The Impact of Dust Mineralogical Compositions on CALIOP-IIR-Based Retrievals of the Optical and Microphysical Properties of Dust Plumes

Mineral dust aerosols are an important constituent of the atmosphere that regulates the planetary energy budget through their interactions with radiation and influences on clouds and ecosystems. Due to diverse source regions and changes during long-range transport, dust aerosols exhibit varying mineralogical compositions, leading to distinct regional optical and microphysical properties. However, the impact of mineralogical composition on satellite-based dust property retrievals is far from being well understood. This study develops a physics-based synergistic retrieval system to infer two fundamental properties, dust aerosol optical thickness (DAOT) and effective radius, leveraging observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Infrared Imaging Radiometer (IIR) onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. This algorithm relies on the TAMUdust2020 aerosol single-scattering database with a region- and mineralogy-dependent refractive index data set and does not depend on an empirical assumption about the lidar ratio. Through simulations and retrievals utilizing a region-specific dust optical property model, this study demonstrates that the measurements made by CALIOP and IIR, as well as the retrievals of DAOT and effective particle radius, are significantly influenced by the mineralogical composition of dust aerosols, exhibiting distinct behavior that varies depending on their source regions. This influence is particularly pronounced for dust aerosols originating from Taklamakan, Namib, Niger, and Australia, which underscores the importance of incorporating regional mineralogical variations into the retrieval process.