AI 中文总结
针对粗糙界面与相关随机介质，提出非正交坐标变换统一计算表面与体散射，揭示非加性干涉效应，偏差可达20%并影响介电参数反演。
AI 中文摘要
我们计算了具有随机波动介电常数的半空间上粗糙表面的非相干一阶反向散射截面，当两个随机场相关时，表面散射和体散射不是可加的。非正交坐标变换使粗糙边界平坦化，并将几何粗糙度转化为与介电波动相同的亥姆霍兹方程的体源，由相同的格林函数传播：两种机制及其干涉均来自单一计算，无需等效表面电流，也无需场不连续性的规定。振幅的几何部分精确再现了小扰动核，适用于任意入射角、介电常数和剖面函数。干涉项在共极化两个通道中获得，并带有显式的表面-介电相关系数。与可加性的偏差在完全相关时达到百分之二十，随该系数改变符号，并受相关层深度的平衡条件和相干条件控制。它没有角度特征，使共极化比偏移不到十分之一分贝，因此可加性反演吸收了它，使介电波动的反演振幅偏差达数十个百分点。
英文摘要
We compute the first-order incoherent backscattering cross-section of a rough surface over a half-space with randomly fluctuating permittivity, when the two random fields are correlated, so that surface and volume scattering are not additive. A non-orthogonal coordinate transformation flattens the rough boundary and turns the geometric roughness into volume sources of the same Helmholtz equation as the dielectric fluctuations, propagated by the same Green's function: both mechanisms and their interference follow from one calculation, with no equivalent surface currents and no prescription for the field discontinuity. The geometric part of the amplitude reproduces the small-perturbation kernel exactly, for any incidence angle, permittivity and profile function. The interference term is obtained for both co-polarized channels, with an explicit surface-dielectric correlation coefficient. The departure from additivity reaches twenty percent at full correlation, changes sign with that coefficient, and is governed by a balance condition and a coherence condition on the depth of the correlated layer. It carries no angular signature and shifts the co-polarized ratio by less than a tenth of a decibel, so an additive inversion absorbs it, biasing the retrieved amplitude of the dielectric fluctuations by tens of percent.
Comments31 pages, 6 Figures
