Variability of Absorption and Optical Properties of Key Aerosol Types Observed in Worldwide Locations

TLDR

Aerosol radiative forcing is a critical but highly variable and uncertain component of the global climate, yet climate models depend on sparse aerosol optical property data and in situ measurements rarely capture the undisturbed aerosol throughout the atmospheric column. The study aims to refine aerosol optical models and reduce uncertainties in satellite observations and climate impact modeling by characterizing aerosol absorption and optical properties. Using eight years of AERONET ground‑based radiometer data worldwide, the authors remotely sensed aerosol absorption and other optical properties, applying standardized calibration, cloud screening, and inversion techniques for consistent retrieval across diverse emission sources. The observations reveal robust differences in magnitude and spectral dependence of absorption among desert dust, biomass burning, urban–industrial, and marine aerosols, and significant variability within the same aerosol type due to meteorological, source, and emission characteristics.

Abstract

Aerosol radiative forcing is a critical, though variable and uncertain, component of the global climate. Yet climate models rely on sparse information of the aerosol optical properties. In situ measurements, though important in many respects, seldom provide measurements of the undisturbed aerosol in the entire atmospheric column. Here, 8 yr of worldwide distributed data from the AERONET network of ground-based radiometers were used to remotely sense the aerosol absorption and other optical properties in several key locations. Established procedures for maintaining and calibrating the global network of radiometers, cloud screening, and inversion techniques allow for a consistent retrieval of the optical properties of aerosol in locations with varying emission sources and conditions. The multiyear, multi-instrument observations show robust differentiation in both the magnitude and spectral dependence of the absorption—a property driving aerosol climate forcing, for desert dust, biomass burning, urban–industrial, and marine aerosols. Moreover, significant variability of the absorption for the same aerosol type appearing due to different meteorological and source characteristics as well as different emission characteristics are observed. It is expected that this aerosol characterization will help refine aerosol optical models and reduce uncertainties in satellite observations of the global aerosol and in modeling aerosol impacts on climate.