Surficial distribution of suspended sediment in Beibu Gulf of the South China Sea

The study of surficial suspended matter based upon remote sensing is not accurate enough in Beibu Gulf, especially in the western part of the Gulf, due to location constraint. In addition, the data on seasonal variation in suspended sediment concentration (SSC) is lacking in the area. In this paper, a retrieval algorithm for surficial suspended sediment concentration was established by analyzing the images from the MODIS-Aqua satellite in the years from 2003-2017 and the in situ measured data from the Gulf, and thus the distribution of surficial SSC in Beibu Gulf is revealed and carefully studied. The results suggest that the main high-value areas of the surficial suspension are located along the coast of Guangxi, the west side of Hainan Island and the Red River Delta. Under the influence of fluvial sediment transport and ocean dynamics, SSC are higher in winter and summer rather than other seasons in the coastal areas, and reaches the lowest in spring. The transit of tropical cyclones will lead to the increase in SSC. SSC on the west side of Leizhou Peninsula increased by 75% compared with the multi-year average owing to the transit of tropical storm Bebinca.