Assessing the importance of deep ocean topographic scattering of low mode internal tides

评估低模内潮汐的深海地形散射的重要性

• 批准号: 1129757
• 负责人: Thomas Peacock
• 金额: $ 23.56万
• 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: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129757&HistoricalAwards=false
• 关键词: Assessing; importance; deep; ocean; topographic

Despite several decades of research, there is still much ambiguity about the importance of deep ocean topographic scattering of the low mode internal tide. Theoretical studies based on infinitesimal topography predict a modest 6-10% scattering efficiency (Muller & Xu 1992; StLaurent & Garrett 2002), and recent field data reveals long range propagation of the low mode internal tide northeast from Hawaii (Zhao et al. 2010). A recent theoretical study using finite-amplitude random topography, however, indicates that scattering can provide a rapid decay mechanism for internal tides (Buhler & Holmes-Cerfon 2011), and the currently underway NSF EXperimental study of Internal Tide Scattering (EXITS) field program is focusing on the Line Islands Ridge, where satellite altimetry data indicates 37% of the mode-1 flux propagating southwest from Hawaii is dissipated (Johnston, Merrfield & Holloway 2003).The intellectual merit of this project is in the advancement and utilization of an analytical Green function method to make reasonable predictions of topographic internal tide scattering in the deep ocean. The method, which the PI has already used for internal tide generation studies, is not subject to many of the idealizations of previous theoretical approaches (e.g. infinitesimal topography and/or constant stratification). The theoretical model will be validated through comparison with laboratory experiments that employ a novel internal tide generator; a proof-of-concept experiment has already been performed to demonstrate the feasibility of the experimental program (Peacock et al. 2010). The work will be integrated with the field studies and numerical simulations of the NSF-funded EXITS program.The primary broader impact of this research is a robust and quantitative assessment of the efficiency of deep ocean topographic scattering of low mode internal tides. The analytical method, validated by laboratory experiments, will provide a benchmark for testing numerical models and interpreting field data; it will also be integrated into a MATLAB code called iTide that will be made freely available to oceanographers. The project will support the training of a postdoctoral researcher and an undergraduate MIT researcher. The theoretical method and experimental results will be incorporated in graduate and undergraduate courses on wave mechanics, fluid mechanics and instrumentation. The results of this study will be disseminated through journal articles, invited seminars and the PI?s website. A workshop on internal waves at the Aspen Center for Physics will be proposed.

尽管进行了数十年的研究，但对于低模式内部潮汐的深海地形散射的重要性仍然存在很多歧义。基于无穷小地形的理论研究预测了适度的6-10％的散射效率（Muller＆Xu 1992; Stlaurent＆Garrett 2002），最近的田间数据揭示了夏威夷北部低潮汐的远距离传播（Zhao etal。2010）。 A recent theoretical study using finite-amplitude random topography, however, indicates that scattering can provide a rapid decay mechanism for internal tides (Buhler & Holmes-Cerfon 2011), and the currently underway NSF EXperimental study of Internal Tide Scattering (EXITS) field program is focusing on the Line Islands Ridge, where satellite altimetry data indicates 37% of the mode-1 flux propagating southwest from Hawaii is消散（Johnston，Merrfield＆Holloway，2003年）。该项目的智力优点在于进步和利用分析绿色功能方法，以合理地预测深海的地形内部潮汐散射。 PI已经用于内部潮汐生成研究的方法不受以前理论方法的许多理想化（例如，无穷小地形和/或恒定分层）。理论模型将通过与采用新型内部潮汐发生器的实验室实验进行比较来验证。已经进行了概念验证实验，以证明实验计划的可行性（Peacock等，2010）。这项工作将与NSF资助的退出计划的现场研究和数值模拟集成。这项研究的主要广泛影响是对低模式内部潮汐深海地形散射效率的强大和定量评估。通过实验室实验验证的分析方法将为测试数值模型和解释现场数据提供基准。它也将集成到称为ITIDE的MATLAB代码中，该代码将免费提供给海洋学家。该项目将支持博士后研究人员和本科麻省理工学院研究员的培训。理论方法和实验结果将纳入波浪力学，流体力学和仪器的研究生和本科课程中。这项研究的结果将通过期刊文章，受邀研讨会和PI的网站来传播。将提出关于阿斯彭物理中心内波的研讨会。