Comparison of Deepglider and RAPID-MOCHA Moored Array Observations

Deepglider 和 RAPID-MOCHA 系泊阵列观测的比较

• 批准号: 1458174
• 负责人: Charles Eriksen
• 金额: $ 108.57万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1458174&HistoricalAwards=false
• 关键词: Comparison; Deepglider; RAPID; MOCHA; Moored

The Atlantic Meridional Overturning Circulation (AMOC) is a principal element of the global climate system. At 26.5 degrees North latitude, the AMOC is responsible for carrying about sixty percent of the net poleward heat flux carried by the oceans and about thirty percent of the total heat flux carried by the atmosphere and ocean together, integrated zonally around the globe. Through sea surface temperature modulation, the AMOC is linked to climate signals on interannual to multi-decadal time scales that can have extensive societal impact. Climate models predict substantial weakening of the AMOC over the next century, a change with potentially wide ramifications. For the past decade, U.S. and U.K. scientists have maintained a transatlantic heavily instrumented moored array to observe fluctuations in the AMOC and its heat flux. Variability on time scales longer than ten days is dominated by geostrophic current fluctuations inferred from transatlantic dynamic height differences and boundary current fluctuations. While effective, the moored array is costly to maintain. This project is an attempt to assess the effectiveness of very long-range full ocean depth underwater gliders in measuring aspects of the AMOC side-by-side the moored array. These autonomous vehicles, named Deepgliders, collect sea-surface to sea-floor profiles of temperature, salinity, and dissolved oxygen along slanting trajectories through the ocean in near-real time. They also return estimates of the full-depth average current. Successful application of Deepgliders to the 26.5 degrees North latitude line will motivate applying the technique to other transects of interest (such as in the North Atlantic subpolar gyre and the South Atlantic subtropical gyre), to address the challenges of repeat hydrography globally, and reduce the overall cost of such programs in order that such ocean climate projects can be afforded as a whole by funding agencies. These together will lead to deeper understanding of earth?s climate.The overall goal of the project is to learn how to assist the sustainable continuation of AMOC monitoring through coming decades. Learning to measure the AMOC using Deepgliders will help sustain operation of the current array at 26.5 degrees North for the many decades required to resolve interannual and multi-decadal variability. Only by operating for several decades will the signals associated with natural climate variability and anthropogenic climate change be evident and potentially distinguishable. A Deepglider is designed to make about 250 dives to as deep as 6000 m in missions lasting as long as 18 months while traveling as much as 10,000 km through the ocean on a single set of lithium batteries. It samples temperature, salinity, and dissolved oxygen along saw tooth paths through the ocean and communicates them to shore each time it reaches the sea surface via satellite telemetry. Two-way communication allows commands to be transmitted to Deepgliders so that its autonomous behavior can be controlled remotely from a pilot anywhere with an internet connection. As a pilot experiment, four one-year Deepglider missions are planned over a 2-year period overlapping moored deployments. Two of these will concentrate on maintaining position close to a RAPID-MOCHA mooring just offshore Abaco, Bahamas to resolve the principal variability in dynamic height for use in estimating the interior ocean contribution to AMOC variability. Two more will repeat a short section intended to capture temporal and spatial variations in Antilles and Deep Western Boundary Current flow. Deepglider and moored measurements will be compared to assess relative efficacy.

大西洋经向翻转环流（AMOC）是全球气候系统的主要组成部分。在北纬 26.5 度，AMOC 负责承载海洋所承载的净极地热通量的约 60%，以及大气和海洋共同承载的总热通量的约 30%，并在全球范围内进行整合。通过海面温度调节，AMOC 与年际至数十年时间尺度的气候信号相关联，这些信号可能产生广泛的社会影响。气候模型预测 AMOC 在下个世纪将大幅减弱，这一变化可能会产生广泛的影响。在过去的十年中，美国和英国的科学家一直在跨大西洋维护着一个装备齐全的系泊阵列，以观察 AMOC 及其热通量的波动。超过十天的时间尺度的变化主要由跨大西洋动态高度差和边界流波动推断出的地转流波动主导。虽然有效，但系留阵列的维护成本很高。该项目旨在评估超远距离全海洋深度水下滑翔机在测量 AMOC 并排系泊阵列方面的有效性。这些名为 Deepgliders 的自动驾驶车辆沿着海洋的倾斜轨迹近乎实时地收集海面到海底的温度、盐度和溶解氧剖面。它们还返回全深度平均电流的估计值。 Deepgliders在北纬26.5度线的成功应用将激励将该技术应用于其他感兴趣的横断面（例如北大西洋副极地环流和南大西洋副热带环流），以解决全球重复水文学的挑战，并减少此类方案的总成本，以便供资机构能够整体承担此类海洋气候项目的费用。这些共同将加深对地球气候的了解。该项目的总体目标是了解如何在未来几十年内协助 AMOC 监测的可持续持续。学习使用 Deepgliders 测量 AMOC 将有助于当前阵列在北纬 26.5 度处维持运行数十年，以解决年际和跨年代际变化问题。只有经过几十年的运行，与自然气候变化和人为气候变化相关的信号才会变得明显并可能被区分。 Deepglider 的设计目的是在长达 18 个月的任务中进行约 250 次下潜至 6000 m 的深度，同时使用一组锂电池在海洋中航行长达 10,000 公里。它沿着穿过海洋的锯齿路径对温度、盐度和溶解氧进行采样，并在每次到达海面时通过卫星遥测将它们传送到海岸。双向通信允许将命令传输到 Deepgliders，以便飞行员可以在任何有互联网连接的地方远程控制其自主行为。作为一项试点实验，计划在两年内进行四次为期一年的深度滑翔机任务，与系泊部署重叠。其中两个将集中于保持靠近巴哈马阿巴科近海的 RAPID-MOCHA 系泊点的位置，以解决动态高度的主要变化，用于估计内海对 AMOC 变化的贡献。另外两个将重复一个简短的部分，旨在捕捉安的列斯群岛和深西部边界流的时间和空间变化。将比较深度滑翔机和系泊测量值以评估相对功效。