Observations from the sun-photometer station (EMA_2 AERONET, 30.08°N, 31.29°E) located in Cairo, Egypt, indicate the aerosol content over the region includes a mixture of three individual components: background pollution by urban activities, biomass burning in the Nile Delta, and mineral dust from the desert regions (e.g., Sahara).58,59 Therefore, the Greater Cairo Region (GCR) is an area where aerosols from different origins are mixed in variable proportions, serving as a proper test site for the validation of the dust-soot mixture look-up tables constructed in this study. During two dust storm events, three MODIS observations around the megacity of Cairo were collected for examination of AOD and SSA retrievals of pure dust and dust-soot mixtures. The events include a pure-dust-like case (May 27, 2010) and two polluted-dust-like cases (May 16, 2010, and February 25, 2011) shown in Fig. 9. During the period from May 15 to 28, 2010, two dust storm events were recorded by the sun-photometer at Cairo_EMA_2 site (Fig. 10). The measurements of the aerosol optical properties indicated the dust plumes began to blow over the greater Cairo region with a slight loading on May 15 (e.g., small AOD value), and the concentration of dust particles was intensified by a storm on May 16 and 17 (see also Fig. 9). After May 18, the mineral dust characteristics could not be tracked (e.g., slight aerosol loading with relative large AE value) until a strong dust plume appeared on May 27. Accordingly, the MODIS/Aqua observations of May 16 and 27 are employed for the case studies; Case 1 for pure dust and Case 2 for polluted dust (dust-soot mixture). Case 3 is the dust storm event on February 25, 2011, similar to the May 16, 2010 polluted dust case, but with heavier dust aerosol loading, and additionally examined for polluted dust (dust-soot mixture).