Optical and Microphysical Properties of Dust and Polluted Continental Aerosols in Europe Using AERONET and CALIPSO data

This study provides a comprehensive long-term analysis (2006–2021) of the optical and microphysical properties of dust and polluted continental aerosols across nine European AERONET stations, including Thessaloniki, Limassol, Leipzig, Ispra, Potenza, Gozo, Granada, Évora, and Barcelona. Specifically, it evaluates optical properties—such as aerosol optical depth, particle linear depolarization ratio, single scattering albedo, and lidar ratio—alongside microphysical size parameters, namely the Angstrom exponent and particle effective radius. To ensure robust aerosol classification, two complementary methodologies were employed: the satellite-derived CALIPSO automated aerosol subtyping algorithm within a 100 km radius of each AERONET station and an independent ground-based classification scheme based on the particle linear depolarization ratio (Rd). This dual-scheme approach accurately discriminates between dust and polluted continental particles, restricting the analysis to pure cases co-identified by both methodologies.

The evaluation highlights specific variations between the two classification frameworks. In pure dust regimes, the ground-based scheme samples cases characterized by enhanced shape asymmetry and higher optical depth. Conversely, the satellite-derived aerosol typing captures cases with differing optical and microphysical characteristics, displaying lower values of optical depth at 440nm, depolarization ratio at 440nm, and particle size. For polluted continental particles, the two classifications agree more closely, with minor disagreements in the single scattering albedo at 440nm and mainly in the depolarization ratio at 440nm.

These findings suggest certain patterns of variation between ground-based and satellite classification, pointing to potential areas where satellite retrieval algorithms could be refined for a more nuanced understanding of climate trends in Europe.