Relating optimal growth to counterpropagating Rossby waves in shear instability
Relating optimal growth to counterpropagating Rossby waves in shear instability
复制标题
将最佳生长与剪切不稳定中反向传播的罗斯贝波联系起来
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
J. Methven
中科院分区：
文献类型：
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作者：
E. Heifetz;J. Methven
对平面平行剪切流的保守扰动的最佳动力学可以根据称为反向传播罗斯贝波 (CRW) 的分量的传播和相互相互作用来解释。 Bretherton 最初使用 CRW 对来为正压瑞利模型和斜压两层模型中的不稳定正态模态提供机械解释。第一个 CRW 在正平均跨流势涡 (PV) 梯度区域具有较大振幅，而第二个 CRW 在负 PV 梯度区域具有较大振幅。每个 CRW 传播到平均 PV 梯度向量的左侧，与平均流平行。如果 PV 梯度为正时平均流量更正，则两个 CRW 的固有相速度将相似。 CRW 相互作用，因为一个 CRW 的 PV 异常会在另一个 CRW 的位置引起横流速度，从而平流平均 PV。虽然单个罗斯比波是中性的，但它们的相互作用可以导致锁相......
The optimal dynamics of conservative disturbances to plane parallel shear flows is interpreted in terms of the propagation and mutual interaction of components called counterpropagating Rossby waves (CRWs). Pairs of CRWs were originally used by Bretherton to provide a mechanistic explanation for unstable normal modes in the barotropic Rayleigh model and baroclinic two-layer model. One CRW has large amplitude in regions of positive mean cross-stream potential vorticity (PV) gradient, while the second CRW has large amplitude in regions of negative PV gradient. Each CRW propagates to the left of the mean PV gradient vector, parallel to the mean flow. If the mean flow is more positive where the PV gradient is positive, the intrinsic phase speeds of the two CRWs will be similar. The CRWs interact because the PV anomalies of one CRW induce cross-stream velocity at the location of the other CRW, thus advecting the mean PV. Although a single Rossby wave is neutral, their interaction can result in phase locking an...