This letter presents the computation of electromagnetic (EM) forward scattering from and the full-wave inversion (FWI) of 2-D inhomogeneous scatterers straddling multiple subsurface planar layers covered by 1-D locally rough surface. In the forward scattering, the electric field integral equation (EFIE) is formulated and the 2-D Green’s functions are evaluated by the transmission-line analogy method and the buried object approach (BOA) to account for both the reflection and transmission in the multiple planar layer boundaries and the random scattering from the locally rough surface. The computation accuracy of the forward solver is verified by comparing the simulation results with the finite element method (FEM) outcomes. Meanwhile, the additional computational cost caused by the rough surface is investigated in numerical experiments and also explained in theory. It is shown that, for the numerical case in this letter, the forward solver needs nearly 90 times computation time and consumes nearly 30 times memory when the rough surface is present compared with those when it is absent. Meanwhile, In FWI, the variational Born iterative method (VBIM) is adopted to reconstruct multiple scatterers straddling multiple subsurface planar layers when the rough surface is present or absent. Numerical experiments show that neglecting a rough surface with the root mean square (rms) height of 0.1 m almost causes the failure of the inversion.

中文翻译：

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来自跨越多个具有粗糙表面的地下平面层的非均匀物体的二维电磁散射和逆散射

这封信介绍了跨越由一维局部粗糙表面覆盖的多个地下平面层的二维非均匀散射体的电磁 (EM) 前向散射和全波反演 (FWI) 的计算。在前向散射中，公式化了电场积分方程 (EFIE)，并通过传输线类比方法和掩埋物体方法 (BOA) 评估了二维格林函数，以考虑多重散射中的反射和透射平面层边界和局部粗糙表面的随机散射。通过将仿真结果与有限元法（FEM）结果进行比较，验证了正向求解器的计算精度。同时，通过数值实验研究了粗糙表面引起的额外计算成本，并从理论上进行了解释。结果表明，对于本文的数值情况，与不存在粗糙表面时相比，当存在粗糙表面时，正向求解器需要近 90 倍的计算时间和消耗近 30 倍的内存。同时，在FWI中，当粗糙表面存在或不存在时，采用变分玻恩迭代法（VBIM）来重建跨越多个地下平面层的多个散射体。数值实验表明，忽略均方根（rms）高度为0.1 m的粗糙表面几乎会导致反演失败。