Dust-rainfall feedback in West African Sahel

TitleDust-rainfall feedback in West African Sahel
Publication TypeJournal Article
Year of Publication2015
AuthorsYu K.L, D'Odorico P., Bhattachan A., Okin G.S, Evan AT
JournalGeophysical Research Letters
Date Published2015/09
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000363412400041
Keywordsaerosols; biosphere-atmosphere interactions; climate; dust emissions; emission; precipitation; Sahara Desert; Saharan; sahel; sea-surface; summer rainfall; temperature; tropical north-africa; variability; Vegetation

Drought persistence in West African Sahel has often been explained as an effect of positive vegetation-atmosphere feedback associated with surface albedo or the partitioning of solar radiation into sensible and latent heat fluxes. An often overlooked aspect of land-atmosphere coupling results from vegetation controls on dust emissions and the ability of mineral aerosols to suppress precipitation. Here we first consider the case of local (endogenous) dynamics within the Sahel, whereby enhanced dust emissions resulting from a decrease in vegetation partly suppress precipitation, thereby further reducing vegetation cover. We then account for teleconnections between Sahel precipitation and exogenous (i.e., Saharan) dust emissions due to an increase in Saharan wind speed in years of above average Sahel precipitation. We find that in both cases vegetation-climate dynamics may have two stable states, one with low precipitation and high concentration of atmospheric dust and the other with high precipitation and lower levels of atmospheric dust.

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