ANALYSIS OF PM2.5 POTENTIAL SOURCE AREAS FOR CHANGCHUN CITY, CHINA USING A BACKWARD TRAJECTORY MODEL

摘要

In this paper, the HYSPLIT model and Global Data Assimilation System (GDAS) are applied to simulate backward flow trajectories from Changchun for the entire year of 2014. The cluster analysis method is used to classify 8760 trajectories, and then, 8 cluster trajectories are obtained. The atmospheric transport characteristics in the region are analysed. The results indicate that the trajectories coming from the northwest of Changchun account for the highest proportion, 38.6%. These trajectories mostly transmit over a long distance and are susceptible to the effects of coal combustion in the north and other emission factors of high pollution. The trajectories coming from the southwest of Changchun mainly occur in summer and are easily affected by rain washout and wet deposition. The contributions of different source areas to the PM2.5 concentrations in Changchun city are demonstrated by the original and improved Potential Source Contribution Function (PSCF) method. According to the original PSCF results, the northeast of Inner Mongolia, northwest and middle of Heilongjiang province, and parts of Jilin province and Liaoning province make relatively large contributions to PM2.5 in Changchun. Remote transport from Mongolia and parts of Russia as well as the transport pass to the southwest of the sea also make certain contributions to PM2.5 in Changchun. According to the improved PSCF results, central Jilin province and northeast Liaoning are the main pollution source areas and central Jilin province is the high pollution period source area. These results show that the improved PSCF method can better distinguish the contribution extents of each area to the PM2.5 concentration in Changchun.