【摘要】 针对2013年1月27—31日中国华北平原地区持续5 d的雾霾天气进行综合分析和数值预报.研究表明,雾霾过程期间华北平原高空以平直纬向环流为主,没有明显冷空气活动,地面多为风速小、相对湿度较大等不利于污染物扩散和稀释的弱气压场;大气层结构稳定、低空逆温频率高强度大,且存在明显的低层逆湿条件,边界层内污染物的水平和垂直扩散能力差.稳定、高湿的气象条件对细粒子PM2.5质量浓度的形成、积聚和维持比较有利,造成严重的区域性低能见度和雾霾天气.气象化学耦合模式WRF-Chem预报系统对此次雾霾过程期间天气系统演变和PM2.5质量浓度的空间分布及高浓度持续时间、消散减弱等过程做出了较好的预报.模式预报出雾霾期间PM2.5质量浓度在京津冀平原地区达到300μg/m3严重污染,主要分布在北京城区及以南的河北、天津等重点城市和区域,部分地区可达400μg/m3以上,与华北地形和城市群分布有很好的对应关系,在华北平原山前容易形成气流的辐合区和高污染区.更多还原

【Abstract】 We analyzed the weather situation,boundary layer structure,and PM2. 5concentration during the haze-fog event of 27 to 31 Jan 2013 occurred in the North China plain( NCP). The weather conditions indicated that latitudinal circulation and weak pressure system controlled the NCP area during that period. There were continuous inversion layer and stable structure within the boundary layer. The surface and lower level wind was usually less 2 m / s,and relative humidity washigher. Such stable weather situation and high emissions were favorable to pollutant accumulation and fine aerosol’s formation. Then,the high PM2. 5concentration directly leaded to low visibility and heavy fog-haze. Real-time WRF-Chem model made a good forecast for the PM2. 5concentration and the haze spatio-temporal distribution and evolution in the NCP area. The wind convergence and pollutant accumulation usually occurred along the mountain edge and in the NCP area.更多还原