北京市夏季臭氧前体物控制区的分布特征

利用Models-3/CMAQ模式系统, 对北京市2010年6-8月逐日的臭氧前体物控制区进行5种类型的划分, 使用各类控制区在研究期间出现的频率表征北京夏季臭氧控制区空间分布的总体特征。结果表明, 从北京市城近郊区到远郊区县, O₃生成由主要受VOCs控制逐渐转变为VOCs和NO_x共同控制, 进而过渡到主要受NO_x控制。在北京城近郊区, 人为源VOCs减排能够有效控制当地O₃的天数占夏季总天数的一半左右, 而在昌平、延庆和怀柔等西北远郊区县, 人为源NO_x减排能够有效控制其O₃的天数约占40%~50%。北京市前体物减排对O₃控制效果不明显的情况在各区县普遍存在, 其中东部和南部区县出现这种情况的天数比例可达70%以上。对于臭氧的最大1小时浓度和最大8小时浓度, 二者的前体物控制区在北京市有相似的分布特征。

Characteristics of the Spatial Distributions of Ozone-Precursor Sensitivity Regimes in Summer over Beijing

Models-3/CMAQ was applied to simulate the ozone-precursor sensitivity during June, July, and August, 2010 in Beijing. Frequencies of ozone-precursor sensitivity regimes were used to represent the characteristics of the spatial distributions of the regimes. Results showed that ozone formation was VOCs-sensitive in urban Beijing, and turned to be mixed sensitive and NO_x-sensitive in suburban areas and more remote areas of Beijing. In urban Beijing, the number of days that a reduction of anthropogenic VOCs could reduce ozone efficiently accounted for about 50% of the whole summer; while in Changping, Yanqing and Huairou, the number of days that a reduction of anthropogenic NO_x could reduce ozone efficiently accounted for 40%~50%. The situation that ozone gave little response to the reduction of both two precursors occurred in every district/county. The number of days in this situation accounted for more than 70% in eastern and southern districts/counties. The distributions of the sensitivity regimes of maximum 8-hour ozone concentration were similar to that of 1-hour ozone concentration.