中文摘要：

2012年6月9-11日淮安及周边地区出现了一次严重雾霾天气,PM2.5、NOx、CO、SO2等大气污染物浓度急剧升高.本文综合利用地面空气污染监测资料、气象观测资料,分析了该次雾霾过程中污染物的变化特征和影响因素,并对污染物的来源进行了探讨.结果发现：在这次连续雾霾过程中,SO2的质量浓度都在0.049 mg/m3以下;NOx、PM2.5、CO的质量浓度与能见度呈反相关,并在整个雾霾过程中出现两个峰值,均出现在能见度低于1 000m的雾过程中;在雾霾天气过程中,中低层一直维持一个逆温层结,其中四个时次中逆温层底在975 hPa,逆温层顶在925 hPa附近,这种稳定的大气垂直结构不利于大气湍流、水汽的垂直交换以及污染物的垂直扩散,为雾霾的长时间维持创造了良好的热力条件.整个雾霾过程中,近地层始终维持偏东风向,能见度在风速下降的时候随之下降,在风速增大的时候随之增大.应用轨迹模式分析表明,有利的天气条件和大面积秸秆燃烧的结合是造成这次淮河下游连续雾霾过程发生的主要原因.

英文摘要：

Huai＇an and surrounding area experienced a serious fog-haze event during June 9--11,2012. The concentrations of PMz 5, NOx, CO, SO2 increased remarkably during this period. Based on the air pollution monitor data and the synoptic observation information, the air pollution characteristics, influence factors and the sources were analyzed.The results showed that the SO2 concentration was always lower than 0. 049 mg/m3, NOx, PM2.5, CO concentration was inversely related with visibility and had two peaks when the visibility was lower than 1 000 m in the whole process.During the fog-haze progress,inversion layers maintained at the low-level, whose bottom was at 975 hPa and the top near 925 hPa.The stable structure restrained the atmospheric turbulences, vertical exchanges of water vapor aswell as vertical diffusion of pollutants, and thus created good thermal conditions for the maintenance of the fog-haze process.There remained easterly winds during the whole progress and the visibility changed with the wind speed synchronically.By tracking the air mass from the simulations of the HYSPLIY4. 8 model, we found that this fog-haze process over the lower reaches of Huaihe River was mainly caused by the weather condition and crop residue burning.