用高阻方向滤波器提高低磁纬度地区磁异常化极效果

在频率(波数)域中利用化极转换函数可以将具有方向性的斜磁化异常转换为方向性不明显的垂直磁化异常。考虑到在低磁纬度区,实际资料中含有随机干扰,会使化极结果出现严重畸变,从而给定量反演计算或定性解释带来很大的困难。所以在化极处理过程中对高频段和低频段分别采用高阻滤波器和反汉宁窗滤波器进行滤波处理,提高了化极结果的信噪比。在低磁纬度区作化极处理时,还要特别注意磁倾角偏差的影响。因为它使化极异常的等值线发生扰动、幅值增大,并沿磁场水平方向拉长。为消除这种现象,也要采用高阻滤波器处理。

Improving the effect of reducing magnetic anomaly to pole in low magnetic latitude area by using directional high cut filter

Transfer function for reduction to pole can be used to reduce directional oblique magnetic anomaly to vertical magnetic anomaly in frequency(or wavenumber)domain.Random noises in real magnetic data in low latitude area greatly distort the result of reducing magnetic anomaly to pole,thus causing dif- ficulty in quantitative inversion or qualitative interpretation.Consequently we apply high cut filter and inverse Hanning window filter to high-frequency band and low frequency band respectively in the processing of reduction to pole,so that S/N ratio of the result of reduction to pole is improved obviously.Further- more,we must pay particular attention to the influence of magnetic dip deviation in the course of reducing magnetic data to pole in low magnetic latitude area be- cause the influence makes anomaly contours after reduction to pole disturbed, increased and lengthened along horizontal magnetic field.High cut filter is also used to remove these phenomena.