Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, Washington 98105-6698, USA.
J Acoust Soc Am. 2012 Feb;131(2):1711-21. doi: 10.1121/1.3666009.
Geoacoustic inversion work has typically been carried out at frequencies below 1 kHz, assuming flat, horizontally stratified bottom models. Despite the relevance to Navy sonar systems many of which operate at mid-frequencies (1-10 kHz), limited inversion work has been carried out in this frequency band. This paper is an effort to demonstrate the viability of geoacoustic inversion using bottom loss data between 2 and 5 kHz. The acoustic measurements were taken during the Shallow Water 2006 Experiment off the coast of New Jersey. A half-space bottom model, with three parameters density, compressional wave speed, and attenuation, was used for inversion by fitting the model to data in the least-square sense. Inverted sediment sound speed and attenuation were compared with direct measurements and with inversion results using different techniques carried out in SW06. Inverted results of the present work are consistent with other measurements, considering the known spatial variability in this area. The observations and modeling results demonstrate that forward scattering from topographical changes is important at mid-frequencies and should be taken into account in sound propagation predictions and geoacoustic inversion. To cope with fine-scale topographic variability, measurement technique such as averaging over tracks may be necessary.
地质声学反演工作通常在低于 1 kHz 的频率下进行，假设底部模型是平坦的、水平分层的。尽管许多海军声纳系统都在中频（1-10 kHz）运行，但其在该频段的反演工作却很有限。本文旨在证明使用 2-5 kHz 之间的底部损耗数据进行地质声学反演的可行性。声学测量是在新泽西海岸的 2006 年浅海实验期间进行的。使用半空间底部模型，具有三个参数密度、纵波速度和衰减，通过最小二乘拟合模型到数据来进行反演。将反演得到的沉积物声速和衰减与直接测量值以及在 SW06 中使用不同技术进行的反演结果进行了比较。考虑到该地区已知的空间变异性，本工作的反演结果与其他测量结果一致。观测和建模结果表明，在中频时，地形变化的正向散射很重要，在声传播预测和地质声学反演中应考虑到这一点。为了应对精细的地形变化，可能需要使用诸如沿轨迹平均等测量技术。
