A Crossroads of the Atlantic Meridional Overturning Circulation: The Charlie-Gibbs Fracture Zone

大西洋经向翻转环流的十字路口：查理-吉布斯断裂带

• 批准号: 0926656
• 负责人: Amy Bower
• 金额: $ 291.38万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0926656&HistoricalAwards=false
• 关键词: Crossroads; Atlantic; Meridional; Overturning; Circulation

Intellectual Merit: Recently the oceanographic community has agreed that we should work quickly to advance our understanding of the Atlantic Meridional Overturning Circulation (AMOC) in recognition of its importance in Earth's climate system. While intense observational effort has been made to describe the basic structure and (in some cases) low-frequency variability at a few locations along the paths of the AMOC, relatively little attention has been paid to the Charlie-Gibbs Fracture Zone (CGFZ), a gateway for both the warm and cold limbs of the AMOC over the Mid-Atlantic Ridge. The result is an incomplete description of even the most fundamental characteristics of this exchange flow. This project presents a combined observational and modeling study of the AMOC at the CGFZ. The primary objectives are:(1) to obtain an improved direct estimate of the mean and low frequency variability of the deep westward transport of Iceland-Scotland Overflow Water through the CGFZ, and(2) to gain a better understanding of the causes of the low-frequency variability in the transport of overflow waters through the CGFZ, especially of the role of the NAC in generating this variability.An array of eight current meter and hydrographic moorings will be installed across the CGFZ that will measure the currents and water properties between the bottom and 500 m for two years beginning in 2010. This array will provide the first long-term, simultaneous observations of both the westward and eastward flows over the CGFZ. An exploratory study of diapycnal mixing intensity in the CGFZ will also be conducted. The modeling component of the proposed work will be idealized in order to address basic dynamical questions about how baroclinic, energetic flows are partitioned between one or more narrow gaps in mid-ocean ridges. The connection between model and data will be made through the phenomenology of interest, i.e., the space and time scales of the variability and the coupling in both the vertical over a single gap and meridionally between gaps.Broader Impacts: By providing an improved understanding of the strength and variability of the warm and cold limbs of the AMOC where they cross over the Mid-Atlantic Ridge, the research will help to sort out the ocean's role in global climate and provide a transport benchmark for critical evaluation of climate models. This project will also contribute to the scientific literacy of blind and visually impaired middle and high school students through a continuing collaboration with the Perkins School for the Blind in Massachusetts. The primary objectives of this effort are to stimulate interest in the earth sciences through face-to-face and online interaction with a working researcher who shares the students' particular disability and to develop accessible physical and virtual tools for teachers of the visually impaired to use with students at Perkins and in the Massachusetts public schools.

智力优势：最近，海洋学界一致认为，我们应该迅速努力，以提高我们对大西洋经向翻转环流（AMOC）的认识，认识到它在地球气候系统中的重要性。虽然已经进行了大量的观测工作来描述AMOC路径上沿着几个位置的基本结构和（在某些情况下）低频变率，但相对较少关注查理-吉布斯断裂带（CGFZ），这是大西洋中脊AMOC温暖和寒冷分支的门户。其结果是，即使是对这种交换流最基本的特征，也描述得不完整。该项目提出了一个综合的观测和模拟研究的AMOC在CGFZ。主要目标是：（1）获得对冰岛-苏格兰溢流水通过CGFZ向西深层输送的平均值和低频变率的改进直接估计，以及（2）更好地了解溢流沃茨通过CGFZ输送的低频变率的原因，尤其是NAC在产生这种变率中的作用。将在CGFZ上安装一个由8个流速计和水文系泊装置组成的阵列，从2010年开始，测量底部和500 m之间的水流和水特性，为期两年。这个阵列将提供第一个长期的，同时观测的向西和向东流动的CGFZ。还将对CGFZ中的纵裂混合强度进行探索性研究。拟议的工作的建模部分将理想化，以解决基本的动力学问题，斜压，充满活力的流量之间的一个或多个狭窄的差距在大洋中脊划分。模型和数据之间的联系将通过感兴趣的现象学来实现，即，在单一气隙的垂直方向和气隙之间的垂直方向上的变异和耦合的空间和时间尺度。通过更好地了解AMOC在大西洋中脊上空的冷暖分支的强度和变化，这项研究将有助于理清海洋在全球气候中的作用，并为气候模型的关键评估提供运输基准。该项目还将通过继续与马萨诸塞州的帕金斯盲人学校合作，促进盲人和视力受损中学生的科学素养。这项工作的主要目标是，通过与一名工作研究人员进行面对面和在线互动，激发对地球科学的兴趣，该研究人员与学生分享他们的特殊残疾情况，并开发无障碍的实物和虚拟工具，供视力受损的教师与帕金斯和马萨诸塞州公立学校的学生一起使用。