Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events
Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events
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DOI：
10.1175/jas-d-11-07.1
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发表时间：
2011-11
影响因子：
3.1
通讯作者：
-N.;J. Matthewman;G. J.;Esler
中科院分区：
文献类型：
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作者：
-N.;J. Matthewman;G. J.;Esler
摘要利用极涡的理想单层f-平面模型，对平流层突然变暖（SSWs）的“涡旋分裂”的基本动力学进行了重新研究。目的是阐明静止地形强迫导致模式涡旋分裂的条件，并将分裂条件表示为决定地形和环流的模式参数的函数。对于特定的地形强迫剖面，模式行为由两个非量纲参数控制：地形强迫高度M和冲浪区位涡量参数Ω.对于相对较低的M，与观测到的ssw相似的涡旋分裂仅在Ω值的狭窄范围内发生。此外，还观察到参数空间的分岔：Ω（或M）在超过临界值时的微小变化会导致低幅度涡罗斯比波状态和突然涡分裂状态之间的突变。模型的行为可以完全地…
AbstractThe fundamental dynamics of “vortex splitting” stratospheric sudden warmings (SSWs), which are known to be predominantly barotropic in nature, are reexamined using an idealized single-layer f-plane model of the polar vortex. The aim is to elucidate the conditions under which a stationary topographic forcing causes the model vortex to split, and to express the splitting condition as a function of the model parameters determining the topography and circulation.For a specified topographic forcing profile the model behavior is governed by two nondimensional parameters: the topographic forcing height M and a surf-zone potential vorticity parameter Ω. For relatively low M, vortex splits similar to observed SSWs occur only for a narrow range of Ω values. Further, a bifurcation in parameter space is observed: a small change in Ω (or M) beyond a critical value can lead to an abrupt transition between a state with low-amplitude vortex Rossby waves and a sudden vortex split. The model behavior can be fully u...