Abstract
For the first time, HY-2A/GM-derived gravity anomalies determined with the least-squares collocation method and ship-borne bathymetry released from the National Centers for Environmental Information (NCEI) are used to predict bathymetry with the gravity-geologic method (GGM) over three test areas located in the South China Sea (105–122°E, 2–26°N). The iterative method is used to determine density contrasts (1.4, 1.5, and 1.6 g/cm3) between seawater and ocean bottom topography, improving the accuracy of GGM bathymetry. The results show that GGM bathymetry is the closest to ship-borne bathymetry at check points, followed by SRTM15+V2.0 model and GEBCO 2020 model. It is found that in a certain range, the relative accuracy of GGM bathymetry tends to improve with the increase of depth. Different geological structures affect the accuracy of GGM bathymetry. In addition, the influences of gravity anomalies and data processing method on GGM bathymetry are analyzed. Our assessment result suggests that GGM can be widely applied to bathymetry prediction and that HY-2A/GM-derived gravity data are feasible with good results in calculating ocean depth.
Highlights
Ocean depth plays a very important role in marine geology, geophysics and geodesy, such as the study of earth’s plate tectonics, changes of ocean currents and tides, and navigation of ships
The results show that HY-2A/geodetic mission (GM)-derived gravity anomalies can be used to predict bathymetry, and geologic method (GGM) can be effectively applied to areas with sparse shipborne bathymetry
It can be seen from the mean depths that GGM data are closest to National Centers for Environmental Information (NCEI) data in the test areas, while General Bathymetric Chart of the Oceans (GEBCO) data are closest to SRTM15 data in various statistical indicators
Summary
Ocean depth plays a very important role in marine geology, geophysics and geodesy, such as the study of earth’s plate tectonics, changes of ocean currents and tides, and navigation of ships. Bathymetry prediction mainly includes satellite remote sensing, sonar images and satellite altimetry gravity anomalies. Satellite remote sensing (Jay and Guillaume, 2014) has advantages in economy and flexibility, its accuracy needs to be improved. High-resolution seafloor topography prediction of sonar images is achieved with the shape from shaping (Coiras et al, 2007), which needs to be constrained by external bathymetry. In the past 50 years, great progress has been made the technical performance of satellite altimetry technology (e.g., Born et al, 1979; Cheney et al, 1986; Francis et al, 1995; Hwang et al, 2002; Guo et al, 2014, 2015, 2016), and its measurement accuracy and resolution (Hsiao et al, 2016) have been greatly improved. The technology has made a significant contribution to the satellite altimetry-derived ocean gravity field
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