Dust Aerosol Optical Properties for Applications to Lidar and Polarimetric Retrievals

The complexity of dust aerosol optical and microphysical properties leads to large uncertainties in the dust aerosol radiative effects. To reduce these uncertainties, it is necessary to have a quantitative understanding of the spatial and temporal variability of dust aerosol properties. Spaceborne lidar observations (specifically, from CALIOP/CALIPSO) provide an unprecedented opportunity to study dust aerosol properties. The lidar signals are not only sensitive to dust aerosol optical thickness and nonsphericity, but also to the effective particle size and have a vertical resolution capability. However, these dust aerosol properties cannot be determined uniquely from lidar observations alone due to insufficient a priori knowledge. Multi-channel and multi-angle polarization measurements will provide more information about particle size and optical thickness. In support of lidar/polarimetric retrievals of dust aerosol properties, we present a new approach of simulating the radiometric and polarimetric properties of dust particles. In particular, new regional, and size-dependent datasets of the index of refraction of African and Asian dusts will be discussed, followed by the complete single-scattering properties, namely, the phase matrix, extinction efficiency, and singe-scattering albedo of dust particles. In the light-scattering simulations, we use a new dust optical property model based on an ensemble of nonspherical dust particles. Finally, we will show some applications of the new light-scattering capabilities.