Chapter 3 - Remote Sensing of Aerosols From Space: Retrieval of Properties and Applications

Abstract

Atmospheric aerosols are multicomponent mixtures typically composed of liquid and/or solid particles suspended in the atmosphere. Aerosols originate from numerous sources, having successively evolved through various microphysical processes before being removed either by wet or dry depositions. The implications of these airborne particulates on the regional and global climate are many but most notably through regulating the atmospheric heat budget either by absorbing/scattering insolation or by modifying cloud microphysical properties. Global distributions of aerosols are typically regional; thereby, they pose a strong regional signature that induces additional uncertainties in estimating aerosols, induced climate forcing. Satellite remote sensing of aerosols has extensive applications in identifying aerosol columnar properties, especially in terms of optical depth, composition, morphology, and vertical distribution. This ultimately provides evidence in establishing the source-transport-receptor relations of aerosols over a synoptic scale. Further, satellite data of atmospheric compositions are often used for identifying pollutant emissions, transboundary movement, forecasting air quality, and, more recently, in associating air quality with human health. The principles of remote sensing of aerosols are quite different from that of trace gases as the extinction of light by aerosols is a function of wavelength. With the gradual advancement of sensing technologies, monitoring of atmospheric aerosols has become more precise. Therefore, it has become more widely applied in various academic disciplines, studies, policies, and decision-making processes. This article emphasizes the state of the art in the field of satellite remote sensing, specifically in terms of polar-orbiting satellites for tropospheric aerosols including both active- and passive-based observations; associated complexities and uncertainties; brief descriptions of data products; and the subsequent applications in climate science.