0000000001180834
AUTHOR
P. Roucou
How could hydro-climatic conditions evolve in the long term in West Africa? The case study of the Bani River catchment
International audience; This paper assesses the future variability of water resources in the long term over a large Sudano- Sahelian catchment in West Africa. Flow simulations were performed with a daily conceptual model. The climate models HadCM3 and MPI-M (based on SRES-A2) were used to provide future climate scenarios over the catchment. Outputs from these models were used to generate daily rainfall and temperature series for the 21st century according to: (i) application of the unbias and delta methods, and (ii) spatial and temporal downscaling. A temperature-based formula was used to calculate present and future potential evapotranspiration (PE). The daily rainfall and PE series were i…
Assessment of water budgets from NWP model analyses and reanalyses over West Africa
International audience; Water budgets from ECMWF reanalysis ERA-Interim and NCEP reanalysis I and II are inter-compared and compared to GPS precipitable water and to a 6-yr so-called "hybrid" budget dataset composed of ALMIP (AMMA Land surface Model Intercomparison Project) offline simulations forced with TRMM precipitation data. Deficiencies are evidenced in the reanalyses which are the most pronounced over the Sahel. Results from operational models (ECMWF-IFS, NCEP-GFS, and ARPEGE-Tropiques) and the special ECMWF AMMA reanalysis confirm and help understand these findings. A bias (~1-2 mm day-1) in precipitation and evapotranspiration leads to an unrealistic view of West Africa as a moistu…
Investigation of the West African Monsoon water cycle from Numerical Weather Prediction models and elaborate products.
This study investigates the atmospheric water cycle over West Africa at seasonal and intra-seasonal timescales during AMMA Extended Observing Period (2005 to 2007). It aims at characterizing the scales of variability and inter-relations of atmospheric water budget terms and the underlying processes. The regional-scale moisture budget is examined using Numerical Weather Prediction (NWP) models and elaborate products. The latter are: TRMM 3B42v6 satellite precipitation estimates and evapo-transpiration estimates produced by land surface models (ALMIP project). These products allow for a comprehensive description of the water budget. NWP models provide also their own complete description of th…
Past and future spatio-temporal variability of rainfall of the Bani catchment in West Africa.
6 pages; International audience; Since 1970, on the Bani, main tributary of the upper Niger, annual discharges have decreased by 69% while annual rainfall has decreased only by 15% to 25% over the catchment. Among the possible causes for this very strong discharge decrease changes of precipitation patterns must be explored. Four different methods of spatial interpolation of rainfall fields were compared on intra-seasonal indices (number of dry days, the dry spells, EDI, SPI, etc.) for the period 1950-2006. This study was also conducted on simulated pluviometric data generated by a regional climatic model (WRF) for the 2032-2041 period. The pluviometric deficit is explained by a conjunction …
West African Monsoon Water Cycle : Assessment of numerical weather prediction water budgets
This study investigates the atmospheric water cycle over West Africa at seasonal and intraseasonal timescales during AMMA Extended Observing Period (2005 to 2007). It aims at characterizing the scales of variability and inter-relations of atmospheric water budget terms and the underlying processes. The regional-scale moisture budget is examined using Numerical Weather Prediction (NWP) models and elaborate products. The latter are: TRMM 3B42v6 satellite precipitation estimates and evapo-transpiration estimates produced by land surface models (ALMIP project). These products allow for a comprehensive description of the water budget. NWP models provide also their own complete description of the…