Analyses of regional pollution and transportation of PM2.5 and ozone in the city clusters of Sichuan Basin, China

Regional PM2.5 and ozone pollution and inter-city transportation in the city clusters of the Sichuan Basin (SB) were revealed using k-means clustering and the HYSPLIT backward trajectory model. The PSCF (potential source contribution function) and CWT (concentration-weighted trajectory) methods also were used to identify potential source regions of PM2.5 and ozone in the basin. The regional PM2.5 pollution was obvious with high levels at western and southern SB, while regional pollution characteristics of ozone were less significant than that of PM2.5 inside the basin. Additionally, PM2.5 was often transported directionally from one city to another city, while regional transportation of ozone was less significant than PM2.5 inside the basin, which may be related to the fact that ozone reacted easily with primary emissions during transportation. The Tibetan Plateau (TP) also may be an important source region of high ozone in the city clusters of Sichuan Basin, especially west part of the basin. The results will provide advice to the government to take measures in improving air quality of SB.