As an active remote sensing technique, ground-based lidar can detect the backscattered signals of atmospheric cloud and aerosol layers. The measured signals can be used to obtain the vertical profile information of aerosol extinction coefficients. The atmospheric aerosol is measured in Beijing during Asia-Pacific Economic Cooperation (APEC) conference in early November 2014. Fernald method is chosen as the inversion method, and a comparison is made by using Klett’s method. Using the aerosol optical depth(AOD) measured by sunphotometer as a constraint data. The results are used for the analysis of the vertical distribution of aerosol extinction coefficients, three periods are considered, which including several days before, during and after the APEC conference. From the retrieved results of lidar measurement, it was found that the maximum value of extinction coefficients at vertical height in the beginning period reached beyond 2, but it decreased to the range of 0.05 during the conference. Then it gradually increased to more than 2 after the APEC conference. The results show that vertical distribution range of aerosol extinction coefficients decreased to 1km with increasing of AOD. The retrieved AOD results illustrate the extinction characteristics of aerosol,and it relates with the concentration distribution of atmospheric particles. According to the relationship between extinction coefficients and atmospheric visibility, the weather condition can be analyzed.
Information on the vertical distribution of aerosol is important for understanding its transport characteristics as well as aerosol retrieval uncertainty. In this paper, the believable lidar ratio under clear sky condition during December 2014 is determined from ground-based lidar and sun-photometer site in Beijing. Then two methods are adopted to derive typical aerosol extinction profiles by averaging attenuated backscatter and retrieved extinction profiles respectively. The results indicate that the former vertical gradient of dispersion (standard deviation) is smaller than the latter. Moreover, the comparison of the aerosol extinction coefficient profiles shows a good consistency above 2km but significant difference below that altitude.
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