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首页> 外文期刊>Journal of the Atmospheric Sciences >Nonhydrostatic, three-dimensional perturbations to balanced, hurricane-like vortices. Part II: Symmetric response and nonlinear simulations
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Nonhydrostatic, three-dimensional perturbations to balanced, hurricane-like vortices. Part II: Symmetric response and nonlinear simulations

机译:非静水三维扰动,平衡的飓风状涡流。第二部分:对称响应和非线性仿真

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摘要

This paper is the second part of a study on the dynamics of nonhydrostatic perturbations to dry, balanced, atmospheric vortices modeled after tropical cyclones. In Part I, the stability and evolution of asymmetric perturbations were presented. This part is devoted to the stability and evolution of symmetric perturbations particularly those that are induced by the wave-mean flow interactions of asymmetric perturbations with the symmetric basic-state vortex. The linear model shows that the vortices considered in Part I are stable to symmetric perturbations. Furthermore, the model can be used to derive the steady, symmetric response to stationary symmetric forcing, similar to the results from quasi-balanced dynamics as originally presented by Eliassen. The secondary circulations that develop act to oppose the effects of the forcing, but also to warm the core and intensify the vortex. The model is also used to simulate the response to impulsive symmetric forcings, that is, symmetric perturbations. Much like the asymmetries considered in Part I, symmetric perturbations go through two kinds of adjustment: a fast adjustment that generates gravity waves, and then a slow adjustment leading to a final state that represents a net change in both the wind and mass fields of the symmetric vortex. The nonhydrostatic, unsteady, symmetric response of the tropical-storm-like vortex to the evolving asymmetries from Part I is presented. In contrast with results from previous studies with initially two-dimensional or balanced asymmetric vorticity perturbations, asymmetric temperature perturbations are found to have a negative effect on overall intensity. These changes are about two orders of magnitude smaller than those caused by symmetric perturbations of equal amplitude. The asymmetric/symmetric adjustment process for purely asymmetric temperature perturbations are also simulated with a fully nonlinear, compressible model. Excellent agreement is found between the linear, nonhydrostatic and the nonlinear, compressible models. The vortex intensification caused by a localized, impulsive thermal perturbation can be accurately estimated from the projection of this perturbation onto the purely symmetric motions. [References: 34]
机译:本文是研究热带风暴之后模拟的非静水扰动对干燥,平衡,大气涡旋动力学的第二部分。在第一部分中,介绍了非对称扰动的稳定性和演化。该部分致力于对称扰动的稳定性和演化,特别是那些由非对称扰动与对称基态涡流的波均流相互作用引起的扰动的稳定性和演化。线性模型表明,在第一部分中考虑的涡流对于对称扰动是稳定的。此外,该模型可用于导出对平稳对称强迫的稳定,对称响应,类似于最初由Eliassen提出的准平衡动力学的结果。形成的二次循环不仅可以抵抗强迫作用,还可以使岩心变暖并加剧涡旋。该模型还用于模拟对脉冲对称强迫的响应,即对称扰动。就像在第一部分中考虑的不对称性一样,对称扰动经历两种调整:快速调整产生重力波,然后缓慢调整导致最终状态,最终状态表示风场和质量场的净变化。对称涡旋。提出了热带风暴状涡旋对第一部分中不断发展的不对称现象的非静力学,非稳态,对称响应。与先前对二维或平衡非对称涡旋扰动的研究结果相反,非对称温度扰动对整体强度具有负面影响。这些变化比等幅度对称扰动引起的变化小两个数量级。还使用完全非线性的可压缩模型来模拟纯非对称温度扰动的非对称/对称调节过程。在线性,非静液压模型和非线性,可压缩模型之间发现了极好的一致性。可以根据该扰动在纯对称运动上的投影来精确估算由局部脉冲热扰动引起的涡流增强。 [参考:34]

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