基于最小垂直梯度泛函的二维MT数据反演方法

分析了大地电磁测深法反演中聚焦反演方法的原理，从反演目标函数构建方式出发，提出将最小垂直梯度泛函作为模型目标函数的二维MT反演方法，采用再加权正则化共轭梯度法求解目标函数的极小值。在正演模拟时采用基于二次场的有限单元法．引入互易定理计算灵敏度矩阵。并且在前几次迭代后，利用Broyden公式更新灵敏度矩阵．提高了计算效率。所实现的反演方法具有迭代稳定收敛、异常体的聚焦程度高等特点，特别是界面的垂向分辨能力比最小梯度支撑泛函有所提高，模型试算结果表明了本文方法的正确性。

Inversion Algorithm of 2-D Magnetotelluric Data Based on the Minimum Vertical Gradient Support

In this paper we discuss the focusing inversion method of MT data.The minimum vertical gradient support is introduced into inversion function after we analyse the foundation method of object function.The re-weighted regularized conjugate gradient method is utilized to search for the minimum of the parametric function.The forward modeling uses finite element method based on secondary field.The principle of electromagnetic reciprocity is applied and we update the sensitivity matrix by Broyden formula after the initial several iterations.This kind of new inversion stabilizer helps to generate clearer and more focused images for geological structures and is so suitable for the horizontal resistive structures that inversion results of synthetic data show the inversion approach is effective.