Abstract

In the present methods to estimate seafloor topography from gravimetric data, some parameters need be computed in advance from the known bathymetric data, which leads some uncertainties in applying the methods. To overcome such uncertainties, an analytical method to estimate the seafloor topography from the vertical gravity gradient (VGG) is introduced in the paper. Based on the expression of VGG generated by a cubic prism, the observation equations for the seabed depth are established firstly. Then, the simulation results show that the observation equations established are solvable. Especially, the piecewise bilinear interpolation is introduced to separate the influence of the far-field anomalous bodies on VGG. In addition, some imitation arithmetic examples are given in order to examine the solvability of the observation equations and estimate the accuracies of their solutions. Finally, an actual seafloor topography located in South China Sea (117.6-118.25°E, 17-17.65°N), is estimated by the method proposed in the paper, and compared with ship depth sounding, the root mean square (RMS) error of bathymetry prediction is 77 m.

摘要

目前根据重力数据估计海底地形的方法中，需要根据已知的测深数据预先计算一些参数，这导致该方法在应用中存在一些不确定性。为了克服这种不确定性，本文介绍了一种从垂直重力梯度 (VGG) 估计海底地形的分析方法。基于立方棱镜产生的VGG表达式，首先建立了海底深度的观测方程。仿真结果表明，所建立的观测方程是可解的。特别是引入了分段双线性插值来分离远场异常体对VGG的影响。此外，给出了一些模拟算术例子，以检验观测方程的可解性并估计其解的精度。最后，利用本文提出的方法估算了位于南海（117.6-118.25°E，17-17.65°N）的一个实际海底地形，并与船舶测深比较，均方根（RMS）误差测深预测为 77 m。