常州地区霾的变化特征及影响因子分析

Analysis of characteristics and impact factors of haze in Changzhou

利用2001—2011年常州地区气象观测资料和大气污染物监测资料,对常州地区霾的变化特征及影响因素进行了分析。结果表明:常州地区年霾日数呈波动变化特征。常州地区11月至翌年1月霾出现较多,夏季霾出现最少;11时霾出现频次最多,14时次之,05时霾出现频次最少。霾发生时高空主要存在两种天气形势,地面存在3种天气形势。有降水出现时,如降水明显,不易出现霾;如降水较弱,可能出现霾,但出现几率较小。大气垂直方向的逆温对霾的出现有重要作用。常州地区霾出现时以2级以下偏东风为主,相对湿度多为41.0%—70.0%。大部分雾日(除雨雾外)基本上均出现霾,有雾霾的转换现象发生。2001—2011年常州地区污染物中CO、PM_(10)浓度与霾关系较密切(2012年常州环境监测中心开始PM_(2.5)的监测)。个例分析表明,秸秆焚烧在有利的风向下将污染物输送至下游地区,加上气团的下沉运动使污染物聚集是霾出现的主要原因。

Based on the meteorological observations and air quality data obtained from environmental monitoring center in Changzhou from 2001 to 2011, the characteristics of haze and its impact factors were analyzed in this study. The results indicate that annual cumulative haze days fluctuate largely. The occurrence frequency of haze is larger from November to January,and smallest in summer. Haze occurs most frequently at 11： 00,f ollowed by14： 00,and least at 05： 00 in order. The haze formation is usually accompanied with two weather types at upper atmosphere,and three weather types near the surface. Haze dose not occur under strong rainfall conditions,but sometimes occur under weak precipitation conditions. The inversion layer favors greatly the haze formation. Haze in Changzhou usually occurs under conditions with weak easterly winds under 2 grades and with relative humidity between41. 0% and 70. 0%. The fog-haze transmission always exists in most of fog events（ except rain-fog）. There is very close relationship between haze,CO,and PM10 from 2001 to 2011 at Changzhou. According to a haze case,it shows that the straw burnings,pollutants transported by winds,and air descending motions are major reasons for this haze process.