Helal Khaled Mohsen, von Oppeln-Bronikowski Nicolai, Moro Lorenzo
Department of Ocean and Naval Architectural Engineering, Faculty of Engineering and Applied Science, Memorial University, St. John's, Newfoundland and Labrador, Canada.
Department of Physics and Physical Oceanography, Faculty of Science, Memorial University, St. John's, Newfoundland and Labrador, Canada.
J Acoust Soc Am. 2024 Oct 1;156(4):2467-2484. doi: 10.1121/10.0032357.
Ocean gliders are versatile and efficient passive acoustic monitoring platforms in remote marine environments, but few studies have examined their potential to monitor ship underwater noise. This study investigates a Slocum glider's capability to assess ship noise compared to the ability of fixed observers. Trials were conducted in shallow coastal inlets and deep bays in Newfoundland, Canada, using a glider, hydrophone array, and single-moored system. The study focused on (1) the glider's self-noise signature, (2) range-depth-dependent propagation loss (PL) models, and (3) identifying the location of the vessel to the glider using glider acoustic measurements. The primary contributors to the glider's self-noise were the buoyancy pump and rudder. The pitch-motor noise coincided with the buoyancy pump activation and did not contribute to the glider self-noise in our experiments. PL models showed that seafloor bathymetry and sound speed profiles significantly impacted estimates compared to models assuming flat and range-independent profiles. The glider's performance in recording ship noise was superior to that of other platforms. Using its hydrophones, the glider could identify the bearing from the vessel, although a third hydrophone would improve reliability and provide range. The findings demonstrate that gliders can characterize noise and enhance our understanding of ocean sound sources.
海洋滑翔器是远程海洋环境中多功能且高效的被动声学监测平台，但很少有研究考察其监测船舶水下噪声的潜力。本研究调查了Slocum滑翔器与固定观测者相比评估船舶噪声的能力。试验在加拿大纽芬兰的浅海沿岸海湾和深海海湾进行，使用了滑翔器、水听器阵列和单锚定系统。该研究重点关注：（1）滑翔器的自噪声特征；（2）距离-深度相关的传播损失（PL）模型；（3）利用滑翔器声学测量确定船舶相对于滑翔器的位置。滑翔器自噪声的主要来源是浮力泵和方向舵。俯仰电机噪声与浮力泵启动同时出现，在我们的实验中对滑翔器自噪声没有影响。PL模型表明，与假设海底平坦且与距离无关的剖面模型相比，海底地形和声速剖面显著影响估计值。滑翔器在记录船舶噪声方面的表现优于其他平台。利用其水听器，滑翔器可以确定船舶的方位，不过增加第三个水听器将提高可靠性并提供距离信息。研究结果表明，滑翔器能够表征噪声并增进我们对海洋声源的理解。
