长三角背景区域一次污染过程特征及成因分析

Analysis of Characteristics and Causes During a Pollution Process in Background Area of Yangtze River Delta

该文基于偏振拉曼激光雷达探测及大气污染物浓度数据,结合气象观测资料和HYSPLIT后向轨迹模式,对2019年12月2-16日长三角背景区域一次典型的大气污染过程开展分析。结果表明:颗粒物浓度上升与边界层降低存在较好的时空一致性,边界层降低8 h后,颗粒物浓度上升至峰值,PM;浓度为107.4μg/m^(3)。污染过程开始时,垂直尺度的消光系数廓线逐渐抬升,污染地区上空出现消光系数的高值区,高度为500~600 m,与边界层高度一致。污染期间消光系数变化规律与洁净期间背景值存在时间差异,洁净期间的高值出现在14-18时,污染期间高值出现在20-22时,垂直尺度方面两者保持一致。污染过程形成的主要原因为:局地输送、静稳天气形势和边界层高度下降使污染物浓度快速增长。

Based on polarization Raman lidar detection and atmospheric pollutant concentration data,combined with meteorological observation data and HYSPLIT backward trajectory model,a typical atmospheric pollution process in the background area of the Yangtze River Delta from December 2 to December 16,2019 was analyzed.The results show that there is a good temporal and spatial consistency between the increase of the particle concentration and the decrease of the boundary layer.After 8 hours of the decrease of the boundary layer,the particle concentration rises to the peak,and the PM;concentration is 107.4μg/m^(3).At the beginning of the pollution process,the extinction coefficient profile of the vertical scale gradually rises,and the high value area of the extinction coefficient appears over the polluted area,the height is 500~600 m,which is consistent with the height of the boundary layer.There is a time difference between the extinction coefficient change rule during the pollution period and the background value during the cleaning period.The high value during the cleaning period appears from 14:00 to 18:00,and the high value during the pollution period appears from 20:00 to 22:00.The vertical scale of the two is consistent.The formation of this pollution process is mainly due to local transportation,static and stable weather conditions,and the decline in the height of the boundary layer,which has caused the concentration of pollutants to increase rapidly.