基于离散余弦变换(DCT)的化磁极方法

Reduction to the pole of magnetic anomalies based on discrete cosine transform

针对提高磁异常化磁极的质量问题,提出基于离散余弦变换(DCT)的化磁极方法.以位场余弦变换谱分析为基础,从理论上推导了基于DCT的二度和三度体总场磁异常化磁极转换公式.在倾斜板状体模型实验中,化磁极误差小于0.001 nT,具有较高的精度;在单球体及多球体模型实验中,采用基于DCT的化磁极方法在5°倾斜磁化时就可以取得较好的化磁极结果,15°时化磁极的效果更加明显,其等值线的形态、幅值以及所反映的磁性体的水平位置都得到较好的恢复;这说明,采用本文方法进行化磁极时,可以取得较好的效果.

In order to improve the calculating quality on reduction to the pole （RTP） of magnetic anomalies, the paper propose a method of RTP based on the discrete cosine transform （DCT）. We deduce theoretical formulas conversion of RTP of the total field anomalies for two and three dimensional bodies according to the cosine transform spectra analysis of the potential field in theory. There is high precision in the model experiment of sloping plate and the RTP field errors are less than 0. 001 nT. In the model experiments of single and multi-sphere, we can obtain the better RTP results using the DCT method when the magnetic dip is 5°, and the results are excellent when the dip is 15°. The shape of contour line, the maximum and the plane location of magnetic model are all good comparing with the theoretical anomalies when the model is perpendicular magnetization.