The Antarctic stratospheric sudden warming of 2002: A self‐tuned resonance?
The Antarctic stratospheric sudden warming of 2002: A self‐tuned resonance?
复制标题
2002 年南极平流层突然变暖：自调谐共振？
DOI：
10.1029/2006gl026034
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发表时间：
2006
影响因子：
5.2
通讯作者：
Richard K. Scott
中科院分区：
文献类型：
--
作者：
J. G. Esler;L. M. Polvani;Richard K. Scott
2002年南极平流层异常变暖事件具有显著的垂直结构特征，观测到的涡旋在平流层上层分裂，但在低层却没有分裂：这种“部分”分裂的涡旋事件相对罕见。建立了一个简单但完全三维的模型来研究这一独特事件的动力学。行星波在模式涡旋边缘被一个下边界强迫激发，该下边界强迫的特征是两个参数：相对于静止框架测量的幅度HF和频率ωF。对于实际的强迫幅度，只在特定的、狭窄的强迫频率范围内发现了类似于2002年事件期间观察到的部分涡旋分裂。利用我们模型的相对简单性，这些频率被证明是那些引起最严重线性模式的‘自调谐’共振激励的频率，在此期间，非线性反馈导致最初的非共振强迫接近共振。
The extraordinary Antarctic stratospheric warming event of 2002 was characterized by a remarkable vertical structure, with the vortex observed to divide at upper levels in the stratosphere but not at lower levels: such ‘partially’ split vortex events are relatively rare. A simple, yet fully three‐dimensional, model is constructed to investigate the dynamics of this unique event. Planetary waves are excited on the model vortex edge by a lower boundary forcing characterized by two parameters: an amplitude hF and a frequency ωF, measured relative to a stationary frame. For realistic forcing amplitudes, a partial vortex split resembling that observed during the 2002 event is found only within a specific, narrow band of forcing frequencies. Exploiting the relative simplicity of our model, these frequencies are shown to be those causing a ‘self‐tuning’ resonant excitation of the gravest linear mode, during which nonlinear feedback causes an initially off‐resonant forcing to approach resonance.