Atmospheric water cycle and moisture fluxes in the West African monsoon: mean annual cycles and relationship using NCEP/NCAR reanalysis

[1] Atmospheric water (Precipitation minus Evaporation, P-E) and moisture fluxes from the NCEP/NCARand observed rainfall data from the Climatic Research Unit are analyzed over the West African Monsoon region (WAM: 5degreesN-20degreesN; 18degreesW-18degreesE) on the period 1968-1998. The main results show that 1) P-E averaged over the 15degreesN-20degreesN belt in July-September (JAS) is a better proxy of observed rainfall in Sudan-Sahel (12degreesN-18degreesN) than NCEP/NCAR rainfall in this reanalysis; 2) part of the moisture fluxes vertically integrated in the layers 1000-300 hPa or 1000-925 hPa advected into WAM originate from the Mediterranean sea and Central Africa; 3) their interannual March-April and JAS variations, especially north of 20degreesN, present significant relationship with Sahelian P-E in JAS; 4) at more local scales moisture advections and convergences are also significantly associated with observed Sudan-Sahel rainfall and, in wet (dry) situations, with a clear dominance of westerly (easterly) anomalies in the moisture flux south of 15degreesN.