Tracing local and long-range aerosol emission areas using multi-method and multi-site analyses in central Europe

Atmospheric aerosols significantly influence air quality, climate and human health, making detailed source attribution and transport characterization essential. This study integrates multiple advanced techniques- air mass cluster analysis, Concentration Weighted Trajectory (CWT) analysis and Conditional Bivariate Probability Function (CBPF) analysis; to investigate aerosol emission sources and transport pathways at three Central European measurement stations: Melpitz (MEL, Germany), Frýdlant (FRY, Czech Republic) and Košetice (NAOK, Czech Republic). Online measurements of non-refractory submicron aerosols (NR-PM 1 ) using aerosol mass spectrometer, combined with equivalent black carbon (eBC) and brown carbon (BrC) data from aethalometers, enabled detailed characterization of aerosol composition and sources during winter (February-March 2021) and summer (July-August 2021) campaigns. In winter, the highest PM 1 mass concentrations were recorded at NAOK (13.2 μg/m 3 ), followed by FRY (6.4 μg/m 3 ) and MEL (6.3 μg/m 3 ), with OA and nitrate as major components. Diurnal trends revealed strong nighttime enhancements, especially at NAOK, indicating residential heating influence. Cluster analysis identified eastern continental air masses as dominant contributors to elevated PM levels at all sites. CWT analysis showed significant source regions for eBC, BrC and secondary inorganic aerosols in Poland and the Czech Republic, particularly for MEL and FRY. In contrast, CBPF analysis indicated local sources as the primary contributors to high OA, eBC, and BrC levels at NAOK, especially under low wind conditions (< 2 m/s), suggesting biomass burning and residential heating as key sources. During summer, PM 1 concentrations were more uniform across sites, with slightly higher values at MEL (8.6 μg/m 3 ) compared to NAOK (7.3 μg/m 3 ) and FRY (6.5 μg/m 3 ). Enhanced biogenic emissions and photochemical activity led to increased organic fractions, with NAOK exhibiting the highest proportion (75% of PM 1 mass). This study demonstrates the advantages of integrating multiple analytical techniques to distinguish between local and long-range sources, assess seasonal variability, and characterize long-range transport patterns, providing key insights for air quality management in Central Europe. • Multi-site, high-time-resolution investigation of submicron aerosols (PM 1 ) across three Central European rural background stations Melpitz (MEL), Frýdlant (FRY) and Košetice (NAOK). • Integrated cluster analysis, Conditional Bivariate Probability Function, and Concentration Weighted Trajectory techniques to disentangle local versus long-range contributions. • Winter dominated by eastern continental transport, with elevated PM 1 , OA, and eBC at MEL and FRY; NAOK strongly influenced by local residential heating. • Summer characterized by more uniform PM 1 levels, biogenic SOA formation, and increased marine/continental sulfate transport. • Findings show pronounced seasonal and site-specific contrasts, providing critical input for transboundary air quality management.