Dynamical Origin of Low-Frequency Variability in a Highly Nonlinear Midlatitude Coupled Model
Dynamical Origin of Low-Frequency Variability in a Highly Nonlinear Midlatitude Coupled Model
复制标题
高度非线性中纬度耦合模型中低频变化的动力学起源
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
J. McWilliams
中科院分区：
文献类型：
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作者：
S. Kravtsov;P. Berloff;W. Dewar;M. Ghil;J. McWilliams
摘要提出了一种新的中纬度年代际耦合变率机制，该机制主要依赖于大气和海洋的非线性动力学。所研究的耦合模式涉及准等转大气和海洋分量，它们通过一个定深的海洋混合层相互通信。一系列的耦合和不耦合实验表明，年代际耦合模式在允许大气纬向流双峰与海洋湍流共存的参数范围内是活跃的。后者在惯性再循环（IR）区域最为强烈。双峰型与存在两种明显的异常持续纬向流模式有关，这两种纬向流模式以大气急流的不同纬度为特征。大气从高纬度到低纬度状态的转变引起的红外重组造成了海面温度异常，这种异常倾向于诱导向相反的大气状态的转变。T…
Abstract A novel mechanism of decadal midlatitude coupled variability, which crucially depends on the nonlinear dynamics of both the atmosphere and the ocean, is presented. The coupled model studied involves quasigeostrophic atmospheric and oceanic components, which communicate with each other via a constant-depth oceanic mixed layer. A series of coupled and uncoupled experiments show that the decadal coupled mode is active across parameter ranges that allow the bimodality of the atmospheric zonal flow to coexist with oceanic turbulence. The latter is most intense in the regions of inertial recirculation (IR). Bimodality is associated with the existence of two distinct anomalously persistent zonal-flow modes, which are characterized by different latitudes of the atmospheric jet stream. The IR reorganizations caused by transitions of the atmosphere from its high- to low-latitude state and vice versa create sea surface temperature anomalies that tend to induce transition to the opposite atmospheric state. T...