A numerical study of the seasonal variations for tracer redistribution by clouds over West Africa |
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| Authors: | M Renard N Chaumerliac S Cautenet N Audiffren E C Nickerson |
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| Institution: | (1) LAMP/OPGC, Université Blaise Pascal 24, Avenue des Landais, 63177 Aubiere Cedex, France;(2) FSL/NOAA, Boulder, CO, USA |
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| Abstract: | The sensitivity of the horizontal and vertical transport of an inert tracer to seasonal variability of the complex West Africa circulations is explored by means of a 2D mesoscale meteorological model including explicit microphysics and describing the cloud dynamics of these circulations. The seasonal variations of the location and spatial extent of the cloudy masses associated with the Inter Tropical Convergence Zone (ITCZ) are reproduced in a meridional cross section over West Africa. The redistribution of the inert tracer is shown to be due to the northward migration of the ITCZ from January to July and also to the enhancement of the convective activity of the ITCZ in July. The redistribution of carbon monoxide during the dry and wet seasons is discussed, highlighting the importance of the biomass burning during the dry season as a source of trace gas enrichment in the upper levels of the tropical troposphere over West Africa. |
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| Keywords: | West African circulations cloud vertical transport impact of clouds on tropospheric chemistry |
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