基于后向轨迹模式对北京市PM2.5来源的探讨

Discussion on the Source Distribution and Transmission Characteristics of PM2.5 in Beijing Based on Backward Trajectory Model

中文关键词:  后向轨迹模式  PM_2.5来源分布  传输特征  北京市

英文关键词:backward trajectory model  source distribution of PM_2.5  transmission characteristics  Beijing

中文摘要:

      近年来中国经历了数次大范围雾霾天气，北京等多个城市更是遭遇连续雾霾。造成雾霾天气的主要污染物PM_2.5又称细颗粒物。为了进一步治理北京雾霾，为制定政策提供依据，须了解北京地区PM_2.5的来源。本文基于后向轨迹模式并结合PM_2.5浓度计算了2015年9月1日0：00至2016年8月31日23：00以北京为起始点，向后推算48小时的轨迹，并结合轨迹聚类分析法、潜在源贡献因子法（PSCF）、浓度权重轨迹分析法（CWT）等，探讨北京地区PM_2.5的来源。结果表明：模拟的后向轨迹经过聚类分析可分为6类，其中来自内蒙古西部的轨迹最多，来自西北、北西北方向的轨迹次之，来自西西北方向且在京津冀地区停留一段时间的轨迹占比最小，来自河北、山东、河南的交接地区及河北的沿海地区的轨迹占比也较小。其中来自内蒙古西部地区及河北、山东、河南交界地区的两类轨迹对北京的空气质量有较大的影响，是北京PM_2.5污染的主要潜在源区；来自北西北方向及河北的沿海地区两类轨迹的气团最为清洁，为北京带来良好的天气；来自西北及西西北方向的部分轨迹对应的PM_2.5浓度严重超标，说明来自此方向的气团对北京的空气质量也有一定的影响。

英文摘要:

      China has experienced several large-scale haze weather in recent years, Beijing and other cities are facing to consecutive haze. The main pollutants of haze weather are PM_2.5, also called fine particulate matter. In order to better governance haze in Beijing, provide reference for making policy, its source of PM_2.5 must be understood. Based on the backward trajectory model and combining the PM_2.5 concentrations, using Beijing as the starting point, the backward 48 hours trajectory from 0:00 on September 1, 2015 to 23:00 on August 31, 2016 were calculated, and then the trajectory clustering analysis method, the potential source contribution factor weights (PSCF) and the concentration of the trajectory analysis (CWT), etc., were used to discuss the source of PM_2.5 in Beijing. The results showed that the simulated track after a clustering analysis can be divided into six categories, trajectories from western Inner Mongolia were the most, second with trajectories from northwest and north-northwest, trajectories from west-northwest which stay in Beijing-Tianjin-Hebei region for a period of time are the minimum, trajectories from the transition region of Hebei, Shandong, Henan and from coastal areas of Hebei were also smaller. Two types of PM_2.5 trajectories from western Inner Mongolia and transition region of Hebei, Shandong, Henan have large effects on local air quality, which are major potential source areas of PM_2.5 pollution in Beijing; Air mass from north-northwest and the coastal areas of Hebei are the most clean, which bring good weather for Beijing; PM_2.5 concentration of parts trajectories from northwest and west-northwest exceeded bid badly, which also had certain impact on the air quality in Beijing.