All Title Author
Keywords Abstract

Impacts of the Sahel-Sahara Interface Reforestation on West African Climate: Intra-Annual Variability and Extreme Temperature Events

DOI: 10.4236/acs.2019.91003, PP. 35-61

Keywords: RegCM4, Reforestation, Heat Waves, Sahel

Full-Text   Cite this paper   Add to My Lib


The impacts of the reforestation of the Sahel-Sahara interface on the seasonal distribution of the surface temperature and thermal extremes are studied in the Sahel (West African region lying between 11°N and 18°N). We performed a simulation with the standard version of the RegCM4 model followed by another one using the altered version of the same model taking into account an incorporated forest. The impacts of the vegetation change are assessed by analyzing the difference between the two runs. The reforestation may influence strongly the frequency of warm days (TG90P) and very warm days (TX90P) by decreasing it over the reforested zone from March to May (MAM) and the entire Sahel during the June-August (JJA) period. These TG90P and TX90P indices decrease may be due to the strengthening of the atmospheric moisture content over the whole Sahel region and the weakening of the sensible heat flux over the reforested zone. The analysis also shows a decrease of the TN90P indice (warm nights) over the Sahel during the wet season (JJA) which could be partly associated with the strengthening of the evapotranspiration over the whole Sahel domain. The analysis of additional thermal indices shows an increase of the tropical nights over the entire Sahel from December to February (DJF) and during the warm season (MAM). The strengthening of the tropical night is partly associated with an increase of the surface net downward shortwave flux over the reforested zone. When considering the heat waves, an increase (a decrease) of these events is recorded over the southern Sahel during JJA and SON periods (over the whole Sahelian region during DJF), respectively. Changes in latent heat flux appear to be largely responsible for these extreme temperatures change. This work shows that the vegetation change may impact positively some regions like the reforested area by reducing the occurrence of thermal extremes; while other Sahel regions (eastern part of the central Sahel) could suffer from it because of the strengthening of thermal extremes.


[1]  John, C., Oreskes, N., Doran, P.T., Anderegg, W.R.L., Verheggen, B., Maibach, E., Carlton, J.S., Lewandowsky, S., Skuce, A.G., Green, S.A., Nuccitelli, D., Jacobs, P., Richardson, M., Winkler, B., Painting, R. and Rice, K. (2016) Consensus on Consensus: A Synthesis of Consensus Estimates on Human-Caused Global Warming. Environmental Research Letters, 11, Article ID: 048002.
[2]  IPCC (2013) Summary for Policymakers. Climate Change, 2013. The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
[3]  Karl, T.R., Knight, R.W., Gallo, K.P., Peterson, T.C., et al. (1993) A New Perspective on Recent Global Warming: Asymmetric Trends of Daily Maximum and Minimum Temperature. Bulletin of the American Meteorological Society, 74, 1007-1023.<1007:ANPORG>2.0.CO;2
[4]  Easterling, D.R., Horton, B., Jones, P.D., Peterson, T.C., Karl, T.R., Parker, D.E., Salinger, M.J., et al. (1997) Maximum and Minimum Temperature Trends for the Globe. Science, 277, 364-367.
[5]  Easterling, D.R., Meehl, G.A., Parmesan, C., Changnon, S.A., Karl, T.R. and Mearns, L.O. (2000) Climate Extremes: Observations, Modeling and Impacts. Science, 289, 2068-2074.
[6]  Coumou, D. and Rahmstorf, S. (2012) A Decade of Weather Extremes. Nature Climate Change, 2, 491-496.
[7]  Rome, S., Caniaux, G., Ringard, J., Dieppois, B. and Diedhiou, A. (2015) Identification de tendances récentes et ruptures d’homogénéité des températures : exemple en Afrique de l’Ouest et sur le Golfe de Guinée. Présenté au 28ème colloque internationnal de l’AIC. Liège, Belgique, 591-596.
[8]  Christensen, J.H., Hewitson, B., Busuioc, A., et al. (2007) Regional Climate Projections: The Physical Science Basis-Contribution of Working Group 1 to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, New York, Climate Change.
[9]  Stocker, T.F., Qin, D., Plattner, G.K., Tignor, M., et al. (2013) Climate Change. The Physical Science Basis. Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change-Abstract for Decision-Makers. WMO, Geneva, Switzerland, 1552 p.
[10]  Diedhiou, A., Bichet, A., Wartenburger, R., Seneviratne, S.I., Rowell, D.P., Sylla, M.B., Diallo, I., Todzo, S., Touré, N.E., Camara, M., et al. (2018) Changes in Climate Extremes over West and Central Africa at 1.5°C and 2°C Global Warming. Environmental Research Letters, 13, Article ID: 065020.
[11]  Fontaine, B., Janicot, S. and Monerie, P.A. (2013) Recent Changes in Air Temperature, Heat Waves Occurrences and Atmospheric Circulation in Northern Africa. Journal of Geophysical Research, 118, 8536-8552.
[12]  Moron, V., Oueslati, B., Pohl, B., Rome, S. and Janicot, S. (2016) Trends of Mean Temperatures and Warm Extremes in Northern Tropical Africa (1961-2014) from Observed and PPCA-Reconstructed Time Series. Journal of Geophysical Research: Atmospheres, 121, 5298-5319.
[13]  Oueslati, B., Pohl, B., Moron, V., Rome, S. and Janicot, S. (2017) Characterisation of Heat Waves in the Sahel and Associated Physical Mechanisms. Journal of Climate, 30, 3095-3115.
[14]  Alo, C.A. and Wang, G. (2010) Role of Vegetation Dynamics in Regional Climate Predictions over Western Africa. Climate Dynamics, 35, 907-922.
[15]  Abiodun, B.J., Pal, J.S., Afiesimama, E.A., Gutowski, W.J. and Adedoyin, A. (2008) Simulation of West African Monsoon Using RegCM3 Part II: Impacts of Deforestation and Desertification. Theoretical and Applied Climatology, 93, 245-261.
[16]  Abiodun, B.J., Adeyewa, Z.D., Oguntunde, P.G., Salami, A.T. and Ajayi, V.O. (2012) Modeling the Impacts of Reforestation on Future Climate in West Africa. Theoretical and Applied Climatology, 110, 77-96.
[17]  Sylla, M.B., Pal, J.S., Wang, G.L. and Lawrence, P.J. (2015) Impact of Land Cover Characterization on Regional Climate Modeling over West Africa. Climate Dynamics, 46, 637-650.
[18]  Diba, I., Camara, M. and Sarr, A.B. (2016) Impacts of the Sahel-Sahara Interface Reforestation on West African Climate: Intra-Seasonal Variability and Extreme Precipitation Events. Advances in Meteorology, 2016, Article ID: 3262451.
[19]  Naik, M. and Abiodun, B.J. (2016) Potential Impact of Forestation on the Future Climate Change on Southern Africa. International Journal of Climatology, 36, 4560-4576.
[20]  Odoulami, R.C., Abiodun, B.J., Ajayi, A.E., Diasso, U.J. and Saley, M.M. (2017) Potential Impacts of Forestation on Heat Waves over West Africa in the Future. Ecological Engineering, 102, 546-556.
[21]  Balling, R.C. (1988) The Climatic Impacts of a Sonoran Vegetation Discontinuity. Climatic Change, 13, 99-109.
[22]  Campra, P., Garcia, M., Canton, Y. and Palacios-Orueta, P.-O.A. (2008) Surface Temperature Cooling Trends and Negative Radiative forcing Due to Land Use Change toward Greenhouse Farming in Southeastern Spain. Journal of Geophysical Research, 113, D18109.
[23]  Lee, E., Chase, T.N., Rajagopalan, B., Barry, R.G., Biggs, T.W. and Lawrence, P.J. (2009) Effects of Irrigation and Vegetation Activity on Early Indian Summer Monsoon Variability. International Journal of Climatology, 29, 573-581.
[24]  Feddema, J.J., Oleson, K.W., Bonan, G.B., Mearns, L.O., Buja, L.E., Meehl, G.A. and Washington, W.M. (2005) The Importance of Land-Cover Change in Simulating Future Climates. Science, 310, 1674-1678.
[25]  Lawrence, P.J., Feddema, J.J., Bonan, G.B., Meehl, G.A., O’Neill, B.C., Oleson, K.W., Levis, S., Lawrence, D.M., Kluzek, E., Lindsay, K. and Thornton, P.E. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100. Journal of Climate, 25, 3071-3095.
[26]  Mahmood, R., Pielke Sr., R.A., Hubbard, K.G., DevNiyogi, P.A., Dirmeyer, C.M., Andrew, M., et al. (2014) Land Cover Changes and Their Biogeophysical Effects on Climate. International Journal of Climatology, 34, 929-953.
[27]  Xue, Y., Juang, H.M.H., Li, W., Prince, S., DeFries, R., Jiao, Y. and Vasic, R. (2004) Role of Land Surface Processes in Monsoon Development: East Asia and West Africa. Journal of Geophysical Research, 109, D03105.
[28]  Zheng, X. and Eltahir, E.A.B. (1998) The Role of Vegetation in the Dynamics of West African Monsoon. Journal of Climate, 11, 2078-2096.
[29]  Abiodun, B.J., Pal, J., Afiesimama, E.A., Gutowski, W.J. and Adedoyin, A. (2010) Modeling the Impacts of Deforestation on Monsoon Rainfall in West Africa. IOP Conference Series and Environmental Science, 13, Article ID: 012008.
[30]  Giorgi, F., Coppola, E., Solmon, F., Mariotti, L., Sylla, M.B., Bi, X., et al. (2012) RegCM4: Model Description and Preliminary Tests over Multiple CORDEX Domains. Climate Research, 52, 7-29.
[31]  Grell, G.A., Dudhia, J. and Stauffer, D.R. (1994) Description of the Fifth Generation Penn State/NCAR Mesoscale Model (MM5). Technical Note NCAR/TN-398 + STR, NCAR, Boulder.
[32]  Kiehl, J.T., Hack, J.J., Bonan, G.B., Boville, B.A., Briegleb, B.P., Williamson, D.L. and Rasch, P.J. (1996) Description of the NCAR Community Climate Model (CCM3). NCAR Tech. Note 4201STR, 152.
[33]  Giorgi, F., Mearns, L.O., Shields, C. and McDaniel, L. (1998) Regional Nested Model Simulations of Present Day and 2 × CO2 Climate over the Central Plains of the US. Climatic Change, 40, 457-493.
[34]  Dickinson, R.E., Henderson, S.A. and Kennedy, P.J. (1993) Biosphere-Atmosphere Transfer Scheme (BATS) Version 1E as Coupled to the NCAR Community Climate Model. NCAR Tech. rep. TN-387+STR, 72 p.
[35]  Zeng, X., Zhao, M. and Dickinson, R.E. (1998) Intercomparison of Bulk Aerodynamic Algorithms for the Computation of Sea Surface Fluxes Using TOGA COARE and TAO Data. Journal of Climate, 11, 2628-2644.<2628:IOBAAF>2.0.CO;2
[36]  Pal, J.S., Small, E.E. and Eltahir, E.A.B. (2000) Simulation of Regional Scale Water and Energy Budgets: Representation of Subgrid Cloud and Precipitation Processes within RegCM. Journal of Geophysical Research, 105, 29579-29594.
[37]  Sylla, M.B., Dell’Aquila, A., Ruti, P.M. and Giorgi, F. (2010) Simulation of the Intraseasonal and the Interannual Variability of Rainfall over West Africa with a RegCM3 during the Monsoon Period. International Journal of Climatology, 30, 1865-1883.
[38]  Mariotti, L., Coppola, E., Sylla, M.B., Giorgi, F. and Piani, C. (2011) Regional Climate Model Simulation of Projected 21st Century Climate Change over an All Africa Domain: Comparison Analysis of Nested and Driving Model Results. Journal of Geophysical Research, 116, D15111.
[39]  Camara, M., Diedhiou, A., Sow, B.A., Diallo, M.D., Diatta, S., Mbaye, I. and Diallo, I. (2013) Analyse de la pluie simulée par les modèles climatiques régionaux de CORDEX en Afrique del’Ouest. Sécheresse, 24, 14-28.
[40]  Holtslag, A.A.M., et al. (1990) A High Resolution Air Mass Transformation Model for Short-Range Weather Forecasting. Monthly Weather Review, 118, 1561-1575.<1561:AHRAMT>2.0.CO;2
[41]  Grell, G.A. (1993) Prognostic Evaluation of Assumptions Used by Cumulus Parameterizations. Monthly Weather Review, 121, 764-787.<0764:PEOAUB>2.0.CO;2
[42]  Fritsch, J.M. and Chappell, C.F. (1980) Numerical Prediction of Convectively Driven Mesoscale Pressure Systems. Part I: Convective Parameterization. Journal of the Atmospheric Sciences, 37, 1722-1733.<1722:NPOCDM>2.0.CO;2
[43]  Emanuel, K.A. (1991) A Scheme for Representing Cumulus Convection in Large-Scale Models. Journal of the Atmospheric Sciences, 48, 2313-2335.
[44]  Simmons, A.S., Uppala, D. and Kobayashi, S. (2007) ERA-Interim: New ECMWF Reanalysis Products from 1989 Onwards. ECMWF Newsletter, 110, 29-35.
[45]  Uppala, S., Dee, D., Kobayashi, S., Berrisford, P. and Simmons, A. (2008) Towards a Climate Data Assimilation System: Status Update of ERA-Interim. ECMWF Newsletter, 115, 12-18.
[46]  Jones, P.D. (2014) Climatic Research Unit (CRU) Time-Series (TS) Version 3.22 of High Resolution Gridded Data of Month-by-Month Variation in Climate (Jan. 1901-Dec. 2013) University of East Anglia. NCAS British Atmospheric Data Centre.
[47]  Kothe, S. and Ahrens, B. (2010) On the Radiation Budget in Regional Climate Simulations for West Africa. Journal of Geophysical Research, 115, D23120.
[48]  Oettli, P., Sultan, B., Baron, C. and Vrac, M. (2011) Are Regional Climate Models Relevant for Crop Yield Prediction in West Africa? Environmental Research Letter, 6, Article ID: 014008.
[49]  Paeth, H., Hall, N.M., Gaertner, M.A., et al. (2011) Progress in Regional Downscaling of West African Precipitation. Atmospheric Science Letters, 12, 75-82.
[50]  Diallo, I., Sylla, M.B., Camara, M. and Gaye, A.T. (2013) Interannual Variability of Rainfall over the Sahel Based on Multiple Regional Climate Models Simulations. Theoretical and Applied Climatology, 113, 351-362.
[51]  Dee, D.P., Uppala, S.M., Simmons, A.J., et al. (2011) The ERA-Interim Reanalysis: Configuration and Performance of the Data Assimilation System. Quarterly Journal of the Royal Meteorology Society, 137, 553-597.
[52]  Diallo, I., Bain, C.L., Gaye, A.T., Moufouma-Okia, W., Niang, C., Dieng, M.D.B. and Graham, R. (2014) Simulation of the West African Monsoon Onset Using the HadGEM3-RA Regional Climate Model. Climate Dynamics, 43, 575-594.
[53]  Peterson, T.C., Folland, C., Gruza, G., Hogg, W., et al. (2001) Report on the Activities of the Working Group on Climate Change Detection and Related Rapporteurs 1998-2001. WMO Rep. WCDMP 47, WMO-TD 1071, Geneva.
[54]  Hagos, S.M. and Cook, K.H. (2007) Dynamics of the West African Monsoon Jump. Journal of Climate, 20, 52-64.
[55]  Thorncroft, C.D., Nguyen, H., Zhang, C. and Peyrillé, P. (2011) Annual Cycle of the West African Monsoon: Regional Circulations and Associated Water Vapour Transport. Quarterly Journal of the Royal Meteorology Society, 137, 129-147.
[56]  Mohr, K.I. and Thorncroft, C.D. (2006) Intense Convective Systems in West Africa and Their Relationship to the African Easterly Jet. Quarterly Journal of the Royal Meteorological Society, 132, 163-176.
[57]  Steiner, A.L., Pal, J.S., Rauscher, S.A., Bell, J.L., Diffenbaugh, N.S., Boone, A., Sloan, L.C. and Giorgi, F. (2009) Land Surface Coupling in Regional Climate Simulations of the West African Monsoon. Climate Dynamics, 33, 869-892.
[58]  Sylla, M.B., Giorgi, F. and Stordal, F. (2012) Origins of Rainfall and Temperature Bias in High Resolution Simulations over Southern Africa. Climate Research, 52, 193-211.
[59]  Konaré, A., Zakey, A.S., Solmon, F., Giorgi, F., Rauscher, S., Ibrah, S. and Bi, X. (2008) A Regional Climate Modeling Study of the Effect of Desert Dust on the West African Monsoon. Journal of Geophysical Research, 113, D12206.
[60]  Rome, S., Oueslati, B., Moron, V., Pohl, B. and Diedhiou, A. (2016) Les vagues de chaleur au Sahel: Définition et principales caractéristiques spatio-temporelles (1973-2014). Actes du IXXXème colloque de l’Association Internationale de Climatologie, Besançon, 6-9 juillet 2016, 345-350.


comments powered by Disqus