Research On The Inversion Of Seafloor Topography Of Satellite Altimeter Gravity Anomalies

A series of marine activities such as marine engineering construction,marine resources development,marine science experiments,and the maintenance of marine rights and interests have prompted the exploration results of submarine topography to develop in the direction of large-scale,high-precision,high-resolution,and high-efficiency.Based on the correlation between ocean gravity anomaly data and the sea floor topography in a certain band,this paper makes a corresponding study on the conversion of large-scale,high-precision,long-time sequence of marine gravity field data to seafloor topography provided by satellite altimetry technology.The main works and innovations are as follows:1?The basic methods for inversion of seabed topography based on height anomaly were combed,comparing the advantages and disadvantages of each inversion method by the aspects of the initial data,required parameters,applicable range,and wave filter.The theory of obtaining the gravity anomaly data of the ocean and the inversion of ocean gravity anomalies by satellite altimetry are introduced.The flow of gravity anomaly reduction and the calculation examples are given.2?Taking the South China Sea as a test area,the seabed topographic model was retrieved by the Gravity-geologic method(GGM)and the Smith&Sandwell method(SAS).The ETOPO1 model was introduced and some of the ship's water depth points were chosen as checkpoints.The assessment of the accuracy of the inversion of the submarine topographic model shows that the GGM bathymetry model in this area is better than the SAS bathymetry model.3?The key to inverting the submarine topographic model based on GGM method is the difficulty of determining the density difference constant.Using the iterative calculation method based on ship control points and the downward continuation based on gravity anomaly to obtain the density difference constant as 1.4g·cm-3 and 2.15g·cm-3,from which the corresponding GGM sea depth model was obtained and a statistical comparison was made to determine that 2.15g·cm-3 is the best density difference constant in the South China Sea,improved the seabed terrain inversion effect effectively.4?Taking the Ross Bay area as an improved experimental sea area,the GGM2 and GGM3 sea bathymetry models were successively determined by the waveform retracking of the altimetry data and algorithm of local terrain correction,combined with the GEBCO-2014 sea bathymetry model,the accuracy of the two models is improved by 4.79%and 9.88%respectively compared with the GGM1 sea bathymetry model,which verifies the effectiveness of the improved algorithms.