Dynamics of Potential Vorticity Fronts and Eddy Detachment
Dynamics of Potential Vorticity Fronts and Eddy Detachment
复制标题
位涡锋和涡脱离的动力学
DOI：
--
复制
发表时间：
1986
期刊：
影响因子：
--
通讯作者：
M. Stern
中科院分区：
文献类型：
--
作者：
L. Pratt;M. Stern
摘要采用分段均匀位涡模型研究了1 / 2层射流中准地转涡旋的形成和分离。涡度锋将这两部分分开，因此射流具有尖状特征。用等高线动力学方法计算了大振幅初始扰动（其起源可能归因于模型中未明确的正斜压不稳定机制）的演化过程。某些数值结果，如涡旋分离前锋面的变陡，可以用微分平均场平流和涡旋感应来物理解释。对各种初始条件进行了计算，并指出了涡流分离所需的幅度/尺度条件。讨论的重点是墨西哥湾流中冷暖环的形成问题。本文还简要讨论了海岸对射流大扰动的影响。
Abstract The formation and detachment of quasi-geostrophic eddies in a 1½ layer jet is studied using a piecewise uniform potential vorticity model. A vorticity front separates the two pieces, and thus the jet has cusplike character. The evolution of large amplitude initial disturbance (whose origin may be attributed to barotropic-baroclinic instability mechanisms not explicit in our model) is computed by the method of contour dynamics. Certain numerical results such as the steepening of the front prior to eddy detachment can be physically explained in terms of differential mean field advection and vortex induction. Computations are made for a variety of initial conditions and we indicate the amplitude/scale conditions necessary for the detachment of an eddy. The discussion is directed to the problem of the formation of warm/cold rings in the Gulf Stream. The effect of a coast on large perturbations of a jet is also briefly discussed.