ENSO循环年代际变化及其数值模拟

从20世纪70年代后期的观测资料分析中显示了全球气候的年代际变化, 同时也表现在热带太平洋上最重要的海气耦合现象ENSO的年代际变化上。本文利用中国科学院大气物理研究研究所 (IAP) 大气科学和地球流体力学数值模拟国家重点实验室 (LASG) 的气候系统海洋模式 (简称LICOM), 对ENSO的年际以及年代际变率进行模拟, 结果表明LICOM基本能够模拟出ENSO年际变化的特征, 通过对海洋上层热含量的计算以及对热量和质量输送的变化分析, 能够看到模式中ENSO循环中的反馈机制与理论研究的结论是一致的。同时, 作者还发现模式能够重现ENSO循环的年代际变化特征, 例如周期、 传播方向和冷暖事件不对称性等特征的模拟也基本接近观测事实, 其中重点分析了冷暖事件的不对称性与非线性加热 (NDH) 之间的关系, 进一步分析还发现ENSO的强度、 不对称性与海洋内部的非线性过程之间在年代际尺度上也存在密切的关系。但是, 模式模拟与观测结果之间仍然存在着一定的误差, 模式有待于进一步改进。

Numerical simulation of decadal modulation of ENSO

The remarkable decadal shift of global climate in the late 1970s has been observed,as well as the decadal variability of ENSO which is the most significant coupled air-sea phenomenon in the tropical Pacific.In order to evaluate the ability of LASG/IAP(State Key Laboratory of Numerical Modeling for Armospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics,Chinese Academy of Sciences) Climate System Ocean Model(version 1.0,abbreviated as LICOM1.0),the simulations of interannual and decadal variability of ENSO are made by the model,and the results show: LICOM could simulate the interannual variability of ENSO basically,and it is found that the ENSO feedback mechanism in the model is in agreement with theoretical investigation by calculating the surface heat content and analyzing the heat transport and the mass transport.Moreover,the model can reproduce decadal modulation of ENSO,such as period and propagation direction as well as asymmetry between the cold and warm events and their simulations are also basically near to realistic observations.And the relationship between the skewness and nonlinear dynamic heating is mainly analyzed.Further analysis also shows that there is a close relationship between the Nonlinear Dynamic Heating(NDH) and the amplitude and skewness of ENSO on the decadal timescale.It is found that there exist errors in the model simulation compared with SODA results.The model needs to be improved in the future.