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Objectives

Objectives. RCA4 (GCMs). Driving GCMs. Only RCP45 for HadGEM2-ES. Projection. to evaluate ability of an ensemble of regional simulations to simulate WAM precipitation (RCA4 driven by different GCMs: CanESM2, CNRM-CM5, NorESM1-M, EC-EARTH, MIROC5 and HadGEM2-ES)

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Objectives

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  1. Objectives RCA4 (GCMs) Driving GCMs Only RCP45 for HadGEM2-ES Projection • to evaluate ability of an ensemble of regional simulations to simulate WAM precipitation (RCA4 driven by different GCMs: CanESM2, CNRM-CM5, NorESM1-M, EC-EARTH, MIROC5 and HadGEM2-ES) • to analyze possible future changes in the WAM precipitation under the RCP45 and RCP85 scenarios for both driving and downscaled GCMs 2 Evaluation 1 RCA4 (GCMs) Driving GCMs Projected changes in the West African Monsoon from an ensemble of Africa-CORDEX simulationsGrigoryNikulin, Colin Jones and Erik KejllströmRossbyCentre, Swedish Meteorological and HydrologicalInstitute (SMHI), grigory.nikulin@smhi.se • the ensemble mean projected changes in temperature are similar between the RCA4 and GCM ensembles • RCA4 ensemble shows smaller spread in the projected precipitation changes (an increase) than the GCM ensemble GPCC6 mean JAS precipitation and differences compared to GPCC GPCP22 mean JAS precipitation and differences compared to GPCP • RCA4 changes precipitation climate of driving LBCs to its own one with a positive bias over central Africa • in most cases RCA4 corrects large biases in driving GCMs over West Africa (see MIROC5 and HadGEM2-ES) • the RCA4 ensemble average show substantial smaller biases over West Africa compared to the GCM ensemble average but al larger dry bias over central Africa RCA4 (GCMs) ENSEMBLE MEAN Driving GCMs RCA4 (GCMs) Driving GCMs JAS precipitation averaged over West Africa • a common tendency to a northward shift of the ITCZ precipitation band for both the RCA4 and driving GCM ensemble and subsequently to an increase in the WAM precipitation • local details differ: a decrease in the GCM ensemble mean precipitation over Senegal is not seen in the RCA4 ensemble mean • the GCM ensemble mean is influenced by the large positive bias in MIROC5 Summary • RCA4 corrects large precipitation biases in driving GCMs over West Africa and substantially reduces spread of individual GCM simulations around observations, although shows a permanent dry bias in central Africa • both RCA4 and GCM ensembles project an increase in precipitation over West Africa (rcp45 and rcp85) • the RCA4 ensemble shows more consistent increase in precipitation than the GCM ensemble • RCA4 corrects large precipitation biases in driving GCMs over West Africa (see MIROC5 and HadGEM2-ES) • most of the downscaled GCMs have more accurate precipitation averaged over West Africa then GCMs themselves • RCA4 substantially reduces spread in the simulated precipitation across the driving GCMs over West Africa • the RCA4 ensemble average outperforms nearly all the individual simulations and the GCM ensemble average

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