## 3 Results and Discussions
### Transmission Path Characteristics
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Season**} & \multirow{2}{*}{
\begin{tabular}{c} **Track** \\ **Number** \\ \end{tabular} } & \multirow{2}{*}{**Passing Areas**} & \multicolumn{2}{c}{**All Tracks**} & \multicolumn{2}{c}{**Contamination Trajectory**} \\  & & & **Proability of Occurrence** & **Concentration** & **Seasonal** & **Concentration** \\  & 1 & & **Occurrence** & **(\(\upmu\)g\(\cdot\)m\({}^{-3}\))** & **Ratio 1** & **(\(\upmu\)g\(\cdot\)m\({}^{-3}\))** \\ \hline \multirow{8}{*}{Spring} & 1 & Chengdu, Chongqing, Guiyang & 12.68\% & 37.65 & 8.57\% & 92.75 \\  & 2 & Jinan, Anyang, Jingzhou & 20.02\% & 44.47 & 12.22\% & 102.02 \\  & 3 & Xi’an, Linfen, Shaoyang, & 10.46\% & 39.26 & 9.52\% & 113.91 \\  & 4 & Shaoguan, Qingyuan & 23.19\% & 50.96 & 13.87\% & 93.59 \\  & 5 & Nanchang, Yichun, Pingxiang & 8.70\% & 36.71 & 13.54\% & 106.46 \\  & 6 & Jiangxi Ganzhou, Xinyu & 24.95\% & 47.83 & **20.69\%** & 112.46 \\  & 1 & Jinan, Zhengzhou, Xiangyang, & Shiyan & 21.65\% & 22.18 & 1.05\% & 80.80 \\ Summer & 2 & Shaoguan, Qingyuan, Heyuan & 35.60\% & 29.13 & 1.02\% & 77.13 \\  & 3 & Nanchang, Ji’an, Fuzhou & 21.22\% & 31.08 & 0.86\% & 79.00 \\  & 4 & Chongqing, Zunyi, Tongren & 21.65\% & 26.44 & 1.05\% & 79.20 \\  & 1 & Nanchang, Ji’an, Fuzhou & 24.04\% & 54.04 & **26.72\%** & 121.51 \\ Autumn & 2 & Huizhou, Shaoguan, Qingyuan, & 40.06\% & 57.51 & **22.06\%** & 126.82 \\  & 3 & Hefei, Anqing, Shiyan, Yichang & 13.19\% & 34.48 & 12.54\% & 101.5 \\  & 4 & Shaoyang, Yongzhou and Loudi & 22.71\% & 50.68 & 23.64\% & 118.55 \\  & 1 & Guangzhou, Huizhou, & 46.57\% & 68.66 & **40.10\%** & 123.89 \\ Winter & 2 & Hefei, Chizhou, Tongling, Shiyan & 15.56\% & 38.82 & 9.82\% & 189.09 \\  & 3 & Nanchang, Ji’an, Pingxiang & 30.37\% & 71.00 & **43.90\%** & 124.28 \\  & 4 & Yinchuan, Yulin, Xi’an, Shiyan, & 7.05\% & 61.00 & 21.74\% & 175.29 \\ \hline \hline \end{tabular} Note: 1 Bolded trajectories represent predominant pollution pathways (constituting over 20% of the seasonal distribution).  
\end{table} 
Table 2: Seasonal analysis of trajectory data and PM\({}_{2.5}\) concentration statistics. through Nanchang, Ji'an, and Fuzhou, which constitutes the predominant segment of pollution pathways at 26.72%, accompanied by a pollution concentration of 121.51 ug\(\cdot\)m\({}^{-3}\). Simultaneously, Trajectory 4 winds its way from northwest Hunan, passing through Shaoyang, Yongzhou, and Loudi. Meanwhile, Trajectory 2 originates from northwest Guangdong, traversing Huizhou, Shaoguan, Qingyuan, and Heyuan. These trajectories account for 23.64% and 22.06% of the pollution pathways, with pollution concentrations recorded at 118.55 ug\(\cdot\)m\({}^{-3}\) and 126.82 ug\(\cdot\)m\({}^{-3}\), respectively. These findings corroborate that the primary sources of autumal pollution in Chenzhou City are rooted in this province and its contiguous regions. Furthermore, in comparison to the spring and summer seasons, Chenzhou City witnesses a pronounced escalation in PM\({}_{2.5}\) pollution levels during autumn, accompanied by a notable surge in pollutant influx from the surrounding vicinities. During the winter season, the predominant atmospheric patterns are chiefly influenced by Trajectory 1, stemming from northwest Guangdong through Guangzhou, Huizhou, Shaoguan, and Qingyuan. Concurrently, Trajectory 3 meanders from Jiangxi, passing Nanchang, Ji'an, and Pingxiang. Collectively, these trajectories represent 40.10% and 43.90% of the pollution pathways, manifesting pollution concentrations of 123.89 ug\(\cdot\)m\({}^{-3}\) and 124.28 ug\(\cdot\)m\({}^{-3}\), respectively. Although Trajectories 2 and 4 register higher pollution concentrations during winter, at 189.09 ug\(\cdot\)m\({}^{-3}\) and 175.29 ug\(\cdot\)m\({}^{-3}\), respectively, their occurrence probabilities and the proportion of pollution trajectories remain relatively subdued, indicating their limited representational significance.