热带太平洋、印度洋海温异常对处于厄尔尼诺事件成熟期的东亚Hadley环流的影响

分析了热带太平洋El Nino事件和热带印度洋海盆一致的暖海温异常事件（记为暖海盆模态）与东亚Hadley环流的关系及海温异常对东亚Hadley环流的影响。结果表明：（1）东亚Hadley环流与El Nino循环的关系密切,El Nino事件从开始到消亡的不同位相期,东亚地区表现为随位相变化的异常经向垂直环流,在El Nino成熟期由异常顺时针经向环流圈转换为异常逆时针经向环流圈,意味着东亚Hadley环流圈的显著减弱。（2）冬季Nino3指数、赤道印度洋海盆一致型模态指数（IOBMI）与东亚Hadley环流指数间呈负相关关系,相关系数分别为-0.42、-0.39,远超过0.01信度的显著性检验,表明当El Nino事件和印度洋暖海盆模事件发生时,东亚Hadley环流减弱。模拟结果与诊断分析结果一致。（3）鉴于印度洋海盆模态和太平洋El Nino事件的密切联系,在考虑冬季东亚Hadley环流变化时,应考虑El Nino事件和印度洋海盆一致型海温异常事件的共同作用。数值试验结果表明两大洋的共同作用会产生更强的东亚异常逆时针经向垂直环流,使得东亚Hadley环流显著减弱。

Effects of the SSTA over Tropical Pacific Ocean and Indian Ocean on the Hadley Circulation over East Asia in the Mature Phase of El Ni(n)o Event

Based on observational data and an atmospheric general circulation model,the paper examined the relationship between the El Nino events and the Hadley circulation in East Asia in boreal winter as well as the relationship between the Indian Ocean basin-wide warming event and the East Asia Hadley circulation.The influence of the sea surface temperature anomalies（SSTA） over the two tropical Oceans on the East Asia Hadley circulation was investigated.The main conclusions are as follows：（1） the intensity variation of the East Asia Hadley circulation associates with the El Nio event through its whole process.The anomalous East Asia Hadley circulation cell is fully developed during the mature phase of El Nio;（2） the correlations of the Nio3 index and the Indian Ocean basin-wide mode index（IOBMI） with the East Asia Hadley circulation index（EAHI） are-0.42 and-0.39,respectively（above 0.01% significance level）,which means that when the El Nino events and the warm SSTA over IOBM in winter occur,the intensity of the East Asia Hadley circulation is much weaker than normal.Results of simulations confirm the diagnostic analysis results;（3） the IOBM in winter develops in response to both atmospheric and oceanic processes of El Nio.Thus,effects of the two oceanic events both need to be considered when examining the influence of El Nio on the East Asia Hadley circulation and the combined influence of El Nio and IOBM events tends to produce stronger East Asia Hadley circulation in winter.