The vertical propagation of internal waves through the ocean

内波在海洋中的垂直传播

• 批准号: 1357434
• 负责人: Thomas Peacock
• 金额: $ 26.82万
• 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: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1357434&HistoricalAwards=false
• 关键词: vertical; propagation; internal; waves; through

Overview: The vertical propagation of internal waves through a wide range of density stratifications and vertical shear structures of the ocean is an important problem in physical oceanography. A pressing matter is to develop a better understanding of the flow of internal wave energy that propagates down towards the deep ocean from the base of the mixed layer, as this has the potential to impact ocean mixing and thus play a role in influencing ocean circulation and climate. This issue is currently being very actively pursued in regards to near-inertial waves in the Arctic Ocean due to the retreating summer ice. At present, however, the conclusions of large-scale numerical models are at odds with the observed seasonal cycle of near-inertial wave energy in the deep ocean. Furthermore, there are other potentially important scenarios such as the energy-flux and fate of high-frequency internal waves excited by Langmuir circulation, and the transmission and reflection properties of complex double-diffusive staircase structures, about which little is currently known.Intellectual Merit: The intellectual merit of this project is in the advancement and utilization of a semi-analytical method to reasonably model the propagation of internal waves through arbitrary stratifications and vertical shear. The method is designed to handle the challenging scenarios that can arise in the ocean, in which the vertical scale of variations in the stratification and shear are comparable to the vertical wavelength of the transiting internal waves. The theoretical model will be systematically validated for increasingly complex scenarios through comparison with laboratory experiments and numerical simulations. The laboratory experiments and numerical model will enable investigations of nonlinear regimes the linear theoretical model cannot access. The modeling effort will be closely coordinated with past, present and future field studies of the North Pacific and Arctic Ocean via a number of collaborations, keeping it grounded in what happens in the ocean, and both the Principal Investigator and his graduate student will participate in a 2015 NSF-funded field study.Broader Impacts: The broader impact of this research is insight into the propagation and dissipation of internal waves through complex ocean stratifications, thereby supporting investigations of mechanisms that influence ocean mixing. Specifically, the investigators will improve understanding of, and the ability to predict, the downward propagation and instability of internal waves from the base of the mixed layer and through double-diffusive staircase stratifications. The validated theoretical method, prepared as a MATLAB GUI with user guide and made freely available, will provide a new tool for interpreting field data and assisting in the planning of field studies. The project will support the training of a graduate student, an undergraduate researcher and part of the training of a postdoc at MIT. Graduate students, postdocs and faculty at WHOI, Yale and University of Washington will also be trained in the theoretical method. A fellow of the WHOI Geophysical Fluid Dynamics summer program will be recruited to participate in experiments, and MIT-WHOI Joint Program students will be recruited to produce short and inspiring educational videos on the ocean through collaboration with the MIT+K12 program. The theoretical method and experiments will be incorporated in a graduate course on environmental fluid dynamics. The results of this study will be disseminated through journal articles, invited seminars and a website.

概述：内波通过海洋的大范围密度分层和垂直剪切结构的垂直传播是物理海洋学中的一个重要问题。当务之急是更好地了解从混合层底部向下传播到深海的内波能量流，因为这有可能影响海洋混合，从而在影响海洋环流和气候方面发挥作用。由于夏季冰层消退，目前正在积极研究北冰洋近惯性波的这一问题。然而，目前大规模数值模型的结论与观测到的深海近惯性波浪能季节周期不一致。此外，还有其他潜在的重要场景，例如朗缪尔环流激发的高频内波的能量通量和命运，以及复杂的双扩散阶梯结构的透射和反射特性，目前对此知之甚少。 智力优点：该项目的智力优点在于改进和利用半解析方法来合理地模拟内波的传播 任意分层和垂直剪切。该方法旨在处理海洋中可能出现的具有挑战性的场景，其中分层和剪切力的垂直变化范围与传输内波的垂直波长相当。通过与实验室实验和数值模拟的比较，理论模型将针对日益复杂的场景进行系统验证。实验室实验和数值模型将能够研究线性理论模型无法访问的非线性状态。建模工作将通过多项合作与北太平洋和北冰洋过去、现在和未来的实地研究密切协调，以海洋中发生的情况为基础，首席研究员和他的研究生都将参加 2015 年 NSF 资助的实地研究。 更广泛的影响：这项研究的更广泛影响是深入了解内波通过复杂海洋分层的传播和消散，从而支持调查 影响海洋混合的机制。具体来说，研究人员将提高对来自混合层底部并通过双扩散阶梯分层的内波向下传播和不稳定性的理解和预测能力。经过验证的理论方法以带有用户指南的 MATLAB GUI 形式提供并免费提供，将为解释现场数据和协助规划现场研究提供新工具。该项目将支持麻省理工学院一名研究生、一名本科生研究员的培训以及部分博士后的培训。 WHOI、耶鲁大学和华盛顿大学的研究生、博士后和教师也将接受理论方法的培训。将招募 WHOI 地球物理流体动力学夏季项目的研究员参与实验，并通过与 MIT+K12 项目合作，招募 MIT-WHOI 联合项目的学生制作关于海洋的简短且鼓舞人心的教育视频。理论方法和实验将纳入环境流体动力学研究生课程。这项研究的结果将通过期刊文章、特邀研讨会和网站传播。