Abstract
In this paper, we use simulations from the Swedish Meteorological and Hydrological Institute (SMHI) regional climate model (RCM) version 3.5 (SMHI-RCA3.5) following a multi-GCM boundary forcing approach. The model is run at a horizontal resolution of 50 km on the CORDEX-AFRICA domain. Key characteristics of precipitation, mean temperature and its extremes (minimum and maximum temperature) have been investigated over West Africa and on 3 designed sub-domains, the Sahel (SAH), the Senegal-Gambia (SEN) and the Gulf of Guinea (GOG). The analysis covers a historical period 1981-2005 and two future time slices, an intermediate term (IT) 2031-2055 and a fat term (FT) 2071-2095, under the Representative Concentration Pathways 8.5 (RCP8.5). The regional climate model RCA, forced by the reanalysis ERA-Interim, 6 CMIP5 GCMs and their ensemble, reproduces realistically the climatology of precipitation and temperatures over West Africa. Compared to observed datasets GPCP for precipitation and CRU for temperature, the ensemble outperforms both other GCMs and the verification model (ERA-Interim). The major biases in precipitation are the early onset over the Sahel and the little dry season (LDS), from mid-July to mid-September over the Gulf of Guinea, and a few models either overestimate and/or reflect rather poorly. The strong warming in extreme temperatures (minimum and maximum) combined with the drying mainly over Western Sahel (SEN) found in this study will very likely impact notably a vital sector like agriculture, both during the near and far terms.
Highlights
The two last Inter Governmental Panel on Climate Change (IPCC) reports, AR4 [1] and AR5 [2] have demonstrated the fact that global warming, due to human activities, is a reality
The Swedish Meteorological and Hydrological Institute (SMHI), regional climate model (RCM) RCA version 3.5 (Samuelsson et al, 2011), in the framework of the Coordinated Downscaling Experiment for Africa (CORDEX-AFRICA), is run at 50 km horizontal resolution over a wide area covering the whole of the African continent with initial and lateral boundary conditions from six Climate Models Intercomparison Project version 5 (CMIP5) Global Circulation Models (GCMs) and a verification simulation driven by ERA-Interim
ERA, with higher spatial resolution compared to Global Precipitation Climatology Project (GPCP) even though regridded at 0.5 ̊, shows more detailed patterns and even exhibits a bell shape over the Sahel region following the well-known structure of the Inter Tropical Convergence Zone (ITCZ) [26]
Summary
The two last Inter Governmental Panel on Climate Change (IPCC) reports, AR4 [1] and AR5 [2] have demonstrated the fact that global warming, due to human activities, is a reality This changing climate will continue to affect the whole world, and more severely, highly vulnerable regions like Africa. A lot of efforts are underway to reduce the climate change impacts, to help countries and communities resilient to the adverse effects of climate change and related extremes. This is important in a region like West Africa, especially its northern part, known as Sahel. Key sectors of the economy, like agriculture including pastoralism and water resources were most affected
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