A 3-D Acoustic Current Meter for Upper Ocean Measurements

OCE 93 -14357威廉姆斯 伍兹霍尔海洋研究所将开展一个海洋科学仪器开发项目，以开发一种低成本、模块化的3-D声学海流计，用于系泊的上层海洋测量。 开发将逐步完成，从现有的海底声学应力传感器（BASS）;通过一个传感器电缆悬挂仪器;到一个独立的通量计配置;最后到一个模块化的一次性速度传感器。 在每一步中，原型都将在实验项目中进行测试。 独立的通量计将在美国能源部的海洋边际计划中进行测试，而模块化速度传感器将作为与NSF项目相关的Richardson数浮子进行测试。 在海上试验期间，将部署一个声学涡度计，以测量与朗缪尔型三维相干运动有关的剪切和湍流。 每个原型包括涡度计，将被拖或坦克测试，以确定其流动变形，尾流障碍，涡脱落和罗盘响应。 流量测量是海洋研究中的一项首要任务，但除了一些专门的研究，如边界层流中的湍流，人们依赖于昂贵的（而不是消耗性的）流速计的双轴速度测量来确定流量。 目前有三个一般性的研究领域需要三维海流计：在近表面测量中，存在连贯的三维运动，表面波和内波产生显著的垂直流;在输运研究中，矢量流与标量的乘积必须在时间和深度上，也许在一个剖面上取平均值;以及用于在存在波动的情况下确定切变的涡度分辨阵列。 最有前途的过渡到一个3-D的解决方案，今天是声学技术和这个项目的基础上的经验与声学矢量测速仪，以解决这些任务。

OCE93-14357 Williams The Woods Hole Oceanographic Institution will undertake an Ocean Sciences Instrumentation development project to develop a low-cost, modular 3-D acoustic current meter for moored, upper ocean measure- ments. The development will be accomplished in incremental steps building from the existing Benthic Acoustic Stress Sensor (BASS); through a single sensor cable suspended instrument; to a self- contained flux meter configuration; and finally to a modular, expendable velocity sensor. At each step, the prototype will be tested in an experimental program. The self-contained flux meter will be tested in DOE's Ocean Margin Program, and the modular velocity sensor will be tested as a Richardson number float in association with a separate NSF project. During at sea testing, an acoustic vorticity meter will be deployed to measure the shear and turbulence associated with 3-D coherent motions of the Langmuir type. Each prototype including the vorticity meter, will be tow or tank tested to determine its flow distortion, wake obstruction, vortex shedding and compass response. Measurement of flow is a first order task in ocean studies, yet except for several specialized studies such as turbulence in boundary layer flows, one depends on two axis velocity measurements from expensive (as opposed to expendable) current meters for this flow determination. There are now three general research areas where 3-D current meters are needed: in near surface measurements where coherent 3-D motions are present and where surface and internal waves produce significant vertical flow; in transport studies where the product of vector flow with a scalar quantity must be averaged over time and depth and perhaps across a section; and in vorticity resolving arrays for determining shear in the presence of wave motions. The most promising transitions to a 3-D solution today are acoustic techniques and this project builds upon experience with an acoustic vector veloc imeter to address each of these tasks.