, JA, Pollard, D, Levis, S 2004Decadal variability of rainfall in the Sahel: results from the coupled GENESIS-IBIS atmosphere-biosphere modelClim Dynam22625637Google Scholar
  33. Wang, GL, Eltahir, EAB 2000aRole of vegetation dynamics in enhancing the low-frequency variability of the Sahel rainfallWater Resour Res3610131021CrossRefGoogle Scholar
  34. Wang, GL, Eltahir, EAB 2000bEcosystem dynamics and the Sahel droughtGeophys Res Lett27795798CrossRefGoogle Scholar
  35. Webster, PJ, Magaña, VO, Palmer, TN, Shukla, J, Tomas, RA, Yanai, M, Yasunari, T 1998Monsoons: processes, predictability, and the prospects for predictionJ Geophys Res10314,45115,51097JC02719CrossRefGoogle Scholar
  36. Xue, Y 1997Biosphere feedback on regional climate in tropical North AfricaQuart J Roy Meteor Soc123 B14831515CrossRefGoogle Scholar
  37. Xue, Y, Shukla, J 1993The influence of land surface properties on Sahel climate. Part I: DesertificationJ Climate622322245CrossRefGoogle Scholar
  38. Zheng, XY, Eltahir, EAB 1998The role of vegetation in the dynamics of West African monsoonsJ Climate1120782096Google Scholar

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • B. J. Abiodun
    • 1
    • 5
  • J. S. Pal
    • 2
    • 3
  • E. A. Afiesimama
    • 4
  • W. J. Gutowski
    • 5
  • A. Adedoyin
    • 6
  1. 1.Department of MeteorologyFederal University of TechnologyAkureNigeria
  2. 2.Earth System Physics GroupInternational Centre for Theoretical PhysicsTriesteItaly
  3. 3.Department of Civil Engineering and Environmental ScienceLoyola Marymount UniversityLos AngelesUSA
  4. 4.WMO Regional Research and Training InstituteLagosNigeria
  5. 5.Department of Geological and Atmospheric SciencesIowa State UniversityIowaUSA
  6. 6.Department of PhysicsUniversity of BotswanaGaboroneBotswana

Personalised recommendations