热带北大西洋海温异常对南海夏季风的影响及其机理

Influence of northern tropical Atlantic SST anomaly on South China Sea summer monsoon and its mechanism

利用HadiSST资料、CMAP降水资料和NCEP/NCAR再分析资料,分析了热带北大西洋(Northern Tropical Atlantic,NTA)海表温度异常(Sea Surface Temperature Anomaly,SSTA)与南海夏季风(South China Sea Summer Monsoon,SCSSM)的联系及可能机制。观测分析表明,夏季NTA海温异常与SCSSM存在显著的负相关关系;NTA海温正异常时,北半球副热带东太平洋至大西洋区域存在气旋式环流异常,有利于热带大西洋(热带中太平洋)地区产生异常上升(下沉)运动,使得西北太平洋地区出现反气旋环流异常,该反气旋环流异常西侧的南风异常使得SCSSM增强。利用春季NTA指数、东南印度洋海温异常指数、北太平洋海温异常指数、南太平洋经向模(South Pacific Ocean Meridional Dipole,SPOMD)及Niňo3.4指数构建了SCSSM季节预测模型,预测模型后报与观测的SCSSM指数的相关系数为0.81,表明该模型可较好预测SCSSM。

This paper analyzes the connection and possible mechanism between sea surface temperature anomaly (SSTA) in the northern tropical Atlantic (NTA) and the South China Sea summer monsoon (SCSSM) using HadiSST data,CMAP precipitation data and NCEP/NCAR reanalysis data.The observation analysis shows that there is a significant negative correlation between NTA SSTA and SCSSM in summer.Positive NTA SSTA can cause cyclonic circulation anomalies in the subtropical East Pacific to Atlantic region of the Northern Hemisphere,which is conducive to abnormal ascending (descending) motion in the tropical Atlantic (tropical central Pacific) region.The motions can cause the anomalous anticyclone circulation in the northwestern Pacific region,and the south wind anomalies on the west side of the anticyclone circulation anomaly enhance the SCSSM.The SCSSM seasonal prediction model is constructed by using spring NTA index,SST anomaly index in southeastern Indian Ocean,SST anomaly index in North Pacific,South Pacific Ocean Meridional Dipole (SPOMD),and Ni?o3.4 index.Correlation coefficient between the observed SCSSM index and the hindcast of the model is 0.81,showing that the model can predict SCSSM well.