Vertically resolved light-absorption characteristics and the influence of relative humidity on particle properties : Multiwavelength Raman lidar observations of East Asian aerosol types over Korea

Abstract

Optical and microphysical particle properties, including the particle single-scattering albedo, were derived from multiwavelength aerosol Raman lidar observations at Gwangju (35.10 degrees N, 126.53 degrees E), and Anmyeon Island (36.54 degrees N, 126.33 degrees E), South Korea. The results present aerosol properties in various heights of the atmospheric aerosol layers on 12 different measurement days. The measurement cases differ in terms of aerosol loading as well as aerosol types (long-range transported urban/industrial haze from China, regional/local haze that mainly originated from the Korean peninsula, and smoke from forest fires in east Siberia). The origin of the particle plumes was determined from chemical transport modeling with the FLEXPART model. We find comparably clear differences between the optical and microphysical properties of the aerosol types. Local haze aerosols show effective radii of 0.32 +/- 0.02 mu m at relative humidity of 60-80%. The effective radii of urban/industrial haze and smoke aerosols are approximately 0.26 mu m and 0.27 mu m at relative humidity of 35-60%. Light absorption, expressed in terms of single-scattering albedo, is 0.87 +/- 0.02 (at 532 nm) for urban/industrial haze from China. This value is considerably lower than the single-scattering albedo of smoke aerosols from Siberia and northern China (0.92 at 532 nm) and of regional/local haze aerosols (0.97 +/- 0.01 at 532 nm). We find a hygroscopic growth factor (from relative humidity of 30% to relative humidity of 85%) of 1.49 +/- 0.36, if we consider all measurements.