A 3-D Acoustic Current Meter for Upper Ocean Measurements

14357威廉姆斯伍兹霍尔海洋研究所将承担一个海洋科学仪器开发项目，以开发一种低成本、模块化的三维声学海流计，用于系泊的、上层海洋的测量。开发将分步骤完成，从现有的底栖声应力传感器(BASS)；通过单一传感器电缆悬挂式仪器；到独立的流量计配置；最后到模块化的、可消耗性的速度传感器。在每一步，原型都将在一个实验程序中进行测试。自给式流量计将在能源部的海洋边缘计划中进行测试，模块化速度传感器将在另一个NSF项目中作为理查森数字浮点进行测试。在海上测试期间，将部署一个声涡度计来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，将被拖曳或水槽测试，以确定其流动扭曲、尾流障碍物、涡流脱落和罗盘响应。在海洋研究中，流量测量是一项首要任务，但除了一些专门的研究，如边界层流中的湍流外，流量的测量依赖于昂贵的(而不是消耗性的)海流计的两个轴速度测量。目前有三个一般研究领域需要三维海流计：在近地表测量中，在存在相干三维运动的情况下，表面波和内波产生显著的垂直流动；在交通研究中，标量流与矢量流的乘积必须随时间和深度平均，并可能跨断面平均；以及在涡度分辨率阵列中，用于在存在波动时确定切变。当今最有希望过渡到3-D解决方案的是声学技术，该项目建立在声学矢量测速仪经验的基础上，以解决这些任务中的每一个。

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.