This study investigates how long-term changes in mesoscale wind systems have influenced near-surface PM10 concentrations in central Korea, focusing on Chungcheongbuk-do (Chungbuk Province) during spring from 2000 to 2024. Observational data reveal a nationwide decline in near-surface wind speeds, particularly during spring in the 2010s. Empirical Orthogonal Function (EOF) analysis of 850 hPa wind speed anomalies indicates that this weakening trend is linked to synoptic-scale atmospheric variability over the East Asia-North Pacific region. As transboundary contributions of PM10, particularly from eastern China, have declined in recent years, the role of mesoscale wind patterns in shaping local PM10 concentrations in central Korea has become increasingly significant. To assess the influence of weakened mesoscale winds, two contrasting years were analyzed: 2011, marked by anomalously strong winds, and 2023, characterized by anomalously weak winds. Eulerian PM10 flux convergence (PMFC) analysis revealed a shift from divergence-driven dispersion in 2011 to weak PM10 convergence and accumulation in 2023. Despite these stagnant conditions in 2023, PM10 concentrations continued to decline in both Chungbuk and across Korea, underscoring the dominant effect of anthropogenic emission reductions. These findings suggest that although weakened wind conditions can limit pollutant dispersion, sustained emission control measures remain effective in improving air quality.

Abstract
1. Introduction
2. Data and methods
    2.1. Research Area
    2.2. Meteorological observations in Korea
    2.3. Synoptic-scale reanalysis data and analysismethods
    2.4. PM10 concentration dataset
    2.5. Near-surface PM10 and winds grid databy applying the Kriging method
3. Results and Discussions
    3.1. Long-term trends of near-surface PM10concentrations and wind speeds in Korea
    3.2. Influence of synoptic-scale wind variabilityover East Asia on mesoscale wind patterns inKorea
    3.3. Influence of near-surface wind patternchanges on PM10 concentrations in Korea
4. Summary and conclusions
References

• Hak-Sung Kim(Department of Earth Science Education, Korea National University of Education, Cheongju 28173, Korea) Corresponding author
• Jae-Hee Cho(Department of Environmental Education, Kongju National University, Gongju 32588, Korea)