Evaluating the Relative Importance of Northern African Mineral Dust Sources Using Remote Sensing

Abstract. Mineral dust from the Sahara and Sahel provides the Amazon Basin with essential nutrients, although the process is still poorly understood. There is little understanding where the dust is coming from, and thus what the concentration of nutrients in the dust is. This information, however, is vital to assess the impact it will have on the Amazon. This study analyses northern African dust sources of the boreal winter dust seasons between the years 2015–2017. It utilises high spatio-temporal resolution remote sensing data from SEVIRI, MODIS, VIIRS and Sentinel-2 to identify dust sources, classify them according to a geomorphic dust source scheme, and quantify the relative importance of source regions by calculating the total dust mass they produce. Results indicate that paleolakes emit the most dust, with the Bodele Depression as the single largest dust source region, however, that alluvial deposits also produce a substantial amount of dust. During the boreal winter dust seasons of 2015–2017, ~ 36 % of the total dust mass emitted from northern Africa was associated to alluvial deposits, yet this geomorphic category has been relatively understudied to date. Furthermore, sand deposits were found to produce relatively little dust, in contrast to the results of other recent studies.