Upper-Tropospheric Synoptic-Scale Waves. Part I: Maintenance as Eady Normal Modes.
Upper-Tropospheric Synoptic-Scale Waves. Part I: Maintenance as Eady Normal Modes.
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对流层上层天气尺度波。
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
B. Farrell
中科院分区：
文献类型：
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作者：
Chantal Rivest;C. Davis;B. Farrell
对流层上层波在中纬度天气尺度动力学中具有重要意义。它们的寿命通常长于被周围的雪破坏的时间尺度，并且它们经常引起地表旋流。本文提出了一种基于上层伊迪正态的上层波维持的动力学模型。在具有均匀的对流层和平流层位涡度的基本状态下，建立了一种波的解析模型。虽然标准Eady基本态代表无限平流层静态稳定性的极限情况，但发现在实际对流层顶和平流层存在时，标准Eady正模态特征仍然成立。特别地，研究的基本态支持天气尺度的高层正态，这也是准等转方程的非线性解。前面已经证明，即使对流层中存在无穷小的g，上层模态解也不存在。
Abstract Upper-tropospheric waves are important in midlatitude synoptic-scale dynamics. Their life duration is typically longer than time scales for disruption by the ambient shaer and they often induce surface cyclogenesis. In this paper a dynamical model is proposed for the maintenance of these upper-level waves based on the upper-level Eady normal modes. An analytical model of waves is developed on Eady basic states that have uniform tropospheric and stratospheric potential vorlicity. While the standard Eady basic state represents the limiting case of infinite stratospheric static stability, it is found that the standard Eady normal-mode characteristics hold in the presence of realistic tropopause and stratosphere. In particular, the basic states studied support upper-level normal modes of synoptic scale, which are also nonlinear solutions of the quasigeostrophic equations. It was demonstrated earlier that the upper-level modal solutions do not exist in the presence of even infinitesimal tropospheric g...