Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019
Water color, often quantified using the Forel-Ule Index (FUI), is a crucial parameter for assessing the water quality and ecological health of coastal waters. However, there is limited research on the spatiotemporal variations of FUI and the associated influencing factors in the Bohai and Yellow Sea...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-07-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/14/3487 |
| _version_ | 1797587624092762112 |
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| author | Baohua Zhang Junting Guo Zengrui Rong Xianqing Lv |
| author_facet | Baohua Zhang Junting Guo Zengrui Rong Xianqing Lv |
| author_sort | Baohua Zhang |
| collection | DOAJ |
| description | Water color, often quantified using the Forel-Ule Index (FUI), is a crucial parameter for assessing the water quality and ecological health of coastal waters. However, there is limited research on the spatiotemporal variations of FUI and the associated influencing factors in the Bohai and Yellow Seas. In this study, we utilized multi-sensor satellite datasets to retrieve monthly FUI products for the Bohai and Yellow Seas spanning the period from September 1997 to December 2019. Subsequently, we examined significant spatial disparities and variations across multiple timescales in the remotely sensed FUI time series. The climatological annual mean FUI map reveals a decreasing trend from nearshore to offshore regions, with similar spatial patterns observed in terms of overall and interannual FUI variability. The annual variations in wind field, sea surface temperature (SST), and ocean stratification play a key role in the seasonal dynamics of FUI by modulating the sediment resuspension process, resulting in low FUI values in summer and high FUI values in winter. Linear regression analysis of FUI anomaly indicates a long-term decreasing trend in FUI for the three bays of the Bohai Sea, while upward trends in FUI predominantly prevail in the central Yellow Sea. Factors related to interannual FUI variations, such as surface winds, SST, river outflow, rainfall, and anthropogenic activities, are qualitatively discussed. The findings of this study provide the first comprehensive evaluation of water color variations and their underlying mechanisms in the Bohai and Yellow Seas. |
| first_indexed | 2024-03-11T00:42:31Z |
| format | Article |
| id | doaj.art-f421d51fe3ec4292bdb0cad06e3a4231 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-11T00:42:31Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-f421d51fe3ec4292bdb0cad06e3a42312023-11-18T21:11:28ZengMDPI AGRemote Sensing2072-42922023-07-011514348710.3390/rs15143487Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019Baohua Zhang0Junting Guo1Zengrui Rong2Xianqing Lv3Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, ChinaFrontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, ChinaFrontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, ChinaFrontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, ChinaWater color, often quantified using the Forel-Ule Index (FUI), is a crucial parameter for assessing the water quality and ecological health of coastal waters. However, there is limited research on the spatiotemporal variations of FUI and the associated influencing factors in the Bohai and Yellow Seas. In this study, we utilized multi-sensor satellite datasets to retrieve monthly FUI products for the Bohai and Yellow Seas spanning the period from September 1997 to December 2019. Subsequently, we examined significant spatial disparities and variations across multiple timescales in the remotely sensed FUI time series. The climatological annual mean FUI map reveals a decreasing trend from nearshore to offshore regions, with similar spatial patterns observed in terms of overall and interannual FUI variability. The annual variations in wind field, sea surface temperature (SST), and ocean stratification play a key role in the seasonal dynamics of FUI by modulating the sediment resuspension process, resulting in low FUI values in summer and high FUI values in winter. Linear regression analysis of FUI anomaly indicates a long-term decreasing trend in FUI for the three bays of the Bohai Sea, while upward trends in FUI predominantly prevail in the central Yellow Sea. Factors related to interannual FUI variations, such as surface winds, SST, river outflow, rainfall, and anthropogenic activities, are qualitatively discussed. The findings of this study provide the first comprehensive evaluation of water color variations and their underlying mechanisms in the Bohai and Yellow Seas.https://www.mdpi.com/2072-4292/15/14/3487Forel-Ule Index (FUI)Bohai and Yellow Seasspatiotemporal variationsmultiple timescalesunderlying mechanismsremote sensing |
| spellingShingle | Baohua Zhang Junting Guo Zengrui Rong Xianqing Lv Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019 Remote Sensing Forel-Ule Index (FUI) Bohai and Yellow Seas spatiotemporal variations multiple timescales underlying mechanisms remote sensing |
| title | Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019 |
| title_full | Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019 |
| title_fullStr | Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019 |
| title_full_unstemmed | Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019 |
| title_short | Variations of Remote-Sensed Forel-Ule Index in the Bohai and Yellow Seas during 1997–2019 |
| title_sort | variations of remote sensed forel ule index in the bohai and yellow seas during 1997 2019 |
| topic | Forel-Ule Index (FUI) Bohai and Yellow Seas spatiotemporal variations multiple timescales underlying mechanisms remote sensing |
| url | https://www.mdpi.com/2072-4292/15/14/3487 |
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