Collaborative Research: The Internal Tide and Mixing in Monterey and Ascension Canyons

合作研究：蒙特雷和阿森松峡谷的内潮和混合

• 批准号: 0751226
• 负责人: Glenn Carter
• 金额: $ 40.92万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0751226&HistoricalAwards=false
• 关键词: Collaborative; Research; Internal; Tide; Mixing

Intellectual MeritBased on theory, laboratory experiments and field observations, canyons have long been identified as sites of intense internal waves. Turbulence measurements in Monterey Canyon (MC) and density overturns in Kaoping Canyon (Taiwan), which has similar size and shape, confirm very strong mixing. The processes generating the mixing, however, have not been determined, nor has mixing been measured in enough canyons to assess its variability from one to another. Observations and recent modeling indicate that the internal tide is a major source of energy in Monterey Canyon, coming from offshore as well as being generated locally. In addition, ridges and constrictions along the canyon make it likely that lee waves and hydraulic jumps are also major sources of mixing, as has been inferred for abyssal canyons.The project will undertake modeling and intensive observations for Monterey Canyon and exploration of nearby Ascension Canyon which is much straighter than Monterey and apparently lacks a significant offshore source for the internal tide. The goals are to: 1) understand how the internal tide propagates in canyons, and in particular how the M2 energy flux is steered around bends and when turns are so sharp that the energy is dissipated, 2) determine whether mixing locations and levels can be predicted by convergences in the along-canyon M2 energy flux, 3) identify and quantify mixing produced by internal wave scattering, lee waves and hydraulic jumps, and 4) assess the effects that canyon shape, smoothness and alignment with offshore M2 sources have on mixing and baroclinic energy by measuring mixing and the internal tide in a relatively short, straight canyon ending on the outer shelf.Broader ImpactsU.S. coasts have dozens of canyons, and they account for almost half of the western continental slope from 45N to Alaska. Though they appear to be biologically rich and export both water and sediments, dynamical processes within canyons are too poorly understood to make a general assessment of the importance of canyons or whether they require special representation in large-scale or regional models. One set of measurements cannot resolve all questions about canyon dynamics, but the proposed work should provide qualitative and quantitative bases for assessing mixing in other canyons.. If fully successful, this project may unable the parameterization of some of the mixing or at least be able to point the way to parameterizations. As part of the proposed effort the investigators have also begun talks with regional modelers to incorporate intense canyon mixing into the models and to do sensitivity runs to define how accurately the mixing must be known to predict its effect on flows and structures outside the canyon. Two post-doc will be hired, one at APL/UW and another at the University of Hawaii. Both willparticipate in all phases of the work for their postdoctoral training. Coordination and collaboration with the regular MBARI sampling of Monterey Bay will benefit this project, and vice versa. Outreach activities will combine earlier canyon measurements and the future measurements.

在理论上，实验室实验和现场观察的理论上，峡谷长期以来一直被确定为强烈的内部波浪部位。蒙特雷峡谷（MC）中的湍流测量和具有相似尺寸和形状的Kaoping Canyon（台湾）的密度倾覆，证实了非常强大的混合。但是，尚未确定产生混合的过程，也没有在足够的峡谷中测量混合以评估其从一种到另一个的变异性。观察结果和最近的建模表明，内部潮汐是蒙特雷峡谷的主要能源，来自海上以及本地生成。此外，沿峡谷沿线的山脊和收缩使Lee波浪和液压跳跃可能也是混合的主要来源，正如对Abyssal Canyons所推断的。该项目将对蒙特雷峡谷进行建模和密集的观察，对附近的船尾峡谷的探索和对蒙特利的内部范围更加紧密，并且对附近的canyne则缺乏大量的偏置。 The goals are to: 1) understand how the internal tide propagates in canyons, and in particular how the M2 energy flux is steered around bends and when turns are so sharp that the energy is dissipated, 2) determine whether mixing locations and levels can be predicted by convergences in the along-canyon M2 energy flux, 3) identify and quantify mixing produced by internal wave scattering, lee waves and hydraulic jumps, and 4) assess the effects that峡谷形状，与海上M2源的平滑度和对齐方式通过在相对较短的直峡谷中测量混合和内部潮汐，以在外架上的尾巴上进行混合和斜压力。海岸有数十个峡谷，它们占西部大陆坡度从45N到阿拉斯加的一半。尽管它们似乎在生物学上富含水和沉积物，但峡谷内的动态过程对峡谷的重要性进行了一般评估，或者它们是否需要在大规模或区域模型中进行特殊代表。一组测量结果无法解决有关峡谷动态的所有问题，但是所提出的工作应提供定性和定量基础以评估其他峡谷中的混合。如果完全成功，该项目可能无法对某些混合的参数化或至少能够指向参数化的方式。作为拟议的努力的一部分，研究人员还开始与区域建模者进行对话，以将强烈的峡谷混合融入模型中，并进行敏感性运行，以定义如何准确地知道混合的方式，以预测其对峡谷以外的流量和结构的影响。将雇用两名大约两个后，一个在APL/UW，另一个在夏威夷大学。两者都将在作品的所有阶段进行博士后培训。与蒙特雷湾的常规MBARI采样协调和合作将使该项目受益，反之亦然。外展活动将结合较早的峡谷测量和未来的测量。