EAGER: Deepglider Pilot Observations of Western Boundary Current Structure Offshore Abaco

EAGER：深滑翔机对阿巴科近海西边界水流结构的试点观测

• 批准号: 1031780
• 负责人: Charles Eriksen
• 金额: $ 29.96万
• 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: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1031780&HistoricalAwards=false
• 关键词: EAGER; Deepglider; Pilot; Observations; Western

This project is funded as an EArly-concept Grant For Exploratory Research (EAGER).The Rapid Climate Change-Meridional Overturning Circulation and Heat Flux Array (RAPID-MOCHA) began monitoring meridional mass transports in the North Atlantic Ocean along a transatlantic section from North America to Africa in 2004. It estimates the climatically critical meridional overturning circulation (MOC) by differencing dynamic height profiles gathered from small clusters of moorings on either side of the Atlantic basin, measuring boundary current flows with current meters, measuring transport in the Florida Strait electrically, and using satellite winds to estimate Ekman transport. While bottom pressure gauges are used to estimate time-varying barotropic contributions, RAPID-MOCHA relies on an assumed spatially uniform temporally constant barotropic flow to estimate mean transport.The first scientific use of the newly developed full-ocean-depth (surface to 6 km) autonomous underwater glider, Deepglider will complement the RAPID-MOCHA array. Deepgliders will be used to estimate absolute transports independently of RAPID-MOCHA by collecting repeat hydrographic sections of the extended western boundary region off Abaco, Bahamas. A pair of vehicles will repeatedly transit across 100 and 500 km wide overlapping sections between end members of the RAPID-MOCHA dynamic height moorings. These sections will be repeated about weekly and monthly, respectively, by Deepgliders, providing substantial spatial resolution compared to that provided by the moorings, although at considerably coarser temporal resolution. Each Deepglider is expected to last well over 1 year, possibly up to about 18 months. Integrated geostrophic shear inferred from horizontal density gradients resolved in the sections will be referenced to depth-averaged current inferred from each glider dive cycle. The difference between dead-reckoned glider displacement through the water and GPS displacement over the ground is used to estimate depth-averaged current. The Deepglider estimates will include the likely possibility of horizontally varying time-mean barotropic contributions to transport. The independent Deepglider estimates of transports will be compared to those from the RAPIDMOCHA array. In addition, Deepgliders temporarily will be used in 'virtual mooring' mode to check the adequacy of the moorings in measuring dynamic height. Together, the complement of repeat section and moored time series will be used to assess errors and improve estimates of meridional transports in the extended western boundary region.Intellectual Merit: The intellectual merit of this work lies in its connections to basic issues of global climate dynamics. The variability of the MOC is not well observed, let alone understood. The same can be said for the deep flow. Comparison of techniques by which the MOC is monitored is essential to establish their credibility and effectiveness. Deepglider repeat hydrography will provide independent measures of climatically critical ocean circulation transports, the western boundary contributions to MOC. Resolution of the temporal/spatial structure of western boundary currents is prerequisite to understanding how this portion of the climate system operates.Broader Impact: This project will serve as a demonstration of efficacy and economy of full-depth gliders in monitoring ocean circulation not only along the RAPID-MOCHA line, but also along other transects. It will pioneer the use of autonomous gliders to monitor not only the upper ocean, but its deep regions as well. Currently Argo floats monitor the upper ocean globally, but the deep ocean is severely under-observed for climate change, a situation Deepgliders could alter. By making deep ocean access affordable, the Deepglider technology opens the possibility that the complete extent of global ocean climate change may be observed.

该项目作为探索性研究早期概念资助 (EAGER) 获得资助。快速气候变化-经向翻转环流和热通量阵列 (RAPID-MOCHA) 开始监测北大西洋沿跨大西洋部分的经向质量输送2004 年从美洲到非洲。它通过区分从小簇收集的动态高度剖面来估计气候关键的经向翻转环流 (MOC)。大西洋盆地两侧的系泊装置，用海流计测量边界水流，用电测量佛罗里达海峡的输运，并使用卫星风来估计埃克曼输运。虽然底部压力计用于估计随时间变化的正压贡献，但 RAPID-MOCHA 依赖于假设的空间均匀、时间恒定的正压流来估计平均输送。首次科学使用新开发的全海洋深度（表面至 6 公里） ）自主水下滑翔机 Deepglider 将补充 RAPID-MOCHA 阵列。 Deepglider 将用于通过收集巴哈马阿巴科附近扩展的西部边界区域的重复水文剖面来独立于 RAPID-MOCHA 来估计绝对输运。两辆车将反复穿越 RAPID-MOCHA 动态高度系泊装置端部之间 100 公里和 500 公里宽的重叠路段。 Deepgliders 将分别每周和每月重复这些部分，与系泊装置提供的空间分辨率相比，提供了相当大的空间分辨率，尽管时间分辨率要低得多。每台 Deepglider 预计使用寿命超过 1 年，可能长达 18 个月左右。从剖面中解析的水平密度梯度推断出的综合地转切变将参考从每个滑翔机潜水周期推断出的深度平均电流。航位推算的滑翔机在水中的位移与 GPS 在地面上的位移之间的差异用于估计深度平均电流。 Deepglider 的估计将包括水平变化的时间平均正压对运输的贡献的可能性。 Deepglider 的独立传输估计将与 RAPIDMOCHA 阵列的估计进行比较。此外，Deepgliders将暂时在“虚拟系泊”模式下使用，以检查系泊装置在测量动态高度方面是否足够。重复剖面和停泊时间序列的补充将共同用于评估误差并改进对扩展的西部边界区域经向输送的估计。 智力价值：这项工作的智力价值在于其与全球气候动力学基本问题的联系。 MOC 的变异性尚未得到很好的观察，更不用说理解了。对于深流也可以这样说。比较 MOC 监测技术对于确定其可信度和有效性至关重要。深滑翔机重复水文学将为气候关键的海洋环流运输提供独立的测量，即西部边界对 MOC 的贡献。解决西部边界流的时间/空间结构是了解这部分气候系统如何运作的先决条件。更广泛的影响：该项目将展示全深度滑翔机在监测海洋环流方面的有效性和经济性，不仅沿着RAPID-MOCHA 线，但也沿着其他横断面。它将率先使用自主滑翔机，不仅可以监测上层海洋，还可以监测其深层区域。目前，Argo 浮标监测全球上层海洋，但深海的气候变化观测严重不足，而 Deepgliders 可能会改变这种情况。通过使深海进入变得经济实惠，Deepglider 技术开启了观测全球海洋气候变化完整范围的可能性。