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There is great uncertainty regarding the role of mineral dust aerosols in Earth’s climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction), are poorly constrained because ground observations are limited to a few locations and satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength, which makes robust retrievals difficult. Here, we develop a method to estimate the spatial distributions of the aerosol single scattering albedo (omega(0)) and optical depth (tau(a)), with daily 1A degrees x1A degrees spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) as well as model simulations of radiative transfer. This approach is based on the ’critical surface reflectance’ method developed in the literature, which estimates omega(0) from the top of the atmospheric radiance. We estimate the uncertainties in omega(0) over the Sahara (Asia) to be approximately 0.020 and 0.010 (0.023 and 0.017) for bands 9 and 1, respectively, while the uncertainty in tau(a) is approximately 0.235 and 0.228 (0.464 and 0.370) for bands 9 and 1, respectively. The 5-95% range of the spatial distribution of omega(0) over the Sahara (Asia) is approximately 0.90-0.94 and 0.96-0.99 (0.87-0.94 and 0.89-0.97) for bands 9 and 1, respectively, and that of tau(a) over the Sahara (Asia) is approximately 0.8-1.4 and 0.8-1.7 (0.7-2.0 and 0.7-1.9) for bands 9 and 1, respectively. The results for the Sahara indicate a good correlation between omega(0) and the surface reflectance, and between omega(0) and tau(a). However, the relationships between omega(0), tau(a), and surface reflectance are less clear in Asia than in the Sahara, and the omega(0) values are smaller than those in the Sahara. The regions with small omega(0) values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are reported to be transported in previous studies. Because the coal-burning and carbonaceous aerosols are known to be more absorptive and have smaller omega(0) values than dust aerosols, our results indicate that the dust aerosols in Asia are contaminated by these anthropogenic aerosols. The spatial distribution of dust optical properties obtained in our work could be useful in understanding the role of dust aerosols in Earth’s climate system, most likely through future collaboration with regional and global modelling studies.