Geoacoustic inversion

地声反演

• 批准号: 185710-2009
• 负责人: Dosso, Stan
• 金额: $ 3.79万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=523075
• 关键词: Geoacoustic; inversion

GEOACOUSTIC INVERSION: Seabed geoacoustic parameters, such as sediment layering structure, sound speed, density, attenuation and scattering strength, strongly affect the propogagion of ocean acoustic fields. Hence, knowledge of these parameters is required to understand and model sound propagation in shallow-water environments, as required for many sonar applications (as well as geotechnical and geological purposes). Estimating seabed parameters from ocean acoustic measurements provides an economical and convenient in situ alternative to direct sampling (e.g., coring), with a sensitivity relevant to sonar. However, this requires solving a strongly nonlinear inverse problem that is inherently nonunique (i.e., a range of solutions can acceptably fit the data). A variety of geoacoustic inversion approaches have been applied, with varying degrees of success, including the inversion of full-field acoustic measurements, acoustic reverberation, seabed reflectivity, ambient noise, and ship noise. These approaches differ in their ability to estimate various geoacoustic parameters and to resolve parameter variations as a function of depth and/or range; however, the efficacy of these approaches has not been examined in a systematic or rigorous way. The overall objectives of this proposal are to develop and quantitatively study and compare the above-mentioned approaches to geoacoustic inversion. A key component of quantitative analysis of geoacoustic inversion is estimating the uncertainties of the recovered parameters, which indicates the information content of the data and provides an objective basis for comparison of different data sets. Further, only with quantitative uncertainty estimation can issues such as resolving parameter spatial variability or frequency dependence be addressed in a meaningful manner (e.g., differentiating uncertainty from variability). Parameter uncertainty estimation in nonlinear inversion is itself a challenging research problem. This proposal is based on a Bayesian inference formulation and a numerical (statistical) sampling approach, under development, that builds up probability distributions for the unknown seabed parameters based on the data and available physical constraints (prior information).

地声反演：海底声学参数，如沉积层结构、声速、密度、衰减和散射强度等，对海洋声场的传播有重要影响。因此，需要了解这些参数的知识来理解和模拟浅水环境中的声音传播，这是许多声纳应用（以及岩土工程和地质目的）所需的。从海洋声学测量估计海底参数提供了一种经济和方便的现场替代直接采样的方法（例如，取芯），具有与声纳相关的灵敏度。然而，这需要求解固有地非唯一的强非线性逆问题（即，一系列解可以可接受地拟合数据）。已经应用了各种地声反演方法，取得了不同程度的成功，包括全场声学测量、声学混响、海底反射率、环境噪声和船舶噪声的反演。这些方法在估计各种地声参数和解决作为深度和/或范围的函数的参数变化的能力方面有所不同;然而，这些方法的功效尚未以系统或严格的方式进行审查。本提案的总体目标是发展、定量研究和比较上述地声反演方法。地声反演定量分析的一个重要组成部分是估计反演参数的不确定度，它反映了数据的信息含量，为不同数据集的比较提供了客观依据。此外，只有通过定量不确定性估计，才能以有意义的方式解决诸如解析参数空间变异性或频率依赖性的问题（例如，不确定性与可变性的区别）。非线性反演中的参数不确定性估计本身就是一个具有挑战性的研究问题。这一提议的依据是正在开发的贝叶斯推断公式和数字（统计）抽样方法，根据数据和现有的物理限制（先验信息）建立未知海底参数的概率分布。