利用重力地质法反演南极阿蒙森海海底地形

Predicting bathymetry of the Amundsen Sea in Antarctica using the Gravity Geologic Method

根据船测单波束数据和V30.1重力异常模型,采用重力地质法(Gravity Geologic Method,GGM)反演得到南极阿蒙森海1'×1'分辨率海底地形。在精度分析中,首先通过GGM反演模型与其他常用的水深模型对比,验证了使用GGM水深模型所反演的南极阿蒙森海海底地形的整体精度最高;然后,分析了水深控制点数量和地形起伏度对反演精度的影响,结果表明地形起伏对反演精度影响较大,而通过增加水深控制点数量则能够提高反演精度;最后,对研究区域进行水深分区处理,分析了密度差异常数与外界因素的关系,得出密度差异常数也受地形起伏影响较大,为此提出了一种基于水深分区计算局部区间最优密度差异常数的GGM法,相比采用全局最优密度差异常数反演海底地形,该方法使反演精度有了明显提高。

In this study,the submarine topography of the Amundsen Sea in Antarctica was inverted at 1'×1'resolution using the Gravity Geologic Method(GGM),shipboard single-beam echosounding data and altimeter-derived gravity anomaly data,version V30.1,from the Scripps Institution of Oceanography model,as input.First,an accuracy analysis confirmed that the GGM-based model yielded the highest overall accuracy,compared with other universal bathymetric models.Then,the influence of the number of control points and of the topographic relief on inversion accuracy was analyzed.Results showed that topographic relief strongly influenced inversion accuracy and that increasing the number of control points improved the inversion accuracy.Finally,the research area was partitioned by depth to analyze the relationship between density contrast and external factors.Density contrast was markedly influenced by topographic relief,thus the GGM was used in this study to calculate local interval partitioning depending on the optimal density contrast depth.Compared with global optimal density contrast inversion of seafloor topography,the method used in this study showed considerably higher accuracy.