School of Ocean and Earth Science, Tongji University, Shanghai 200092, China.
Institute of Deep-sea and Engineering, Chinese Academy of Science, Sanya 572000, China.
Sensors (Basel). 2018 Nov 29;18(12):4186. doi: 10.3390/s18124186.
The suspended particulate matter (SPM) in Changjiang Estuary is characterized by a high concentration of significant diurnal dynamics. With a higher temporal resolution (eight images obtained per day), Geostationary Ocean Color Imager (GOCI) was selected as the primary remote sensor for the dynamics monitoring in this paper, instead of other satellite sensor working in polar orbit. Based on the characteristics of the field spectra measured in the estuary, an empirical model was established with the band ratio of R745 divided by R490 and proven effective in Suspended Particulate Matter (SPM) estimation (R² = 0.9376, RMSE = 89.32 mg/L). While, Validation results showed that the model performed better in coastal turbid waters than offshore clear waters with higher chlorophyll-a concentration, stressing the importance of partitioning SPM into its major components and doing separate analysis. The hourly observations from GOCI showed that the diurnal variation magnitudes exhibited clear regional characteristics, with a maximum in the turbidity belt near the mouth and a minimum in the offshore deeper areas. In addition, comparing the monthly averaged SPM distribution with the amount of sediment discharged into the estuary, the variation in estuarine turbidity maximum zone is more likely contributed by the sediments resuspended from the sea bed that has already accumulated in the estuarine delta.
长江口悬浮颗粒物（SPM）具有显著的高浓度日变化特征。本文选择了具有更高时间分辨率（每天可获取 8 幅图像）的静止轨道海洋成像仪（GOCI）作为主要的遥感监测工具，而不是使用其他工作在极轨上的卫星传感器。基于在河口测量的现场光谱特征，建立了一个经验模型，该模型使用 R745 波段与 R490 波段的比值，证明在悬浮颗粒物（SPM）估算方面非常有效（R²=0.9376，RMSE=89.32mg/L）。然而，验证结果表明，该模型在沿海混浊水域比在叶绿素-a 浓度较高的近海清澈水域表现更好，这强调了将 SPM 划分为其主要成分并进行单独分析的重要性。GOCI 的每小时观测结果表明，日变化幅度表现出明显的区域特征，在河口附近的混浊带中最大，在近海较深区域中最小。此外，将每月平均的 SPM 分布与排入河口的泥沙量进行比较，河口最大浑浊带的变化更可能是由已经在河口三角洲中积累的海底再悬浮的泥沙所引起的。
