Descent Rate Models of the Synchronization of the Quasi-Biennial Oscillation by the Annual Cycle in Tropical Upwelling
Descent Rate Models of the Synchronization of the Quasi-Biennial Oscillation by the Annual Cycle in Tropical Upwelling
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DOI：
10.1175/jas-d-17-0267.1
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发表时间：
2018-06
影响因子：
3.1
通讯作者：
K. Rajendran;I. Moroz;S. Osprey;P. Read
中科院分区：
文献类型：
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作者：
K. Rajendran;I. Moroz;S. Osprey;P. Read
通过使用一类称为下降率模型的方程对赤道零风线的动态进行建模，研究了准两年期振荡（QBO）对周期性调制施加的平均上升流的响应。这些是简单的数学模型，通过关注零风线高度的动态来捕捉 QBO 同步的本质。描述了零风线的启发式下降率模型，并显示该模型捕获了 QBO 先前研究中看到的许多同步特征。然后使用简单的变换证明，如果假设零风线以下有二次速度剖面，则 QBO 的标准 Holton-Lindzen 模型本身可以转化为下降率模型的形式。由此产生的非自治常微分方程捕获了在完整 Holton-Lindzen 偏微分方程中观察到的大部分同步行为。新一类模型提供了一个新颖的框架来理解 QBO 的同步，并且我们证明了这些模型与数学文献中众所周知的圆图之间的密切关系。最后，我们分析再分析数据集以验证下降率模型的一些预测，并找到与模型行为一致的 QBO 同步的统计显着证据。
The response of the quasi-biennial oscillation (QBO) to an imposed mean upwelling with a periodic modulation is studied, by modeling the dynamics of the zero wind line at the equator using a class of equations known as descent rate models. These are simple mathematical models that capture the essence of QBO synchronization by focusing on the dynamics of the height of the zero wind line. A heuristic descent rate model for the zero wind line is described and is shown to capture many of the synchronization features seen in previous studies of the QBO. It is then demonstrated using a simple transformation that the standard Holton–Lindzen model of the QBO can itself be put into the form of a descent rate model if a quadratic velocity profile is assumed below the zero wind line. The resulting nonautonomous ordinary differential equation captures much of the synchronization behavior observed in the full Holton–Lindzen partial differential equation. The new class of models provides a novel framework within which to understand synchronization of the QBO, and we demonstrate a close relationship between these models and the circle map well known in the mathematics literature. Finally, we analyze reanalysis datasets to validate some of the predictions of our descent rate models and find statistically significant evidence for synchronization of the QBO that is consistent with model behavior.