珠三角地区秋季臭氧生成敏感性时空变化模拟研究

Spatial and temporal distribution of ozone sensitive district in Pearl River Delta region during autumn

应用大气化学在线耦合模式WRF/Chem模式,对发生在珠三角地区秋季臭氧重污染事件进行了模拟.通过敏感性分析,划分臭氧敏感性区域,并研究敏感性区域随时间变化规律与成因.研究发现:在一定的气象条件和污染物排放情况下,VOCs敏感区主要分布在珠三角中心城区及其下风向地区(例如:佛山、中山、江门、珠海、深圳、广州南部以及肇庆南部地区),而NOx敏感区分布在珠三角的上风向郊区(例如:广州北部、惠州).珠三角臭氧敏感区表现出明显的时间变化特征,上午11-12时相较下午14-15时,VOCs敏感区域范围减少,NOx敏感区域范围增加且增幅达51.4%,其变化原因与生物源VOCs排放增加、气团老化、大气稀释扩散增加有关.

Understanding the evolution of severe ozone pollution events is critical for managing public health issues. The Weather Research and Forecasting-Chemistry model（WRF/Chem）is used to study a severe ozone-pollution episode occurred in autumn 2009 over the Pearl River Delta（PRD）.Through analyzing WRF/Chem sensitivity simu-lations,NOx and VOCs-sensitive regimes of ozone chemistry are discerned to assess the mechanisms controlling the time variation of sensitive regimes.The results show that,for given weather and pollution-emission conditions,the VOCs-sensitive regime is mainly located in the central PRD and in its downwind areas （i.e.,the southern＆amp;nbsp;Guangzhou,Foshan,Zhongshan,Zhuhai,Shenzhen,Dongguan,Jiangmen and Zhaoqing）.The NOx-sensitive regime is located in the upwind areas（i.e.,northern Guangzhou and Huizhou）.These sensitive regimes are characterized with significant diurnal variations,and some areas that are previously VOCs sensitive shifted to NOx-sensitive conditions from morning to afternoon by 5 1 .4%.Such a shift can be attributed to the photochemical aging,increased vertical di-lution,and increasing biogenic VOCs emission.