Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method
Transparency (Zsd) can most intuitively reflect changes in marine ecosystems, therefore; the data of Zsd is crucial to protect marine ecosystems. However, there is still a relative lack of long-term sequence data on Zsd for coastal turbid waters. Satellite remote sensing inversion provides an effici...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2024-12-01
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| Series: | Frontiers in Marine Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmars.2024.1503177/full |
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| author | Shuhui Cao Shuhui Cao Fei Xiao Miaomiao Chen Miaomiao Chen Zhou Wang Zhou Wang Jiahuan Luo Jiahuan Luo Yun Du |
| author_facet | Shuhui Cao Shuhui Cao Fei Xiao Miaomiao Chen Miaomiao Chen Zhou Wang Zhou Wang Jiahuan Luo Jiahuan Luo Yun Du |
| author_sort | Shuhui Cao |
| collection | DOAJ |
| description | Transparency (Zsd) can most intuitively reflect changes in marine ecosystems, therefore; the data of Zsd is crucial to protect marine ecosystems. However, there is still a relative lack of long-term sequence data on Zsd for coastal turbid waters. Satellite remote sensing inversion provides an efficient means of obtaining long-term, large-scale Zsd. The method proposed by Lee et al. is currently one of the most widely used methods, which is divided into clear water and turbid water models based on the 670 nm remote sensing reflectance (Rrs). In this study, we employed an improved model building upon the aforementioned method. The improved model simulates the continuous transition from clear to turbid water, which allows for automatic adjustment of model weights based on a logistic curve. Utilizing this improved model, this study inverts Zsd within 100 km of the eastern coast of China from 2003 to 2023 using MODIS Aqua Level 2 Rrs data. Zsd shows an increasing trend with the distance from the coast, with high Zsd in the northern Yellow Sea, the southern Shandong Peninsula, and the far shore of the East China Sea, and the low Zsd in the coast of Bohai Sea and northern Jiangsu. As for the long-term changes, the number of pixels with significantly increased Zsd and those with significantly decreased Zsd and no significant changes accounted for 20.84%, 1.14%, and 78.02%, respectively. The order of seasonal Zsd is summer > autumn > spring > winter, and the seasonal variability amplitude increases synchronously with the offshore distance of seawater on the whole. Interestingly, the correlation between Zsd and the annual runoff of rivers exhibits spatial differentiation among six typical estuaries: there are positive correlations in northern, whereas negative correlations in the south. Additionally, the Zsd in five of six estuaries have negative correlations with annual sediment transport. Overall, this study not only provides more accurate and continuous data of Zsd for nearshore turbid waters compared to those obtained by the original model, but also offers valuable insights on the spatiotemporal variation in the Zsd of large-scale seawater. |
| format | Article |
| id | doaj-art-13611b43bc1e4db3b61c5cae22e8244e |
| institution | OA Journals |
| issn | 2296-7745 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Marine Science |
| spelling | doaj-art-13611b43bc1e4db3b61c5cae22e8244e2025-08-20T02:19:34ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452024-12-011110.3389/fmars.2024.15031771503177Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based methodShuhui Cao0Shuhui Cao1Fei Xiao2Miaomiao Chen3Miaomiao Chen4Zhou Wang5Zhou Wang6Jiahuan Luo7Jiahuan Luo8Yun Du9Key Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, ChinaUniversity of Chinese Academy of Sciences, Beijing, ChinaKey Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, ChinaKey Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, ChinaUniversity of Chinese Academy of Sciences, Beijing, ChinaKey Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, ChinaUniversity of Chinese Academy of Sciences, Beijing, ChinaKey Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, ChinaUniversity of Chinese Academy of Sciences, Beijing, ChinaKey Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, ChinaTransparency (Zsd) can most intuitively reflect changes in marine ecosystems, therefore; the data of Zsd is crucial to protect marine ecosystems. However, there is still a relative lack of long-term sequence data on Zsd for coastal turbid waters. Satellite remote sensing inversion provides an efficient means of obtaining long-term, large-scale Zsd. The method proposed by Lee et al. is currently one of the most widely used methods, which is divided into clear water and turbid water models based on the 670 nm remote sensing reflectance (Rrs). In this study, we employed an improved model building upon the aforementioned method. The improved model simulates the continuous transition from clear to turbid water, which allows for automatic adjustment of model weights based on a logistic curve. Utilizing this improved model, this study inverts Zsd within 100 km of the eastern coast of China from 2003 to 2023 using MODIS Aqua Level 2 Rrs data. Zsd shows an increasing trend with the distance from the coast, with high Zsd in the northern Yellow Sea, the southern Shandong Peninsula, and the far shore of the East China Sea, and the low Zsd in the coast of Bohai Sea and northern Jiangsu. As for the long-term changes, the number of pixels with significantly increased Zsd and those with significantly decreased Zsd and no significant changes accounted for 20.84%, 1.14%, and 78.02%, respectively. The order of seasonal Zsd is summer > autumn > spring > winter, and the seasonal variability amplitude increases synchronously with the offshore distance of seawater on the whole. Interestingly, the correlation between Zsd and the annual runoff of rivers exhibits spatial differentiation among six typical estuaries: there are positive correlations in northern, whereas negative correlations in the south. Additionally, the Zsd in five of six estuaries have negative correlations with annual sediment transport. Overall, this study not only provides more accurate and continuous data of Zsd for nearshore turbid waters compared to those obtained by the original model, but also offers valuable insights on the spatiotemporal variation in the Zsd of large-scale seawater.https://www.frontiersin.org/articles/10.3389/fmars.2024.1503177/fulltransparencyremote sensingcoastal watersinversionspatiotemporal variability |
| spellingShingle | Shuhui Cao Shuhui Cao Fei Xiao Miaomiao Chen Miaomiao Chen Zhou Wang Zhou Wang Jiahuan Luo Jiahuan Luo Yun Du Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method Frontiers in Marine Science transparency remote sensing coastal waters inversion spatiotemporal variability |
| title | Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method |
| title_full | Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method |
| title_fullStr | Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method |
| title_full_unstemmed | Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method |
| title_short | Inversion and analysis of transparency changes in the eastern coastal waters of China from 2003 to 2023 by an improved QAA-based method |
| title_sort | inversion and analysis of transparency changes in the eastern coastal waters of china from 2003 to 2023 by an improved qaa based method |
| topic | transparency remote sensing coastal waters inversion spatiotemporal variability |
| url | https://www.frontiersin.org/articles/10.3389/fmars.2024.1503177/full |
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