Abstract
ABSTRACTThe Weather Research and Forecasting model coupled to Chemistry (WRF-Chem model) was modified with an online primary PM2.5 source-apportionment method to simulate a severe aerosol pollution episode that occurred over the Beijing-Tianjin-Hebei (BTH) region of China from October 29 to November 8, 2015. The temporal and spatial distributions and transport characteristics of this episode were examined, and the quantified primary PM2.5 contributions by various geographical source regions to the BTH region were also analyzed in this study. The results showed that pollution in this region was mainly due to the combined effects of the synoptic conditions, terrain, and boundary layer characteristics. Before the heavy pollution event, the most parts of the BTH region were controlled by northwest wind, and the local primary PM2.5 contribution to the BTH region accounted for 90.7%. During the heavy pollution period, the BTH region was under isobaric synoptic conditions with light horizontal winds and a stable temperature stratification structure and a lower PBLH, allowing pollutants to accumulate easily in the region. Large quantities of pollutants were transported to the BTH region from Shandong, Jiangsu, Anhui, and Henan provinces via the southerly wind, accounting for 11.6%, 9.2%, 6.7%, 11.8%, respectively. Furthermore, pollutants accumulated more significantly under a stable boundary layer structure and the northwest-southeast terrain structure. Therefore, regional contributions increased, and other polluted areas, especially the long-distance transport from a source in the Yangtze River Delta city group region, contributed about 15.9%. It should be noted that the percentage of primary PM2.5 within the total PM2.5 in the study period almost exceeded 50%, and in the BTH region nearly surpassed 60%. To a certain extent, primary PM2.5 can help characterize total PM2.5.
Highlights
In recent years, severe aerosol pollution events have occurred frequently in the Beijing-Tianjin-Hebei (BTH) region, impacting residents’ health, life, and productivity (Pope et al, 2003; Parrish and Zhu, 2009; Brook and Rajagopanlan, 2010; Ding et al, 2013; Huang et al, 2014; Zhang et al, 2015)
The Weather Research and Forecasting model coupled to Chemistry (WRF-Chem model) was modified with an online primary PM2.5 source-apportionment method to simulate a severe aerosol pollution episode that occurred over the BeijingTianjin-Hebei (BTH) region of China from October 29 to November 8, 2015
The WRF-Chem model coupled with an online primary aerosol tagging method was used to simulate an episode of high concentration of PM2.5 that occurred in the BTH region in late October and early November 2015
Summary
Severe aerosol pollution events have occurred frequently in the Beijing-Tianjin-Hebei (BTH) region, impacting residents’ health, life, and productivity (Pope et al, 2003; Parrish and Zhu, 2009; Brook and Rajagopanlan, 2010; Ding et al, 2013; Huang et al, 2014; Zhang et al, 2015). Aerosol and Air Quality Research, 17: 2966–2980, 2017 used the Nested Air Quality Prediction Modeling System (NAQPMS) to quantify the contributions of Beijing and its surrounding areas to transportation-related pollutants within the city and determined that the surrounding regions were the greatest regional contributors to such pollution in Beijing. Secondary aerosols are contingent upon the presence of primary aerosols and the relevant gaseous precursors in the atmosphere. Because of this relationship and the differences of source regions and distribution of primary and secondary aerosol, the most effective way to reduce aerosol pollution is to reduce primary emissions (Fan et al, 2005). Understanding the contributions of different source regions to pollution within the BTH will provide a valid scientific basis for conservation-oriented policies and governance of these source regions
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