中文摘要：

基于中国160站的逐月降水观测资料及NOAA扩展重建的海表温度资料,从1951~2012年逐月的历史时间序列中提取出准2 a振荡（TBO）分量,对中国江南地区春季（3~5月）降水的TBO特征及其与热带海温的关系进行了分析。结果发现：①TBO为江南春季降水最主要的年际周期,TBO分量的方差贡献占到原始序列的52.2%。②江南春季降水与热带海温异常存在明显的时滞关系,其TBO分量与前期Nino3.4区和印度洋海表面温度距平（SSTa）的相关较原始序列更为显著,且持续时间更长,说明热带海温异常对江南春季降水TBO分量的影响是非常显著的。③江南春季降水TBO与Nino3.4指数的时滞关系还呈现出显著的年代际转折,20世纪80年代中期之前,江南春季降水TBO分量与Nino3.4指数在滞后1~11个月内都表现出明显的正相关关系,但从80年代中期至90年代末期这种时滞关系减弱,直至21世纪以来,江南春季降水TBO与Nino3.4指数的时滞关系又重新建立。④通过对比分析年代际转折前后与江南春季降水TBO循环所对应的热带海温演变特征,发现在20世纪80年代中期之前,TBO分量与超前1个季节的赤道中东太平洋海温异常演变具有同步性,使得两者之间的正相关关系稳定;而1986~1999年期间,无论是赤道中东太平洋地区或者印度洋地区海温的演变,都没有表现出像之前类似的TBO循环特征,从而导致两者的相关关系减弱。也就是说,江南春季降水的TBO与中东太平洋海温时滞关系的年代际转折与赤道中东太平洋海温是否具有显著的TBO周期密切相关。

英文摘要：

Based on the 160 stations precipitation data in China and NOAA extended reconstructed SST v3b data,this article focuses on the interannual component of the tropospheric biennial oscillation（TBO）,which is extracted from the original time series of monthly precipitation over southeast China in MAM from 1951 to 2012,and its relationships with the tropical sea surface temperature（SST） anomaly.It is found that： 1） As the major interannual period of the precipitation over southeast China in MAM,the variance contribution of TBO accounts for 52.2% of the original time series.2） The time-lag correlations between the TBO of the precipitation over southeast China in MAM and SST anomaly in Nino3.4 area and Indian Ocean are more significant than its original time series,with longer correlation duration.It is indicated that the tropical SST anomaly has much significantly influence on the TBO component.3） The time-lag correlation between them also presents the interdecadal transition.Before the middle of the 1980s,the positive time-lag correlations between the Nino3.4 index and the TBO component with lagging 1 to 11 months were obvious,while the relationships were reducing and the TBO and ENSO were practically unrelated to each other until 21st century,and the positive time-lag correlations between them were rebuilt again.4） In the TBO cycle of the precipitation over southeast China in MAM,the evolution of tropical central and eastern Pacific SST anomaly with leading 3 months is synchronous with the TBO before the middle of the 1980s,which made the stably positive correlations between them.During 1986-1999,however,whether the tropical central and eastern Pacific SST or Indian Ocean SST,their evolutions were not presenting the characteristics similar to the TBO cycle before 1985,resulting in the correlation between them weakening.In other words,the interdecadal transition of the relationship between the TBO of precipitation over southeast China in MAM and the tropical SST anomaly is closely related to whether t