Examining the characteristics of aerosols: a statistical analysis based on a decade of lidar and photometer observations  at the Eastern border of ACTRIS

Doina Nicolae

doi:10.5194/amt-19-1179-2026

Examining the characteristics of aerosols: a statistical analysis based on a decade of lidar and photometer observations at the Eastern border of ACTRIS

10.5194/amt-19-1179-2026

2026-02-27

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Abstract. A decade-long (2015–2024) analysis of aerosol properties was conducted at RADO (Romanian Atmospheric 3D Observatory)-Bucharest station in Romania; a key atmospheric observational site at the Eastern border of the Aerosol; Clouds and Trace gases Research Infrastructure (ACTRIS). This study aims to characterize the optical and microphysical properties of aerosols; classify predominant aerosol types; and investigate their seasonal variability and transport pathways based on long-term multiwavelength Raman lidar and sun/sky/lunar photometer measurements. Results indicate a dominance of fine-mode aerosols; with an average Aerosol Optical Depth (AOD) of ∼ 0.2 and Ångström Exponent (AE) values between 1.5 and 2.0; highlighting pollution-driven aerosol regimes. Seasonal variations were observed; with continental aerosols prevailing in winter; dust transport peaking in spring (altitudes of 2–8 km); and biomass-burning aerosols increasing during summer. Analysis of 408 aerosol layers using the NATALI (Neural network Aerosol Typing Algorithm based on LIdar data) identified complex aerosol mixtures; with 63 high-resolution cases revealing a predominance of “dust polluted” and “continental smoke” types. In the lower troposphere; the extinction-related Ångström exponent shows a narrow mono-modal distribution with the peak at 0.9; indicating predominantly medium-sized particles; whereas in the high troposphere it becomes bi-modal; reflecting alternating occurrences of small and large particles. Lidar ratio values have a distribution peak at around 48–49 sr in both altitude regions; but their spread is much wider in the lower troposphere – revealing frequent layers of highly absorbing aerosols – while lofted layers in the high troposphere exhibit a narrower range typical of moderately absorbing particles. Distinct differences between fresh and aged biomass-burning aerosols (smoke) are identified through their altitude; depolarization; Ångström exponent; and lidar-ratio characteristics; demonstrating microphysical change during transport. FLEXPART (FLEXible PARTicle dispersion model) retro-plume simulations provided insights into aerosol source regions and transport patterns showing contributions from local emissions; long-range transported desert dust; and biomass burning events from Europe and North America. These findings emphasize the persistent influence of regional pollution and transported aerosols on air quality and climate. The integration of ground-based remote sensing and advanced retrieval algorithms like NATALI provides a robust framework for aerosol characterization; enhancing climate models and air quality assessments.

Keywords:

aerosol properties

lidar observations

aerosol typing

seasonal variability

transport pathways

Examining the characteristics of aerosols: a statistical analysis based on a decade of lidar and photometer observations at the Eastern border of ACTRIS

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