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On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali

Drobinski, P. and Bastin, S. and Janicot, S. and Bock, O. and Dabas, A. and Delville, P. and Reitebuch, O. and Sultan, B. (2009) On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali. Journal of Geophysical Research, 114 (D09108), pp. 1-16. DOI: 10.1029/2008JD011159.

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Official URL: http://www.agu.org/pubs/crossref/2009/2008JD011159.shtml


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.

Document Type:Article
Title:On the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali
AuthorsInstitution or Email of Authors
Drobinski, P.CNRS, Palaiseau, F
Bastin, S.CNRS, Palaiseau, F
Janicot, S.CNRS, Palaiseau, F
Bock, O.CNRS, Palaiseau, F
Dabas, A.Météo-France, Toulouse, F
Delville, P.CNRS, Meudon, F
Sultan, B.CNRS, Paris, F
Journal or Publication Title:Journal of Geophysical Research
Refereed publication:Yes
In Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 1-16
Keywords:Monsoon, AMMA, Doppler lidar WIND
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Projekt ADM II (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Lidar
Deposited By: Oliver Reitebuch
Deposited On:22 Jul 2009 14:40
Last Modified:23 Jan 2014 11:36

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