| Popis: |
A portable micro-pulse polarization lidar system with 3D scanner at eye-safety level is developed,in which Nd∶YAG pulsed laser is employed as the exciting source with 2 μJ pulse energy and 1 kHz repetition rate,to detect the spherical characteristics and distribution of bottom aerosols in urban area.To ensure high accuracy detection near the earth's surface at the range from 80 m to 1000 m in the region of high-density aerosols such as northwest region,analog photoelectric detection technique is adopted.Continuous observations with scanning in zenith angle are carried out for the first time for depolarization ratio of atmospheric aerosols below 1 km in Xi′an in winter,the results of depolarization ratio scanning profiles are obtained and the effect of weather process and state of ground on depolarization ratio is analyzed.The experimental results show that,the depolarization ratio is around 0.1,where there were no sandstorms during the observations,and the depolarization ratio in certain regions is relative higher,which are occurred at the crossings of roads without greenbelts.The experimental results validate the feasibility of the system and will also provide scientific data for investigating the generation,transmission and diffusion characteristics of urban pollution particles. |
