Numerical Simulation of Air Pollution over Kanto area in Japan using the MM5/CMAQ Model -Comparison of Air Pollution Concentration between two different climatic days

In recent years, the air pollution has become an important problem in parallel with the increasing energy use. The sources of the pollutants are the emissions from the industrial facilities, motor vehicles and heating systems. The climatologic factors such as precipitation, cloud, fog especially urban heat island (UHI) play important roles on the concentration of the air pollutants. Conversely, air pollution also has important effects in modifying urban climate in various ways such as by increasing long-wave radiation from the sky in the canopy layer, and increasing absorption of short-wave radiation in the boundary layer. It is found that UHI can increase the rate of chemical reaction between nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs), this lead to significantly increase surface ozone concentrations in city areas. In this paper, as the first stage we would like to investigate influence of climatic change on the atmospheric pollution over Kanto area in Japan using the MM5/CMAQ model by two case studies; (1) simulation period with normal weather, and (2) the period that it's the weather pattern associated with climatic change. The simulation results were compared with observation data. The results indicate that the high temperature and weak wind speed lead to significantly increase O3 concentration, especially in the afternoon. When the temperature increases by 1 to 3oC, the O3 concentration can increase 10 to 30 (ppbV) at Otemachi, Tokyo. From this research, it is said that effect of UHI event on atmospheric environment is very significant. However, there were only two case studies, it is necessary to exactly simulate structure and characteristic of UHI and its impact on atmospheric pollution. That is our research interests in future work.