Episode-Dependent Variations in Atmospheric Composition at the Anmyeon-Do Global Atmosphere Watch Station in November 2025

This study investigated episode-dependent variations in aerosol physical, optical, and chemical properties and in reactive gases using integrated atmospheric composition observed at the Anmyeon-do Global Atmosphere Watch Station, Republic of Korea, in November 2025. Asian dust, haze, high-particulate matter (PM) episodes, and a wildfire-influenced period were examined, and air-mass pathways were assessed using HYbrid Single-Particle Lagrangian Integrated Trajectory backward trajectories. PM10 concentrations during all event periods were more than twice the non-event mean (24.8±9.9 µg/m3), reaching its peak during Asian dust (66.1±19.2 µg/m3). The scattering Ångström exponent was lowest during Asian dust (1.1±0.5), consistent with a greater contribution from coarse particles. By contrast, aerosol scattering and absorption coefficients increased during haze, high-PM, and wildfire-influenced periods. Ion composition indicated enhanced natural-source components (chloride, sodium, and non-sea-salt calcium) during Asian dust, whereas secondary aerosol components (ammonia, nitrate-, non-sea-salt sulfate) accounted for 93.4% and 75.1% of reported composition during haze and high-PM episodes, respectively. NOX concentrations were 1.5–1.7 times higher during haze and high-PM episodes, while carbon monoxide showed the largest increase during the wildfire-influenced period. Back trajectories linked Asian dust to northwestern China, Inner Mongolia, and the Gobi region, whereas haze and high-PM episodes were linked with air-mass transport from eastern China and relatively slow air-mass movement. These results demonstrate distinct aerosol and gas profile across pollution episodes.