El Nio对东亚气候年际异常影响的数值模拟

Numerical simulations of the interannual climate responses of East Asia to an El Nio event

根据1949-1998年期间8次显著El Nino事件合成的24个月年际海温异常（SSTAs）和气候平均的海温（SST）,利用CCM3分别进行了3个包含10次积分的集合试验,即控制试验（CTRL）,热带太平洋海洋全球大气试验（TOGA）以及整个太平洋海洋全球大气试验（TOGA-NP）,通过对比分析这3个试验之间的集合模拟结果,揭示了在El Nino不同演变阶段东亚气候年际异常响应结构以及北太平洋年际SSTAs在此过程中的调制作用.结果表明：El Nino发展阶段夏季,东亚地区大气环流异常呈显著的负PJ波列,副热带高压减弱、偏东,东亚夏季风增强,东北和江淮流域降水偏多,华北和长江流域及其以南地区降水偏少;El Nino成熟阶段冬季,东亚大槽加强,东亚北部冬季风加强,西太平洋副热带地区低层有显著的反气旋式异常风场,华南地区降水显著增多;El Nino衰亡阶段夏季东亚气候年际异常型与其发展阶段夏季几乎相反.同时,北太平洋年际SSTAs对El Nino影响东亚气候年际异常有一定的调制作用,使模拟的我国降水异常分布更符合观测.

With the 24-month composite Sea Surface Temperature Anomalies（SSTAs） by 8 distinct El Nino events selected from 1949 to 1998 and the corresponding climatological SST during the same period,three numerical experiments with 10 realizations for each,such as the Control Experiment（CTRL）,Tropical Ocean Global Atmosphere（TOGA） and Pacific Ocean Global Atmosphere （TOGA-NP）,are carried out,so as to reveal the interannual climate responses of East Asia to an El Nino event during its different stages and the modulations to these responses of interannual SSTAs in the North Pacific.The results show that during the summer when an El Nino event develops,there exists a significant negative Pacific Japan（PJ） wave pattern over East Asia.The the western Pacific subtropical high is weaker and shifts eastward,and East Asian summer monsoon is strengthened.In China,there is much more precipitation in North East and Jianghuai Valley,however less precipitation in North China and Changjiang River Valley.During the winter when an El Nino event is matured,the East Asian trough is deepened,winter monsoon over the north of East Asia is intensified while there is a strong anticyclone over the subtropical western Pacific.In China,there is much more precipitation in South China.During the summer when an El Nino event decays,the atmosphere circulation response and precipitation in China are nearly completely opposite to the summer when an El Nino event develops.At the same time,the interannual SSTAs in North Pacific indeed has some modulations to the atmosphere response in East Asia to an El Nino event,and their impacts can make the simulated precipitation in China much more resembling to the observations.