2013年12月石家庄一次霾天气过程中的黑炭浓度特征

Characteristics of black carbon concentration in Shijiazhuang under haze weather conditions during December,2013

2013年12月5日-27日石家庄地区连续出现霾天气,大气日均能见度为0.2-8km,其中大约89.53%的时间大气能见度不足5km.分析12月10-27日期间的黑炭固定观测数据表明：1）黑炭浓度均值为39.84μg/m^3,日变化具有明显的双峰结构,第1个峰值在上午9：00左右,第2个峰值在夜晚21：00-24：00;2）黑炭浓度小时均值与大气能见度小时均值之间呈负相关关系,当黑炭浓度大于固定观测期间的均值时,重度霾发生的概率为97.78%.此外,通过在车辆上安装黑炭分析仪和GPS接收机对石家庄市区主干道进行了多天的移动观测,结果表明：黑炭浓度与交通密度和街道特点（道路类型、交通密度）直接相关;市区二环的黑炭浓度较高,大约是二环内黑炭浓度均值的1.48倍;市中心区的黑炭浓度相对较低,且呈现明显的东西-南北向差异性.

A prolonged heavy haze event occurred in Shijiazhuang, Hebei province, China, from December 5th to 27th, 2013. The visibilities variates from 0.2 to 8 km and there are approximately 89.53% days with visibility lower 5 km during this period. The aethalometer for measuring black carbon was deployed in the 2^nd Institute of Surveying and Mapping of Hebei Province, and the data showed that, 1） the averaged black carbon mass concentration （CBc） was 39.84lag/m^3; 2） the diurnal variation presented a bimodal distribution with the first peak at 01：00 （UTC Time） and the second peak at 13：00-16：00; （UTC Time） 3） a negative correlation can be observed between hourly averaged CBc and hourly averaged visibility; 4） the probability of occurrence of serve haze hours was 97.78% when the CBC was higher than the averaged CBC. In addition to the fixed station measurements, mobile measurements were conducted on the main roads in Shijiazhuang downtown for several days, using a car which was equipped with an aethalometer and a GPS receiver. The results showed that the CBC was obviously related to the traffic density and street characteristics （road type and traffic density）. The CBC over the 2^nd ring road was 1.48times higher than that within the 2^nd ring road. The CBC over downtown areas was lower and presented a significance difference between south, north direction.