NUMERICAL SIMULATION OF THE SEASONAL VARIATION OF TROPOSPHERIC OZONE OVER CHINA

An updated version of the Regional Acid Deposition Model(RADM)driven by meteorological fields derived from Chinese Regional Climate Model(CRegCM)is used to simulate seasonal variation of tropospheric ozone over the eastern China.The results show that:(1)Peak O₃ concentration moves from south China to north China responding to the changing of solar perpendicular incidence point from south to north.When solar perpendicular incidence point moves from north to south,so does the peak O₃ concentration.(2)In the eastern China.the highest O₃ month-average concentration appears in July.the lowest in January and the medium in April and October.The pattern mainly depends on the solar radiation,the concentration of O₃ precursors NO_x and NMHC and the ratio of NMHC/NO_x.(3)Daily variations of O₃ over the eastern China are clear.Namely,O₃ concentrations rise with the sun rising and the maximums appear at noon.then O₃ concentrations decrease.The highest daily variation range of O₃ appears in summer(40×10^-9 in volume fraction)and the lowest in winter(20×10^-9 in volume fraction).(4)Daily variations of O₃ over the western China are not clear.The daily variation range of O₃ is less than 10×10^-9 in volume fraction.