Formation and evolution mechanism of regional haze: a case study in the megacity Beijing, China
Formation and evolution mechanism of regional haze: a case study in the megacity Beijing, China
复制标题
区域灰霾的形成与演化机制：以中国特大城市北京为例
DOI：
10.5194/acp-13-4501-2013
复制
发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
Hu, M.
中科院分区：
文献类型：
--
作者：
Liu, X. G.;Li, J.;Hu, M.
本研究的主要目的是通过对2011年9月20-27日发生的一次特大城市灰霾天气过程的分析，探讨北京特大城市区域性灰霾天气的形成和演变机制。在北京市区大气环境监测站同时进行了气溶胶粒子的质量浓度、粒度分布以及气溶胶光学性质的测量。同时监测了气态污染物(SO2、NO-NO2-NOx、O-3、CO)和气象参数(风速、风向、相对湿度)。同时，从卫星信号和激光雷达(LIDAR)信号中反演气溶胶的空间分布和行星边界层高度。9月23日至27日监测到的NO、NO2、SO2、O-3和CO浓度超过了国家居民环境空气质量标准。PM2.5的质量浓度在测量过程中逐渐积累，9月26日达到220亩/立方米(-3)，对应的大气能见度仅为1.1公里。北京的日平均气溶胶光学厚度在波长500纳米处由9月22日的相似增加到0.16，并在9月26日达到接近3.5。地面稳定的反气旋天气条件、边界层高度的降低、城市重污染排放、气溶胶数量和大小的演变以及气溶胶散射的吸湿性增长是影响此次灰霾形成和演变的关键因素。这一个例研究可以为公众认识特大城市区域性霾事件的形成机制提供有价值的信息，也有助于政府采取科学的方法对中国区域性霾的发生进行预测和消除。
The main objective of this study is to investigate the formation and evolution mechanism of the regional haze in megacity Beijing by analyzing the process of a severe haze that occurred 20-27 September 2011. Mass concentration and size distribution of aerosol particles as well as aerosol optical properties were concurrently measured at the Beijing urban atmospheric environment monitoring station. Gaseous pollutants (SO2, NO-NO2-NOx, O-3, CO) and meteorological parameters (wind speed, wind direction, and relative humidity) were simultaneously monitored. Meanwhile, aerosol spatial distribution and the height of planetary boundary layer (PBL) were retrieved from the signal of satellite and LIDAR (light detection and ranging). Concentrations of NO, NO2, SO2, O-3, and CO observed during 23-27 September had exceeded the national ambient air quality standards for residents. The mass concentration of PM2.5 gradually accumulated during the measurement and reached at 220 mu gm(-3) on 26 September, and the corresponding atmospheric visibility was only 1.1 km. The daily averaged AOD in Beijing increased from similar to 0.16 at lambda = 500 nm on 22 September and reached similar to 3.5 on 26 September. The key factors that affected the formation and evolution of this haze episode were stable anti-cyclone synoptic conditions at the surface, decreasing of the height of PBL, heavy pollution emissions from urban area, number and size evolution of aerosols, and hygroscopic growth for aerosol scattering. This case study may provide valuable information for the public to recognize the formation mechanism of the regional haze event over the megacity, which is also useful for the government to adopt scientific approach to forecast and eliminate the occurrence of regional haze in China.