Experimental study of roughness spectrum of sandy seafloor with an underwater laser 3D scanning system

Abstract

To measure and characterize the roughness spectrum of sea-bottom, which is an important input parameter of the bottom acoustic backscattering model, an underwater laser three-dimensional (3D) scanning system for measuring seafloor microtopography has been developed successfully. The proposed underwater laser 3D scanning system can provide 3D seafloor microtopography with the resolution of millimeter levels in both horizontal and vertical directions and obtain the roughness spectrum of sea-bottom further. Two sets of data, which were suitable to model low- and mid-frequency acoustic backscattering at 6–24 kHz, were collected in two sites of sandy bottom during the acoustic scattering experiment in the southern Yellow Sea. The one-dimensional (1D) and two-dimensional (2D) roughness spectrum of the seafloor have been calculated at the two sites named S1 and S2, respectively. The result shows that calculated 2D spectral indices and spectral intensities, respectively, were 3.45 and 2.17 × 10⁻⁴ m⁴ at S1 and 3.33 and 4.66 × 10⁻⁴ m⁴ at S2. 2 D roughness spectrum parameters were used to model the acoustic scattering at S1, and the result indicates that the measurement results of the seafloor roughness spectrum is suitable for modeling bottom acoustic scattering.

Keywords:

• Bottom acoustic scattering model
• bottom roughness spectrum
• southern Yellow Sea
• underwater laser scanning system

Acknowledgments

We would like to thank the crew of the R/V Haili for their assistance of measurement experiment of seafloor microtopography of sandy seafloor in the southern Yellow Sea using the underwater laser 3D scanning system. We would like to thank Dr. Ling Qi and Hao Fan from Ocean University of China for assistance of data processing

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Basic Scientific Fund for National Public Research Institutes of China under Grant [number GY0220Q09]; the National Natural Science Foundation of China under Grant [numbers 41676055, 41527809 and 41330965]; the Opening Fund of Qingdao National Laboratory for Marine Science and Technology under Grant [number QNLM2016ORP0209]; and the Taishan Scholar Project Funding under Grant [number tspd20161007].