Study on Diurnal Variation of Turbidity in the Yangtze Estuary and Adjacent Areas by Remote Sensing

In this study, we established a turbidity inversion model for the Rayleigh-corrected reflectance data from the geostationary ocean color imager (GOCI) based on the buoy observation data obtained from the Yangtze estuary and the East China sea. In addition, remote sensing was used to retrieve the turbidity of the Yangtze estuary and the adjacent sea areas. This research results show that the 680 nm band is the most sensitive to turbidity signals and that the inversion effect can be optimally established by model combining multiple bands. The turbidity distributions in the Yangtze estuary and the adjacent sea areas are observed to be high near the shore and low away from the shore. Further, the turbidity initially increases and subsequently decreases from the Yangtze estuary to the Hangzhou bay, and the changing trend is reversed toward the south of the Hangzhou bay within a day. The diurnal variation of the turbidity of water body, which is affected by the ocean dynamics, can be characterized based on the turbidity zone, and the turbidity of the water outside the turbidity zone does not change significantly within days. The turbidity zone exhibits significant seasonal characteristics, showing a tendency of farther in winter and nearer in summer, which is related to ocean currents.