Radhakrishnan Sreeram, A P Anu
Naval Physical and Oceanographic Laboratory, Defence Research and Development Organisation, Kochi, Kerala 682021, India.
J Acoust Soc Am. 2020 Nov;148(5):2987. doi: 10.1121/10.0002354.
Measurements of the reverberation time series are made at frequencies of 8, 10, and 12 kHz, and the corresponding acoustic bottom backscattering strengths are estimated as functions of grazing angle. The experiment was conducted in the western continental shelf of India (off Kerala) in water depth of ∼61 m where hard sandy sediments of biogenic origin are predominant. The average values of two-dimensional (2D) spectral strength (w) and exponent (γ) of seafloor roughness are obtained by inverting bottom backscattering strength data with the help of a scattering model, utilizing the genetic algorithm method. Measurements of one-dimensional interface roughness height are also carried out using a single beam echosounder to analyze the variability of bottom roughness in terms of spatial frequency. The spectral parameters estimated from roughness height measurements are compared to that obtained from inversion results. The 2D spectral strength and exponent of seafloor roughness estimated from the two methods agree with each other and are consistent with the typical values associated with sandy sediments.
在8千赫、10千赫和12千赫的频率下测量混响时间序列，并将相应的海底反向散射强度估计为掠射角的函数。该实验在印度西部大陆架（喀拉拉邦附近）进行，水深约61米，那里以生物源硬砂质沉积物为主。借助散射模型，利用遗传算法方法对海底反向散射强度数据进行反演，得到二维（2D）光谱强度（w）和海底粗糙度指数（γ）的平均值。还使用单波束回声测深仪对一维界面粗糙度高度进行测量，以分析海底粗糙度在空间频率方面的变化。将从粗糙度高度测量中估计的光谱参数与反演结果获得的参数进行比较。从这两种方法估计的海底粗糙度的二维光谱强度和指数相互一致，并且与砂质沉积物的典型值相符。
