Variability of aerosols over Changchun, Northeast China, based on new AERONET site observations

We study the seasonal variability of aerosols over Changchun, Northeast China, using ground-based observations from the recently established AERONET Changchun_JLU site. A sun-lunar-sky photometer was installed in the city in October 2024. The seasonal variability of key aerosol optical properties, including aerosol optical depth and the Ångström exponent, is analyzed, along with the influence of extreme events such as biomass burning and mineral dust transport. Aerosol types are first examined using the traditional AOD–AE classification scheme, which is commonly applied for broad aerosol type identification. In addition, a more advanced aerosol classification is performed using a hybrid approach that combines clustering centroids derived from global AERONET data with a Nearest-Center Matching (NCM) algorithm. This method uses data on the Single Scattering Albedo at 440 nm and the Extinction Ångström Exponent at 440-870 nm. The analysis focuses on how aerosol types vary seasonally over Changchun and evaluates the effectiveness of the clustering-centroid combined with the NCM approach in a cold urban environment. The results highlight the influence of human activities, including residential heating, waste burning, and biomass burning, as well as regional transport processes, particularly mineral dust transport from the Taklamakan and Gobi deserts, on the seasonal distribution of aerosols.