网格剖分对大地电磁测深反演精度的影响

网格剖分的合适与否,影响着反演结果的精度。用不同模型、不同反演方法,对比验证粗细两种不同的网格对反演精度的影响。研究结果表明,从整体上看两种不同网格剖分方式,粗网格在深部比细网格模拟精度高,但是近地表开始阶段,粗网格与细网格波动幅度都较大,都脱离正常值,粗网格模拟精度不如细网格;粗网格的整体变化幅度比细网格缓和,其中对低阻异常体反演精度较好,但对高阻异常体反演精度较差,与真实值相去甚远。

The effects of grid subdivision on the accuracy of MT inversion

The problem whether the grid subdivision is suitable or not constitutes a prerequisite for the accuracy of the inversion results. Using different models and different inversion methods, the authors made a comparative study to detect the effects of two different grids on the accuracy of inversion. The employment of the two different ways of grid subdivision shows that, on the whole, the coarse grid has higher simulation precision than the fine grid in the depth, but at the starting stage of near-surface, the amplitude of fluctuation of the coarse grid and that of the fine grid are both relatively large, i.e., both obviously deviate from the normal value. The simulation accura-cy of the fine grid is better than that of the coarse grid. The overall change in the coarse grid is more smooth than the fine grid, and the inversion accuracy of the coarse grid for the anomalous body of low resistance is better;nevertheless, for abnormal body of high resist-ance, the inversion accuracy is poorer, and the value widely deviates from the real value.