Determination of the mixing weights of soot aggregates for dust optical property retrievals with satellite and ground observations

Many papers regarding aerosol monitoring pointed out that there are up to 90% dust storm aerosols might be mixed/polluted with the local aerosols, especially over the downstream areas, during their long-distance transportations. These polluted dust will possess quite different radiometric property to their original property, inducing more uncertainties in the retrievals of the aerosol parameters, e.g. the aerosol optical depths (AOD) and single scattering albedo (SSA), etc. Therefore, the aim of this study is to establish a method in determining the mixing weights for dust/soot aerosol aggregated particles, to reduce the estimation uncertainties, and improve the aerosol retrieval accuracy. Assuming that SSA is constant, the optical property for aerosols can be calculated by an aerosol external mixing process, and which the mixing weights can be estimated with SSA values. With the long-term AErosol RObotic NETwork (AERONET) observation data, the typical radiometric parameters for dust storm particles can be assessed. Again by using the Deep Blue concept (Hsu et al., 2004), along with the apparent reflectivity from radiative transfer models, the mixing weights can be obtained. Three dust storm cases in the Mid-East area observed with the Moderate Resolution Imaging Spectroradiometer (MODIS) were investigated in this study. The result shows that the satellite-derived result is very agreeable to the AERONET observations, revealing that the method is potential for further applications in dust storm monitoring. Copyright