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首页> 外文期刊>Journal of Physical Oceanography >Length Scale of the Finite-Amplitude Meanders of Shelfbreak Fronts
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Length Scale of the Finite-Amplitude Meanders of Shelfbreak Fronts

机译：搁板前沿有限幅曲的长度尺度

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摘要

Through combining analytical arguments and numerical models, this study investigates the finite-amplitude meanders of shelfbreak fronts characterized by sloping isopycnals outcropping at both the surface and the shelfbreak bottom. The objective is to provide a formula for the meander length scale that can explain observed frontal length scale variability and also be verified with observations. Considering the frontal instability to be a mixture of barotropic and baroclinic instability, the derived along-shelf meander length scale formula is [b(1)/(1 + a(1)S(1/2))]NH/f, where N is the buoyancy frequency; H is the depth of the front; f is the Coriolis parameter; S is the Burger number measuring the ratio of energy conversion associated with barotropic and baroclinic instability; and a(1) and b(1) are empirical constants. Initial growth rate of the frontal instability is formulated as [b(2)(1 + a(1)S(1/2))/(1 + a(2)S(1/2))]NH/L, where is the bottom slope at the foot of the front, and a(2) and b(2) are empirical constants. The formulas are verified using numerical sensitivity simulations, and fitting of the simulated and formulated results gives a(1) = 2.69, b(1) = 14.65, a(2) = 5.1 x 10(3), and b(2) = 6.2 x 10(-2). The numerical simulations also show development of fast-growing frontal symmetric instability when the minimum initial potential vorticity is negative. Although frontal symmetric instability leads to faster development of barotropic and baroclinic instability at later times, it does not significantly influence the meander length scale. The derived meander length scale provides a framework for future studies of the influences of external forces on shelfbreak frontal circulation and cross-frontal exchange.
机译：通过将分析论证和数值模型相结合，本研究研究了以断面倾斜和等腰突露头为特征的架子断裂锋面的有限振幅曲折。目的是为曲折长度标度提供一个公式，该公式可以解释观察到的额叶长度标度的变异性，并可以通过观察得到验证。考虑到额面不稳定性是正压和斜压不稳定性的混合，推导的沿架子弯曲长度比例公式为[b（1）/（1 + a（1）S（1/2））] NH / f， N是浮力频率； H是前面的深度； f是科里奥利参数； S是汉堡数，其测量与正压和斜压不稳定性相关的能量转化率； a（1）和b（1）是经验常数。额叶不稳定性的初始增长率表示为[b（2）（1 + a（1）S（1/2））/（1 + a（2）S（1/2））] NH / L，其中是前脚底部的斜率，而a（2）和b（2）是经验常数。使用数值敏感性仿真验证了公式，对仿真和公式化结果的拟合得出a（1）= 2.69，b（1）= 14.65，a（2）= 5.1 x 10（3）和b（2）= 6.2 x 10（-2）。数值模拟还显示了当最小初始势涡为负时，快速增长的额叶对称不稳定的发展。尽管额叶对称性不稳定性会导致正压和斜压不稳定性的发展更快，但不会显着影响曲折长度范围。得出的曲折长度量表为将来研究外力对货架断裂额叶循环和跨额叶交换的影响提供了框架。

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