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首页> 外文期刊>Journal of Physical Oceanography >Steep Shelf Stabilization of the Coastal Bransfield Current: Linear Stability Analysis
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Steep Shelf Stabilization of the Coastal Bransfield Current: Linear Stability Analysis

机译：海岸布兰斯菲尔德潮流的陡架稳定：线性稳定性分析

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摘要

In situ measurements obtained during the 2010 COUPLING cruise were analyzed in order to fully characterize the velocity structure of the coastal Bransfield Current. An idealized two-layer shallow-water model was used to investigate the various instability processes of the realistic current along the coastal shelf. Particularly studied is how the topographic parameter To (ratio between the shelf slope and the isopycnal slope of the surface current) impacts the growth and the wavelength of the unstable perturbations. For small bottom slopes, when the evolution of the coastal current is controlled by the baroclinic instability, the increase of the topographic parameter To yields a selection of smaller unstable wavelengths. The growth rates increase with small values of To. For larger values of To (To ≥ 10, which is relevant for the coastal Bransfield Current), the baroclinic instability is strongly dampened and the horizontal shear instability becomes the dominant one. In this steep shelf regime, the unstable growth rate and the wavelength selection of the baroclinic coastal current remains almost constant and weakly affected by the amplitude of the bottom velocity or the exact value of the shelf slope. Hence, the linear stability analysis of an idealized Bransfield Current predicts a typical growth time of 7.7 days and an alongshore scale of 47 km all along the South Shetland Island shelf. The fact that these large growth times are identical to the typical transit time of water parcels along the shelf may explain why the current does not exhibit any unstable meanders.
机译：为了全面表征沿海布兰斯菲尔德潮流的速度结构，分析了在2010年耦合航行期间获得的现场测量结果。一个理想的两层浅水模型被用来研究沿岸架子现实水流的各种不稳定性过程。专门研究的是地形参数To（表面电流的架子坡度和等腰坡度之比）如何影响不稳定扰动的增长和波长。对于较小的底坡，当沿海水流的变化受斜压不稳定性控制时，地形参数To的增加会产生较小的不稳定波长。 To的值越小，增长率越高。对于较大的To值（To≥10，这与沿海的Bransfield流有关），斜压不稳定性被大大减弱，水平剪切不稳定性成为主要因素。在这种陡峭的陆架条件下，斜度沿海海流的不稳定增长率和波长选择几乎保持不变，并且受底部速度幅度或陆架坡度的精确值影响很小。因此，理想化的布兰斯菲尔德潮流的线性稳定性分析预测，整个南设得兰群岛陆架的典型生长时间为7.7天，沿岸规模为47 km。这些较大的生长时间与水包沿架子的典型运输时间相同的事实可能解释了为什么水流没有任何不稳定的弯曲。

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    《Journal of Physical Oceanography》 |2014年第2期|714-732|共19页
  • 作者

    F. J. Poulin; A. Stegner; M. Hernandez-Arencibia; A. Marrero-Diaz; P. Sangra;

  • 作者单位

    Department of Applied Mathematics, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada;

    Laboratoire de Meteorologie Dynamique, Ecole Polytechnique, Palaiseau, France;

    Departamento de Fisica, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas, Spain;

    Departamento de Fisica, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas, Spain;

    Departamento de Fisica, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, Las Palmas, Spain;

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