| Download | - View supplementary information: Quantifying the fractal dimension and morphology of individual atmospheric soot aggregates (DOCX, 4.8 MiB)
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| DOI | Resolve DOI: https://doi.org/10.1029/2021JD036055 |
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| Author | Search for: Pang, Yuner; Search for: Wang, Yuanyuan; Search for: Wang, Zhicheng; Search for: Zhang, Yinxiao; Search for: Liu, LeiORCID identifier: https://orcid.org/0000-0002-7171-1454; Search for: Kong, ShaofeiORCID identifier: https://orcid.org/0000-0001-9735-6852; Search for: Liu, Fengshan1; Search for: Shi, ZongboORCID identifier: https://orcid.org/0000-0002-7157-543X; Search for: Li, WeijunORCID identifier: https://orcid.org/0000-0003-4887-4260 |
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| Affiliation | - National Research Council of Canada. Metrology Research Centre
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| Funder | Search for: National Natural Science Foundation of China |
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| Format | Text, Article |
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| Abstract | The complex morphology of soot aggregates is a major source of uncertainty in evaluating their warming effects in the atmosphere. Fractal dimension (Df) is a key parameter in quantifying the morphology of soot particles. Previous studies are mostly based on manual identification of soot monomers in electron microscopic images and are hard to provide comparable results in determination of Df. Here we develop a novel image recognition technique to automatically determine the Df of individual soot aggregates from electron microscopy images. The novel method has been shown to be able to trace the small change of the soot Df from an urban tunnel (1.61 ± 0.19) to its exit (1.70 ± 0.15). By applying this new method, we show a substantial difference in average Df of soot particles emitted from vehicles (1.66 ± 0.17) than from biomass burning (1.75 ± 0.18) and coal burning (1.76 ± 0.18). Average Df of soot from an urban atmosphere (1.77 ± 0.18) is close to that from biomass and coal combustion but much lower than that from a rural atmosphere (1.85 ± 0.13). In summary, the new technique provides an automatic, accurate and reliable quantification of soot morphology Df, enabling an improved understanding of soot aging processes and a more accurate modeling of soot impact on their climate.
Key Points
- A novel image recognition technique is used to calculate the fractal dimension of individual soot particle based on electron microscope
- An aging process of soot particles collected at an urban tunnel is observed from the entrance to its exit
- The fractal dimension of soot particles from different sources is similar with that of urban site but lower than that of rural site
Plain Language Summary: Soot particles play a significant role in global climate warming by affecting the radiative balance at both global and regional scales. A key challenge of evaluating the warming effects of soot particle is to quantify their complex morphology. We for the first time developed a novel image recognition technique to quantify the morphology of individual soot particles on electron microscopy and collected a large amount of soot particles from various combustion sources and ambient atmosphere. We compared the new method with previous methods and found aging process of soot particles from tunnel entrance to exit. Our results show substantial differences in the morphology of soot particles from different sources and allow us to better model the soot impact on the climate. |
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| Publication date | 2022-02-28 |
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| Publisher | John Wiley & Sons |
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| In | |
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| Language | English |
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| Peer reviewed | Yes |
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| Export citation | Export as RIS |
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| Report a correction | Report a correction (opens in a new tab) |
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| Record identifier | 9ee668c0-e54b-495b-9bef-41bef8ac634e |
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| Record created | 2023-06-29 |
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| Record modified | 2023-06-29 |
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