时间域航空电磁数据的反演

INVERSION OF TIME-DOMAIN AIRBORNE ELECTROMAGNETIC DATA

本文用广义逆矩阵理论讨论了时间域航空电磁数据的反演方法.以水平二层大地和球体模型为例进行了计算,结果表明这种方法对时间域电磁数据的反演是行之有效的.对于理论数据,一般仅需迭代数次即可稳定地收敛到真值.通过奇异值分析,可以确定一个模型中的相对重要参数和无关紧要参数;对于求解某一特定参数,可确定哪些数据起决定性的作用.由奇异值分解而得出的信息密度矩阵、模型分辨矩阵,分别给出了模型响应拟合数据和模型参数分辨率的度量.这些信息对于时间域航空电磁系统的设计、野外测量和资料解释都具有重要的参考价值.最后给出了实例.

An inversion procedure for time-domain airborne electromagnetic (AEM) data, which are based on singular value decomposition (SVD) along with damped least square inversion, is developed for two-layered earth and sphere model. The procedure provides stable and rapidly convergent solutions. Several models are chosen to test the algorithm and all of them are resolved with a very high degree of accuracy from noise free data. The analyses of singular values and eigenvectors can indicate which parameters are relatively important in a model and which channels data are significant for resolving specific model parameters. A field example is presented.