科研之友
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摘要
Due to complexity of terrain and industrial structures, Fenwei Plain has become one of the most polluted regions with a similar rank to Beijing-Tianjin-Hebei and the Yangtze River Delta, in China. In this study, various observational data including hourly concentrations of gaseous pollutants and particulate matter, together with the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model are used to characterize temporal and spatial variations in major air pollutants, identify potential sources, and understand formation mechanism of particulate matter with diameter less than 2.5 micrometers (PM2.5) during the winters from 2014 to 2019. A T-mode with oblique rotation principal component analysis (PCT) method is used with ERA5 data to identify the synoptic weather patterns which are conducive to occurrence and aggravation of PM2.5 pollution events in the study region. Several findings are identified from the detailed analyses. First, HYSPLIT simulations show that the cities located in Bellmouth basin are mainly affected by local and neighboring emission sources; the cities located at mountain basin are mainly affected by the emission sources from the regions with distance from 100 km to 300 km. Meanwhile, the emission sources in the range of 300~600 km exert a greater transport impact on the cities with canyon topography. The pollutant concentrations are greatly affected by regional transport in plain cities. Finally, four types of synoptic patterns are responsible for the occurrence of heavy PM2.5 pollution events in this region. They include the front of a high-pressure system, the rear of a high-pressure system, the weather system with uniform-distribution pressure, and the system with an inverted trough.
