| Qi Lehua,Kan Guangming,Liu Baohua,Pei Yanliang,Yang Zhiguo,Yu Shengqi. 2020. Sea-surface acoustic backscattering measurement at 6-25 kHz in the Yellow Sea. Acta Oceanologica Sinica, 39(3):113－122 |
| Sea-surface acoustic backscattering measurement at 6-25 kHz in the Yellow Sea |
| 黄海海面6–25 kHz声反向散射测量 |
| Received:October 29, 2018 |
| DOI：10.1007/s13131-020-1539-7 |
| Key words:sea-surface acoustic scattering moderate frequency scattering model bistatic backscattering frequency dependence |
| 中文关键词: 海面声散射 中频 散射模型 双基地反向散射 频率依赖性 |
| 基金项目:The National Natural Science Foundation of China under contract Nos 41330965 and 41527809; the Opening Fund of Qingdao National Laboratory for Marine Science and Technology under contract No. QNLM2016ORP0209; the Taishan Scholar Project Funding under contract No. tspd20161007. |
| Author Name | Affiliation | E-mail | | Qi Lehua | College of Marine Geo-sciences, Ocean University of China, Qingdao 266100, China
Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China | | | Kan Guangming | Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China
Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China | kgming135@fio.org.cn | | Liu Baohua | Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China
National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China | | | Pei Yanliang | Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China
Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China | | | Yang Zhiguo | Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China
National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China | | | Yu Shengqi | Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China
National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China | |
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| Abstract: |
| Sea-surface acoustic backscattering measurements at moderate to high frequencies were performed in the shallow water of the south Yellow Sea, using omnidirectional spherical sources and omnidirectional hydrophones. Sea-surface backscattering data for frequencies in the 6-25 kHz range and wind speeds of (3.0±0.5) and (4.5±1.0) m/s were obtained from two adjacent experimental sites, respectively. Computation of sea-surface backscattering strength using bistatic transducer is described. Finally, we calculated sea-surface backscattering strengths at grazing angles in the range of 16°-85°. We find that the measured backscattering strengths agree reasonably well with those predicted by using second order small-roughness perturbation approximation method with "PM" roughness spectrum for all frequencies at grazing angles ranged from 40° to 80°. The backscattering strengths varied slightly at grazing angles of 16°-40°, and were much stronger than roughness scattering. It is speculated that scattering from bubbles dominates the backscattering strengths at high wind speeds and small grazing angles. At the same frequencies and moderate to high grazing angles, the results show that the backscattering strengths at a wind speed of (4.5±1.0) m/s were approximately 5 dB higher than those at a wind speed of (3.0±0.5) m/s. However, the discrepancies of backscattering strength at low grazing angles were more than 10 dB. Furthermore the backscattering strengths exhibited no significant frequency dependence at 3 m/s wind speed. At a wind speed of 4.5 m/s, the scattering strengths increased at low grazing angles but decreased at high grazing angles with increasing grazing angle. |
| 中文摘要: |
| 使用全向性球形声源和无指向性水听器，在南黄海浅海海域开展了中高频海面反向声散射测量。获得了6-25kHz频段内风速分别为3 ±0.5 和 4.5 ±1 m/s的海面反向声散射数据。介绍了使用双基地换能器计算海面反向散射强度的方法。最终计算得到了掠射角16到85度范围内海面反向散射强度。我们发现在40到80度掠射角范围内，测量结果与二阶小粗糙微扰近似预测吻合较好。而16到40度范围内反向散射强度远大于粗糙散射强度，与气泡散射相接近。因此可以推断气泡散射在大风速和中小掠射角范围内占主导。此外，测量结果还显示在中高掠射角，4.5m/s风速下海面反向散射强度比3m/s风速海面强约5dB。而两种风速海面反向散射强度在小掠射角时相差超过10dB。更重要的是，3m/s风速下，反向散射强度没有呈现出明显的频率依赖关系。但是在4.5m/s风速下，随着频率的升高，小掠射角反向散射强度增加而大掠射角反向散射强度减小。 |
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