Process-oriented assessment of RCA4 regional climate model projections over the Congo Basin under 1.5. C and 2. C global warming levels: influence of regional moisture fluxes
WESTERN EQUATORIAL AFRICA
; EARTH SYSTEM MODEL
; CORDEX-AFRICA
; RAINFALL VARIABILITY
; CONVECTIVE PARAMETERIZATION
; ATMOSPHERIC CIRCULATION
; PART 1
; PRECIPITATION
; SIMULATIONS
; CMIP5
WOS学科分类:
Meteorology & Atmospheric Sciences
WOS研究方向:
Meteorology & Atmospheric Sciences
英文摘要:
Understanding the processes responsible for precipitation and its future change is important to develop plausible and sustainable climate change adaptation strategies, especially in regions with few available observed data like Congo Basin ( CB). This paper investigates the atmospheric circulation processes associated with climate model biases in CB rainfall, and explores drivers of projected rainfall changes. Here we use an ensemble of simulations from the Swedish Regional Climate Model ( RCM) RCA4, driven by eight General Circulation Models ( GCMs) from the Coupled Model Intercomparison Project Phase 5 ( CMIP5), for the 1.5. C and 2. C global warming levels ( GWLs), and under the representative concentration pathways ( RCPs) 4.5 and 8.5. RCA4 captures reasonably well the observed patterns of CB rainfall seasonality, but shows dry biases independent of seasons and large scale driving atmospheric conditions. While simulations mimic observed peaks in transition seasons ( March- May and September- November), the rain- belt is misplaced southward ( northward) in December- February ( June- August), reducing the latitudinal extent of rainfall. Moreover, ERA- Interim reanalysis driven RCM simulation and RCM- GCM combinations show similar results, indicating the dominance of systematic biases. Modelled dry biases are associated with dry upper- tropospheric layers, resulting from a western outflow stronger than the eastern inflow and related to the northern component of African Easterly Jet. From the analysis of the climate change signal, we found that regional scale responses to anthropogenic forcings vary across GWLs and seasons. Changes of rainfall and moisture divergence are correlated, with values higher in March- May than in September- November, and larger for global warming of 2.0. C than at 1.5. C. There is an increase of zonal moisture divergence fluxes in upper atmospheric layers ( > 700 hPa) under RCP8.5 compared to RCP4.5. Moreover, it is found that additional warming of 0.5. C will change the hydrological cycle and water availability in the CB, with potential to cause challenges to water resource management, agriculture, hydro- power generation, sanitation and ecosystems.
1.Univ Yaounde I, Dept Phys, LEMAP, POB 812, Yaounde, Cameroon 2.Univ Yaounde I, IRGM, 2LMI DYCOFAC, IRD, BP1857, Yaounde, Cameroon 3.Univ Paris Saclay, Intergovt Panel Climate Change IPCC Working Grp 1, TSU, St Aubin, France 4.European Commiss, JRC, Ispra, Italy 5.Univ Oxford, Environm Change Inst, Oxford, England 6.Univ Yaounde I, Higher Teacher Training Coll, Dept Phys, POB 47, Yaounde, Cameroon 7.Natl Inst Cartog, CCRL, POB 157, Yaounde, Cameroon 8.Univ Dschang, Fac Sci, Dept Phys, Lab Mech & Modeling Phys Syst, POB 67, Dschang, Cameroon 9.NOAA, Climate Predict Ctr, Natl Ctr Environm Predict, College Pk, MD USA 10.Univ Corp Atmospheric Res, Cooperat Programs Adv Earth Syst Sci, Boulder, CO USA 11.Swedish Meteorol & Hydrol Inst, Rossby Ctr, Norrkoping, Sweden 12.Univ Cape Town, Nansen Tutu Ctr Environm Marine Res, Dept Oceanog, Cape Town, South Africa 13.Univ Cape Town, Dept Environm & Geog Sci, Cape Town, South Africa 14.Univ Douala, Fac Sci, CEPAMOQ, Douala, Cameroon 15.Helmholtz Zentrum Geesthacht, Climate Serv Ctr Germany, Hamburg, Germany 16.Univ Yaounde I, Dept Phys, Lab Geophys & Geoexplorat, POB 812, Yaounde, Cameroon
Recommended Citation:
Tamoffo, Alain T.,Moufouma-Okia, Wilfran,Dosio, Alessandro,et al. Process-oriented assessment of RCA4 regional climate model projections over the Congo Basin under 1.5. C and 2. C global warming levels: influence of regional moisture fluxes[J]. CLIMATE DYNAMICS,2019-01-01,53(3-4):1911-1935