基于气溶胶和大气风场激光雷达对北京一次沙尘过程分析

Analysis of a Dust Process in Beijing Based on Aerosol and Atmospheric Wind Field Lidar

基于北京南郊观象台的气溶胶激光雷达探测得到的气溶胶消光系数和粒子退偏振比,多普勒测风激光雷达探测的大气风场、地面气象要素PM10等综合观测资料,对北京2017年5月4日至5日的一次强沙尘天气过程进行分析。结果表明:5月3日下午水平风速开始减小,高空中出现垂直向下的气流,利于沙尘从高空降落到地面;5月4日12时至20时之间,在40~1350m整个高度层出现统一向上的垂直气流,速度最高达到2m/s,导致低空沙尘向高空扩散;从激光雷达的数据可以得到沙尘的立体分布情况,初期沙尘层高度在1km左右,中期沙尘高度在2km左右,后期沙尘高度回归到1km左右;激光雷达最低观测高度处的消光系数与地面PM10浓度变化的相关系数为0.8308。研究表明气溶胶激光雷达和测风激光雷达相结合能够有效地监测和预报大气气溶胶的分布及扩散。

Based on the comprehensive observation data observed in the Beijing southern suburbs observatory,such as aerosol extinction coefficient and particle depolarization ratio obtained from aerosol lidar detection,wind field obtained from Doppler wind lidar,PM10 and ground meteorological elements,we analyse strong sand and dust weather process on May 4-5,2017.The results show that on the afternoon of May 3,the horizontal wind speed begins to decrease,and the vertical downward airflow appears in the upper air,which are conducive to the dust falling from high altitude to the ground.During 12：00 to 20：00 of May 4,the vertical air flow occurs in the entire height layer from 40 m to 1350 m,and the maximum speed reaches 2 m/s,leading to the spread of low-level dust to high altitude.The three-dimensional distribution of dust is obtained from the lidar product：the initial dust layer height is about 1 km,the mid-term dust height is about 2 km,and the later dust height gets over to be about 1 km.The related coefficient of variation between the extinction coefficient of the lowest observation height of lidar and the variation of ground PM10 concentration is 0.8308.The study shows that the combination of aerosol lidar and windmeasuring lidar can effectively monitor and predict the distribution and diffusion of atmospheric aerosol.