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Baroclinic frontal dynamics in the presence of continuous stratification and topography.

机译：在存在连续分层和地形的情况下的斜压锋面动力学。

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摘要

An investigation of subinertial dynamics involving oceanic fronts is presented in the context of layered models, which allow for vanishing thickness in the frontal layer and continuous stratification in the ambient fluid. The focus of the study is the baro-clinic destabilization and subsequent evolution of surface-trapped, bottom-trapped and intermediate-depth currents, as well as their interaction with topography. Two new theories are derived that include the effect of ambient stratification, and a previous theory is generalized. Reduction of all three models to simpler governing equations in the limit of no stratification is demonstrated and basic analytical results are established with respect to boundary conditions, flow invariants and linear stability criteria.; The linear stability problems for an abyssal current and a surface current in the presence of sloping topography are solved for physically-relevant configurations. It is shown that growth rates increase and dominant lengthscales decrease with the relative current thickness or ambient stratification. Predicted instability characteristics and results of fully nonlinear numerical simulations are compared with several oceanographic phenomena of interest, in particular the Denmark Strait Overflow. It is argued that the models presented provide a superior description of baroclinic dynamics than traditional quasigeostrophic theory, in that the assumed lengthscales are larger than the Rossby radius and variations in the frontal layer thickness scale with the layer thickness itself. The resulting balances still allow reasonably straightforward interpretation of the physical mechanisms involved but are appropriate in many situations where quasigeostrophic models are not.
机译：在分层模型的背景下，对涉及海洋前沿的亚惯性动力学进行了研究，该模型可以使额叶层中的厚度消失并在环境流体中进行连续分层。该研究的重点是表层捕获，底部捕获和中等深度的洋流的斜压稳定和随后的演化，以及它们与地形的相互作用。导出了两种新的理论，其中包括环境分层的影响，并且对以前的理论进行了概括。证明了在没有分层的情况下将所有三个模型简化为更简单的控制方程，并针对边界条件，流量不变性和线性稳定性标准建立了基本分析结果。对于与物理相关的配置，解决了倾斜地形下深海电流和表面电流的线性稳定性问题。结果表明，随着相对电流厚度或环境分层的增加，增长率增加，主导长度尺度减小。将预测的不稳定性特征和完全非线性的数值模拟结果与感兴趣的几种海洋现象（尤其是丹麦海峡溢流）进行了比较。有人认为，所提出的模型比传统准古营养学理论提供了更好的斜压动力学描述，因为假定的长度尺度大于Rossby半径，并且额层厚度尺度随层厚度本身而变化。由此产生的平衡仍然可以合理，直接地解释所涉及的物理机制，但适用于许多不需要准拟营养理论的情况。

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  • 作者

    Reszka, Mateusz Krzysztof.;

  • 作者单位

    University of Alberta (Canada).;

  • 授予单位 University of Alberta (Canada).;
  • 学科 Mathematics.; Physical Oceanography.; Geophysics.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 220 p.
  • 总页数 220
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 数学;海洋物理学;地球物理学;
  • 关键词

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