Retrieval of remotely sensed sea surface salinity using MODIS data in the Chinese Bohai Sea
2017
Yu, Xiang | Xiao, Bei | Liu, Xiangyang | Wang, Yebao | Cui, Buli | Liu, Xin
Salinity dominates seawater density and directly affects physical and biochemical processes. Having a reliable retrieval model is essential to providing frequent and accurate sea surface salinity (SSS) data for marine research. Remote-sensing techniques provide alternatives for SSS data retrieval with its advantages of wide area surveys and real-time monitoring. In the present study, inverse relationship between SSS and coloured dissolved organic matter (CDOM) concentration in the Chinese Bohai Sea was verified. Thus, four simple band ratios of the original remote-sensing reflectance (Rᵣₛ) used to retrieve the CDOM concentration were compared and tested during SSS retrieval. Rᵣₛ (531)/Rᵣₛ (551) performed best among the four given band ratios. The model employed here can be applied to derive SSS with a root mean square error (RMSE) of 0.26 practical salinity units (psu) (R² = 0.76). A calibration model was verified using a discrete dataset of the measured SSS and was tested further during mapping of SSS in the Chinese Bohai Sea during 2010–2014. The yielded spatial patterns of SSS were satisfactory and an inverse relationship between SSS and the Yellow River discharge was confirmed.
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