Collaborative Research: Diagnosing Eddy mixing in DIMES

合作研究：诊断 DIMES 中的涡流混合

• 批准号: 1233832
• 负责人: Raffaele Ferrari
• 金额: $ 90.42万
• 依托单位: Massachusetts Institute of Technology
• 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: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1233832&HistoricalAwards=false
• 关键词: Collaborative; Research; Diagnosing; Eddy; mixing

Climate-scale ocean models unanimously stress the key regulatory function played by the oceanic overturning circulation in the Earth's climate and biogeochemical cycles over decadal and longer time scales. Yet in their quest to resolve many topical climate problems, the models' credibility is challenged by their extreme sensitivity to the representation of mixing processes in the Southern Ocean. This peculiarity of model behavior reflects the unique role of mixing in mediating the vertical and horizontal transports of water masses in the Antarctic Circumpolar Current (ACC), which shape the overturning circulation through their respective impacts on the overturning rate and inter-ocean exchange. The Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) has collected a wealth of data to quantify mixing, including the spreading of a chemical tracer and of 150 floats at two different depths. The goal of this proposal is to analyze the tracer and float data to estimate the vertical and horizontal variations in lateral eddy mixing. The principal investigators' previous work has shown that tracer and floats are, by themselves, insufficient to accurately constrain these variations. Therefore the data will be analyzed together with surrogate tracers and floats advected with a numerical simulation of the regions under study.Intellectual Merit: This project tackles the formidable problem of quantifying the role of small-scale eddies in the large-scale circulation. Because these eddies are so challenging to observe and model, it is difficult to quantify their large-scale effect. Indeed the ocean uptake of heat and carbon over the next century in climate models can be very different in models that parameterize mesoscale eddies compared to models that explicitly resolve them. This implies that present parameterizations, which either ignore or improperly represent the horizontal and vertical variations in mesoscale eddy mixing, may not have the skill to make accurate climate projections. The goal of this project is to ground new understanding of eddy mixing in data and use these results to develop new parameterizations for climate models. The connection between data and models is key to ensure that the DIMES experiment will have a long term legacy in the climate community.Broader Impacts: This project addresses the important problem of quantifying mixing by eddies in the ocean and their role in the climate system. Furthermore the work should be seen in the wider context of studies of eddy-mean flow interaction in turbulent flows. The ideas have importance for the general circulation of the atmosphere and of planetary atmospheres, particularly those of the gas giants such as Jupiter. Indeed, parametrically, the ocean is closely akin to Jupiter, with an eddy scale that is hundreds of times smaller than that of the large-scale circulation. Finally, there is a strong educational component through the training of three graduate students and two post-docs, and the development of new curricula to introduce students in the MIT/WHOI Joint Program to the role of the Southern Ocean in the climate system.The DIMES project is a process study sponsored by the U.S. CLIVAR (climate variability and predictability) program.

气候尺度的海洋模型一致强调了地球气候中海洋倾覆的循环和生物地球化学周期在十年和更长的时间尺度上发挥的关键调节功能。然而，为了解决许多主题气候问题，这些模型的信誉受到对南方海洋混合过程的极端敏感性的挑战。模型行为的这种特殊性反映了混合在介导南极循环电流（ACC）中水质量的垂直和水平运输中的独特作用，该电流（ACC）通过各自对倾覆速率和近距离交换的影响来塑造倾覆的循环。南大洋（Dimes）的Diapynal和Isopyclal混合实验已收集了大量数据以量化混合，包括化学示踪剂的扩散以及在两个不同深度的150个浮子。该建议的目的是分析示踪剂和浮动数据，以估计侧向涡流混合的垂直和水平变化。主要研究人员的先前工作表明，示踪剂和浮子本身不足以准确限制这些变化。因此，将与替代示踪剂和浮子一起对数据进行分析，并通过对正在研究的区域进行数值模拟。智能优点：该项目解决了量化小规模涡流在大规模循环中的作用的强大问题。由于这些涡流的观察和模型非常具有挑战性，因此很难量化它们的大规模效果。实际上，与明确解决它们的模型相比，在参数化中尺度涡流的模型中，在气候模型中，海洋吸收热量和碳的吸收可能会大不相同。这意味着当前的参数化忽略或不正确地表示中尺度涡流混合的水平和垂直变化，可能没有技巧来进行准确的气候投影。该项目的目的是对数据中的涡流混合进行新的了解，并使用这些结果为气候模型开发新的参数化。数据和模型之间的联系是确保Dimes实验在气候社区中具有长期遗产的关键。Boader的影响：该项目解决了量化海洋中涡流混合及其在气候系统中的作用的重要问题。此外，在湍流中涡流流相互作用的更广泛的背景下，应该可以看出这项工作。这些想法对于大气和行星气氛的一般流通至关重要，尤其是木星等天然气巨头的循环。实际上，在参数上，海洋与木星非常类似，涡流比大循环小数百倍。最后，通过培训三名研究生和两个后的培训，还有一个很强的教育组成部分，以及开发新课程，以在MIT/WHOI联合计划中介绍学生在气候系统中的角色。