Abstract: Space and time scales for analysis of the interannual variability of Sahelian rainfall are determined. Regionalizations of annual and monthly rainfall fields are performed in West Africa for the period 1948?78. Four coherent ...

Abstract: In the second part of this study, the variability of surface and airmass characteristics associated with West African rainfall fields is investigated. Ship observations over the tropical Atlantic and rawinsonde records ...

Abstract: Four West African rainfall anomaly types are defined in relation to the northern summer rainfall departure signs in the Sahel and in the Guinean region in order to investigate the statistical links between interannual ...

Abstract: The arrival of the summer monsoon over West Africa has been documented by using daily gridded rainfall data and NCEP?NCAR reanalyses during the period 1968?90, and OLR data over the period 1979?90. Two steps have been ...

Abstract: The wind-field coherence over West Africa is investigated during two contrasted periods, 1953?63 (abnormally wet) and 1963-75 (abnormally dry) in the Sahel. Zonal and meridional components of the monthly mean wind are ...

Abstract: This paper presents an investigation of the mechanisms giving rise to the main intraseasonal mode of convection in the African monsoon during northern summer, here identified as the quasi-biweekly zonal dipole (QBZD). The ...

Abstract: Intraseasonal variability in the West African monsoon is documented by using daily gridded datasets of rainfall and convection, and reanalyzed atmospheric fields, over the period 1968?90. Rainfall and convection over West ...

Abstract: The dominant mode of convectively coupled Kelvin waves has been detected over the Atlantic and Africa during northern summer by performing composite analyses on observational fields based on an EOF reconstructed convection ...

Abstract: This study investigates the diurnal cycle of the West African monsoon and its seasonal modulation with particular focus on the monsoon onset period. A composite analysis around the monsoon onset date is applied to the ...

Abstract: The variability of the West African monsoon on the intraseasonal time scale is a major issue for agricultural strategy, as the occurrence of dry spells can strongly impact yields of rain-fed crops. This study investigates ...