Acoustic multibeam system for 3-dimensional bedform evolution studies

用于 3 维床形演化研究的声学多波束系统

• 批准号: 345318-2007
• 负责人: Hay, Alexander
• 金额: $ 3.87万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments - Category 1 (<$150,000)
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=364753
• 关键词: Acoustic; multibeam; system; dimensional; bedform

The equipment requested is a high-frequency acoustic multibeam system for obtaining high-resolution profiles of the seafloor at frame rates approaching that of video systems. The bed elevation profile is obtained by steering the acoustic beam spot electronically over the seafloor. Based on an earlier design operating at an acoustic frequency of 260 kHz (6-mm wavelength), this newly-developed Canadian-built sensor operates at 2.25 MHz (0.7-mm wavelength), the shorter wavelength providing much higher spatial resolution. To obtain a 3-dimensional map, the acoustic sensor must be mechanically driven in a direction orthogonal to the beam-steering plane, and thus funds are also requested to purchase a rotator unit for this purpose.   The combined multibeam/rotator system will be capable of generating 3-d maps of the small-scale seafloor topography over a 5-m by 5-m area with a horizontal resolution of a few cm or better, and better than 1-cm vertical resolution, in tens of seconds. Given the 10-s typical periods of wind-generated sea-and-swell waves, this acquisition time is commensurate with the passage of several surface gravity waves. Thus, the system will enable first-time investigations of the evolution of mobile seafloor topography on the time scales of wave-groups. The system will be deployed in the fall of 2007 for 2 months as part of an investigation of the temporal evolution of wave-formed ripples on inner shelf in coarse- and fine-grained sands.

所要求的设备是一个高频声学多波束系统，用于以接近视频系统的帧速率获取高分辨率海底剖面图。海底高程剖面是通过在海底上方电子操纵声束点获得的。基于早期的设计，工作在260 kHz（6 mm波长）的声频，这种新开发的瑞士制造的传感器工作在2.25 MHz（0.7 mm波长），较短的波长提供了更高的空间分辨率。为了获得三维图，必须在与波束操纵平面正交的方向上机械地驱动声传感器，因此还需要资金来购买用于此目的的旋转器单元。 多波束/旋转器组合系统将能够在几十秒内生成5米乘5米区域的小规模海底地形三维地图，水平分辨率为几厘米或更好，垂直分辨率优于1厘米。鉴于10秒的典型周期的风产生的海和涌浪波，这个采集时间是相称的几个表面重力波的通道。因此，该系统将能够首次调查波群时间尺度上移动的海底地形的演变。该系统将于2007年秋季部署，为期2个月，作为调查粗、细粒沙内陆架波浪形成的波纹随时间演变的一部分。