A 3-D Acoustic Current Meter for Upper Ocean Measurements

伍兹霍尔海洋研究所（Woods Hole Oceanographic Institution）将承担一项海洋科学仪器开发项目，开发一种低成本、模块化的3-D声学流计，用于系泊的上层海洋测量。开发将在现有底栖声学应力传感器（BASS）的基础上逐步完成；通过单传感器电缆悬吊仪表；要有一个独立的通量计配置；最后是一个模块化的，一次性的速度传感器。在每一步中，原型都将在实验程序中进行测试。独立的通量计将在美国能源部的海洋边缘项目中进行测试，模块化速度传感器将作为理查森数字浮子在美国国家科学基金会的一个单独项目中进行测试。在海上测试期间，将部署一个声波涡度仪来测量与Langmuir型三维相干运动相关的剪切和湍流。包括涡量计在内的每个样机都将进行拖曳或水箱测试，以确定其流动畸变、尾流阻塞、涡脱落和罗盘响应。在海洋研究中，测量流量是一项一级任务，然而，除了一些专门的研究，如边界层流动中的湍流，人们依赖于昂贵的（与消耗性相反的）流速仪的两轴速度测量来确定流量。目前，需要三维流计的一般研究领域有三个：存在相干三维运动的近地表测量和表面波和内波产生显著垂直流的地方；在输运研究中，矢量流与标量量的乘积必须随时间、深度和可能跨越一段求平均值；在涡度分辨阵列中用于确定存在波动的切变。目前，最有希望过渡到3d解决方案的是声学技术，该项目建立在声学矢量速度计的经验基础上，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.