The authors previously prepared a model of coherent acoustic reflection loss at the ocean surface by combining a model of surface roughness loss with determination of surface incidence angle that accounted for the refractive effects of a uniformly stratified distribution of wind-driven bubbles. Originally, the surface roughness loss was based on a second-order small-slope approximation and the surface incidence angle was obtained using an exact solution for propagation of the incident acoustic plane wave in a layer of particular sound-speed variation. In this paper, the previous solution for surface incidence angle is simplified with the assumption that the grazing angle at the bottom of the layer is small. An approximate solution for the surface grazing angle is found in terms of grazing angle below the layer and a polynomial series in a derived parameter, which in turn is a function of wind speed and acoustic frequency. This determination of surface angle is combined with a simplified model of surface roughness loss to produce a complete model suitable for use with ray-type transmission calculations or hand calculations. The resulting model permits the prediction of the coherent surface reflection loss with only wind speed and frequency as input parameters. Results from the use of this approximated model with a Gaussian beam acoustic propagation code are compared with predictions based on Monte Carlo parabolic equation transmission calculations for surface ducted scenarios including various levels of roughness. The zones of validity of the model are considered at length.

中文翻译：

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包含风驱动气泡层中实际折射模型的表面反射损失近似解

作者之前通过将表面粗糙度损失模型与表面入射角的确定相结合，准备了海洋表面相干声反射损失模型，该表面入射角解释了风驱动气泡均匀分层分布的折射效应。最初，表面粗糙度损失基于二阶小斜率近似，表面入射角是使用特定声速变化层中入射声平面波传播的精确解获得的。在本文中，在假设层底部的掠射角较小的情况下，简化了先前的表面入射角解。根据地层下方的掠射角和导出参数中的多项式级数，可以找到表面掠射角的近似解，后者又是风速和声频的函数。表面角度的这种确定与表面粗糙度损失的简化模型相结合，以产生适用于射线型透射计算或手工计算的完整模型。所得模型允许仅使用风速和频率作为输入参数来预测相干表面反射损失。将此近似模型与高斯波束声学传播代码的使用结果与基于蒙特卡罗抛物线方程传输计算的预测结果进行比较，用于表面管道场景，包括各种粗糙度水平。