Measuring and modelling ambient noise in three-dimensional ocean environments

水下信号处理和信号检测方案需要良好的空间和时间环境噪声场特性，以便在探测船舶、潜艇、海洋哺乳动物和其他水下声源等任务中有效地工作。此外，对海洋中噪声场的详细了解导致开发了被动方法，用于查询海洋、海底和次海底的物理性质，并调查噪声源机制的物理和统计数据，例如海气相互作用、面波破裂、降雨、地球物理过程和推移质泥沙输送。最近，水下噪声被提出作为一种监测工具来研究海洋的生态健康。*该研究计划的目标是开发、验证和应用新的分析和计算模型，以在任意、真实和复杂的三维域中准确地预测环境海洋噪声的频谱、时间和空间特性。这将通过使用抛物线方程(PE)传播模型来实现，而模型验证将通过与被动声剖面仪上环境噪声的深度依赖关系的现场测量相比较来实现。这些方法的结合将被用来研究非均质性(内波、锋面)、海洋动力学和非均匀表面噪声过程(暴雨、冰场)对噪声场的影响，开发用于估计海冰厚度和海底地球物理性质的反演技术，以及更好地检测和定位海洋哺乳动物、跟踪生态系统健康，并量化人为噪声对海洋声景观的作用。*估计人为、环境和生物噪声对整个噪声场的相对贡献的能力在声海洋学中有应用，例如估计浅水环境中的降水和风速，以及在持续航运和生物噪声存在的情况下。便携式计算模型有可能成为水下安全和防御以及海洋哺乳动物定位和跟踪研究的业务工具。这项研究可以应用于对海洋偏远地区的环境参数进行声学测量，特别是在北极，那里的气象浮标太容易被海冰和风暴破坏。*仪器开发和现场计划将支持这一模拟研究。主要目标将是测量噪声的空间特性和功率谱密度及其与海洋和大气条件、水深测量和海底特性以及作为源的物理过程的关系。将开发一台全海洋深度垂直剖面仪，用于研究功率谱密度以及垂直和水平相干性随深度的变化。**

Underwater signal processing and signal detection schemes require well-characterized spatial and temporal ambient noise field properties to operate effectively in tasks such as detecting ships, submarines, marine mammals, and other underwater sound sources. Additionally, a detailed understanding of the noise field in the ocean has led to the development of passive methods for querying the physical properties of the ocean, seabed and sub-bottom as well as investigating the physics and statistics of noise source mechanisms such as air-sea interaction, surface wave breaking, rainfall, geophysical processes, and bedload sediment transport. More recently, underwater noise has been proposed as a monitoring tool to study the ecological health of the oceans.*** The objective of this research program is to develop, validate, and apply new analytic and computational models that accurately predict ambient ocean noise spectral, temporal and spatial properties in arbitrary, realistic, and complex 3D domains. This will be achieved by using a parabolic equation (PE) propagation model, while model validation will be achieved by comparison with field measurements of the depth-dependence of ambient noise made on passive acoustic profilers. This combination of methods will be used to study the effect of inhomogeneities (internal waves, fronts), ocean dynamics and non-uniform surface noise processes (rain storms, ice fields) on the noise field, to develop inversion techniques for estimating sea-ice thickness and geophysical properties of the seabed, and to better detect and localize marine mammals, track ecosystem health, and quantify the role of anthropogenic noise on the marine soundscape.*** The ability to estimate the relative contributions of anthropogenic, environmental, and biological sound to the overall noise field has applications in acoustical oceanography, such as the estimation of precipitation and wind speeds in shallow water environments and in the presence of persistent shipping and biological noise. A portable computational model has the potential to be an operational tool for underwater security and defence, as well as research in the localization and tracking of marine mammals. The research may be applied in performing acoustic measurements of environmental parameters in remote regions of the ocean, particularly the Arctic, where weather buoys are too easily destroyed by sea ice and storms.*** An instrument development and field program will support this modelling research. The main objective will be to measure the spatial properties and power spectral density of noise and their relationship to oceanographic and atmospheric conditions, bathymetry and seabed properties, and the physical processes that act as sources. A full-ocean depth vertical profiler will be developed and used to investigate the depth-dependence of power spectral density, and vertical and horizontal coherence. **