The Downwelling Limb of the Thermohaline Circulation

温盐环流的下降流

• 批准号: 0726339
• 负责人: Michael Spall
• 金额: $ 73.97万
• 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: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0726339&HistoricalAwards=false
• 关键词: Downwelling; Limb; Thermohaline; Circulation

Intellectual Merit: Recent observational, theoretical, and modeling studies all suggest that the upper part of the downwelling limb of the thermohaline circulation is concentrated in strong currents subject to buoyancy loss near lateral boundaries. Nonetheless, the dynamics and thermodynamics that control where waters sink from the upper ocean to mid- and deep-depths, and what the consequences of these downwelling regions are for the general circulation, are not well understood. There is a lack of clear understanding on whether the downwelling occurs over the spatial scale of the boundary current or within a narrower, mixing-driven, boundary layer, as suggested by previous theories. The proposed study seeks to explicitly represent these downwelling regions in high resolution, non-hydrostatic numerical model calculations and laboratory experiments. The scientific objectives of the proposed study are to: i) To determine what controls the rate and spatial scales of downwelling near lateral boundaries; ii) To test previous theoretical models of downwelling boundary layers and their influence on the basin-scale circulation; iii) To determine if the details of the near-boundary buoyancy-forced turbulence needs to be explicitly resolved in order to faithfully represent the influence of the downwelling regions on the basin-scale circulation Broader Impacts: The proposed study will have broader impacts spanning both research and educational activities. The science objectives of the proposed study will have direct impact on our understanding of the mean and low frequency variability of the thermohaline circulation, its role in the climate system, and our ability to model it. The processes of mixing and downwelling near boundaries also impacts other branches of oceanography such as biology and chemistry. The results of this study will also be made broadly available to the scientific community through publication in scientific journals, presentation at national and international meetings, and in seminars. Both PIs are staff in a joint educational/research institution within which they have played a role (and plan to continue) in teaching, advising, supervising and training graduate students and summer student fellows (undergraduate). This research will also help maintain the Woods Hole Oceanographic Institution Geophysical Fluid Dynamics laboratory as a teaching and training facility.

智力价值：最近的观测、理论和模拟研究都表明，温盐环流向下流动的上部集中在强流中，在侧向边界附近容易失去浮力。尽管如此，控制海水从上层海洋下沉到中深层的动力学和热力学，以及这些下沉区域对一般环流的影响，还没有被很好地理解。对于下流是发生在边界流的空间尺度上，还是像以前的理论所说的那样，发生在较窄的混合驱动的边界层内，目前还缺乏明确的认识。这项拟议的研究试图在高分辨率、非静力数值模式计算和实验室实验中显式地表示这些下涌区。拟议研究的科学目标是：i)确定是什么控制了侧边界附近下沉的速度和空间尺度；ii)检验以前关于下沉边界层的理论模型及其对盆地规模环流的影响；iii)确定是否需要明确地解决边界附近浮力强迫湍流的细节问题，以便如实地反映下沉区域对盆地规模环流的影响：拟议的研究将产生跨越研究和教育活动的更广泛的影响。拟议研究的科学目标将直接影响我们对温盐环流的平均和低频变化、其在气候系统中的作用以及我们对其进行建模的能力的理解。边界附近的混合和下流过程也影响到海洋学的其他分支，如生物学和化学。这项研究的结果还将通过在科学期刊上发表、在国家和国际会议上介绍以及在研讨会上介绍的方式向科学界广泛提供。这两名私人助理都是一家联合教育/研究机构的工作人员，他们在该机构中发挥了教学、咨询、监督和培训研究生和暑期学生研究员(本科生)的作用(并计划继续发挥作用)。这项研究还将有助于维持伍兹霍尔海洋研究所地球物理流体动力学实验室作为教学和培训设施的地位。