Cuddy Decay: Observation of Subthermocline Eddy Spindown and Property Exchange

卡迪衰变：亚温跃层涡旋下降和属性交换的观察

• 批准号: 1153980
• 负责人: Charles Eriksen
• 金额: $ 89.74万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1153980&HistoricalAwards=false
• 关键词: Cuddy; Decay; Observation; Subthermocline; Eddy

This is a project to study the decay of a subthermocline eddy as it travels from near its generation site in the California Undercurrent (CU) over the continental slope into offshore waters. The CU, a prominent element of the California Current System (CCS), transports relatively warm, saline, anoxic Pacific Equatorial Water north along the North American west coast. Temperature and salinity generally decrease both poleward and offshore, while dissolved oxygen increases, as the CU spins off long lived eddies transporting its water properties away from the CCS into the eastern Pacific. These eddies, nicknamed cuddies for their origin, have been tracked by solitary floats for many months and surveyed hydrographically on occasion, but their structural evolution as they decay has yet to be observed. They take the form of submesoscale coherent vorticies and are largely invisible to remote sensing techniques due both to their small size and subsurface intensification. The extent to which cuddies contribute to broad scale property gradients in the CCS and beyond is tied to the evolution of their radial-vertical structure.This study will use a pair of extended-range Seagliders to frequently survey a cuddy over many months as it travels. A cuddy will be identified and located for study by an ongoing Seaglider repeat transect, separately supported by NOAA and maintained by University of Washington colleagues. With improvements to performance efficiency, Seagliders are projected to be capable of operating as long as a year while transmitting slanting profiles of upper-ocean structure ashore in near real time. Simultaneous transects at 4-6 km resolution along nearly perpendicular paths repeated every week or less over the course of ten months appear feasible, with an additional two months of mission time devoted to reaching from and returning to the coastal region for launch and recovery. The sequence of approximately 50 three-dimensional surveys of a cuddy will be used to observe its decay rate, associated frequency and intensity of fine scale stratification features, and changes in vertical-radial structure.The observed structural evolution of a subsurface eddy will be used to infer the exchange rates of physical, chemical, and biological properties with the surrounding waters. While cuddies are widely suspected to be important agents of property exchange in the CCS, the observations proposed will be the first to describe a cuddy in four dimensions over an appreciable portion of its lifetime.This study will contribute to understanding of eddy transport in general and the role of submesoscale coherent vorticies in particular in transmitting eastern boundary region properties to the ocean interior. Implications of eddy transport are important not only to physical distributions in the ocean, but to chemical and biological ones as well. The project will train a graduate student to be expert in an emerging observational technique as well as in the role of eddies in ocean circulation.

这是一个研究次温跃层涡旋从其生成地点附近的加州暗流（CU）越过大陆坡进入近海沃茨时的衰减的项目。 CU是加州海流系统（CCS）的重要组成部分，它将相对温暖、含盐、缺氧的太平洋赤道水沿着北美西海岸向北输送。 温度和盐度一般都降低极地和近海，而溶解氧增加，作为CU旋转了长期存在的漩涡运输其水的性质远离CCS到东太平洋。 这些漩涡，因其起源而被昵称为cuddies，已经被单独的浮子跟踪了好几个月，有时还进行了水文调查，但它们在衰变时的结构演变还有待观察。 它们采取亚中尺度相干涡旋的形式，由于其体积小和次表层增强，遥感技术基本上看不到它们。 在多大程度上cuddies有助于广泛的规模属性梯度在CCS和超越是绑在他们的径向垂直结构的演变。这项研究将使用一对扩展范围的Seagliders经常调查cuddy在许多个月，因为它的旅行。 一个cuddy将被确定和定位的研究正在进行的海滑翔机重复样带，分别由美国国家海洋和大气管理局和华盛顿大学的同事保持。 随着性能效率的提高，预计海上滑翔机能够运行长达一年，同时以接近真实的时间向岸上传输上层海洋结构的倾斜剖面。 在10个月的时间里，沿着沿着几乎垂直的路径以4-6公里分辨率同时进行断面扫描似乎是可行的，每周或更少的时间重复一次，另外还有两个月的使命时间专门用于从沿海地区到达和返回沿海地区进行发射和回收。 一个Cuddy的大约50个三维测量的序列将被用来观察它的衰减率，细尺度分层特征的相关频率和强度，以及垂直-径向结构的变化。所观察到的地下涡流的结构演变将被用来推断与周围沃茨的物理、化学和生物特性的交换率。 虽然cuddies被广泛怀疑是重要的代理商的CCS中的财产交换，建议的意见将是第一个描述一个cuddy在四个维度上的一个可观的一部分，其lifes.This研究将有助于理解一般的涡输运和亚中尺度相干涡的作用，特别是在传输东部边界区域的属性到海洋内部。涡旋输送不仅对海洋中的物理分布，而且对化学和生物分布都有重要意义。该项目将培训一名研究生，使其成为一种新兴观测技术以及涡旋在海洋环流中的作用的专家。