Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery
We evaluated six empirical and semianalytical models of the diffuse attenuation coefficient at 490 nm (<i>K<sub>d</sub></i>(490)) using an in situ dataset collected in the Pearl River estuary (PRE). A combined model with the most accurate performance (correlation coefficient,...
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MDPI AG
2020-07-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/12/14/2269 |
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| author | Chaoyu Yang Haibin Ye Shilin Tang |
| author_facet | Chaoyu Yang Haibin Ye Shilin Tang |
| author_sort | Chaoyu Yang |
| collection | DOAJ |
| description | We evaluated six empirical and semianalytical models of the diffuse attenuation coefficient at 490 nm (<i>K<sub>d</sub></i>(490)) using an in situ dataset collected in the Pearl River estuary (PRE). A combined model with the most accurate performance (correlation coefficient, <i>R</i><sup>2</sup> = 0.92) was selected and applied for long-term estimation from 2003 to 2017. Physical and biological processes in the PRE over the 14-year period were investigated by applying satellite observations (MODIS/Aqua data) and season-reliant empirical orthogonal function analysis (S-EOF). In winter, the average <i>K<sub>d</sub></i>(490) was significantly higher than in the other three seasons. A slight increasing trend was observed in spring and summer, whereas a decreasing trend was observed in winter. In summer, a tongue with a relatively high <i>K<sub>d</sub></i>(490) was found in southeastern Lingdingyang Bay. In Eastern Guangdong province (GDP), the relatively higher <i>K<sub>d</sub></i>(490) value was found in autumn and winter. Based on the second mode of S-EOF, we found that the higher values in the eastern GDP extended westward and formed a distinguishable tongue in winter. The grey relational analysis revealed that chlorophyll-a concentration (<i>C<sub>chla</sub></i>) and total suspended sediment concentration (<i>C<sub>tsm</sub></i>) were two dominant contributors determining the magnitude of <i>K<sub>d</sub></i>(490) values. The <i>C<sub>tsm</sub></i>-dominated waters were generally located in coastal and estuarine turbid waters; the <i>C<sub>chla</sub></i>-dominated waters were observed in open clear ocean. The distribution of constituents-dominated area was different in the four seasons, which was affected by physical forces, including wind field, river runoff, and sea surface temperature. |
| first_indexed | 2024-03-10T18:27:57Z |
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| language | English |
| last_indexed | 2024-03-10T18:27:57Z |
| publishDate | 2020-07-01 |
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| series | Remote Sensing |
| spelling | doaj.art-bba8b9221a1a4927837ef7ca3f5bffa22023-11-20T06:50:50ZengMDPI AGRemote Sensing2072-42922020-07-011214226910.3390/rs12142269Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing ImageryChaoyu Yang0Haibin Ye1Shilin Tang2South China Sea Marine Prediction Center, State Oceanic Administration, Guangzhou 510300, ChinaState Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, ChinaState Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, ChinaWe evaluated six empirical and semianalytical models of the diffuse attenuation coefficient at 490 nm (<i>K<sub>d</sub></i>(490)) using an in situ dataset collected in the Pearl River estuary (PRE). A combined model with the most accurate performance (correlation coefficient, <i>R</i><sup>2</sup> = 0.92) was selected and applied for long-term estimation from 2003 to 2017. Physical and biological processes in the PRE over the 14-year period were investigated by applying satellite observations (MODIS/Aqua data) and season-reliant empirical orthogonal function analysis (S-EOF). In winter, the average <i>K<sub>d</sub></i>(490) was significantly higher than in the other three seasons. A slight increasing trend was observed in spring and summer, whereas a decreasing trend was observed in winter. In summer, a tongue with a relatively high <i>K<sub>d</sub></i>(490) was found in southeastern Lingdingyang Bay. In Eastern Guangdong province (GDP), the relatively higher <i>K<sub>d</sub></i>(490) value was found in autumn and winter. Based on the second mode of S-EOF, we found that the higher values in the eastern GDP extended westward and formed a distinguishable tongue in winter. The grey relational analysis revealed that chlorophyll-a concentration (<i>C<sub>chla</sub></i>) and total suspended sediment concentration (<i>C<sub>tsm</sub></i>) were two dominant contributors determining the magnitude of <i>K<sub>d</sub></i>(490) values. The <i>C<sub>tsm</sub></i>-dominated waters were generally located in coastal and estuarine turbid waters; the <i>C<sub>chla</sub></i>-dominated waters were observed in open clear ocean. The distribution of constituents-dominated area was different in the four seasons, which was affected by physical forces, including wind field, river runoff, and sea surface temperature.https://www.mdpi.com/2072-4292/12/14/2269Pearl River estuarydiffuse attenuation coefficientMODISS-EOF |
| spellingShingle | Chaoyu Yang Haibin Ye Shilin Tang Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery Remote Sensing Pearl River estuary diffuse attenuation coefficient MODIS S-EOF |
| title | Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery |
| title_full | Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery |
| title_fullStr | Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery |
| title_full_unstemmed | Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery |
| title_short | Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery |
| title_sort | seasonal variability of diffuse attenuation coefficient in the pearl river estuary from long term remote sensing imagery |
| topic | Pearl River estuary diffuse attenuation coefficient MODIS S-EOF |
| url | https://www.mdpi.com/2072-4292/12/14/2269 |
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