Synergetic analysis of springtime air pollution episodes over Gwangju, Korea

The characteristics of springtime aerosols, including their optical and microphysical properties, were analyzed for the months of March to May of 2009 in Gwangju (35.23°N, 126.84°E), Korea. A high Light Detection and Ranging (LIDAR)-derived aerosol depolarization ratio (δ) of 0.25 ± 0.04 was determined on dust particles during the observation period. The Ångström exponent values of the 440-870 nm wavelength pair (Å440-870) and single-scattering albedo at 675 nm (Ω675) measured by a CIMEL sun/sky radiometer were 0.77 ± 0.19 and 0.95 ± 0.01, respectively. The elevated dust layers reached a maximum elevation of 4 km above sea level. Anthropogenic/smoke particles that originated from highly populated/industrialized regions could be distinguished by their relatively smaller particle size (Å440-870 ranged between 1.33 and 1.36) and higher light-absorbing (Ω675 of 0.92 ± 0.01) characteristics. These aerosols are mostly distributed at altitudes < 1.2 km. The root-mean-square deviation (RMSD) between the aerosol optical depth (AOD, τ) derived from LIDAR (τLIDAR) and from the CIMEL sun/sky radiometer (τCIMEL) varied with respect to the surface PM10 concentration. The RMSD between τLIDAR and τCIMEL was as low as 13% under lower PM10 concentration levels (< 100 μg/m3). In contrast, the RMSD between τLIDAR and τCIMEL increased three times (~ 31%) under high surface PM10 concentration levels (> 100 μg/m3). These results suggest that the accuracy of τLIDAR is influenced by specific atmospheric conditions, regardless of its uncertainty.

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