Abstract
The purpose of this study is the determination of the seafloor depth from altimetry satellite-derived gravity anomalies. The relationship between seafloor depths and gravity anomalies has been studied. The substance density contrast between the seabed and the seawater is determined by the iterative method. The long-wavelength gravity anomalies are interpolated using the Collocation method. In the experiment, the DTU21GRAV model was evaluated for accuracy by comparing with ship-borne-derived gravity anomalies, reaching ±4.509 mGal. The nine options with different density contrasts were calculated iteratively. After fitting with ship-borne-derived gravity anomalies, the DTU21GRAV gravity anomalies were used to calculate the seafloor depth in the study area (between latitudes 14.5⁰N and 16⁰N and longitudes 115⁰E and 116.5⁰E). The experimental results show that the most suitable density contrast in the study area is 1.29 g/cm3. The accuracy of the gravity derived-depth in the study area reaches ±70.833 m. This accuracy is higher than that of the global bathymetry model DTU18BAT(±181.864 m) and GEBCO2022 (±143.232 m).