Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters
Under anthropogenic disturbances and global warming, coral reef ecosystems are degrading, and there is growing concern about the changes in benthic habitats in shallow coral reef waters. As an essential parameter, bottom reflectance can be used to indicate the health of benthic habitats in coral ree...
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| Format: | Article |
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Elsevier
2025-05-01
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| Series: | International Journal of Applied Earth Observations and Geoinformation |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S156984322500130X |
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| author | Benqing Chen Yanming Yang Mingsen Lin Bin Zou Shuhan Chen Erhui Huang Wenfeng Xu Yongqiang Tian |
| author_facet | Benqing Chen Yanming Yang Mingsen Lin Bin Zou Shuhan Chen Erhui Huang Wenfeng Xu Yongqiang Tian |
| author_sort | Benqing Chen |
| collection | DOAJ |
| description | Under anthropogenic disturbances and global warming, coral reef ecosystems are degrading, and there is growing concern about the changes in benthic habitats in shallow coral reef waters. As an essential parameter, bottom reflectance can be used to indicate the health of benthic habitats in coral reefs. However, accurately determining bottom reflectance from satellite data remains challenging. This study presents an equation-based analytical method to estimate the bottom reflectance from high-spatial-resolution multispectral images in shallow coral reef waters by establishing two equations independent of bottom type and water depth. With the required parameters estimated from the sampling pixels of the multi-spectral image, the bottom reflectance data for the blue and green bands were derived by solving the two equations without a prior knowledge of bottom types, water properties, and water depths. To evaluate the method, simulated remote-sensing reflectance datasets from various combinations of the water properties, depths, and bottom types were used to derive the bottom reflectance. The root mean square errors (RMSEs) of the derived bottom reflectance in the blue band were generally <0.02 for most cases, except when the colored dissolved organic matter spectral absorption coefficient at the 440 nm wavelength [aCDOM (440)] was 0.1 m−1 and concentration of chlorophyll (CCHL) was ≥0.5 μg/L. Comparatively, the lower RMSEs in the green band were observed only when aCDOM(440) < 0.05 m−1, concentration of non-algal particles (CNAP) < 0.25 mg/L, and CCHL < 0.5 μg/L. Furthermore, the proposed method was applied to the two real satellite multispectral images to derive the bottom reflectance. By visually comparing to the subsurface reflectance images and validating with the field-measured reflectance data, we demonstrated that the satellite derived bottom reflectance in the blue and green bands was accurate in both magnitude and shape by the proposed method. Finally, the impacts of the spatial inhomogeneity of the water properties, purity of sampling pixels for estimating the band ratio of the total diffused attenuation coefficients, and errors in the radiometric correction on the bottom reflectance retrieval were discussed and analyzed. |
| format | Article |
| id | doaj-art-3bc4c902c06d4dc2b04b6e31f2e30ad2 |
| institution | Kabale University |
| issn | 1569-8432 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Applied Earth Observations and Geoinformation |
| spelling | doaj-art-3bc4c902c06d4dc2b04b6e31f2e30ad22025-08-20T03:49:32ZengElsevierInternational Journal of Applied Earth Observations and Geoinformation1569-84322025-05-0113910448310.1016/j.jag.2025.104483Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef watersBenqing Chen0Yanming Yang1Mingsen Lin2Bin Zou3Shuhan Chen4Erhui Huang5Wenfeng Xu6Yongqiang Tian7Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China; Fujian Provincial Key Laboratory of Marine Physical and Geological Processes, Xiamen 361005, China; Observation and Research Station of Coastal Wetland Ecosystem in Beibu Gulf, Ministry of Natural Resources, Beihai 536015, China; Corresponding authors at: Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China.Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China; Fujian Provincial Key Laboratory of Marine Physical and Geological Processes, Xiamen 361005, ChinaNational Satellite Ocean Application Service, Ministry of Natural Resources, Beijing 100081, China; Tianjin University, Tianjin 300072, ChinaNational Satellite Ocean Application Service, Ministry of Natural Resources, Beijing 100081, ChinaThird Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China; Fujian Provincial Key Laboratory of Marine Physical and Geological Processes, Xiamen 361005, ChinaThird Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China; Fujian Provincial Key Laboratory of Marine Physical and Geological Processes, Xiamen 361005, China; Corresponding authors at: Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China.Xiamen Environmental Monitoring Center Station in Fujian Province, Xiamen 361005, ChinaXiamen Environmental Monitoring Center Station in Fujian Province, Xiamen 361005, ChinaUnder anthropogenic disturbances and global warming, coral reef ecosystems are degrading, and there is growing concern about the changes in benthic habitats in shallow coral reef waters. As an essential parameter, bottom reflectance can be used to indicate the health of benthic habitats in coral reefs. However, accurately determining bottom reflectance from satellite data remains challenging. This study presents an equation-based analytical method to estimate the bottom reflectance from high-spatial-resolution multispectral images in shallow coral reef waters by establishing two equations independent of bottom type and water depth. With the required parameters estimated from the sampling pixels of the multi-spectral image, the bottom reflectance data for the blue and green bands were derived by solving the two equations without a prior knowledge of bottom types, water properties, and water depths. To evaluate the method, simulated remote-sensing reflectance datasets from various combinations of the water properties, depths, and bottom types were used to derive the bottom reflectance. The root mean square errors (RMSEs) of the derived bottom reflectance in the blue band were generally <0.02 for most cases, except when the colored dissolved organic matter spectral absorption coefficient at the 440 nm wavelength [aCDOM (440)] was 0.1 m−1 and concentration of chlorophyll (CCHL) was ≥0.5 μg/L. Comparatively, the lower RMSEs in the green band were observed only when aCDOM(440) < 0.05 m−1, concentration of non-algal particles (CNAP) < 0.25 mg/L, and CCHL < 0.5 μg/L. Furthermore, the proposed method was applied to the two real satellite multispectral images to derive the bottom reflectance. By visually comparing to the subsurface reflectance images and validating with the field-measured reflectance data, we demonstrated that the satellite derived bottom reflectance in the blue and green bands was accurate in both magnitude and shape by the proposed method. Finally, the impacts of the spatial inhomogeneity of the water properties, purity of sampling pixels for estimating the band ratio of the total diffused attenuation coefficients, and errors in the radiometric correction on the bottom reflectance retrieval were discussed and analyzed.http://www.sciencedirect.com/science/article/pii/S156984322500130XBottom reflectanceRemote sensingCoral reefsSatellite multispectral imageryShallow water |
| spellingShingle | Benqing Chen Yanming Yang Mingsen Lin Bin Zou Shuhan Chen Erhui Huang Wenfeng Xu Yongqiang Tian Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters International Journal of Applied Earth Observations and Geoinformation Bottom reflectance Remote sensing Coral reefs Satellite multispectral imagery Shallow water |
| title | Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters |
| title_full | Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters |
| title_fullStr | Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters |
| title_full_unstemmed | Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters |
| title_short | Satellite retrieval of bottom reflectance from high-spatial-resolution multispectral imagery in shallow coral reef waters |
| title_sort | satellite retrieval of bottom reflectance from high spatial resolution multispectral imagery in shallow coral reef waters |
| topic | Bottom reflectance Remote sensing Coral reefs Satellite multispectral imagery Shallow water |
| url | http://www.sciencedirect.com/science/article/pii/S156984322500130X |
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