Study on the mechanisms of interannual variation in suspended sediment concentration in the Bohai Sea based on GOCI

Abstract

The launch of the Geostationary Ocean Color Imager (GOCI) satellite has made it possible to observe suspended sediment concentration (SSC) in the Bohai Sea (BHS) over a long time and a large area. We utilized remote sensing data from GOCI from 2011 to 2021 to study the spatiotemporal variation characteristics of SSC in the BHS and identified the contribution of each oceanic element to the changes in SSC. Our findings indicate that SSC is high in winter and low in summer, and related to the southeastward winds in winter (>7 m/s) and northwestward winds in summer (<4 m/s), with a correlation coefficient of 0.634. The average annual increase in SSC is 0.07 g/m3 (an increase of 1.2% per year). In terms of spatial distribution, SSC is highest in Bohai Bay and Laizhou Bay, followed by the Liaodong Bay, and is greater than that in the Central Bohai Sea, which is related to multiple river estuaries in the three bays. Additionally, the Bohai and Liaodong Bay in the BHS are covered by sea ice during winter, which affects the response of waves and currents to wind and changes the ocean current field, thereby affecting the resuspension and transport of sediment. Our EOF analysis revealed that wind-induced changes are the dominant factors in the variations of SSC, while changes in river runoff, sediment discharge, and sea ice cover are also important factors influencing SSC changes.