Decadal ENSO amplitude modulations: a nonlinear paradigm
Decadal ENSO amplitude modulations: a nonlinear paradigm
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DOI：
10.1016/s0921-8181(02)00194-7
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发表时间：
2003-06
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影响因子：
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通讯作者：
A. Timmermann
中科院分区：
文献类型：
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作者：
A. Timmermann
本文研究了厄尔尼诺-南方涛动（ENSO）振幅年代际调制的机制。我们的分析是基于一个多世纪的现代气候模拟与ENSO解决耦合大气环流模式（CGCM）。与观测结果相一致的是，ENSO方差在10-20年的时间尺度上发生变化。这种年代际拍频与热带（次）地表温度变率的第二种主要模式密切相关。该模式的偶极子特征主要是由水平平流、垂直平流和混合的相互作用产生的。我们提出了一个非线性机制，这是能够产生十年热带气候异常以及十年ENSO振幅调制（DEAMs），而不调用热带外动力。这种机制是基于同宿轨道的思想。这一新的范式是使用低维ENSO模式，是从CGCM模拟经验得出的验证。
This paper investigates the mechanism which generates decadal modulations in the amplitude of the El Niño-Southern Oscillation phenomenon (ENSO). Our analysis is based on a multicentury present-day climate simulation performed with an ENSO-resolving Coupled General Circulation Model (CGCM). In consistency with observations, it is found that ENSO variance undergoes changes with a time scale of about 10–20 years. This decadal beat is closely linked to the second dominant pattern of tropical (sub)surface temperature variability. The dipole-like characteristic of this mode is generated mainly by the interplay of horizontal, vertical advection and mixing. We suggest a nonlinear mechanism, which is capable of generating decadal tropical climate anomalies as well as decadal ENSO amplitude modulations (DEAMs) without invoking extratropical dynamics. This mechanism is based on the idea of homoclinic orbits. This new paradigm is validated using a low-dimensional ENSO model that is derived empirically from the CGCM simulation.