Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Monsoon Multidisciplinary Analysis (AMMA) : an integrated project for understanding of the West African climate system and its human dimension Atmospheric Science Letters 58-66 West African monsoon intraseasonal variability monsoon onset predictability crop yield 2011 fdi:010053181 ENG Atmospheric Science Letters 1530-261X ISI:000287816700011 1 10.1002/asl.280 https://www.documentation.ird.fr/hor/fdi:010053181 https://www.documentation.ird.fr/intranet/publi/2011/03/010053181.pdf 12 Horizon (IRD) The intraseasonal time scale is critical in West Africa where resources are highly rainfall dependent. Three main modes of variability have been identified, two with a mean periodicity of 15 days and one with a mean periodicity around 40 days. These modes have a regional scale and can strongly influence precipitation and convective activity. They are mainly controlled by atmospheric dynamics and land-surface interactions. They can also modulate the very specific phase of the African summer monsoon onset. A better knowledge of the mechanisms controlling this scale is necessary to improve its predictability. Copyright. 021 ; 032 UR182 / UR065