太行山两侧污染物传输对横谷城市气溶胶的影响分析

利用2017~2019年太行山横谷城市阳泉PM₁₀和PM_2.5逐时浓度资料和对应时刻风速风向数据，结合HYSPLIT后向轨迹模型通过聚类分析、潜在源贡献因子和浓度权重轨迹方法分析了横谷城市气流输送特征及对阳泉市气溶胶的影响，并进一步探讨了太行山两侧大气污染物的交换特征.阳泉市气溶胶日变化为单峰单谷型，冬季最高值出现在10：00~11：00，其他季节多在09：00，最小值均在15：00~16：00；月际变化呈1月最高、8月最低.受横谷地形影响，地面风向以偏东风和偏西风频率最高；除小风天气外，春秋季偏西风引起的沙尘天气和冬季偏东风输送也会引起阳泉气溶胶浓度升高；后向轨迹结合污染特征显示，各季节污染轨迹占比为春季26.2%、秋季36.4%和冬季33.7%，主要分布在阳泉的西南和东南区域，冬季在东北区域也有分布；山脉两侧均存在显著的细颗粒物传输，而起源或途经太行山西侧的轨迹粗颗粒物输送亦相对较多；污染轨迹中偏西气流输送对PM₁₀超标率影响更大，偏东气流则主要影响PM_2.5的超标率.不同季节阳泉市气溶胶主要污染潜在源区存在差异，春季为西南和东南两区域；秋季为西南及偏南区域，冬季主要位于偏南和偏东方向区域，山西东南部及与河南北部交界区域是主要的污染贡献源区，太行山两侧通过井陉通道进行大气污染物的相互传输过程显著，其中东向西的PM_2.5传输影响更显著.

Influence of Pollutant Transport from Both Sides of the Taihang Mountains on Cross-Valley Urban Aerosols

Based on hourly concentration data of PM₁₀ and PM_2.5 from 2017 to 2019 and wind speed and direction data at the corresponding times in Yangquan, an urban valley of the Taihang Mountains, the characteristics of air transport in a cross-valley urban area and their influence on aerosols in Yangquan were analyzed using the HYSPLIT model, cluster analysis, and the potential source contribution factor and concentration weight trajectory methods. The pollutant transport characteristics on the east and west sides of the Taihang Mountains were evaluated. The diurnal variation of the aerosols showed a single peak and single valley, with continuous improvements in aerosol concentration from evening to the morning of the next day. The maximum aerosol concentration occurs at 10:00-11:00 in winter and at 09:00 in other seasons, whereas the minimum value occurs at 15:00-16:00. The monthly mean aerosol concentration in Yangquan was highest in January and lowest in August, and PM₁₀ was also high in March and April. The most frequent surface wind directions in Yangquan are easterly and westerly due to the topography of the cross valley. The average concentrations of aerosols were highest in the calm wind weather. Furthermore, the dust weather caused by the westerly wind in spring and autumn and the easterly transport in winter also causes an increase in aerosol concentration in Yangquan. The backward trajectories in combination with the pollution characteristics showed that 26.2% of the pollution trajectories are in spring, 36.4% are in autumn, and 33.7% are in winter, and that these are mainly distributed in the southwest and southeast of Yangquan and also in the northeast in winter. There was significant fine particle transport on both sides of the mountains, and the trajectories originating from or passing through the west side of the Taihang Mountains also transport coarse particles. As indicated by the pollution trajectory, the westerly air transport has an impact on PM₁₀ in excess of the standard rate. The easterly transport has larger noise and mainly affects the exceedance rate of PM_2.5. The main potential source areas of aerosol pollution in Yangquan differ in different seasons. The potential source areas are to the southwest and southeast of Yangquan in spring, the southwest and south of Yangquan in autumn, and the south and east of Yangquan in winter. The areas with high PSCF and CWT in PM_2.5 were in the southeast region, but those for PM₁₀ were in the southwest region. The area southeast of Shanxi and the border area north of Henan are the main source areas. Based on the influence of aerosol pollution transmission in Yangquan, the cross-valley urban area is affected simultaneously by the areas east and west of the Taihang Mountains, especially by PM_2.5 transport from east to west.