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为了把在地表上记录到的天然电磁场变异整理为适于研究地球内部电性特点的形式,大地电磁资料的处理涉及到电磁理论、时间序列分析以及线性系统理论的概念。电磁场的关系在平行层状地球表面上归结为联系电场分量与正交的磁场分量的标量传输阻抗;而在横向非均匀介质附近导致为联系每一电场分量与一对磁场分量的张量传输阻抗关系。许多时间序列频谱分析方法能用来计算各种场量的复频谱系数。然后这些又用于计算传输函数或者张量阻抗。对两度情况来说,能旋转张量阻抗以确定电性结构的主轴方向。一般对于实际资料来说,甚至当场是在主轴方向上测量时,根据张量要素比根据简单的正交场分量的比率计算的视电阻率要稳定。
In order to organize the variation of natural electromagnetic field recorded on the surface into a form suitable for studying the electrical characteristics of the Earth’s interior, the processing of the magnetotelluric data involves the concepts of electromagnetic theory, time series analysis, and linear system theory. The relationship between electromagnetic fields is attributed to the scalar transmission impedance of the component of the electric field in contact with the orthogonal magnetic field component on the parallel layered earth surface and to the tensor transmission impedance of a pair of magnetic field components in the vicinity of the transverse inhomogeneous medium relationship. Many time-series spectral analysis methods can be used to calculate complex spectral coefficients for various fields. These are then used to calculate the transfer function or tensor impedance. For two cases, the tensor impedance can be rotated to determine the direction of the major axis of the electrical structure. In general, for practical data, the apparent resistivity calculated from the ratio of tensor elements to simple orthogonal field components is stable even when the field is measured in the principal axis direction.