Marginal stability and predator-prey behaviour within storm tracks
Marginal stability and predator-prey behaviour within storm tracks
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DOI：
10.1002/qj.3014
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发表时间：
2017-04-01
影响因子：
8.9
通讯作者：
Tailleux, R.
中科院分区：
文献类型：
--
作者：
Novak, L.;Ambaum, M. H. P.;Tailleux, R.
风暴轴强度和增长率之间的捕食者-猎物的关系，揭示在北大西洋和北太平洋的再分析数据，以及在一个理想化的全球环流模式与纬向不对称的加热偶极子。这两个量在相空间中的平均值揭示了这两个量在近似每月的时间尺度上振荡。这些振荡的发生是由于风暴轴活动中的准周期性爆发，减少了过多的斜压性，并使气流回到对这些爆发稍微稳定的状态。这些振荡的许多详细的属性，以及再现的二维动力系统，特别是在北大西洋风暴轴，这是更多的纬向约束比北太平洋。据预测和观察，平均而言，较强的风暴事件发生的频率较低，但在较短的时间尺度上增长。结果表明，在斜压中性附近的非线性振荡行为是局部风暴轴的一个普遍特征，为斜压不稳定性的研究提供了一个新的视角。
A predator-prey relationship between storm track intensity and growth rate is revealed in reanalysis data of the North Atlantic and North Pacific, as well as in an idealized global circulation model with a zonally asymmetric heating dipole. Averaging in the phase space of these two quantities reveals that both quantities oscillate on approximately monthly time-scales. These oscillations occur due to quasi-periodic bursts in storm track activity that reduce excess baroclinicity and bring the flow back towards a state that is marginally stable to those bursts. Many detailed properties of these oscillations are reproduced well by a two-dimensional dynamical system, especially in respect of the North Atlantic storm track which is more zonally constrained than that in the North Pacific. It is predicted and observed that on average stronger storm events occur less frequently but grow on a shorter time-scale. The results suggest that nonlinearly oscillating behaviour around a state of baroclinic neutrality is a general feature of localized storm tracks, and they offer a new perspective on the study of baroclinic instability.