Shear Madness: New Ways to measure Ocean Currents from a Glider

项目合理性海水流动的速度有多快，是什么造成的，它是如何变化的，我们能预测到吗？这些都是许多海洋科学试图回答的基本问题。传统上，海洋学家使用所谓的地转近似，根据水温和盐度的船基剖面计算切变(水平速度的垂直梯度)。然后，我们必须对已知深度的速度进行独立测量，以参考这一切变，从而获得总的地转速度。几十年来，我们一直使用船载声学多普勒海流剖面仪(ADP)作为切变的参考。新的挑战是研究如何最好地测量被称为滑翔机的长耐力剖面自动水下航行器的电流。滑翔机测量温度和盐度，因此可以推断地转切变。根据它们在潜水过程中的位移，它们还提供了潜水平均水流速度，可以用来参考地转切变。该项目将通过探索将新型ADP安装在Seaglider中来解决这一挑战。方法ADPS已经开始在其他滑翔机上使用(例如喷雾)来确定流场。通过NERC资助的孟加拉湾边界层实验(BOBBLE)项目，我们最近获得了购买集成了Nortek 1 MHz ADP的Seaglider的资金。调试试验计划于2017年3月在加那利群岛进行，届时将比较基于滑翔机的ADP测量结果与更传统平台的测量结果。学生将评估传感器性能并确定利用结果数据集的最佳技术。2012年，UEA在南极的一架海豹滑翔机上试验了以前版本的ADP。吸取了有益的经验教训，这将使该项目受益。我们预计学生将在2017-2018年与其他资助项目一起设计和部署启用ADP的滑翔机，可能是在孟加拉湾。同时，学生将使用UEA Glider Science小组已经获得的滑翔机数据，应用潜水平均流参考地转切变来研究陆架断裂流(例如)在伊比利亚半岛和阿曼海附近。要解决的科学问题包括量化运输、其可变性，以及了解驾驶机制。培训：NEXUSS CDT提供最先进的、高度体验式的培训，内容是应用和开发环境科学的尖端智能和自主观测系统，以及全面的个人和专业发展。通过与学术、研究和产业/政府/政策合作伙伴的广泛网络互动，学生将有广泛的机会扩展他们的多学科视野。这名学生将在诺里奇的UEA海洋与大气科学中心(COAS)注册并接待，但将在南安普敦的NOC与火星工程师合作，分享滑翔机操作的最佳实践。具体培训将包括：-海洋滑翔机驾驶、操作和数据分析-海洋学、海洋动力学、海洋物理学-声学多普勒剖面仪原理-潜水原理-平均海流计算和优化-大型数据集的计算和处理-海洋和海洋数据收集技能-传感器集成和开发的工程挑战。

Project RationaleHow fast is the seawater flowing, what causes this, how does it vary, and can we predict it? These are the fundamental questions that much of ocean science tries to answer. Traditionally, oceanographers calculate the shear (vertical gradient in horizontal velocity) from ship-based profiles of the temperature and salinity of the water, using what is known as the geostrophic approximation. We then have to make an independent measurement of velocity at a known depth in order to reference this shear, and thus obtain the total geostrophic velocity. For a couple of decades now, we have used ship-based acoustic Doppler current profilers (ADP) to reference the shear. The new challenge is to work out how best to make measurements of currents from long-endurance profiling autonomous underwater vehicles known as gliders. Gliders measure temperature and salinity, so the geostrophic shear can be deduced. From their displacement during a dive, they also provide a dive-average current velocity, which can be used to reference the geostrophic shear. This project will address this challenge by exploring the use of a novel ADP installed in a Seaglider.MethodologyADPs have begun to be used on other gliders (e.g. the Spray) to determine the flow field. Through the NERC-funded Bay of Bengal Boundary Layer Experiment (BoBBLE) project, we have recently been awarded funding to purchase a Seaglider with an integrated Nortek 1 MHz ADP. Commissioning trials are scheduled for March 2017 in the Canary Islands, that will compare glider-based ADP measurements with those from more conventional platforms. The student will evaluate the sensor performance and determine the best techniques for exploiting the resulting data set. In 2012 UEA trialled a previous version of the ADP on a Seaglider in the Antarctic. Useful lessons were learnt that will benefit this project. We anticipate that the student will design and undertake a deployment with the ADP-enabled glider in 2017-2018, in conjunction with other funded projects, possibly in the Bay of Bengal.In parallel, the student will use glider data already obtained by the UEA Glider Science group, applying the dive-average currents to reference geostrophic shear to study shelf-break currents (e.g.) off the Iberian Peninsula and in the Sea of Oman. The science questions to be addressed include quantifying the transport, its variability, and understanding the driving mechanisms.Training:The NEXUSS CDT provides state-of-the-art, highly experiential training in the application and development of cutting-edge Smart and Autonomous Observing Systems for the environmental sciences, alongside comprehensive personal and professional development. There will be extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial / government / policy partners. The student will be registered and hosted in the Centre for Ocean and Atmospheric Sciences (COAS) at UEA in Norwich but will spend time based at NOC in Southampton working with MARS engineers to share best practice for glider operations. Specific training will include: - ocean glider piloting, operation, and data analysis- oceanography, ocean dynamics, ocean physics- principles of acoustic Doppler profilers- principles of dive-average current calculation and optimisation- computing and processing of large data sets- seagoing and marine data collection skills- engineering challenges for sensor integration and development.