| dc.description.abstract | The purpose of this study is to characterize the aerosol optical properties measured by the sunphotometer and micro-pulse lidar in Chung-Li during the year of 2005. Combining with meteorological data, backward trajectories and ground level particle mass concentrations, this study also attempt to investigate the characterization of aerosol optical properties with respect to different seasons and weather conditions.
The maximum and minimum values of monthly mean aerosol optical depths at 440 nm occurred in spring (0.814 ± 0.227) and winter (0.442 ± 0.227), respectively. The monthly mean of Ångström exponent varied between 1.051 and 1.259, indicating a relatively stable ratio of the columnar coarse to fine particle size. Moreover, it was found that the averaged aerosol optical depth was higher under the weather conditions B ( high pressure center in high latitude, and easterly wind in Taiwan ), R (outflow of high pressure system to Taiwan ), M (Southwesterly monsoon) and T2 ( the typhoon’s center located at the northwest side of Taiwan), and in a range between 0.68 and 0.82 . In contrast it was lower under the weather conditions C (cold-air outbreak) and T3 (the typhoon’s center located at the southwest side of Taiwan), with the value of 0.3 and 0.4, respectively.
In addition, the aerosol particles within the boundary layer contributed about 57% of the columnar aerosol optical depth under the weather condition R. Relatively higher correlation coefficient between ground-level particle concentration and aerosol optical depth reveals that the former dominated the later in the lower troposphere. | en_US |