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International Journal of Geophysics
Volume 2012 (2012), Article ID 972896, 19 pages
http://dx.doi.org/10.1155/2012/972896
Research Article

Multimodel GCM-RCM Ensemble-Based Projections of Temperature and Precipitation over West Africa for the Early 21st Century

1Laboratory for Atmospheric Physics-Simeon Fongang (LPAF), Polytechnic School, Cheikh Anta Diop University, P.O. Box 5085, Dakar-Fann, Dakar, Senegal
2Earth System Physics (ESP) Section, International Centre for Theoretical Physics (ICTP), 34151 Trieste, Italy
3Department of Physics, UFR of Sciences and Technologies, University of Ziguinchor, 523 Ziguinchor, Senegal

Received 14 May 2011; Revised 6 September 2011; Accepted 21 November 2011

Academic Editor: Alessandra Giannini

Copyright © 2012 I. Diallo et al. 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.

Abstract

Reliable climate change scenarios are critical for West Africa, whose economy relies mostly on agriculture and, in this regard, multimodel ensembles are believed to provide the most robust climate change information. Toward this end, we analyze and intercompare the performance of a set of four regional climate models (RCMs) driven by two global climate models (GCMs) (for a total of 4 different GCM-RCM pairs) in simulating present day and future climate over West Africa. The results show that the individual RCM members as well as their ensemble employing the same driving fields exhibit different biases and show mixed results in terms of outperforming the GCM simulation of seasonal temperature and precipitation, indicating a substantial sensitivity of RCMs to regional and local processes. These biases are reduced and GCM simulations improved upon by averaging all four RCM simulations, suggesting that multi-model RCM ensembles based on different driving GCMs help to compensate systematic errors from both the nested and the driving models. This confirms the importance of the multi-model approach for improving robustness of climate change projections. Illustrative examples of such ensemble reveal that the western Sahel undergoes substantial drying in future climate projections mostly due to a decrease in peak monsoon rainfall.