Analysis on the Source Contributions and Variations of Surface SO_2 at Lin 'an Station

摘要

Trajectory clustering methods were used to determine the source regions for measured surface SO_2 con-centrations at Lin' an regional background station during the period of September to October 1994. In general the clus-tering analyses were able to distinguish large-scale flow but ineffective in explaining the detail differences among the particular clusters. Further more a Lagrangian transport, dispersion, deposition model with grid emission inventory was applied to discern the contributions from different source regions to the surface SO_2 concentrations. Model calcula- tions show quite a good agreement with the measurements on the variations of surface SO_2, but lower in values, which were attributed to the underestimate of source emission and overestimate of wet depositions. In fall, the high surface SO_2 concentrations at Lin' an station were mostly from Zhejiang and Jiangsu provinces, which are the most rapid devel-oped regions in the east part of China. Meanwhile model results imply that Lin 'an as a regional background monitoring station, its data can still reflect the SO_2 polluted levels in that part.