The vertical change in extinction effect of particles during a haze episode in Chengdu
SUN Yong-liang1, ZHAO Tian-liang1, QIU Yu-jun1, LUO lei2, XIA Jun-rong1, CHEN Hong3, XIE Na3
1. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China; 2. Chengdu Plateau Meteorological Research Institution, China Meteorological Administration, Chengdu 610031, China; 3. Chengdu Meteorological Bureau, Chengdu 610031, China
Abstract：Based on the intensive vertical observation of particle size spectrum and synchronous lidar observation during a heavy haze event in Chengdu over January 4~7, 2017, as well as the extinction coefficients calculated using the Mie scattering theory and compared with the lidar observation, the extinction coefficients of particle in sizes and the contributions to the total extinction were estimated. The results showed that during the heavy haze episode, the magnitudes of extinction coefficients of particles with different sizes in heights was ranked with PM1 > PM2.5~10 > PM1~2.5 > PM > 10 within the boundary layer, and the PM1 was the major factor dominating the particle extinction with the contribution of 49.50%~69.44%. In atmospheric boundary layer, extinction of all size particles presented the pronounced vertical and diurnal variations. In the daytime, the high extinction coefficients were located at the altitude below 600m and between 700 and 1100m. In the nighttime, the extinction coefficients vertically decreased more significantly with the high values around 1100m. Additionally, the extinction coefficients and the extinction contributions of PM>1 below 200m in the nighttime were obviously greater than those in the daytime. In general, the extinction contribution rates of PM1 increased with the decreasing contribution rates of PM>1 in total particle extinction following vertical heights.
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