作为斜压涡旋季节内周期行为的解释的涡旋记忆
Eddy memory as an explanation of intra-seasonal periodic behavior in baroclinic eddies
摘要：
斜压环形模态（BAM）是南半球涡动动能的一种高阶模态。季节内时间尺度的振荡行为。振荡机制已被链接到瞬态涡流平均流的相互作用，仍然知之甚少。在这里，我们证明了涡热通量依赖于大尺度流动的有限记忆效应可以解释BAM的振荡行为的起源。我们代表的涡记忆效应的延迟积分核，导致广义朗之万方程的行星尺度热方程。使用行星和天气尺度运动之间的相互作用的数学框架，我们推导出一个简化的动力学模型的BAM -一个随机强迫振荡器的周期成比例的几何平均值之间的涡记忆时间尺度和扩散涡平衡时间尺度。我们的模型提供了一个正式的理由，以前提出的现象学模型的BAM，并可用于明确诊断的内存内核，提高我们的理解瞬态涡流平均流在大气中的相互作用。
英文摘要：
The baroclinic annular mode (BAM) is a leading-order mode of the eddy-kinetic energy in the Southern Hemisphere exhibiting. oscillatory behavior at intra-seasonal time scales. The oscillation mechanism has been linked to transient eddy-mean flow interactions that remain poorly understood. Here we demonstrate that the finite memory effect in eddy-heat flux dependence on the large-scale flow can explain the origin of the BAM's oscillatory behavior. We represent the eddy memory effect by a delayed integral kernel that leads to a generalized Langevin equation for the planetary-scale heat equation. Using a mathematical framework for the interactions between planetary and synoptic-scale motions, we derive a reduced dynamical model of the BAM - a stochastically-forced oscillator with a period proportional to the geometric mean between the eddy-memory time scale and the diffusive eddy equilibration timescale. Our model provides a formal justification for the previously proposed phenomenological model of the BAM and could be used to explicitly diagnose the memory kernel and improve our understanding of transient eddy-mean flow interactions in the atmosphere.
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