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Abstract 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.
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Received: 20 January 2015
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