街道峡谷汽车污染模拟研究

Modeling air pollution from traffic in urban street canyon

为了评价城市环境质量，需要准确模拟城市街道汽车排放污染物的扩散。该文利用道路边ＣＯ和ＮＯｘ的常年监测数据，系统测试了由丹麦国家环境研究所开发的街区空气污染扩散模式ＯＳＰＭ，分析了影响模拟精度的主要因素。针对北京市街道相对比较开阔的特点，在分析街道涡流和流场特征的基础上，修改了模式中街道风速的拟合关系，将地面风速系数增大到２．８倍，经实测数据验证。

The study is aimed to provide a general model for traffic pollution in urban street canyons, which is very crucial for the assessment of human exposures. The monitoring data of hourly average concentration of CO and NO x from a traffic road in Beijing was collected and analyzed for the whole year 1995. An urban street canyon dispersion modelOSPM originally developed in Denmark, was tested by the monitoring data set. Major factors were addressed which have great impact on the performance of the model: NO x emission from stationary sources in heating season and high CO emission factors (about 2 times of Copenhagen). Although the model is capable of reflecting the basic pattern of the dispersion, calculated results are much higher than measurements. When primary modification was carried by enlarging the ground level wind to a factor of about 2.8, some improvement were observed.