Influence of dry-season vegetation variability on Sahelian dust during 2002-2015
Kergoat, L. ; Guichard, Françoise ; Pierre, C. ; Vassal, C.
The drivers of dust emission inter-annual variability in North Africa, the largest dust source on earth, are still debated. Early studies outlined the role of previous-season rainfall and vegetation growth, while some recent studies emphasize the role of wind variability. Here, we use a newly-developed estimation of dry-season nonphotosynthetic vegetation cover in the Sahel based on MODIS short-wave infrared bands over the 2002-2015 period. The vegetation growth anomalies caused by variability of rainfall in June-September translate to anomalies of dry vegetation cover that persist throughout the dry season until May. These vegetation anomalies explain 43% (50%) of the year-to-year variance in Sahelian-mean dry-season Aerosol Optical Depth (AOD) as derived from MODIS Deep Blue (sun-photometers). Similar explained variance is found with 10?m wind speed and Dust Uplift Potential. The central Sahel proves more important than the western Sahel for dry-season AOD variability.
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