Analysis of the Variability and Correlation between Ground-Level Air Pollutant Concentrations and Atmospheric Mixing Layer Height based on Observations

This study analyzed the variability and correlation between ground-level air pollutant concentrations and the atmospheric mixing layer height using data from four types of air pollutants (PM2.5, PM10, NO2, and O-3) collected at AirKorea monitoring stations nationwide over a five-year period (2018 similar to 2022), and aerosol backscatter data observed by the Vaisala CL31 to derive atmospheric mixing layer heights. The five-year trends and variability of ground-level air pollutant concentrations under seasonal and hourly conditions were examined, as well as the seasonal distribution and diurnal variation of the atmospheric mixing layer height. Five correlation coefficient methodologies were applied to analyze the correlations between ground-level air pollutants and atmospheric mixing layer height under various seasonal and hourly conditions, confirming the dilution effect of the atmospheric mixing layer height. The results showed that PM2.5, PM10, and NO2 generally had negative correlations with the atmospheric mixing layer height, while O-3 showed a strong positive correlation up to an altitude of 1,200 similar to 1,500 meters, and a negative correlation beyond that altitude. It was also shown that a single high concentration event (e.g., PM10) can alter the overall correlation. The correlation can also vary depending on the characteristics of the correlation coefficient methodology, highlighting the importance of applying the appropriate methodology for each case during the analysis process.