Spectral aerosol optical depth variation with different types of aerosol at Gwangju, Korea

Simultaneous ground-based measurements of aerosol chemical composition and atmospheric aerosol optical depth (AOD) in the UV and visible regions were carried out at Gwangju (35.13°N, 126.50°E), Korea during a biomass burning period, October 4–November 12, 2002. An Asian dust event and biomass burning events were observed during the study period. The correlation coefficients (R) between AOD and PM2.5 and PM10 mass concentration during the study period are 0.58±0.15 and 0.52±0.14, respectively. Aerosol optical properties (AOD and Ångström exponent) and chemical characteristics were presented for selected days and their impacts on aerosol loading were examined. Both fine and coarse mode particle mass concentrations increased on biomass burning day resulting in high AOD values. The simultaneous occurrence of Asian dust and biomass burning resulted in the highest AOD of 1.20 at 311 nm and the lowest Ångström exponent of 0.42 in the visible range. When both transported urban pollutants and land dust aerosols affected the air quality over the study area, AOD and surface PM mass concentration increased 18–60% and 230–890%, respectively.