It has been observed experimentally that flow-induced ambient noise propagated in an icy thin-plate structure decays quickly. The attenuation rate is sensitive to the ice thickness and is thus potentially an important feature for passive ice detection. The main goal of the present paper is to develop a theoretical model to explain this damping behavior qualitatively and quantitatively. The wave propagation medium is assumed to be an elastic plate and a viscoelastic ice layer sandwiched by two fluid half-space layers. The Kelvin–Voigt model is employed to quantify the viscoelastic behavior of ice which results in complex-valued shear modulus, Lamé constant, and wave velocity. The classical guided wave characteristic equation is simplified by combining the transfer matrix (for the plate-ice interface) and the global matrix (for the fluid–solid interfaces) methods, by which a precise and fast computation of the complex wavenumbers of guided wave modes is realized via the logarithmic residue quadrature method. The attenuation rate, i.e., the imaginary part of a mode wavenumber, is proportional to the ice thickness and wave frequency, which is consistent with the experimental results of both direct and coda wave decay extracted from the cross-correlation of ambient noise.

中文翻译：

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薄板结构中积冰引起的环境噪声衰减：理论解释


实验观察到，在冰冷的薄板结构中传播的流致环境噪声会迅速衰减。衰减率对冰层厚度很敏感，因此可能是被动冰层检测的一个重要特性。本文的主要目标是开发一个理论模型来定性和定量地解释这种阻尼行为。假设波传播介质是一个弹性板和一个粘弹性冰层，夹在两个流体半空间层之间。Kelvin-Voigt 模型用于量化冰的粘弹性行为，从而产生复值剪切模量、Lamé 常数和波速。通过结合传递矩阵（用于板-冰界面）和全局矩阵（用于流-固界面）方法，简化了经典导波特性方程，通过对数残差正交法实现了对导波模式复波数的精确和快速计算。衰减率，即模式波数的虚部，与冰厚度和波频率成正比，这与从环境噪声的互相关中提取的直接波和余声波衰减的实验结果一致。