中文摘要：

本文选取ECMWF ORAS4再分析数据对1959-2015年热带太平洋海平面的低频变化进行了分析。热带太平洋海平面年际变化第一模态反映了ENSO爆发阶段的海平面变化,热带东、西太平洋变化反相,其时间序列与Ni1o3.4指数高度相关。海平面第二模态则体现了El Ni1o爆发前后热带太平洋暖水的输运过程。El Ni1o爆发前热带西太平洋暖水聚集的位置,以及爆发后暖水向赤道外输运的位置在两类El Ni1o事件中均有所不同。此外,ENSO的周期在近半个世纪发生了显著的年代际变化,这一变化与热带太平洋的年代际变化有关。热带太平洋的年代际变化对海平面趋势变化也有着显著的影响。卫星高度计观测到的近20年海平面的快速上升（下降）正是由20世纪90年代后热带太平洋频繁的位相转换引起的。

英文摘要：

The ECMWF ORAS4 reanalysis is used to study the low-frequency variation in sea level in the tropical Pacific in this paper.The first mode of interannual sea level variation in the tropical Pacific reflects the burst of El Ni1 o.The sea level change in the tropical eastern Pacific is opposite to that in the tropical western Pacific,and the principal component of the first mode is highly correlated with the Ni1o3.4index.The second mode shows the warm water transport process during the El Ni1 o.The locations where the warm water gathered in before El Ni1 o,and the positions where the warm water started to transport to high latitude are different in the two types of El Ni1 o events.Besides,there is a remarkable decadal change in the cycles of ENSO,and this is linked with the decadal variation in the tropical Pacific.The sea level trends are also affected by the decadal variation.The high rise（descend）rate after 1993 that observed by altimeter is caused by the phase-switching.