基于颗粒物通量激光雷达的一次颗粒物污染过程分析

Analysis of a Particulate Pollution Process Based on Particle Flux Lidar

为说清城市环境空气污染原因,采用颗粒物通量激光雷达对宜宾市上空大气颗粒物的立体传输情况进行监测。利用2020年2月12日~17日宜宾市颗粒物通量激光雷达资料,结合地面气象观测资料和颗粒物监测数据,统计分析污染过程及颗粒物传输特征。结果表明:(1)颗粒物通量雷达监测结果可以较好地解释地面颗粒物浓度变化情况,本次污染过程共监测到三次明显的PM_(2.5)输入、一次PM_(2.5)和PM_(10)输出、一次PM_(10)输入。(2)边界层高度与大气污染物扩散有一定关系,边界层越高、越有利于污染物扩散,反之,越有利于污染物累积,白天午后边界层高度明显高于夜间。(3)此次冷空气南下带来的沙尘由于远距离输送未对宜宾市PM_(10)浓度造成显著影响,冷空气主体入境后颗粒物浓度显著下降,但沙尘沉降导致近地面PM10浓度升高。(4)气温、风速、相对湿度、边界层高度等气象条件对颗粒物稀释和扩散均有重要影响。通过分析,证明了颗粒物通量激光雷达用于小尺度大气污染物立体传输监测的可行性,可进一步应用于污染来源精确查找、建立大气污染模型、城市空气质量预警预报等方面。

In order to explain the cause of urban air pollution,particle flux lidar was used to monitor the three-dimensional transmission of atmospheric particulate matter over Yibin city.The pollution process and particle transport characteristics were analyzed statistically by using the lidar data of particle flux and combined with ground meteorological observation data and particle monitoring data in Yibin city from February 12 to 17,2020.The results showed that,(1)The monitoring results of particulate flux radar can better explain the variation of the concentration of particulate matter on the ground.In this pollution process,three significant PM_(2.5)inputs,one PM_(2.5)and PM10outputs,one PM10input,were detected.(2)The height of the boundary layer was related to the diffusion of atmospheric pollutants.The higher the boundary layer was,the more conducive it was to the diffusion of pollutants,conversely,the more conducive it was to the accumulation of pollutants.The height of the boundary layer is significantly higher in the afternoon of the day than at night.(3)Due to the long-distance transportation,the dust brought by the cold air southwards has no significant influence on PM10concentration in Yibin,and the concentration of particulate matter decreased significantly after the entry of the main body of the cold air,but the dust settlement led to the increase of PM10concentration near the ground.(4)Meteorological conditions such as air temperature,wind speed,relative humidity,boundary layer height have important effects on the dilution and diffusion of particulate matter.Through the analysis,it is proved that the particle flux lidar can be used to monitor the three-dimensional transmission of small scale air pollutants,and it can be applied in the accurate identification of pollution sources,the establishment of air pollution model,and the early warning and forecast of urbanair quality in the further.