Collaborative Research: A Two-Body Towing System for Swath-Mapping Ocean Turbulence

P.I.加吉特，安（旧自治领大学）提案编号：0220504合作机构：伍尔西，克雷格（弗吉尼亚理工大学）提案编号：0220745 PI建议建造一个双体拖曳系统，为海洋湍流测量创建一个稳定的测量平台。这项工作建立在一个有效的湍流调查工具，使用声学多普勒电流测量的非标准方式的潜力。特别是，通过海洋水平移动的5波束VADCP可以产生垂直平面的“条带图”的关键湍流量，如垂直动量应力，湍流动能，其耗散率，以及平均电流和垂直剪切的标准测量。这些测量需要一个足够稳定的平台，正如这里所提出的。从原型拖曳系统获得的初步海上测量结果表明，两级设计可以提供所需的稳定性。该初步试验还阐明了海上环境中连续测绘所需的设计修改：提供船上控制（i）主拖体和次拖体之间的电缆长度和（ii）次拖体的平均姿态。具体而言，PI建议设计必要的控制系统，建立一个完整的拖曳系统，用于200米深处的操作，并进行沿海海上测试巡航，以记录系统的运动特性，并收集1.2MHz 5波束VADCP的初步数据，部署在向上和向下的模式。在浅系统的工作过程中，他们还将探索在后续系统中完成电缆长度调整的选项，以在整个海洋深度上运行。如果成功，这一发展将对湍流研究以外的上层海洋观测能力产生广泛影响，从而能够对生物薄层和控制海洋与大气之间气体转移的近地表气泡云等特征进行空间测绘。

P.I. Gargett, Ann (Old Dominion University) Proposal #: 0220504Collaborating Inst: Woolsey, Craig (VA Tech.) Proposal #: 0220745 The PIs propose to construct a two-body towing system to create a stable measurement platform for ocean turbulence measurements. This work builds on the potential for an effective turbulence survey tool using acoustic Doppler current measurements in non-standard ways. In particular, horizontally moving a 5-beam VADCP through the ocean can produce vertical-plane "swath-maps" of crucial turbulence quantities such as vertical momentum stresses, turbulent kinetic energy, and its dissipation rate, as well as standard measurements of mean currents and their vertical shear. These measurements require a sufficiently stable platform, as proposed here. Preliminary offshore measurements taken from a prototype towing system suggest that a two-stage design can provide the required stability. This preliminary testing also clarified the design modifications needed for continuous mapping in offshore environments: provision of shipboard controls for (i) the length of cable between primary and secondary tow bodies and (ii) mean attitude of the secondary tow body. Specifically, the PIs propose to design the necessary control systems, build a complete towing system for operation to depths of 200m, and carry out a coastal offshore test cruise to document the motion characteristics of the system and collect preliminary data with a 1.2MHz 5-beam VADCP, deployed in both upward and downward looking modes. During the course of this work with a shallow system, they will also explore options for accomplishing cable length adjustments in a subsequent system to operate over full ocean depths. If successful, this development would have broad impacts on upper ocean observational capabilities in areas other than turbulence research, enabling spatial mapping of such features as biological thin layers and the near-surface bubble clouds that dominate gas transfer between ocean and atmosphere.