Characteristics and potential source areas of ozone pollution in Pamir Plateau

To study the variation characteristics and potential source areas of ozone concentration in the Pamirs Plateau, based on the continuous monitoring data of the Pamirs Plateau Atmospheric Composition Observation Station from 2022 to 2023, the HYSPLIT model, cluster analysis, concentration-weighted trajectory (CWT) analysis and mathematical statistics were used to analyse the transmission path and potential source areas of ozone pollutants in different seasons. The results showed that: (1) The peak value of ozone mass concentration [ρ(O_3-8h)] in 2022 was 110.05 μg·m^-3, and it increased to 138 μg·m^-3 in 2023, both of which were higher than the national annual average standards of 10.5 % and 38 %, respectively. (2) From 2022 to 2023, the seasonal variation in ozone quality was as follows: summer > spring > autumn > winter. (3) The variation of ozone mass concentration from January to December in 2022 and 2023 was significant, showing a symmetrical distribution. (4) The CWT results showed that the pollution contribution areas were mainly concentrated in the border areas of China with Pakistan, Afghanistan and Tajikistan. The summer high value area (weighted CWT > 70 μg·m^-3) appeared in the high temperature areas such as Kashgar, eastern Afghanistan, and southern Tajikistan. These above research results provide a scientific reference for the scientific and effective development of ozone prevention and control work in the Pamir Plateau and the numerical simulation of other atmospheric particulate matter cross-border transmission processes.