Nonlinear Aspects of Symmetric Instability
Nonlinear Aspects of Symmetric Instability
复制标题
对称不稳定性的非线性方面
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
R. Rotunno
中科院分区：
文献类型：
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作者：
A. Thorpe;R. Rotunno
本文讨论的问题是：大气中最初对二维对称扰动不稳定的区域的最终状态是什么？这些区域被认为是锋面雨带的原因，并影响斜压区的对流。观测表明，大气经常沿着绝对动量面接近湿等熵，而这种状态被提出是对称不稳定的结果。在这里，我们试图建立一组动力学原型来理解是否以及如何建立这样的中立状态。文中提出了一些简化的假设，如恒定的涡粘性、非饱和流动和简单的边界条件来阐明讨论。所用的两个初始态是一个均匀的负位涡区，由两个水平表面限制，在垂直边界上要么是周期性的，要么是墙的；第二，一个更大的正位涡区域，其中嵌入了一个负位涡区域。
Abstract This paper addresses the question: What is the ultimate state of a region of the atmosphere which is initially unstable to two-dimensional symmetric disturbances? Such regions are believed to account for frontal rainbands and influence convection in baroclinic zones. Observations show that often the atmosphere is close to moist isentropic along absolute momentum surfaces and this state, it has been proposed, arises as a result of symmetric instability. Here we attempt to establish a set of dynamical archetypes to understand whether and how such a neutral state is established. Certain simplifying assumptions are made such as constant eddy viscosity, unsaturated flow, and simple boundary conditions to clarify the discussion. The two initial states used are a region of uniform negative potential vorticity (PV), confined by two horizontal surfaces with either periodic conditions or walls at the vertical boundaries, and second, a larger domain of positive PV with an embedded zone of negative PV remote...