Process analysis of O3 formation in summer at Beijing
北京市区夏季O3生成过程分析

A three dimension air quality model CMAQ-MADRID was employed to simulate O_ 3 pollution in summer at Beijing. IPR and IRR, modules of process analysis in CMAQ, were used to explore the O_ 3 building process in urban area with focus on radical and NO_x cycles. In urban area, strong oxidation capacity was spread to full boundary layer, and O_ 3 formation was in VOC-limited regime. Obvious discrepancy of O_ 3 building process existed between surface layer and upper level of boundary layer, with high O_ 3 production rate at altitude of 200~800 m, and the high O_ 3 concentration at surface layer mainly came from O_ 3 vertical transportation of upper air. Since NO_x emission was concentrated at surface layer, new NO input was quite high and NO_x chain length was only 1.3, resulting in a low O_ 3 yield. At upper level of boundary layer, where the oxidation capacity was strong and new NO input was low, NO_x chain length reached 5.0, thus O_ 3 yield there was rather high.