A Study On The Dynamic Simulation Of Sulfur Dioxide Distribution In Air Based On Multi-box Model

Many developed cities in our country suffer from air quality problems along with the proceeding urbanization in this decade. Air quality prediction is important for pollution control and environmental management. Air quality prediction models usually play an important role in developing effective air pollution control plans. The sulfur dioxide concentration of Shijiazhuang City were measured in 2002. A comprehensive emissions inventory was established in this district. The Meteorology Modeling system, version 5(MM5), was used to obtain the wind velocity and direction data. The meteorological simulation results were compared with the measured data in 2002. The result showed that the simulation data coincided well the measured value. A three dimensional unsteady multi-box model was firstly used to simulate the sulfur dioxide concentration in this district. We firstly used Mesoscale Meteorology Modeling system, version 5(MM5), to obtain meterological data. The data were used as inputs in the Multi-box models. The wind velocity profile exponent, the value vertical diffusion coefficient and the horizonal diffusion coefficient were studied systematically. The iterative steps is confirmed to be 3600 per hour.When adapting the wind velocity profile exponent value recommend by , the vertical diffusion coefficient recommend by , and the horizonal diffusion coefficient is decuple the vertical diffusion coefficient. The mean square error of SO2 is the lowest. So the results showed that the parameters are the best. The sub-boxes size of multi-box model was studied, and the result showed that the size of sub-box also influences accuracy. When the sub-box height was determined by the height of different sources and the variation of SO2 concentration along the vertical direction, the simulated result attain more accuracy. The width and length of multi-boxes were determined according to the distribution of industrial pollutant sources. Simulation with the sub-box size determined as such agree better with the observed data than that with the box size determined according to the functional area of the city.