晋中盆地主要城市冬季PM2.5传输特征分析

对2017～2019年晋中盆地主要城市PM₁₀和PM_2.5逐时浓度资料进行了分析，给出了晋中市和太原市颗粒物浓度主要分布特征；此外利用PM_2.5逐时浓度资料，结合HYSPLIT后向轨迹模型，通过轨迹密度分析（TDA）、轨迹停留时间分析（RTA）和潜在源贡献因子分析（PSCF）,并对PM_2.5逐时浓度资料和对应时刻风向数据进行分析，探讨了晋中盆地主要城市冬季PM_2.5传输特征.结果表明，太原市颗粒物浓度整体水平高于晋中市，月、季变化特征类似，均呈现冬季高，夏季低的特征，最高值出现在1月.晋中市受静稳型天气形势引起的颗粒物污染较受沙尘型天气形势导致的颗粒物污染相较太原市更普遍一些；颗粒物的分布呈现出晋中市中间值较多，太原市高值偏多、低值偏少的特点，冬季为晋中盆地PM_2.5污染高发季节.晋中盆地主要城市冬季PM_2.5传输通道均可分为4类：第一类通道沿太行山横谷传输，第二类通道为偏东南方向传输通道，第一、二类均为近距离传输通道，气团会携带较多...

Analysis of PM2.5 Transmission Characteristics in Main Cities of Jinzhong Basin in Winter

In this study, we analyzed the hourly concentration data of PM₁₀ and PM_2.5 in major cities in Jinzhong basin from 2017 to 2019. The main distribution characteristics of aerosols in Jinzhong and Taiyuan were determined, and PM_2.5 hourly concentration data and HYSPLIT in Jinzhong basin in winter were discussed. The results showed that the overall level of particulate matter concentration in Taiyuan was higher than that in Jinzhong, and the monthly and seasonal variation characteristics were similar. All showed high concentrations in winter and low concentrations in summer, and the highest concentration value appeared in January. The aerosol pollution caused by the static and stable weather in Jinzhong was more common than that caused by the sand and dust weather in Taiyuan. The distribution of particulate matter showed the characteristics of more intermediate values in Jinzhong and more high and fewer low values in Taiyuan, and winter was the highest incidence season of PM_2.5 pollution in Jinzhong basin. PM_2.5 transmission passageways in the main cities of Jinzhong basin in winter could be divided into four categories:class 1 was transmitted along the transverse valley of Taihang Mountain, and class 2 was the southeast transmission channel. Class 1 and class 2 were the short-range transmission passageways; air masses carried more moisture, and PM_2.5 transmitted along such passageways allowed moisture to be absorbed more easily, increasing levels and aggravating local pollution. Class 3 was the northwest passageway, corresponding to the most serious pollution period of PM_2.5 in Jinzhong basin before the arrival of cold air, which also corresponded to the dust transmission passageway. Class 4 was the Fenwei Plain passageway, corresponding to high-concentration PM_2.5 pollution. Areas with dense pollution tracks (more than 100 pollution tracks) and areas with slow air flow movement (RTA pollution track end points greater than 50) easily became potential source areas of target cities (PSCF contribution greater than 0.7). The main potential source areas of PM_2.5 in winter in Jinzhong (PSCF contributing more than 0.7) were mainly distributed in Linfen, Jincheng, and other places in Shanxi province, as well as in the north of Henan province, the south of Hebei province, and central and south Shaanxi province. The distribution range of main potential source areas of PM_2.5 in Taiyuan in winter was wider than that in Jinzhong, including the south of Lvliang, Yangquan, Linfen, and Yuncheng and the south of Jinzhong in Shanxi, as well as most areas in southern Shaanxi, northern Henan province, and southern Hebei province. In addition, the PSCF distribution of high-value centers above 0.9 was wider than that of Jinzhong. When pollution occurs in cities that PSCF contributed more than 0.9, special attention should be paid to the influence of mutual transmission between them and cities in Jinzhong basin. Jinzhong and Taiyuan showed different distribution characteristics corresponding to the surface wind direction when light and higher pollution occur, when the wind direction near the ground in Jinzhong was E, the frequency of light and higher pollution was 8.1%; it was the highest in all wind directions. When the wind direction near the ground in Taiyuan was SSW, the frequency of light to higher polluted weather was the highest in all wind directions (5.1%). In the case of calm wind, the frequency of light to higher pollution in Taiyuan (3.4%) was higher than that in Jinzhong (0.5%).