Search results for "west Africa"
showing 10 items of 77 documents
Sul far del giorno
2016
Edizione critica dell'autobiografia del Premio Nobel per la Letteratura Wole Soyinka, corredata di Prefazione e Note della curatrice, che ne è anche la traduttrice, di una cronologia storica, di mappe geopolitiche della Nigeria dall'indipendenza, e di un apparato fotografico pubblicato in Italia in anteprima mondiale. Soyinka, classe 1934, drammaturgo, poeta, saggista, romanziere e attivista politico è stato il primo autore africano a essere insignito del Premio Nobel per la Letteratura. In questo avvincente memoir, racconta le proprie vicende di artista, intellettuale e attivista militante nella sua Nigeria e nel palcoscenico del mondo, in cui da sempre porta le voci dell'Africa. Nel lingu…
Notes on Afrotropical Cydnidae (Heteroptera) with emphasis on vehicle-mounted net samples and description of a new species from Liberia, West Africa
2019
Notes on the Cydnidae fauna in Liberia, sampled with a vehicle-mounted net, the species taxonomy and general distribution are reported, including the description of Chilocoris elongatus sp. nov. In addition, new country records are provided for Angola, Ethiopia, Gabon, Guine a-Bissau, Namibia, Niger, Republic of South Africa, Sierra Leone, Tanzania, Togo, Uganda, and Zimbabwe.
Seasonal reproducibility and predictability of the West African Monsoon in coupled GCMs
2009
In the framework of the ENSEMBLES FP6 project, an ensemble prediction system based on five different state-of-the-art European coupled models has been developed. This study evaluates the performance of these models for forecasting the West African monsoon (WAM) at the monthly time scale. From simulations started the 1 May of each year and covering the period 1991–2001, the reproducibility and potential predictability (PP) of key parameters of the WAM—rainfall, zonal and meridional wind at four levels from the surface to 200 hPa, and specific humidity, from July to September—are assessed. The Sahelian rainfall mode of variability is not accurately reproduced contrary to the Guinean rainfall …
Weather Regimes in the Euro-Atlantic and Mediterranean sector and relationship with West African rainfall over the period 1989-2008 from a Self-Organ…
2011
International audience; Weather Regimes (WR) have been defined over the Euro-Mediterranean region [60°W-60°E; 15°N-70°N] from May to October season using the daily Sea Level Pressure, 700 hPa geopotential height and specific humidity from ERA-interim over 1989-2008 period. Computations are based on a neural network lassification technique referred to as Self Organizing Maps and the WR produced can be used by the community for comparison with other periods, projection onto model outputs, seasonal prediction or teleconnection studies. The article particularly examines the relationship between WR and West African (WA) rainfall and our results suggest that changes in particular WR frequencies c…
Global atmospheric response to specific linear combinations of the main SST modes. Part I: numerical experiments and preliminary results
1996
Abstract. This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO) phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns) were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the …
How could hydro-climatic conditions evolve in the long term in West Africa? The case study of the Bani River catchment
2011
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…
Sahel droughts and Enso dynamics
1996
Correlations between summer Sahel rainfall and Southern Oscillation Index has increased during the last thirty years. At high frequency time scale (periods lower than 8 years), an intertropical Atlantic zonal divergent circulation anomaly is forced by the difference of sea surface temperature (SST) anomalies between the eastern equatorial parts of Pacific and Atlantic. This zonal connection worked well during most of the E1 Nino/Southern Oscillation (ENSO) events occurring after 1970; positive/negative SST anomalies in the eastern Pacific/Atlantic led to rainfall deficits over the whole West Africa. At low frequency time scale (periods greater than 8 years), positive SST anomalies in the In…
The West African Monsoon Modeling and Evaluation project (WAMME) and its First Model Intercomparison Experiment
2008
International audience; This paper presents the scientific challenge in West African monsoon (WAM) simulation and discusses the West African Monsoon Modeling and Evaluation project (WAMME) initiative and its approaches to improve WAM simulations. Major scientific highlights from the first WAMME model comparison are the focus of the paper. Based on the first WAMME experiment, the WAMME models' performance is evaluated with precipitation being the major focus. The analyses indicate that the models with specified SST generally have reasonable simulations of the mean spatial distribution of WAM precipitation but largely fail to produce proper daily precipitation frequency distributions. WAMME m…
Past and future spatio-temporal variability of rainfall of the Bani catchment in West Africa.
2011
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 …
Temporal evolution of heavy rainfall in the southern West Africa coastline belt.
2018
The Southern Coastalbelt of West Africa (SCWA) is exposed to recurrent flooding. The two objectives of the study are to show thespecificity of SCWA to heavy rainfall occurrence and to determine the trends of the latter. Daily rainfall data of41 stations in the southern parts of Côte d’Ivoire, Ghana, Togo and Benin for the period 1951–2015 and ClimateHazards Group InfraRed Precipitation data were used. The approach is based on the determination (for eachstation and grid point) of the 95th centile (P95) of precipitations greater than or equal to 1 mm. Results indicatethat rainfall is heavier on the coastal belt than inland (average P95 is 65,4 and 45,5 m/day for coastal and inlandstations res…