Optical properties of nonspherical, light-absorbing particles: Black carbon and mineral dust aerosols

Optical properties of light-absorbing particles in the atmosphere determine aerosol single scattering albedo and direct radiative forcing, thereby influencing climate change. A quantitative understanding of aerosol optical properties is also needed for their global quantification through satellite- and ground-based remote sensing. Two dominant types of light-absorbing aerosols, black carbon and mineral dust, are nonspherical, which complicates the determination of their optical properties. Here, we discuss the basic properties of black carbon and mineral dust aerosols needed to understand, measure, and calculate their optical properties with a focus on recent progress and remaining gaps in obtaining and using these properties. While much progress has been made for black carbon aerosols, such progress is still largely lacking for the much more complex mineral dust aerosols.