Climate Dynamics

, Volume 42, Issue 9–10, pp 2521–2538 | Cite as

Impacts of bias correction of lateral boundary conditions on regional climate projections in West Africa

  • Miao Yu
  • Guiling WangEmail author


Biases existing in the lateral boundary conditions (LBCs) influence climate simulations in regional climate models (RCMs). Correcting the biases in global climate model (GCM)-produced LBCs before running RCMs was proposed in previous studies as a possible way to reduce the GCM-related model dependence of future climate projections using RCMs. In this study the ICTP Regional Climate Model Version 4 (RegCM4) is used to investigate the impact of LBC bias correction on projected future changes of regional climate in West Africa. To accomplish this, two types of present versus future simulations are conducted using RegCM4: a control type where both the present and future LBCs are derived directly from the GCM output (as is done in most regional climate downscaling studies); an experiment type where the present-day LBCs are from reanalysis data and future LBCs are derived by combining the reanalysis data and the GCM-projected LBC changes. For each type of simulations, three different sets of LBCs are experimented on: 6-hourly synoptic forcing directly from the reanalysis or GCM, 6-hourly data interpolated from monthly climatology (without diurnal cycle), and 6-hourly data interpolated from the month-specific climatology of diurnal cycles. It is found that the simulations using different LBCs produce similar present-day summer rainfall patterns, but the predicted future changes differ significantly depending on how the LBC bias correction is treated. Specifically, both the bias correction applied at the synoptic scale and the bias correction applied to the monthly interpolated LBCs without diurnal cycle produce a spurious drying signal caused by physical inconsistency in the corrected future LBCs. Interpolated monthly LBCs with diurnal cycle alleviate the problem to a large extent. These results suggest that using bias-corrected LBCs to drive regional climate models may not guarantee reliable future projections although reasonable present climate can be simulated. Physical inconsistencies may be contained in the bias-corrected LBCs, increasing the uncertainties of RCM-produced future projections.


Bias correction Regional climate prediction Downscaling West Africa 



We thank ECMWF for providing the Interim reanalysis data and NOAA for providing the OISST and NCEP reanalysis data. We thank University of Delaware for the observed precipitation and near-surface air temperature. We also thank Systems Laboratory (CISL) at the National Center for Atmospheric Research (NCAR) providing the CESM output and PCMDI for providing the GFDL-ESM2M output. Funding support for this research is provided by the NSF Climate and Large-Scale Dynamics Program (AGS 1049017 & AGS 1063986). Computing resources were provided by the University of Connecticut BECAT.


  1. Afiesimama EA, Pal JS, Abiodun BJ, Gutowski WJ, Adedoyin A (2006) Simulation of west african monsoon using the RegCM3. Part I: Model validation and interannual variability. Theor Appl Climatol 86(1):23–37. doi: 10.1007/s00704-005-0202-8 Google Scholar
  2. Alo C, Wang G (2010) Role of dynamic vegetation in regional climate predictions over western Africa. Clim Dyn 35(5):907–922. doi: 10.1007/s00382-010-0744-z CrossRefGoogle Scholar
  3. Biasutti M, Held IM, Sobel AH, Giannini A (2008) SST forcings and Sahel rainfall variability in simulations of the twentieth and twenty-first centuries. J Clim 21(14):3471–3486. doi: 10.1175/2007jcli1896.1 CrossRefGoogle Scholar
  4. Christensen JH, Hewitson B, Busuioc A et al (2007) Regional climate projections. In: Solomon S et al (eds) Climate change 2007: the physical science basis. Contribution of working group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, CambridgeGoogle Scholar
  5. Cook KH, Vizy EK (2006) Coupled model simulations of the West African monsoon system: twentieth- and twenty-first-century simulations. J Clim 19(15):3681–3703. doi: 10.1175/jcli3814.1 CrossRefGoogle Scholar
  6. Dee DP, Uppala SM, Simmons AJ et al (2011) The ERA-interim reanalysis: configuration and performance of the data assimilation system. Q J R Meteorol Soc 137(656):553–597. doi: 10.1002/qj.828 CrossRefGoogle Scholar
  7. Déqué M, Rowell D, Lüthi D et al (2007) An intercomparison of regional climate simulations for Europe: assessing uncertainties in model projections. Clim Change 81:53–70CrossRefGoogle Scholar
  8. Dickinson RE, Henderson-Sellers A, Kenedy PJ (1993) Biosphere-atmosphere transfer scheme (BATS) version 1e as coupled to the NCAR community climate model. NCAR/TN-387 + STR, 72 pGoogle Scholar
  9. Druyan LM (2011) Studies of 21st-century precipitation trends over West Africa. Int J Climatol 31(10):1415–1424. doi: 10.1002/joc.2180 CrossRefGoogle Scholar
  10. Druyan L, Feng J, Cook K et al (2010) The WAMME regional model intercomparison study. Clim Dyn 35(1):175–192. doi: 10.1007/s00382-009-0676-7 CrossRefGoogle Scholar
  11. Emanuel KA (1991) A scheme for representing cumulus convection in large-scale models. J Atmos Sci 48(21):2313–2329CrossRefGoogle Scholar
  12. Giorgi F, Jones C, Asrar GR (2009) Addressing climate information needs at the regional level: the CORDEX framework. WMO Bull 58(3):175Google Scholar
  13. Giorgi F, Coppola E, Solmon F et al (2012) RegCM4: model description and preliminary tests over multiple CORDEX domains. Clim Res 52:7–29. doi: 10.3354/cr01018 CrossRefGoogle Scholar
  14. Grell GA, Dudhia J, Stauffer DR (1994) Description of the fifth generation Penn State/NCAR mesoscale model (MM5), 121 ppGoogle Scholar
  15. Gu G, Adler RF (2004) Seasonal evolution and variability associated with the West African monsoon system. J Clim 17(17):3364–3377CrossRefGoogle Scholar
  16. Haarsma RJ, Selten FM, Weber SL, Kliphuis M (2005) Sahel rainfall variability and response to greenhouse warming. Geophys Res Lett 32(17):L17702. doi: 10.1029/2005gl023232 CrossRefGoogle Scholar
  17. Hagos SM, Cook KH (2007) Dynamics of the West African monsoon jump. J Clim 20(21):5264–5284CrossRefGoogle Scholar
  18. Held IM, Delworth TL, Lu J, Findell KL, Knutson TR (2005) Simulation of Sahel drought in the 20th and 21st centuries. PNAS 102(50):17891–17896. doi: 10.1073/pnas.0509057102 CrossRefGoogle Scholar
  19. Hoerling M, Hurrell J, Eischeid J, Phillips A (2006) Detection and attribution of twentieth-century northern and southern African rainfall change. J Clim 19(16):3989–4008. doi: 10.1175/jcli3842.1 CrossRefGoogle Scholar
  20. Huffman GJ, Adler RF, Morrissey MM et al (2001) Global precipitation at one-degree daily resolution from multisatellite observations. J Hydrometeorol 2(1):36–50. doi: 10.1175/1525-7541(2001)002<0036:gpaodd>;2 CrossRefGoogle Scholar
  21. Hulme M, Doherty R, Ngara T, New M, Lister D (2001) African climate change: 1900–2100. Clim Res 17(2):145–168CrossRefGoogle Scholar
  22. IPCC (2007) Climate change 2007: the physical science basis. Contribution of working group I to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
  23. Johns T, Gregory J, Ingram W et al (2003) Anthropogenic climate change for 1860 to 2100 simulated with the HadCM3 model under updated emissions scenarios. Clim Dyn 20(6):583–612Google Scholar
  24. Jung G, Kunstmann H (2007) High-resolution regional climate modeling for the Volta region of West Africa. J Geophys Res 112(D23):D23108CrossRefGoogle Scholar
  25. Kamga AF, Jenkins GS, Gaye AT, Garba A, Sarr A, Adedoyin A (2005) Evaluating the National Center for Atmospheric Research climate system model over West Africa: present-day and the 21st century A1 scenario. J Geophys Res 110(D3):D03106Google Scholar
  26. Koster RD, Dirmeyer PA, Guo Z et al (2004) Regions of strong coupling between soil moisture and precipitation. Science 305(5687):1138–1140CrossRefGoogle Scholar
  27. Le Barbé L, Lebel T, Tapsoba D (2002) Rainfall variability in West Africa during the years 1950–90. J Clim 15(2):187–202CrossRefGoogle Scholar
  28. Lebel T, Ali A (2009) Recent trends in the Central and Western Sahel rainfall regime (1990–2007). J Hydrol 375(1–2):52–64CrossRefGoogle Scholar
  29. Legates DR, Willmott CJ (1990a) Mean seasonal and spatial variability in gauge - corrected, global precipitation. Int J Climatol 10(2):111–127CrossRefGoogle Scholar
  30. Legates DR, Willmott CJ (1990b) Mean seasonal and spatial variability in global surface air temperature. Theoret Appl Climatol 41(1):11–21CrossRefGoogle Scholar
  31. Lenton TM, Held H, Kriegler E, Hall JW, Lucht W, Rahmstorf S, Schellnhuber HJ (2008) Tipping elements in the Earth’s climate system. PNAS 105(6):1786CrossRefGoogle Scholar
  32. Liang X-Z, Kunkel KE, Meehl GA, Jones RG, Wang JXL (2008) Regional climate models downscaling analysis of general circulation models present climate biases propagation into future change projections. Geophys Res Lett 35(8):L08709. doi: 10.1029/2007gl032849 CrossRefGoogle Scholar
  33. Lobell DB, Burke MB, Tebaldi C, Mastrandrea MD, Falcon WP, Naylor RL (2008) Prioritizing climate change adaptation needs for food security in 2030. Science 319(5863):607–610. doi: 10.1126/science.1152339 CrossRefGoogle Scholar
  34. Mariotti L, Coppola E, Sylla MB, Giorgi F, 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. J Geophys Res 116(D15):D15111CrossRefGoogle Scholar
  35. Maynard KM, Royer JFR, Chauvin FC (2002) Impact of greenhouse warming on the West African summer monsoon. Clim Dyn 19(5):499–514. doi: 10.1007/s00382-002-0242-z Google Scholar
  36. Mitchell TD, Jones PD (2005) An improved method of constructing a database of monthly climate observations and associated high-resolution grids. Int J Climatol 25(6):693–712CrossRefGoogle Scholar
  37. Moss RH, Babiker M, Brinkman S et al (2008) Towards new scenarios for analysis of emissions, climate change, impacts, and response strategies. Intergovernmental Panel on Climate Change, Geneva, p 132Google Scholar
  38. Moufouma-Okia W, Rowell D (2010) Impact of soil moisture initialisation and lateral boundary conditions on regional climate model simulations of the West African Monsoon. Clim Dyn 35(1):213–229. doi: 10.1007/s00382-009-0638-0 CrossRefGoogle Scholar
  39. Nicholson SE, Some B, Kone B (2000) An analysis of recent rainfall conditions in West Africa, including the rainy seasons of the 1997 El Niño and the 1998 La Niña years. J Clim 13(14):2628–2640CrossRefGoogle Scholar
  40. Nikulin G, Jones C, Samuelsson P et al (2012) Precipitation climatology in an ensemble of CORDEX-Africa regional climate simulations. J Clim 25:6057–6078CrossRefGoogle Scholar
  41. Oleson KW, Niu GY, Yang ZL et al (2008) Improvements to the Community Land Model and their impact on the hydrological cycle. J Geophys Res 113(G1):G01021. doi: 10.1029/2007jg000563 Google Scholar
  42. Paeth H, Born K, Girmes R, Podzun R, Jacob D (2009) Regional climate change in tropical and northern Africa due to greenhouse forcing and land use changes. J Clim 22(1):114–132CrossRefGoogle Scholar
  43. Paeth H, Hall NMJ, Gaertner MA et al (2011) Progress in regional downscaling of West African precipitation. Atmos Sci Lett 12(1):75–82CrossRefGoogle Scholar
  44. Pal JS, Giorgi F, Bi X et al (2007) Regional climate modeling for the developing world: the ICTP RegCM3 and RegCNET. Bull Am Meteorol Soc 88(9):1395–1409. doi: 10.1175/bams-88-9-1395 CrossRefGoogle Scholar
  45. Patricola C, Cook K (2010) Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models. Clim Dyn 35(1):193–212. doi: 10.1007/s00382-009-0623-7 CrossRefGoogle Scholar
  46. Redelsperger JL, Thorncroft C, Diedhiou A, Lebel T, Parker D, Polcher J (2006) African Monsoon Multidisciplinary Analysis (AMMA): an international research project and field campaign. Bull Am Meteorol Soc 87(12):1739–1746CrossRefGoogle Scholar
  47. Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Clim 15(13):1609–1625CrossRefGoogle Scholar
  48. Steiner A, Pal J, Rauscher S et al (2009) Land surface coupling in regional climate simulations of the West African monsoon. Clim Dyn 33(6):869–892. doi: 10.1007/s00382-009-0543-6 CrossRefGoogle Scholar
  49. Sultan B, Janicot S (2003) The West African monsoon dynamics. Part II: the “preonset” and “onset” of the summer monsoon. J Clim 16(21):3407–3427CrossRefGoogle Scholar
  50. Sultan B, Janicot S, Diedhiou A (2003) The West African monsoon dynamics. Part I: documentation of intraseasonal variability. J Clim 16(21):3389–3406CrossRefGoogle Scholar
  51. Sultan B, Baron C, Dingkuhn M, Sarr B, Janicot S (2005) Agricultural impacts of large-scale variability of the West African monsoon. Agric For Meteorol 128(1–2):93–110. doi: 10.1016/j.agrformet.2004.08.005 CrossRefGoogle Scholar
  52. Sylla MB, Dell’Aquila A, Ruti PM, Giorgi F (2010) Simulation of the intraseasonal and the interannual variability of rainfall over West Africa with RegCM3 during the monsoon period. Int J Climatol 30(12):1865–1883. doi: 10.1002/joc.2029 Google Scholar
  53. van der Linden P, Mitchell JFB (eds) (2009) ENSEMBLES: climate change and its impacts: summary of research and results from the ENSEMBLES project. Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3 PB, UKGoogle Scholar
  54. Vigaud N, Roucou P, Fontaine B, Sijikumar S, Tyteca S (2011) WRF/ARPEGE-CLIMAT simulated climate trends over West Africa. Clim Dyn 36(5):925–944CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Department of Civil and Environmental Engineering and Center for Environmental Sciences and EngineeringUniversity of ConnecticutStorrsUSA

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