2014年北京市CO浓度水平和时空分布

Concentration Level and Spatiotemporal Characteristics of CO in Beijing in 2014

对北京市地面监测站点的CO浓度进行分析,探讨其浓度水平、变化趋势和时空分布特征。2014年春、夏、秋、冬四季北京市CO平均浓度分别为1.06、0.87、1.34、2.17 mg/m^3。CO浓度均呈双峰型变化,第一个峰值出现在07:00—09:00,主要由交通早高峰的排放引起;第二个峰值出现在23:00左右,主要受交通晚高峰排放和夜间边界层高度降低的挤压效应的共同影响。从空间分布来看,全年整体呈现南高北低的分布特征,尤其是秋、冬季较为明显,体现了工业布局和区域传输对CO的影响。从全年来看,湿度对CO浓度的影响最大。对2014年冬季北京市的一次高CO浓度分析结果表明,此次过程是由本地排放和区域传输共同造成的,气象要素中地面气压对CO浓度影响最大。

CO concentrations in air monitoring stations in Beijing were analyzed to investigate their concentration levels,variation trends and temporal-spatial distributions. The average concentrations of CO in spring,summer,autumn and winter in 2014 was 1. 06,0. 87,1. 34 and 2. 17 mg/m^3,respectively. CO diurnal variation showed a double-peak distribution. The first peak of CO appeared at 07： 00-09： 00,which was caused by the early traffic peak. The second peak of CO appeared at 23： 00,which was caused by both evening traffic peak and the decrease of boundary layer height. The annual concentration of CO was higher in the south and lower in the north of Beijing,especially in autumn and winter,reflecting the influence of industrial layout and regional transmission. For the whole year,relative humidity had the most obvious influence on CO concentrations. Both characteristics of local emission and regional transmission were found in a CO pollution episode in winter of 2014,and during which the surface pressure played the most critical meteorological factors.