广州市冬季灰霾天气过程消光特性研究

摘要

In order to understand the origin of haze in Guangzhou and further provide basic data and scientific support for improving atmospheric visibility,the mass concentrations of water-solubility ions,organic carbon,element carbon of fine particle were monitored during two haze events (1st-4th and 5th-8th,Dec 2013) at the Guangzhou Atmospheric Supersite,and the characteristics of atmospheric light extinction were studied by IMPROVE formula.The results indicated as follows.The average value of atmospheric light extinction was (505.55±241.05) Mm-1 in winter while the contribution of OM,(NH4)2SO4,EC,NH4NO3 to atmospheric light extinction were 43.84％,24.1％,13.17％ and 8.4％,respectively.Thus OM replaced (NH4)2SO4 as the primary extinction contributor.Furthermore,the trends of extinction coefficients of OM and EC were similar,which indicated that they had the same source and came from vehicle emission.The extinction contribution of NH4NO3 increased significantly during the first pollution episode,which caused by stable metrologieal condition and local vehicle emission in contrast the extinction contribution of (NH4)2SO4 has significant contribution during the second pollution episode,hence considering the analysis of aerosol Lidar and air mass backward trajectory model of HYSPLIT,regional pollution transportation might be the major reason.%为了解广州地区灰霾天气成因,以及为改善大气能见度提供基础数据和科技支撑,基于广州大气超级站,对广州冬季两次灰霾天气过程(2013年12月1-4日,5-8日)细颗粒物中水溶性离子、有机碳及元素碳进行在线观测,通过IMPROVE核算方程研究了灰霾天气过程的消光特性.结果表明:广州冬季大气消光系数均值为(505.55±241.05)Mm-1,主要消光物质为OM、(NH4)2SO4、EC和NH4NO3,分别占总消光的43.84％、24.1％、13.17％和8.4％,OM消光贡献超过了(NH4)2 SO4成为广州首要的消光物质.观测期间,OM、EC消光变化趋势一致,说明OM和EC具有共源性,主要来自机动车排放.第一次污染过程NH4NO3消光贡献明显增大,与静稳天气,局地机动车排放有关.第二次污染过程(NH4)2SO4的消光贡献较为显著,结合气溶胶激光雷达和HYSPLIT后向轨迹模型分析判断可能与区域污染输送有关.