保定市霾特征与成因分析

Analysis of Haze Characteristics and Formation Causes in Baoding City

选取京津冀典型地区——保定市作为研究对象,分析了保定市霾特征并且从污染物与气象因素角度对保定市霾的成因进行探究。首先,通过对2005~2013期间年均霾日数以及2013年月均霾日数的整理,发现保定市年均霾日数达到100天左右,且冬季月份霾日数最多,春节月份最少。其次,结合2014年2月、3月常规污染物（CO、SO2、NO2、PM10、PM2.5）数据与能见度数值的分析,发现与低能见度（〈10 km）相关的4种污染物（CO与能见度不具有相关性）浓度阈值分别为75 ug/m3,60 ug/m3,200ug/m3,100 ug/m3。当污染物浓度高于此值时,能见度变化不明显;当污染物浓度低于此值时,能见度变化明显。另外,通过分析2013年全年气象因素（相对湿度、温度、风速、气压、雨量）与能见度的变化,发现相对湿度、风速对能见度的影响最大,而小雨可以加重霾污染。最后,通过对比2013年1、2月霾形成因素与往年的变化,表明相对湿度增加是此时期霾污染加重的主要原因。

This paper chooses Baoding City, a typical city in Beijing -Tianjin - Hebei region, as the research object and analyzes its haze characteristics and formation causes from the aspects of pollutants and meteorological factors. First, the annual haze days between 2005 and 2013 and monthly haze days in 2013 were analyzed, indicating that the haze pollution in Baoding City is serious （about 100 days per year） and that the maximum and minimum values in a year occur in winter and spring respectively. Then, the data of normal pollutants （CO, SO2, NO2, PMIO, PM2. 5） in February and March of 2014 and visibility were analyzed, and the results showed that the pollu- tants＇（ CO excluded due to irrelevance） threshold concentration corresponding to the low visibility （ 〈 10 km） are about lOOug/m3, 50ug/m3, 250ug/m3, and 150ug/m3 respectively. Further analysis indicates that the relation- ship between pollutants concentrations and visibility appears in a non-linear correlation. When pollutants concentra- tions are very high （above threshold concentrations） , the change in visibility is not noticeable. By contrast, when pollutants concentrations are lower than threshold concentrations, the change in visibility is very sensitive to pollu- tants concentrations. In addition, the study shows that RH and wind speed have a significant effect on visibility, and small rain can make haze worse. Finally, by comparing haze formation causes in January and February of 2013 with those in previous years, it was found that the severity of haze in January and February of 2013 was caused by the increase of RH.