2013年10月长株潭城市群一次持续性空气污染过程特征分析

2013年10月21~31日长株潭城市群经历了一次持续性空气污染过程.利用地面空气质量监测资料、地面气象资料及探空资料综合分析了此次污染过程与大气环流、边界层气象条件之间的相互关系,并利用卫星遥感火点监测资料和HYSPLIT4模式,分析了此次过程大气污染物的来源及输送路径.结果表明,过程前期(21~26日),污染物缓慢积累,过程后期(27~31日),PM2.5、CO、NO2等焚烧特征污染物浓度急剧升高,秸秆焚烧污染物的长距离输送是后期空气污染加重的主要原因.火点监测和后向轨迹分析表明,过程前期气流主要流经长株潭城市群东北方向的安徽、湖北等地,流经地区火点分布较少,后期气流主要流经长株潭城市群东南方向的江西等地,流经地区火点分布较多.高压均压场背景环流导致的稳定大气层结、南北冷暖气流对峙造成的地面静小风,是长株潭城市群污染过程发展、维持和加强的重要条件,污染物长距离输送对长株潭城市群区域空气质量有重要影响.

Characteristic Analysis of a Multi-day Pollution Event in Chang-Zhu-Tan Metropolitan Area During October 2013

Chang-Zhu-Tan Metropolitan Area experienced a typical multi-day pollution event in October 2013. Based on the air pollution index, conventional pollutants observations, surface meteorological observations and sounding data, the relationships of air pollution, large-scale circumfluence and boundary layer meteorology of this event were comprehensively analyzed. Additionally, the sources and transport paths of pollutions were investigated by application of satellite remote sensing data and HYSPLIT4 model. The results showed that pollutants gradually accumulated in the earlier stage of the event (October 21th to 26th), while in the later stage (October 27th to 31th) the characteristic pollutants of crop residue burning (PM_2.5, CO, NO₂) sharply increased. The deterioration of air quality in the later stage was mainly related to the remote transport of pollutants caused by straw burning. Analysis of simulations of HYSPLIT4 model and fire spots showed that the currents mainly came from Anhui and Hubei Province in the earlier stage, while in the later stage they were mainly from Jiangxi Province where fire spots were intensively located. Stable atmospheric stratification caused by steady uniform high-pressure field and slight wind due to the confrontation of cold and warm currents greatly contributed to the development, maintainability and reinforcement of the pollution event. The remote transport of pollutants had a significant impact on ambient air quality of Chang-Zhu-Tan Metropolitan Area.