National Institute of Oceanography, Council of Scientific and Industrial Research, Dona Paula, Goa 403 004, India.
J Acoust Soc Am. 2011 Dec;130(6):3623-32. doi: 10.1121/1.3658454.
Sediment geoacoustic inversion results are estimated employing a multi-beam (MB) echo-sounding system operable at 95 kHz. To characterize the western continental shelf of India (off Goa) seafloor, MB backscatter signals were acquired along with grab sediment samples. The substrate type and roughness of the site were estimated using the composite roughness scattering model with the measured backscatter values. The seafloor parameters, namely mean grain size (M(φ)); roughness spectrum strength (w(2)) and exponent (γ(2)); and sediment volume parameter (σ(2)), for coarse and fine grain sediments are estimated by employing the MB system. These parameters have also been estimated at two other frequencies (33 and 210 kHz) and are compared to the ground truth data to provide sufficient support in validating the model results and increasing the understanding of the shelf seafloor processes. Distinct interclass separations between the sediment provinces are evident from the estimated mean grain size M(φ) and water-sediment interface roughness w(2). The seafloor parameters for coarse and fine grain sediments derived from the 95 kHz MB data are consistent with the sediment sample data as well as with the inversion results obtained using backscatter data at 33 and 210 kHz from the same locations.
采用工作频率为 95 kHz 的多波束（MB）回声探测系统对海底沉积物的地球声学反演结果进行估算。为了对印度西部大陆架（果阿外海）海底进行特征描述，在采集抓斗沉积物样本的同时，获取 MB 反向散射信号。利用实测反向散射值，通过复合粗糙度散射模型来估算基岩类型和表面粗糙度。利用 MB 系统来估算粗粒和细粒沉积物的海底参数，包括中值粒径（M(φ)）、粗糙度谱强度（w(2)）和指数（γ(2)）以及沉积物体积参数（σ(2)）。这些参数也在另外两个频率（33 和 210 kHz）进行估算，并与实地数据进行比较，为验证模型结果提供充分支持，增强对陆架海底过程的理解。根据估算的中值粒径 M(φ)和水-沉积物界面粗糙度 w(2)，可以明显看出不同沉积区之间的分类差异。从 95 kHz 的 MB 数据得出的粗粒和细粒沉积物的海底参数与沉积物样本数据以及在相同位置利用 33 和 210 kHz 的反向散射数据进行反演得到的结果一致。
