基于卫星遥感和地面观测资料的霾过程分析--以长江三角洲地区一次严重霾污染过程为例

Analysis of haze events based on satellite remote sensing and field observations: a case study of severe haze pollution over the Yangtze River Delta

利用MODIS、CALIPSO卫星观测的气溶胶产品和地面空气质量、气象资料,并结合HYSPLIT后向轨迹模式,探讨了2013年12月1∽9日长江三角洲地区一次持续性的严重霾污染过程的形成、特征及其可能来源.研究表明,此次污染过程中长江三角洲地区8个代表城市大部分时间处于霾污染的状况下,气溶胶光学厚度（AOD）显著增长,空气质量指数（AQI）均达到或超过污染限值,且以中度以上污染为主.污染发生时,气溶胶主要存在于地面至2km的大气层内,尤其是850m以下.根据体积退偏比和色比得出球形气溶胶出现频率高于非球形气溶胶,大粒径气溶胶出现频率高于小粒径气溶胶,进而得到污染期间气溶胶的主要类型为＂污染型＂气溶胶.污染物的近距离的输送和持续小风,无降水的静稳气象条件而导致污染物难以扩散稀释而累积在本地是造成长江三角洲区域污染范围广、时间长、程度重的主要原因.

A continuous air pollution event occurred in the Yangtze River Delta during from December 1 to 9, 2013. The formation, characteristics and potential sources of this air pollution event were explored by using the aerosol products of MODIS and CALIPSO satellite, ground air quality, meteorological data and HYSPLIT backward trajectory model. The results showed that, the 8 typical cities of the Yangtze River Delta were dominated by the haze pollution during this event. Aerosol optical depth（AOD） increased significantly, air quality index（AQI） reached or was higher than the limit value of pollution, and it is mainly higher than the level of moderate pollution. During the event, the aerosol mainly exist in the level from the ground to 2km above, especially under 850 m. Based on volume depolarization ratio and color ratio, the higher frequency of spherical aerosol than that of non-spherical aerosol and the higher frequency of large size aerosol particle than that of small aerosol particle indicated that the main aerosol type was ＂pollution＂ aerosol during the pollution event. Short distance transport of pollutants and static weather conditions with continuous low wind speed and no precipitation which made the pollutants difficult to disperse, led to the widespread, long-time and severe pollution event in the Yangtze River delta.