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Journal Article: ID no. (ISBN etc.):  1477-870X BibTeX citation key:  Flamant2009
Flamant, C., Lavaysse, C., Todd, M. C., Chaboureau, J.-P. & Pelon, J. (2009) Multi-platform observations of a springtime case of Bodélé and Sudan dust emission, transport and scavenging over West Africa. IN Quarterly Journal of the Royal Meteorological Society, 135. 413–430.
Added by: Cyrille Flamant 2009-01-17 23:47:51    Last Edited by: Fanny Lefebvre 2010-11-17 16:23:26
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Categories: Atmospheric processes
Keywords: Aerosol
Creators: Chaboureau, Flamant, Lavaysse, Pelon, Todd
Collection: Quarterly Journal of the Royal Meteorological Society
Bibliographies: Prior150410

Peer reviewed
Number of views:  938
Popularity index:  49.52%
Maturity index:  accepted

 
Abstract
The structure of the Saharan air layer over Niger and Benin during a major springtime dust event from the Bodélé region and Sudan, is investigated using airborne lidar and dropsonde measurements. Aircraft operations were conducted on 13 and 14 June 2006, in the framework of the African Monsoon Multidisciplinary Analysis Special Observing Period. Complementary groundbased and satellite observations, as well as European Centre for Medium-range Weather Forecasts analyses are used to investigate the regional aspects of emission, transport and deposition in the period from 9 to 14 June 2006, to provide a framework for the interpretation of the airborne measurements. The study details the transport patterns of dust from eastern Saharan sources towards the southwest in the springtime, and highlights the role of the inter-tropical discontinuity and the Darfur mountain in injecting the aerosols from Bodélé and Sudan, respectively, over the monsoon flow, and in the African easterly jet (AEJ) region. It also illustrates the impact of the daily variability of the emissions in the source regions on the dust load advected westward by the AEJ and observed over Benin. The impact of a mesoscale convective system (MCS) on the dust load and vertical distribution observed over Benin and southern Niger was also investigated, nearly 12 hours after its passage over Benin. The only discernible impact on the dust distribution is observed to be associated with widespread subsidence in the wake of the MCS, over northern Benin and Niger. Wet scavenging related to convective or stratiform rain could not be observed, as processed air masses were replaced by fresh dust transported in the upper Saharan air layer by the AEJ. Over southern Benin, the dust distribution appeared to be mostly controlled by processes affecting the PBL upstream, i.e. over Nigeria or Chad. Because springtime dust from remote eastern sources such as observed in this case is mainly transported into the AEJ, it could impact the radiation budget in the AEJ region, thereby possibly modifying the West African weather at the synoptic scale.
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Added by: Cyrille Flamant    Last Edited by: Fanny Lefebvre