顾及地磁背景场的多目标磁异常分量换算方法

Transformation of Multi-objects Magnetic Anomaly Components with Geomagnetic Effect

采用快速傅立叶变换方法,理论上推导了基于多目标平面总强度磁异常分量换算的公式;根据恒定地磁背景场网格数据傅立叶变换后频率域除原点外处处为零的特点,利用总场强度换算磁异常分量时,可采取频率域原点强制置零方法消除地磁背景场的影响,分析了强制置零在磁异常分量换算中引入的误差以及总强度磁异常一级近似引起的误差。通过以上技术解决了由平面总场强度向磁性目标磁异常分量换算的问题,仿真计算评定了该方法的换算精度。

Based on multi-objects magnetic anomaly,respective components transformation formulae were deduced theoretically with FFT approach.Regarding normal geomagnetic field as a constant,its Fourier transformation becomes equal to zero except origin in frequency domain.Therefore,the influence of geomagnetic could be eliminated through setting the value of zero on frequency origin,the corresponding error in component transformation has been analyzed as well as the first grade approximate error of anomalous magnetic field.Applying above-mentioned techniques,the transformation of the total field to the component fields was implemented in the frequency domain after calculating the given total field spectrum.The effectiveness of the suggested techniques has been illustrated by three simulated sphere examples and real magnetic data from a collection of environmental ferro-metallic objects.