Internal Tide Studies at the Hawaiian Ridge

0425347智力价值：能量从流域尺度的表面潮汐运动到最小湍流混合尺度的传递途径还没有得到很好的理解。 一个重要的中间步骤是在海洋中部地形，如海山、潜脊和岛屿，表面潮汐分散成内部潮汐，这是正压潮汐能的汇。 模型显示了从这些生成区域发出的内部潮汐，具有梁结构和低模式结构，其中能量密度沿着内部潮汐特征定位。 内潮的高模式分量被认为是消散附近的生成站点，并可能是重要的本地混合，而低模式的内潮传播远离其源区域的衰减尺度上的订单1000公里的观测和模型。我们预测这一过程的能力取决于经过实地观察验证的精心设计的模型。 规模最大、最全面的潮汐转换研究是夏威夷海洋混合实验，重点研究构成夏威夷海脊的海脊、海山和岛屿地形的潮汐散射。 这项研究的建模部分已被证明是非常成功的。 模型模拟的内部潮汐发电和辐射相比，有利的观测电流，位移，能量密度，能量通量和耗散。 HOME潮汐建模工作的继续是基于普林斯顿海洋模型。 该项目的目标是：1）最终确定整个海脊的潮汐能预算，2）检查在海脊顶部观察到的非流体静力学特征，3）评估模型湍流闭合方案与直接微观结构和精细结构测量的对比，4）确定沿着与内部潮梁相关的海脊侧翼发生的深度混合量，以及5）评估内潮对背景分层和环流变化的敏感性。HOME提供了一个理想的测试站点，以扩展我们对潮汐散射过程的理解，评估当前的建模方法，并根据现场结果开发新的工具。 更广泛的影响：最终，这项活动可以改进潮汐消散和混合的参数化，用于更大规模的环流和气候模型以及海山和海脊环境的区域模型。 一名本科生和两名研究生将参加这个项目，目标是完成一个高级论文和博士论文。 该项目将在夏威夷大学的年度公众开放日期间得到重点介绍，这是一项由海洋地球科学和技术学院主办的外联活动。 将联系位于夏威夷檀香山的主教博物馆，讨论基于本研究结果的可能展示。

0425347Intellectual merit: The pathways of energy transfer from the basin-scale surface tidal motions to the smallest turbulent mixing scales are not understood well. An important intermediate step is the scattering of the surface tide into internal tides at mid-ocean topography, such as seamounts, submerged ridges, and islands, which is a sink for barotropic tidal energy. Models show internal tides emanating from these generation regions with both beam structure, where energy density is localized along internal tidal characteristics, and low-mode structure. The high-mode components of the internal tide are believed to dissipate near the generation site and may be important for local mixing, while the low-mode internal tides propagate away from their source regions with decay scales on the order of 1000 km in observations and models. Our ability to predict this process depends on well-conceived models that are validated against field observations. The largest and most comprehensive tidal conversion study has been the Hawaii Ocean Mixing Experiment (HOME), focusing on tidal scattering at the ridge, seamount, and island topography making up the Hawaiian Ridge. The modeling component of this study has proven to be highly successful. The model simulations of internal tide generation and radiation compares favorably to observed currents, displacements, energy densities, energy fluxes, and dissipation. The continuation of the HOME tidal modeling effort is based on the Princeton Ocean Model. The goals of this project are to 1) finalize the tidal energy budget for the entire ridge, 2) examine non-hydrostatic features observed over the ridge crest, 3) assess the model turbulent closure scheme versus direct microstructure and finestructure measurements, 4) determine the amount of deep mixing occurring along the ridge flanks associated with internal tide beams, and 5) assess the sensitivity of the internal tide to changes in the background stratification and circulation. HOME provides an ideal test site to expand our understanding of the tidal scattering process, to assess current modeling approaches, and to develop new tools based on the field results. Broader impacts: Ultimately this activity can lead to improved parameterizations of tidal dissipation and mixing to be used in larger scale circulation and climate models, as well as in regional models for seamount and ridge environments. An undergraduate and two graduate student will participate in this project, with the goal of achieving a senior thesis and PhD dissertations. The project will be highlighted during the annual public open house at the University of Hawaii, an outreach activity sponsored by the School of Ocean Earth Science and Technology. The Bishop Museum in Honolulu, Hawaii will be contacted to discuss a possible display based on the results of this study.