基于分形径向谱的位场向下延拓截止波数自动确定方法

Automatic determination of the cut-off wavenumber for downward continuation of potential field based on fractal radial spectrum

向下延拓是重磁位场数据处理与解释的一项重要技术,并因其固有的不稳定性而成为研究的热点.为获得稳定向下延拓结果,波数域向下延拓一般通过附加低通滤波器或改造向下延拓因子来完成.由此,滤波器或改造因子的截止波数则是精确向下延拓的关键.本文基于分形修正径向平均功率谱的物理特性,提出一种位场向下延拓截止波数的自动确定方法.基于理论重力模型和航磁实测数据的向下延拓对比实验结果表明:(1)本文所提出的自动确定方法物理意义明确,能快速有效地确定截止波数并进而获得向下延拓正则参数;(2)基于本文方法的正则化向下延拓结果优于改进导数迭代法的向下延拓结果.

Downward continuation is an important technique in the processing and interpretation of gravity and magnetic potential field data,and has become a research hotspot due to its inherent instability.In order to obtain the stable downward continuation result,the downward continuation in the wavenumber domain is generally accomplished by adding a low-pass filter or modifying the downward continuation factor.The cut-off wavenumber of the filter or modification factor is the key to accurate downward continuation.In this paper,based on the physical characteristics of the fractal modified radial average power spectrum,an automatic determination method for the cut-off wavenumber of the downward continuation of the potential field is proposed.The comparative experimental results of downward continuation based on theoretical gravity model and aeromagnetic measured data show that:(1)The automatic determination method proposed in this paper has clear physical meaning,and can quickly and effectively determine the cut-off wavenumber and then obtain the regularization parameters of downward continuation.(2)The regularized downward continuation result based on the proposed method is better than that of the improved derivative iterative method.