2019年西安首场雾霾PM2.5关键特征的综合诊断

通过对WRF-Chem（Weather Research and Forecasting Model Coupled to Chemistry）环境模式模拟资料、HYSPLIT（HYbrid Single Particle Lagrangian Integrated Trajectory Model）前/后向气团轨迹资料、环境站监测资料,以及西安理工大学（Xi''an University of Technology,简称XUT）多波长激光雷达、米散射激光雷达、能见度仪、粒谱仪等观测资料的综合诊断,探讨了2019年1月初发生在西安的雾霾过程（记为首场雾霾）PM_2.5组分、分布及传输特征,旨在为雾霾气溶胶研究提供有益的个例积累.定性、定量双重检验表明,Chem模式较成功复制了此次雾霾气溶胶过程.利用这些可靠的模式数据分析表明,PM_2.5中碳气溶胶的主要组分为有机碳,约占85%,强盛期气溶胶各组分随高度增加均呈递减趋势,各组分近地面浓度最高.通过对两类不同方法获取的消光系数对比分析表明,相比于模式数据,激光雷达数据具有更高的垂直分辨率,因此,更善于描述消光廓线的细节特征.通过对多源资料的综合诊断最终揭示出,"北风涌"是雾霾消散的关键影响因子,沿铜川-西安-山阳一带存在着污染物传输的重要路径,雾霾由此体现出自北向南依次消散的特征.

The characteristics of PM2.5 about the component, distribution and transmission during the first fog-haze process in Xi'an in 2019 by using SACDM

Based on the multi-source dataset including the American WRF-Chem (Weather Research and Forecasting Model Coupled to Chemistry) data, the American HYSPLIT (HYbrid Single Particle Lagrangian Integrated Trajectory Model) data, the Chinese environmental station observation data, and the special observation data (the multi-wavelength lidar, the Mie scattering lidar, the visibility meter, and particle size spectrometer) collected from Xi''an University of Technology (XUT), the key characteristics of PM_2.5 about the component, distribution and transmission during the first fog-haze episode occurred in early January 2019 in Xi''an were studied by using the Synthetically Analysis and Classifying Diagnosis Method (SACDM). The paper aimed at providing the features of the fog-haze aerosols in the typical case. The fog-haze process was successfully copied by WRF-Chem according to both qualitative and quantitative test, and the characteristics on the component and distribution of PM_2.5 were discovered by analyzing the model data. The main carbon-aerosol component of PM_2.5 was organic carbon, with a value of 85%. In the mature phase of fog-haze, the aerosol decreased with the increase of height, and got a zero at about 5 km. With a higher vertical resolution than the model data, the lidar data were better at describing the detailed features of the profile of extinction coefficient. And the double fog-haze layers including the surface ground and 3.7 km layer were discovered according to the lidar data. The multi-source data showed that the north-wind surges played a more important role in the transmission process of PM_2.5, and a key pollution channel from Tongchuan to Xi''an to Shanyang was discovered. Therefore, the first fog-haze disappeared with an important phenomenon of south-last and north-first.