In this paper, an analytic range-independent reverberation model based on the first-order perturbation theory is extended to range-dependent waveguide. This model considers the effect of bottom composite roughness: small-scale bottom rough surface provides dominating energy for reverberation, whereas large-scale roughness has the effect of forward and back propagation. For slowly varying bottom and short signal pulse, analytic small-scale roughness backscattering theory is adapted in range-dependent waveguides. A parabolic equation is used to calculate Green functions in range-dependent waveguides, and the orthogonal property of local normal modes is employed to estimate the modal spectrum of PE field. Synthetic tests demonstrate that the proposed reverberation model works well, and it can also predict the reverberation of range-independent waveguide as a special case.

中文翻译：

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范围相关波导中的混响强度衰减

本文将基于一阶微扰理论的解析范围无关混响模型扩展到范围相关波导。该模型考虑了底部复合粗糙度的影响：小尺度的底部粗糙表面为混响提供了主导能量，而大尺度的粗糙度具有正向和反向传播的影响。对于缓慢变化的底部和短信号脉冲，解析小尺度粗糙度后向散射理论适用于范围相关的波导。抛物线方程用于计算范围相关波导中的格林函数，并利用局部法向模式的正交特性来估计PE场的模态谱。综合测试表明，所提出的混响模型效果很好，