Abstract
Two simulations of five years (2003-2007) were conducted with the Regional Climate models RegCM4, one coupled with Land surface models BATS and the other with CLM4.5 over West Africa, where simulated air temperature and precipitation were analyzed. The purpose of this study is to assess the performance of RegCM4 coupled with the new CLM4.5 Land surface scheme and the standard one named BATS in order to find the best configuration of RegCM4 over West African. This study could improve our understanding of the sensitivity of land surface model in West Africa climate simulation, and provide relevant information to RegCM4 users. The results show fairly realistic restitution of West Africa’s climatology and indicate correlations of 0.60 to 0.82 between the simulated fields (BATS and CLM4.5) for precipitation. The substitution of BATS surface scheme by CLM4.5 in the model configuration, leads mainly to an improvement of precipitation over the Atlantic Ocean, however, the impact is not sufficiently noticeable over the continent. While the CLM4.5 experiment restores the seasonal cycles and spatial distribution, the biases increase for precipitation and temperature. Positive biases already existing with BATS are amplified over some sub-regions. This study concludes that temporal localization (seasonal effect), spatial distribution (grid points) and magnitude of precipitation and temperature (bias) are not simultaneously improved by CLM4.5. The introduction of the new land surface scheme CLM4.5, therefore, leads to a performance of the same order as that of BATS, albeit with a more detailed formulation.
Highlights
The complexity and diversity of the dynamic and physical processes of the West African Monsoon (WAM) make its simulation a challenge for climate models
The purpose of this study is to assess the performance of RegCM4 coupled with the new CLM4.5 Land surface scheme and the standard one named BATS in order to find the best configuration of RegCM4 over West African
In order to improve the simulations of the regional climate model RegCM4 over West Africa, two experiments were carried out from January 2003 to December 2007, with BATS and CLM4.5 land surface schemes
Summary
The complexity and diversity of the dynamic and physical processes of the West African Monsoon (WAM) make its simulation a challenge for climate models. In West Africa, many studies have attempted to improve the simulation of precipitation during the summer season, based on the sensitivity of the models to cumulus convection schemes [9]. The accurate simulation of precipitation is directly related to cumulus convection scheme and its interaction with other physical processes, the choice of land surface scheme can contribute to improving the performance of models in simulating climate over West Africa. The new RegCM version 4 has been improved with substantial development of the software code and physical representations [2] and the introduction of CLM4.5 as a new option for describing land surface processes. The performance of RegCM4 coupled with the new CLM4.5 surface scheme needs to be investigated together with the standard BATS scheme to find the best configuration of RegCM4 for the West African, and provide relevant information to RegCM4 users
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