改进的低纬度化极稳定算法

An improved stable algorithm of the reduction-to-the-pole at low latitudes

针对频率域常规化极因子在低纬度地区不稳定这一问题,提出了一种改进的低纬度化极稳定算法。为了对常规化极因子进行改造,提出了局部压制类和全局压制类化极方法,实现对放大区的高频压制;然后通过计算化极结果与归一化磁源强度的相关系数对引入的参数进行寻优,得到最优参数下的化极结果,提高了化极结果的精度;最后针对参数最优的化极因子仍存在高频放大效应这一问题,采用Tikhonov正则化方法稳定化极因子。理论模型的试验结果表明,改进算法可有效压制原始信号中的高频噪声并提高化极结果的信噪比,低纬度化极的精度和稳定性得到提高。

As the routine reduction-to-the pole(RTP)operator at low latitudes is usually unstable in the frequency domain,we propose an improved stable RTP algorithm at low latitudes.First the high frequency noise in amplification zones is suppressed with the local-suppression and global-suppression RTP approaches based on routine RTP operator(RO)modifications.Then the introduced parameters are optimized by calculating the correlation coefficient between the RTP results and the normalized source strength.RTP results with the optimal parameters are obtained,and the accuracy of these RTP results is accordingly improved.Finally,to resolve the problem of high-frequency amplification effect in the optimal RTP operators,the Tikhonov regularization method is utilized to stabilize the operators.Experimental results on theoretical model indicate that the proposed algorithm eliminates the high-frequency noise in the original data and improves the signal-to-noise ratio of the RTP results,and the accuracy and stability of the low latitude RTP are greatly improved.