Study of plumes mixing from biomass burning

and dust haze over West Africa

 

F.-X. D. Bouo Bella1*, Y. Tchétché1, P. Assamoi2, S. Cautenet3, G. Cautenet3

1 Université d’Abobo-Adjamé ; UFR-SFA ; Laboratoire de Physique Fondamentale et Appliquée (LPFA) 02

B.P 801 Abidjan 02, Côte d’Ivoire

2 Université de Cocody ; UFR-SSMT ; LAPA-MF ; 22 BP 582 Abidjan 22, Côte d’Ivoire

3 Université Blaise Pascal ; LAMP - CNRS - ; 24, Avenue des Landais, 63177 Aubière cedex, France

* Corresponding author. E-mail: djezia2001@yahoo.fr

Received: 11 December 2006; revised version accepted: 19 April 2007

 


Abstract

     During the dry season in West Africa in zone of Guinean savanna, there are often mixtures of plumes resulting from fires of vegetation and risings of mineral aerosols transported by Harmattan. Sometimes during this period, meteorological situations are favourable to the development of isolated major convection. It was the case of November 21, 1996 when a storm occurred in Lamto (site geophysics measuring), located at the center of Ivory Coast, in zone of Guinean savanna. The analysis of precipitations of this case by network IDAF showed that the quantities of nitrate, sulphates, formiate, calcium and magnesium were twice higher than cases where only the plume of fires of vegetation existed. A simulation was carried out using the model RAMS coupled to a code of rising of desert aerosols and with a code of gas and aqueous chemistry. For this simulation the mixture of the plumes was established by incorporating the adsorption of the nitric acid on the mineral aerosols and the scrubbing of these aerosols. A study of the numerical results show that the order of magnitude of the ions nitrates is found for the case without mixture and with. This type of research is an illustration of the importance of the impact of the aerosols on heterogeneous chemistry and consists of a pre modeling of the future campaign of AMMA.

 

Keywords: Plumes mixing; Biomass burning; Dust haze; Heterogeneous chemistry; Modeling.

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