Original Paper

Theoretical and Applied Climatology

, Volume 98, Issue 3, pp 293-314

High-resolution simulations of West African climate using regional climate model (RegCM3) with different lateral boundary conditions

  • M. B. SyllaAffiliated withLaboratoire de Physique de l’Atmosphere et de l’Ocean—Simeon Fongang, Ecole Superieure Polytechnique, University Cheikh Anta Diop
  • , A. T. GayeAffiliated withLaboratoire de Physique de l’Atmosphere et de l’Ocean—Simeon Fongang, Ecole Superieure Polytechnique, University Cheikh Anta Diop Email author 
  • , J. S. PalAffiliated withDepartment of Civil Engineering and Environmental Science, Seaver College of Science and Engineering, Loyola Marymount University
  • , G. S. JenkinsAffiliated withHoward University Program in Atmospheric Sciences and Department of Physics and Astronomy
  • , X. Q. BiAffiliated withInternational Centre for Theoretical Physics, Earth System Physics Section, Physics of Weather and Climate Group

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Abstract

To downscale climate change scenarios, long-term regional climatologies employing global model forcing are needed for West Africa. As a first step, this work examines present-day integrations (1981–2000) with a regional climate model (RCM) over West Africa nested in both reanalysis data and output from a coupled atmospheric–ocean general circulation model (AOGCM). Precipitation and temperature from both simulations are compared to the Climate Research Unit observations. Their spatial distributions are shown to be realistic. Annual cycles are considerably correlated. Simulations are also evaluated with respect to the driving large-scale fields. RCM offers some improvements compared to the AOGCM driving field. Evaluation of seasonal precipitation biases reveals that RCM dry biases are highest on June–August around mountains. They are associated to cold biases in temperature which, in turn, are connected to wet biases in precipitation outside orographic zones. Biases brought through AOGCM forcing are relatively low. Despite these errors, the simulations produce encouraging results and show the ability of the AOGCM to drive the RCM for future projections.