基于激光雷达分析2020年冬季镇江地区一次大气污染过程

Analysis of an Air Pollution Process in Zhenjiang in the Winter of 2020 Based on Lidar

利用气溶胶激光雷达观测结果,结合环境监测站污染物浓度数据、气象观测资料及HYSPLIT后向轨迹模式结果,综合分析2020年1月17—22日镇江市一次大气污染过程。结果显示,此次污染过程前期天气形势稳定,不利于污染物的清除及扩散,后期受偏北风影响,北方污染物向镇江输送,使得本地污染物持续累积,污染不断加重。特征雷达图分析表明此次污染为以PM_(2.5)为主的二次污染。激光雷达显示污染日消光系数为0.0~0.9 k^(m^(-1)),消光系数垂直廓线日变化特征明显,气溶胶粒子主要堆积在0.6 km高度以下,并且很好地揭示了污染气团从高空逐渐下沉最终与本地污染叠加的过程,与HYSPLIT模式解析的污染气团来源结果基本一致。

During January 17-22,2020,a moderate pollution process happened in Zhenjiang,which was impacted by accumulation of local pollutants and regional pollutants transportation.Based on the analysis of aerosol lidar data,air pollutant data from surface observation,meteorological data,combined with the simulation results of HYSPLIT backward trajectory model and the analysis of aerosol extinction coefficient data obtained from inversion,the vertical distribution and evolution of pollutant concentration,the pollutant source,evolvement course of weather system during this moderate pollution process were analysed.The results showed that the synoptic situation in the early stage of the pollution process was stable,which was not conducive to remove and diffuse pollutants.In the later stage of the pollution process,affected by the northerly wind,the northern pollutants were transported to Zhenjiang,which caused the accumulation of local pollutants and eventually led to continuous pollution.The characteristic radar chart analysis showed that this pollution was a secondary pollution,and PM_(2.5) was the main pollutant.Lidar related data showed that the daily extinction coefficient of pollution was in the range of 0.0-0.9 km^(-1),and the diurnal variation of vertical profile of the extinction coefficient was obvious.Besides that,the aerosol particles mainly accumulated below 0.6 km.The results of the lidar excellently revealed the developing process of the polluted air mass:the polluted air mass gradually subsided from a height of 1.5 km and finally superimposed with the local pollution.This was basically consistent with the source of polluted air mass analyzed by HYSPLIT model.