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Communication incl. Poster: BibTeX citation key:  BouKaram
Bou Karam, D., Flamant, C., Pelon, J., Tulet, P. & Williams, E. R. 2009. Dust emissions and transport in the Intertropical Discontinuity region of the West African Monsoon. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: roussot 2009-11-24 20:10:30
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Categories: Aerosol and Chemistry, Atmospheric processes
Keywords: Aerosol, Modelling
Creators: Bou Karam, Flamant, Pelon, Tulet, Williams
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Abstract
Dust emission over West Africa is highest during summer (June-July) in coincidence with the northward displacement of the Intertropical discontinuity (ITD) over the West African dust sources (Engelstaedter and Washington, 2007). Despite the high dust activity over this region during summer, the meteorological mechanisms involved in dust emission at the convective scale and mesoscale are still not very well understood and therefore are not well represented in regional and global models (e.g. Schepanski et al., 2009).
In this study, dust emission and transport associated with the atmospheric dynamics in the ITD are investigated using airborne and spaceborne lidar observations as well as mesoscale modelling during July 2006 in the framework of the African Monsoon Multidisciplinary Analyses (AMMA) campaign.
Two mechanisms for dust emissions over West Africa have been identified in the ITD region. The first one is associated with high turbulent winds at the leading edge of the monsoon nocturnal flow (Bou Karam et al., 2008). The second one is related to dry cyclogenesis in the ITD (Bou Karam et al., 2009). Furthermore, the representativeness of each mechanism in the mesoscale model Meso-NH has been investigated and the model results have been used in order to estimate the daily mean dust load in the ITD over Niger and northeastern Mali (3Tg) and to quantify the dust emission associated with each mechanism. In addition, the dynamics and thermodynamics characteristics of the planetary boundary layer in the ITD region have been analysed using airborne Doppler lidar and dropsonde measurements together with the model results. Finally, the diurnal cycle of the intertropical front as well as its day-to-day variability (over Niger and Mali) and their implications on dust emission and transport have been addressed.
Added by: roussot