Identification of atmospheric patterns and processes affecting springtime PM<sub>10</sub> interannual variability in South Korea

Springtime PM₁₀ concentrations in South Korea pose a critical threat to public health and socioeconomic stability, which can be intensified by Asian Dust and anthropogenic emissions. While previous studies have examined wintertime atmospheric patterns affecting PM 10 concentrations, the physical mechanisms linked to land atmosphere interactions during spring remain largely unexplored. This study investigated the dominant synoptic patterns and the associated land and atmospheric processes, regulating inter-annual variability of spring PM₁₀ concentrations (2003 2024) using data from the European Centre for Medium-Range Weather Forecasts Reanalysis v.5 (ERA5) and Copernicus Atmosphere Monitoring Service (CAMS). The results revealed that high spring PM₁₀ concentrations in Korea were significantly associated with anticyclonic anomalies over the Amur River basin in far eastern Russia. The anticyclonic pattern induced the weakening of prevailing westerlies by easterly wind anomalies over the Korean Peninsula, promoting atmospheric stagnation and suppressing pollutant dispersion. The anomalous anticyclonic pattern was statistically and physically linked to snow cover reduction in the Amur River basin. The decreased surface albedo with reducing snow cover enhanced solar radiation absorption and thus greater heat transfer to the atmosphere through sensible and latent heat fluxes. Consequently, the increased atmospheric heating could lead to thermal expansion of the lower to middle troposphere thereby raising geopotential height and inducing the anticyclonic anomaly. By incorporating the atmospheric processes linked to land surface conditions, this research advances the understanding of climate and air quality interactions and offers a robust scientific foundation for developing early warning systems and evidence-based adaptation policies for springtime air quality management.