一个海气耦合环流模式中的ENSO循环特征及控制机理

CONTROLLING MECHANISM RESPONSIBLE FOR THE ENSO CYCLE IN A COUPLED OCEAN-ATMOSPHERE GENERAL CIRCULATION MODEL

本文利用中科院大气所两层全球大气环流模式和十四层热带太平洋模式的耦合环流模式 10 0年积分中的后 30年的月平均输出资料 ,通过分析海表面温度、上层海洋热容量和海表面高度异常的年际变化 ,揭示了模式 ENSO循环 (包括其产生、发展、成熟和消亡过程 )的特征及其控制机理。结果表明 ,控制本文耦合环流模式中 ENSO循环的机理是“时滞振子”模态 ,这和由中间复杂程度耦合模式得到的 ENSO控制机理是一致的。反映了“时滞振子”机制对于解释 ENSO控制机理具有一定的普遍性。另外 ,分析结果也表明 ,海表面高度异常和上层海洋热容量异常以及温跃层变化具有动力上的一致性。

The characteristics of the ENSO cycle including its initiation,development,mature and decay and its controlling mechanism in a coupled general circulation model(GCM) were described in this study.The model used here is the Institute of Atmospheric Physics(IAP) two layers atmospheric (GCM) coupled to a fourteen layer tropical Pacific ocean model with a free oceanic surface.The analyses were focussed on the ENSO-related interannual variability in the ocean inferred from three oceanic variables,the sea surface temperature,the upper ocean heat content and the sea surface height,with using the last 30-yr output dataset of a 100-yr integration of the model.It was shown that the coupled GCM simulates well ENSO-like cycle and that its controlling mechanism is the so-called'delayed oscillator'mode derived from the intermediate coupled model.In addition,the interannual variation of the sea surface height is dynamically coherent with that of the upper ocean heat content and the themocline displacement.