The Use Of CALINE4 Model To Simulate The Motor Mobile CO Diffuse Pollution Of The Main Road In Xi'an City

The number of the motor mobile in the Xi'an city is increasing with the high speed of 12.7% in these years.There have been 370 thousand of motor vehicles in the urban until the end of the year 2004. It brings prosperity to the economy, and it also contributes much to the air pollution in Xi'an city.It's a complicated process for the vehicular exhaust to disperse in the street. Many factors may affect this process such as the meteorological factors , street geometry and so on.This article analyses the composition and the flow of the motor mobile in the Xi'an city. Some typical streets are selected as the objects of this study.The author analyses the CO and NO₂ concentration in the bilateral of the street of the peak time and discovers the CO is overproof seriously in the objects of this study.The highest concentration in a hour is 51.625mg/m³, which is 4.16 higher than the national standard and the rate of it is 83.33%. The highest concentration of NO₂ in a hour is 0.732mg/m³, which is 2.05 higher than the national standard and the rate of it is 50%.CALINE4 is selected to simulate the dispersion process of the vehicular exhausts in the streets according to the characteristics of the meteorological conditions and street geometry in Xi'an city. The author use this model to simulate the motor mobile pollution in the sidewalk of the object of the beidajie,dongdajie and nanerhuan street.The result shows that the CALTNE4 model is suitable for the CO simulation in the sidewalk of the street.Against the situation that the simulated value is less than the measured value, The author modifies the CALINE4 model and set up a parameterize plan. The modeled value of the modified CALINE4 and the measured value show good pertinence. The precise rate of the result in beidajie is from 87.5% to 93.75%.The author uses the modified model simulating the CO in the way of time and space in the sidewalk of the beidajie, dongdajie and nanerhuan street. And use the model calculates themaximum standard car flow in the street at various wind speed in order to make the CO in the sidewalk not overproof. Finally, the auther gives some advices to reduce the motor car pollution.