ENSO及其组合模态对中国东部各季节降水的影响  

Influences of ENSO and its combination mode on seasonal precipitation over eastern China

作　　者：李海燕[1] 张文君[1] 何金海[1] 

机构地区：[1]南京信息工程大学气象灾害预报预警与评估协同创新中心,气象灾害教育部重点实验室,南京210044

出　　处：《气象学报》2016年第3期322-334,共13页Acta Meteorologica Sinica

基　　金：国家重点基础研究发展计划973项目(2012CB417403);公益性行业(气象)科研专项(GYHY201506013,GYHY201406022);江苏省研究生培养创新工程项目(CXZZ13_0505);江苏省高校“青蓝工程”项目

摘　　要：近期的研究发现,热带太平洋低层大气存在两种主要模态,即经向对称ENSO模态和ENSO与海表温度(SST)年循环相互作用产生的经向反对称组合模态。主要探讨了这两种不同ENSO模态对中国东部各季节降水的影响。结果表明,厄尔尼诺年秋季,中国西南、长江及华南大部分区域呈现显著正降水异常;冬季,正降水异常范围扩大,覆盖华南、华东及华北东南部地区。这两个季节的异常降水都主要受ENSO模态的影响。与ENSO模态相关的正异常海温局地强迫导致120°E以西出现反气旋性环流,其西北侧增强的西南暖湿气流使得中国东部地区降水增多。次年春季,从中国华南延伸到东北出现正的异常降水,主要是ENSO组合模态的贡献。因为次年春季热带太平洋地区ENSO模态信号只局限于赤道地区,并没有对中国东部降水有显著的影响,而ENSO与海温年循环相互作用的组合模态使得与ENSO相关的赤道大气异常可以扩展到赤道以外地区。ENSO组合模态对中国降水异常有重要影响,在今后的研究和短期预测中需引起重视。Recent studies have shown that ENSO in the lower atmosphere over the tropical Pacific is comprised of two dominant modes.One is the meridionally quasi-symmetric ENSO mode,and the other is the meridionally anti-symmetric combination mode produced by the interaction between the sea surface temperature（SST）annual cycle and ENSO variability.This paper discusses influences of the two different ENSO modes on seasonal precipitation over eastern China.Results show that significant positive precipitation anomalies occur over southwestern China and most of the area of the Yangtze River Valley and southern China in the autumn of El Ni珘no years.Positive precipitation anomalies appear over southern and eastern China,and southeastern part of North China in the winter.Both these two seasonal precipitation anomalies are mainly affected by the ENSO mode.The ENSO-associated SST anomalies lead to anti-cyclonic circulation anomalies over the western North Pacific west of120°E,which transports more warm and moist air to China and thus is favorable for more precipitation over eastern China.Positive precipitation anomalies occur from southern to northeast China in the following spring,which is mainly attributed to the combination mode of ENSO.The direct ENSO signal over the tropics is confined to the equatorial region and has no significant impact on precipitation over East Asia.The ENSO-associated equatorial anomalies can expand to off-equatorial regions by the combination mode through interaction between ENSO and the annual cycle of SST.The present study suggests that the combination mode has an important impact on ENSO-related precipitation over China during the El Ni珘no decaying spring,which needs to be emphasized in future research and seasonal prediction.

关 键 词：ENSO模态 ENSO组合模态 降水异常 中国东部 

分 类 号：P47[天文地球—大气科学及气象学]