东亚夏季风的自然变率——NCAR Cam3模拟结果分析

Natural Variability of East Asian Summer Monsoon:Analysis of NCAR Cam3 Model Simulations

利用季节循环的全球观测海表温度及海冰驱动NCARCam3全球大气环流模式的100a模拟结果，通过定义东亚夏季风指数，分析了模拟的大气内部变化中东亚夏季风的变化特征。结果表明：模拟的东亚夏季风自然变率主要表现为3—7a较显著的年际周期，并具有较明显的年代际变化特征。在弱夏季风年代，亚洲大陆海平面气压增强，日本附近及东亚沿海地区海平面气压降低；500hPa位势高度上，欧洲地区为负高度距平，里海附近地区为正高度距平，日本及其以东太平洋为负高度距平，易形成类似欧亚（EU）型的遥相关波列。在强夏季风年代，其环流异常分布基本与弱夏季风年代相反。模拟的东亚夏季风变化与夏季大气内部500hPa高度场上EU型遥相关波列的关系密切。

Using the 100-yr simulations from seasonal cycle global SST and sea ice-driven NCAR Cam3 global atmospheric circulation model, the variation of simulated East Asian Summer Monsoon （EASM） in the model atmosphere is investigated with an EASM index. Results suggest that the natural variability of the simulated EASM mainly displays 3-7-yr period and marked interdecadal variation. During the weak EASM period, the sea level pressure （SLP） over the Asian continent increases, with decreased SLP around Japan and eastern Asian littoral;the 500 hPa geopotential height fields exhibit the negative height anomaly over the Europe, the positive anomaly around the Caspian Sea, and the negative anoma- ly around Japan and the Pacific area east of Japan, thus forming an Eurasian （EU） -like teleconnection wavetrain;and almost v. v. during the strong EASM period. It is also found that the simulated EASM variation has a close relation to the EU teleconnection wavetrain at 500 hPa in summer.