In ocean acoustics, shallow water propagation is conveniently described using normal mode propagation. This article proposes a framework to describe the polarization of normal modes, as measured using a particle velocity sensor in the water column. To do so, the article introduces the Stokes parameters, a set of four real-valued quantities widely used to describe polarization properties in wave physics, notably for light. Stokes parameters of acoustic normal modes are theoretically derived, and a signal processing framework to estimate them is introduced. The concept of the polarization spectrogram, which enables the visualization of the Stokes parameters using data from a single vector sensor, is also introduced. The whole framework is illustrated on simulated data as well as on experimental data collected during the 2017 Seabed Characterization Experiment. By introducing the Stokes framework used in many other fields, the article opens the door to a large set of methods developed and used in other contexts but largely ignored in ocean acoustics.

中文翻译：

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海洋声学法向模式的极化

在海洋声学中，浅水传播可以方便地使用法向模式传播来描述。本文提出了一个框架来描述法向模式的极化，如使用水柱中的粒子速度传感器测量的。为此，本文介绍了斯托克斯参数，这是一组广泛用于描述波物理学中的偏振特性的四个实数值，尤其是光的偏振特性。理论上推导了声学常模的斯托克斯参数，并引入了估计它们的信号处理框架。还介绍了偏振光谱图的概念，它可以使用来自单个矢量传感器的数据实现斯托克斯参数的可视化。整个框架通过模拟数据以及 2017 年海底表征实验期间收集的实验数据进行了说明。通过介绍在许多其他领域中使用的 Stokes 框架，本文为在其他环境中开发和使用但在海洋声学中基本上被忽略的大量方法打开了大门。