Thermohaline Interleaving in Baroclinic Frontal Zones

温盐交错是几乎所有大洋盆地水团横向混合的重要机制。温盐交错的理论研究面临两个重要的障碍：(1)需要精确地参数化微尺度混合过程，包括盐指化、扩散对流、对流翻转和剪切驱动的湍流；(2)在线性和非线性理论中包括斜压效应的数学挑战。在这个项目中，线性和非线性理论分析的协调序列将解决这两个问题。线性稳定性分析将划定可以忽略斜模态的参数范围。初步结果表明，这一范围基本上涵盖了除边界附近以外的所有海洋状况。交叉锋模态的一维非线性建模将扩展到最终平衡状态。直接数值模拟将这些结果扩展到三维非线性交错的范围。在每个阶段，结果将与现有的观测数据进行比较。本研究是在盆地和全球尺度模式中发展热盐交错引起的锋面交换参数化的重要一步。它还将为混合参数化提供一个测试平台，可用于更广泛的模型类别。研究生将接受最先进的理论和数值技术方面的培训，并将促进国际合作。

ABSTRACTOCE-0622922Intellectual meritThermohaline interleaving is an important mechanism for the lateral mixing of water masses in virtually every ocean basin. Horizontal diffusivities due to interleaving are often comparable with those due to mesoscale eddies, Theoretical research into thermohaline interleaving faces two important obstacles: (1) the need to accurately parameterize microscale mixing processes, including salt fingering, diffusive convection, convective overturning and shear-driven turbulence, and (2) the mathematical challenge of including baroclinic effects in linear and nonlinear theories. In this project, a coordinated sequence of linear and nonlinear theoretical analyses will address both of these problems. The linear stability analysis will delimit the parameter range in which oblique modes can be ignored. Preliminary results indicate that this range covers essentially all ocean regimes except near boundaries. The one-dimensional nonlinear modeling of cross-front modes will extend to the final equilibrium state. The direct numerical simulations will extend these results into the regime of three-dimensional nonlinear interleaving. At every stage, results will be compared with existing observational data. Broader impactsThe proposed research is a significant step toward the development of parameterizations of frontal exchange due to thermohaline interleaving in basin and global-scale models. It will also provide a test bed for mixing parameterizations that can be used in a wider class of models. A graduate student will receive training in state of the art theoretical and numerical techniques and an international collaboration will be fostered.