Using the satellite sea surface temperature (SST) from 1991 to 2015 over the equatorial Pacific Ocean, the variation of tropical instability waves (TIWs) and its relationship to El Niño-Southern Oscillation (ENSO) were investigated. The activity of TIWs was measured by the root-mean-square value of the 20~50 day band-pass-filtered SST perturbations. Remarkable TIWs were found in the Niño3 area (150°W-90°W, 5°S-5°N), where the mean TIW activity was approximately 0.20°C, with its maximum exceeding 0.35℃ betweenthe equator and 3°N. In addition, the TIW activity was weaker south of the equator, in which its strength reached 0.2 only in the winters of 1998, 2007 and 2010 when La Niña events occurred. The pattern that the TIWs were more active during La Niña and less active during El Niño events was confirmed. Meanwhile, we found that the TIW activity, while in phase with the strength of the surface zonal current shear and the cold tongue front, led the ENSO amplitude about 2~3 months due to its more rapid response than the Niño3 SST to dynamic and thermal processes in the equatorial Pacific associated with ENSO. This implies that the phase and activity of ENSO can be predicated by the TIW activity a few months earlier from satellite SST observations.%文章利用1991—2015年卫星海表温度(sea surface temperature, SST)研究了太平洋赤道不稳定波(tropical instability waves, TIWs)强度变化特征及其与厄尔尼诺-南方涛动现象(El Niño-Southern Oscillation, ENSO)的关系。首先采用带通滤波法将TIWs强度量化为赤道东太平洋SST的季节内(20~50d)波动振幅,发现强TIWs分布于尼诺3(Niño3)区域(150°W—90°W,5°S—5°N),平均强度达到0.2℃,赤道至3°N之间甚至超过0.35℃,在赤道南侧TIWS相对较弱,只在1998、2007、2010年3个拉尼娜(La Niña)年冬季达到0.2℃。文章不但证实La Niña年TIWs较强、厄尔尼诺(El Niño)年TIWs较弱的规律,而且发现TIWs强度与ENSO并非同相变化, TIWs强度变化超前ENSO 2~3个月,这是TIWs与Niño3区SST对ENSO相关赤道动力、热力过程反应时间差异所致, TIWs强度与赤道表层纬向流剪切强度以及冷舌锋面强度呈同期正相关,而Niño3指数滞后这2项指标2~3个月变化,三者都是ENSO循环的一部分。这意味着能够用卫星观测的TIWs活动(如SST)提前表征ENSO的位相和强度。
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