广州地区大气污染物输送通道的特征

运用NCEP的GDAS全球气象要素资料与HYSPLIT后向轨迹模式,计算广州地区2010~2012年逐日72h后向轨迹,利用聚类分析方法,分析了广州地区污染物输送通道垂直特征, 计算不同输送通道下广州市颗粒物浓度日均值,同时分析污染物在输送过程中跨越边界层的特征.结果表明:广州地区近地面污染物输送通道可以分为局地、东北路、北路、西北路、东路、南路,不同输送路径对应的PM2.5浓度存在显著差异.局地与东北路输送时,PM2.5浓度最大,北路次之,东路较小,南路输送时最小.西北路输送时,PM10中粗粒子比重明显增加.影响广州地区主要为湖南东南部、江西中部及东南沿海,超过1000m高度的轨迹数所占百分比为16.1%,而低于500m高度的轨迹数所占百分比为 73.1%,近地面污染物的输送主要发生在边界层内部.

Characteristics of air pollutant transport channels in Guangzhou region

Based on the GDAS global meteorological data of NCEP and HYSPLIT model, 72-hour backward trajectories of air flows arriving at Guangzhou were calculated from 2010 to 2012. By using cluster analysis, the vertical structures of pollutant transport channels and the corresponding pollutant concentrations at different channels in Guangzhou were analyzed. Besides, the characteristics of transport trajectories crossing the boundary layer were also discussed in this paper. The results revealed that the pollutant transport channels near the ground (10m) in Guangzhou could be divided into six types, the local, the northeasterly, the northerly, the northwesterly, the easterly and the southerly, respectively. The PM2.5 concentrations varied a lot among different channels. In particular, The PM2.5 concentrations reached the maximum when local and northeasterly channels dominated, followed by northerly and easterly channels, while southerly channel ranked last. In addition, the ratio of coarse particles in PM10 increased obviously in northwesterly channel. The air pollutants arriving at Guangzhou were mainly affected by the southeastern of Hunan province, the central of Jiangxi province and the southeastern of coastal regions. The percentages of trajectories over 1000m were 16.1% while below 500m were 73.1%, concluding that the regional transport of pollutants to the ground level mainly occurred in the boundary layer.