沙尘影响下华北地区一次重污染天气形成与消散过程分析

Formation and dissipation processes of a severe atmospheric pollution in north China under the influence of dust

以2017年5月4日～5日华北地区出现的一次大范围的严重的天气污染形成与消散过程为研究对象,通过搜集华北地区9个城市空气中主要污染物浓度、AQI(空气质量指数)和常规气象数据,分析AQI、主要污染物(PM_(10)、PM_(2.5)、SO_2、NO_2、CO、O3)浓度变化特征和相关气象因子的关系。结果表明:本次重污染本质为区域性沙尘污染所致。污染过程呈现出形成速度快、消散急促的特点。该污染过程首要污染物为PM_(10),其次为PM_(2.5),而SO_2、NO_2、CO、O_3等由人类活动产生的污染物浓度并未超标。后向轨迹分析和相关分析发现造成此次严重污染颗粒物主要来自蒙古高原,风是主要驱动因子。污染物在空间位置比较接近的城市间传输时,表现出趋势一致性、时间上的滞后性和污染物浓度的累积性特点。

Air quality has been widely concerned for it exerts great influences,on the people's health as well as the quality of their living environment.The more and more frequent and severe atmospheric pollution occurred in North China has brought lots of worries and concerns.To curb atmospheric pollution,we should have a clear understanding of its formation,dissipation process and its influencing factors.Based on data of pollutants (PM10,PM2.5, SO2,NO2,CO,O3),AQI (air quality index),and meteorological data of 9cities (Beijing City ,Tianjin City,Langfang City,Shijiazhuang City,Baoding City,Xingtai City,Cangzhou City,Dezhou City,Handan Chinese Meteorologic website,using research methods of Hybrid Single Particle Lagrangian City)collected from Integrated Trajectory Model (HYSPLIT)and Principal Component Analysis (PCA),we chose a severe atmospheric pollution happened from May 4to May 5,2017in North China as an example to discuss the variations in pollutant concentration,the source and transportation of pollutants,meteorologic factors that governed the pollution.The results show as follows : (1)the pollutant of PM10was the major pollutant,and it was exogenous ,the pollutants such as SO2,NO2that related closely to human activities remained at a low level.Sand dust weather was the meteorological condition for the heavy pollution in North China.The transport channel of pollutants was the Northwest Airflow resulted from the cold anticyclone in Mongolia Plateau.(2)This atmospheric pollution was very serious,which has great influence on the region.The concentration of PM10was as high as 1000g ·m^-3 in all of the 9cities,and lasted over 20hours.(3) Under the influence of sand dust weather,the processes of formation and dissipation of pollution presented the characteristics of forming sharply and dissipating rapidly.(4)Under the influence of the northwest airflow,the cities in the north and west of this region were affected by sand dust earlier than those in the south and east.In addition,the concentration of pollutants in cities with close spatial locations showed obvious consistent trend and time lag,as well as the characteristics of pollutant accumulation.