| YU Shengqi,LIU Baohua,YU Kaiben,YANG Zhiguo,KAN Guangming. 2017. A backscattering model for a stratified seafloor. Acta Oceanologica Sinica, 36(7):56－65 |
| A backscattering model for a stratified seafloor |
| 一种分层海底反向散射模型 |
| Received:October 09, 2016 Revised:December 16, 2016 |
| DOI：10.1007/s13131-017-1084-1 |
| Key words:bottom backscattering model stratified seafloor sediment basement |
| 中文关键词: 海底反向散射模型 分层海底 沉积物 基岩 |
| 基金项目:The National Natural Science Foundation of China under contract Nos 41606081, 41330965 and 41527809; the Taishan Scholar Project Funding under contract No. tspd20161007. |
| Author Name | Affiliation | E-mail | | YU Shengqi | National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China | | | LIU Baohua | National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China
Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China | bhliu@ndsc.org.cn | | YU Kaiben | National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China | | | YANG Zhiguo | National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China | | | KAN Guangming | Key Laboratory of Marine Sedimentology and Environmental Geology, The First Institute of Oceanography, Qingdao 266061, China
Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China | |
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| Abstract: |
| In order to predict the bottom backscattering strength more accurately, the stratified structure of the seafloor is considered. The seafloor is viewed as an elastic half-space basement covered by a fluid sediment layer with finite thickness. On the basis of calculating acoustic field in the water, the sediment layer, and the basement, four kinds of scattering mechanisms are taken into account, including roughness scattering from the water-sediment interface, volume scattering from the sediment layer, roughness scattering from the sediment-basement interface, and volume scattering from the basement. Then a backscattering model for a stratified seafloor applying to low frequency (0.1–10 kHz) is established. The simulation results show that the roughness scattering from the sediment-basement interface and the volume scattering from the basement are more prominent at relative low frequency (below 1.0 kHz). While with the increase of the frequency, the contribution of them to total bottom scattering gradually becomes weak. And the results ultimately approach to the predictions of the high-frequency (10–100 kHz) bottom scattering model. When the sound speed and attenuation of the shear wave in the basement gradually decrease, the prediction of the model tends to that of the full fluid model, which validates the backscattering model for the stratified seafloor in another aspect. |
| 中文摘要: |
| 为了更为准确地对海底反向散射强度进行预报，本文考虑了海底的分层结构，认为海底由有限厚度的沉积层和半无限空间的基岩构成。在计算海水、沉积层和基岩中声场的基础上，考虑了包括海水-沉积物界面粗糙散射、沉积层体积散射、沉积物-基岩界面粗糙散射和基岩体积散射在内的四种散射机制，建立了适用于低频（100 Hz-10 kH）条件下的分层海底反向散射模型。仿真结果表明：频率较低时（小于1 kHz），沉积物-基岩界面粗糙散射和基岩体积散射更为显著；而随着频率的增大，两者对海底反向散射强度的贡献逐渐减弱，反向散射强度最终趋近于高频（10-100 kHz）海底散射模型的预报结果；当基岩中的剪切波声速和衰减逐渐减小时，预报结果趋近于全流体模型，继而从另一个方面验证了本文提出的分层海底散射模型的有效性。 |
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