Estimating Aerosol Absorption, Optical Depth, and Vertical Extent Using Satellite Measurements in the UV/Blue Spectral Domain

Until recently, the retrieval of aerosol absorption properties from space seemed so prone to error as to be almost worthless. The principal difficulty being that if the aerosol optical depth is relatively low, then the signal measured at the satellite is proportional to ωτP(θ), where ω is the singlescattering albedo, τ is the optical depth and θ is the scattering angle. It is, therefore, impossible to separate variations in optical depth from variations in singlescattering albedo. However, the development of a method for the detection of absorbing aerosols using the ultraviolet (UV) measurements made by the Total Ozone Mapping Experiment Spectrometer (TOMS) instrument (Herman et al. 1997) has provided new hope for the reliable estimate of aerosol single-scattering albedo from space, at least in the blue/UV spectral domain.