Ocean Acoustic Inversion

海洋对电磁波是不透明的，但对声音是透明的；因此，声学技术被用于许多水下应用，如海底遥感 声源(如潜艇、海洋哺乳动物)的性质/过程或位置，以及地质、岩土、环境和声纳/防御应用。然而，声学遥感 需要非线性反演，需要定量的模型选择和有意义的解释所需的不确定性估计。拟议的研究建立在我们的海洋声遥感贝叶斯(概率)反演长期研究计划的基础上，该计划有六个项目。 (1)海底声散射参数和过程的反演。我们的初步工作表明，反向散射数据的反演可以解决海底粗糙度和沉积物非均质谱的问题。我们建议发展定量的模型选择 确定各种物理散射机制的相对重要性并估计相关 不同海底类型的散射参数，以更好地了解海底物理 散布。 (2)用于海军数据库或土工数据库的横向变化海底散射参数的估计 电缆敷设等应用。这项研究基于对使用移动系统收集的新声学数据集的顺序贝叶斯反演，该移动系统包括在附近拖曳的声源和接收器阵列 由自主水下航行器在海底作业。 (3)通过考虑横波、散射和倾斜层的影响，扩展了我们现有的高分辨率海底地声参数反演的反射率，并应用于解决海洋沉积物中的色散(声速和衰减频率相关性)。 (4)利用固定记录的全场声学数据进行海底地声特性的层析(2D)反演 接收器阵列。二维定量非线性反演的一个主要组成部分是开发新的自适应 稀疏/不规则网格，以与分辨率一致的方式对环境进行参数化 这些数据似乎可以进行严格的不确定性估计。 (5)声源定位和不确定性估计，包括海洋不确定性的影响 环境属性。我们最初的工作是在海军(被动声纳)应用方面，但我们正在进入海洋哺乳动物领域。 与领先的加拿大海洋技术公司JASCO Research Ltd合作进行的研究。建议 方法包括一种利用非同步阵列系统/子系统进行匹配场定位的新方法， 以及在单个接收器处通过模式色散(时频分析)进行源测距。 (6)使用长期的声学监测数据跟踪未知数量的发声海洋哺乳动物，以提供概率解决方案，从中获得关于 可以提取人口和行为。

Oceans are opaque to electromagnetic waves but transparent to sound; hence, acoustics is used for many underwater applications such as the remote sensing of seabed properties/processes or the locations of sound sources (e.g., submarines, marine mammals), with geological, geotechnical, environmental and sonar/defence applications. However, acoustic remote sensing requires nonlinear inversion, with quantitative model selection and uncertainty estimation required for meaningful interpretations. The proposed research builds on our long-term program in Bayesian (probabilistic) inversion for ocean acoustic remote sensing with six projects. (1) Inversion for seabed acoustic scattering parameters and processes. Our initial work shows that inversion of backscatter data can resolve seafloor roughness and sediment heterogeneity spectra. We propose to develop quantitative model-selection approaches to determine the relative importance of various physical scattering mechanisms and to estimate relevant scattering parameters for different seabed types, to better understand the physics of seabed scattering. (2) Estimation of laterally-variant seabed scattering parameters for naval databases or geotechnical applications such as cable laying. This  is based on sequential Bayesian inversion of novel acoustic data sets collected using a mobile system comprising an acoustic source and receiver array towed near the seabed by an autonomous underwater vehicle. (3) Extending our existing high-resolution reflectivity inversions for seabed geoacoustic parameters by including effects of shear waves, scattering, and dipping layers, with application to resolving dispersion (sound speed and attenuation frequency dependence) in marine sediments.  (4) Tomographic (2D) inversion for seabed geoacoustic properties using full-field acoustic data recorded at a fixed receiver array. A major component of quantitative nonlinear inversion in 2D involves developing new self-adaptive sparse/irregular grids to parameterize the environment in a manner consistent with the resolving power of the data to allow rigorous uncertainty estimation.  (5) Acoustic source localization and uncertainty estimation, including the effects of uncertainty in ocean environmental properties. Our initial work was in naval (passive sonar) applications, but we are moving into marine mammal studies in collaboration with JASCO Research Ltd, a leading Canadian marine-technology company. Proposed methods include a novel approach to matched-field localization with non-synchronized array systems/sub-systems, and source ranging via modal dispersion (time-frequency analysis) at a single receiver. (6) Tracking an unknown number of vocalizing marine mammals using long-term acoustic monitoring data to provide a probabilistic solution from which information on population and behaviour can be extracted.