We use full-wave simulations of rough surfaces to calculate the emissivities of a polar ocean between 0.5 GHz and 2 GHz for applications in ocean salinity. High accuracy is required because the emissivity variations between flat and rough surfaces are at the order of magnitude of $10^{-3}$ . In addition, the changes of emissivity due to salinity change are only about $4.2\times 10^{-4}$ /psu to $2.6\times 10^{-3}$ /psu for 0.5–2 GHz over the polar region. An enhanced method is proposed by combining neighborhood impedance boundary condition (NIBC), Nystrom, and sparse matrix canonical grid (SMCG) to solve the dual surface integral equations (SIEs) using the method of moments (MoM). To simulate large-scale ocean waves using a complete ocean spectrum, the surface root-mean-square (RMS) heights are up to 22.5 cm corresponding to 1.5 times wavelength of 2 GHz. Thus, the surface lengths used are up to 333 wavelengths to account for the large RMS height. Simulation results are illustrated for 0.5–2 GHz. We show that the energy conservations are obeyed to $10^{-4}$ . The effects of roughness and salinity on broadband polar ocean emissivity are studied with the proposed approach. Numerical simulations show that the sensitivity to salinity is still preserved in spite of roughness.

中文翻译：

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使用 NIBC/Nystrom/SMCG 方法准确计算 0.5 至 2 GHz 之间极地海洋表面的发射率

我们使用粗糙表面的全波模拟来计算 0.5 GHz 和 2 GHz 之间极地海洋的发射率，以用于海洋盐度的应用。需要高精度，因为平坦和粗糙表面之间的发射率变化为 $10^{-3}$ . 此外，盐度变化引起的发射率变化仅约为 $4.2\times 10^{-4}$ /电源 $2.6\乘以 10^{-3}$ /psu 用于极地区域的 0.5–2 GHz。提出了一种结合邻域阻抗边界条件（NIBC）、Nystrom 和稀疏矩阵规范网格（SMCG）的增强方法，使用矩量法（MoM）求解双曲面积分方程（SIE）。为了使用完整的海洋光谱模拟大规模海浪，表面均方根 (RMS) 高度高达 22.5 cm，对应于 2 GHz 的 1.5 倍波长。因此，使用的表面长度高达 333 个波长，以解决大的 RMS 高度。仿真结果显示为 0.5–2 GHz。我们证明能量守恒服从 $10^{-4}$ . 使用所提出的方法研究粗糙度和盐度对宽带极地海洋发射率的影响。数值模拟表明，尽管存在粗糙度，但对盐度的敏感性仍然存在。