Long‐Term Variation and Source Apportionment of Black Carbon at Mt. Waliguan, China

• Published in: Journal of geophysical research. Atmospheres 2021-11, Vol.126 (21), p.n/a
• Main Authors: Dai, Mingming, Zhu, Bin, Fang, Chenwei, Zhou, Shunwu, Lu, Wen, Zhao, Delong, Ding, Deping, Pan, Chen, Liao, Hong
• Format: Article
• Language: English
• Subjects: air mass change; Air masses; Annual variations; Anthropogenic factors; Atmospheric models; Black carbon; Carbon; Climate change; Emission measurements; Emissions control; Geophysics; Global climate; Human influences; Interannual variations; long‐term trend; Marking and tracking techniques; Monsoons; Plateaus; Pollution dispersion; Regions; source apportionment; Summer; Tibetan Plateau monsoon; Trajectory analysis; Transport; Trends; Urban areas; Variation
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1029/2021JD035273

Black carbon (BC) is a significant driver of global climate change, and its long‐term variation is affected by a combination of anthropogenic activities and meteorological diffusion conditions. However, distinguishing the effects of these two factors on BC variation has proven difficult. In this study, we used the China Black Carbon Observational Network data set to assess the diurnal, seasonal, and long‐term BC trends at Mt. Waliguan (WLG) from 2008 to 2017. The mean BC concentration at WLG was 449 ± 366 ng/m3, with a decreasing trend of 2 %yr−1, which was mainly related to emission reduction measures in China. The BC concentration at WLG was higher under easterly air masses than that under westerly air masses, which suggests that the former are conducive to BC transport from the highly polluted eastern regions. Due to the origin and velocity of air masses, the BC concentration at WLG in summer is higher than that in winter. The intensity of the Tibetan Plateau monsoon had an important positive influence on the easterly air masses frequency, which modulated BC transport to WLG in summer. According to the concentration‐weighted trajectory analysis, the high‐potential BC source regions were distributed in Lanzhou, Chengdu, and Xi'an urban agglomerations as well as in northern India. Community Atmosphere Model 5 simulations with a BC‐tagging technique inferred North Central China, Northwest China, and Indian Peninsula to be the major BC source regions to WLG, accounting for 56.1%, 17.5%, and 12.1% of the total BC, respectively. Plain Language Summary In this study, we investigated the long‐term variation of black carbon (BC) between 2008 and 2017 at Mt. Waliguan (WLG) in northeast of Tibetan Plateau, the only atmospheric baseline station in the Eurasian hinterland. A decreasing trend of BC was observed at WLG, which can be attributed to emission reduction measures in China during this period. We also found that easterly air masses promoted the transport of BC to the Tibetan Plateau from highly polluted eastern urban agglomerations of China, especially in summer. Moreover, the interannual variation of Tibetan Plateau monsoon affects the easterly air mass frequency and modulates the concentration and sources of BC at WLG. Furthermore, we identified the dominant source regions of BC to WLG. Key Points The decreasing trend and distinct seasonal variation of black carbon (BC) are mainly related to emission reduction and air mass change, respectively The Tibetan P