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On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali / Philippe Drobinski in Journal of geophysical research : Atmospheres, vol 114 n° D9 (2009)  

Public [article]  inJournal of geophysical research : Atmospheres > vol 114 n° D9 (2009) Titre : On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali Type de document : Article/Communication Auteurs : Philippe Drobinski, Auteur ; Sophie Bastin, Auteur ; Serge Janicot, Auteur ; Olivier Bock , Auteur ; A. Dabas, Auteur ; P. Delville, Auteur ; O. Reitebuch, Auteur ; Benjamin Sultan, Auteur Année de publication : 2009 Projets : AMMA & AMMA-2 / Janicot, Serge Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Afrique occidentale [Termes IGN] données GPS [Termes IGN] données météorologiques [Termes IGN] Mali [Termes IGN] mousson [Termes IGN] Niger Résumé : (auteur) This paper investigates the fine‐scale dynamical processes at the origin of the late northward migration of the monsoon flow in summer 2006 in the region of Niger and Mali (onset on 3 July 2006 compared to the climatological onset date, 24 June). Compared to a 28‐year climatology, 2006 NCEP‐2 reanalyses show evidence of an anomalous pattern during 10 days between 25 June and 3 July 2006, characterized by the African Easterly Jet (AEJ) blowing from the northeast along a narrow northeast/southwest band located over the Hoggar and Air mountains associated with an unusually strong northeasterly harmattan in the lee of the mountains. Using data collected during the African Monsoon Multidisciplinary Analysis (AMMA) experiment and mesoscale numerical simulations, this study shows evidence of interaction between the AEJ and the orography supported by the reduced gravity shallow water theory which explains the enhancement of the harmattan downstream of the Hoggar and Air mountains in summer 2006. The enhanced harmattan contributes to move southward the intertropical discontinuity (ITD) defined as the interface between the cool moist southwesterly monsoon flow and the warm dry harmattan. Finally, an interaction between the ITD and African Easterly waves contributes to propagate the ITD southward retreat about 1500 km to the west of the Hoggar and Air mountains. Numéro de notice : A2009-594 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2008JD011159 Date de publication en ligne : 13/05/2009 En ligne : https://doi.org/10.1029/2008JD011159 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96202 [article]