An exploratory satellite gravity approach for detecting the modern marine sedimentary processes in the Bohai Central Basin

Satellite gravity has the capability to cover the entire globe, enabling real-time, high-precision, and periodic monitoring of gravity field changes. We introduce a novel geodesy method to monitor modern marine sedimentation issues, effectively addressing the challenge of insufficient direct observation of modern long-term sediment storage changes in the Bohai Central Basin (BCB). Combining various sources of model data, this paper uses the Newton's integration method and spherical harmonic expansion to present the theory and method for modeling Earth's gravity potential after removing seawater mass, known as the “seawater layer” method. The Marine Deposits Storage (MDS) changes in the BCB are calculated through the new gravity potential model and the method of inverting the changes in Terrestrial Water Storage (TWS). The contemporary time series from 2019 to 2022 of MDS in the BCB has been established. The seasonal fluctuation is approximately ±4 cm, and the annual rate is 0.29 cm/yr, which is highly consistent with the centennial-scale sedimentation rate from box/gravity sediment cores and indicates a rate approximately 3.7 times higher than the historical Holocene sedimentation rate inferred from seafloor seismic profile data. Through a comparative analysis with sediment discharge measurements at the Lijin Station of the Yellow River, a five-month lag period was determined, with a correlation coefficient of 0.5625. The mechanism of suspended sediment flux and diffusion in the Bohai Sea was verified from the perspective of satellite geodesy. In summer, the majority of Yellow River sediments were transported and deposited in the underwater delta; in winter, the sediments were resuspended and transported to the BCB.