Measurements of aerosol optical properties using spectroscopic techniques

Abstract Spectroscopic techniques have been widely used for the measurements of aerosol optical properties mainly to examine their impact on radiation balance in the Earth's atmosphere. The ratio of light scattering to extinction, namely single-scattering albedo, is one of the most important parameters to determine whether aerosol particles heat or cool the atmosphere. To measure this ratio, several types of aerosol albedometer based on a combination of two different spectroscopic techniques have been developed recently. This chapter starts by introducing the importance of the radiative impact of aerosol particles and the basic principle of light interaction with particles. The optical parameters of particles and the principle and characteristics of spectroscopic instruments to measure aerosol optical properties are described. Recent progress from the intercomparison of these spectroscopic instruments and applications of spectroscopic techniques to laboratory and observational studies of aerosol optical properties are also introduced.