| dc.description.abstract | The purpose of this study is to characterize the aerosol optical properties measured by using Sun-Photometer, Nephelometer and Particle Soot Absorption Photometer at Lulin Atmospheric Background Station (LABS, 2,868 m; 23.47°N, 120.87°E) during spring (Mar-May) 2009. In combination with the use of micro-pulse lidar (MPL) in Chung-Li, satellite, ground-level particle mass concentrations and backward trajectory analysis, a comprehensive study of the vertical profile of aerosol optical properties and the source-receptor relationship was achieved.
The mean aerosol optical depths (?500) was 0.120 ± 0.105, and much higher in March and April. The variation of CO and PM10 was consistent ?500. The averaged Ångström exponent????????nm was 1.170 ±0.374, and March and April also higher, indicating the particle size was larger in May.The single scattering albedo (SSA, ?) at surface decreased gently with increasing wavelength, revealing the characteristics of mixing aerosols. Lower ?550nm in March and April showed that aerosol had more absorption capability. The asymmetry factor (g) decreased with increasing wavelength, also indicating the characteristics of mixing aerosols. Extinction coefficients derived from MPL and CALIPSO(Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations) showed a two-layer structure (0.3-2 km and 2.5-5 km). Backward trajectory analyses of upper layer(2.5-5 km) showed that these air masses were mainly from the Indo-China peninsula. Low-level air masses were mainly from Mongolia and northern China.
During the event of 3/16-3/23, variation of OC、EC、K+、Ca2+ and NO3- had similar trends and higher values. There was commonly low ????nm at nighttime, and the value varied significantly at about 12:00 UTC. In addition, the ??decreased gently with increasing wavelength during springtime background situation. Meanwhile, the g first decreased and then increased with increasing wavelength. The vertical profiles of aerosol extinction showed higher values between 0.3 and 1.7 km in springtime normal situation. Influence of biomass burning was the most significant between March 18 and 23, as indicated by a high average AOD of 0.45. The ? and g decreased with increasing wavelength. The vertical profiles of aerosol extinction showed higher values between 1.7 and 4 km during biomass burning event.
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