In this text we make a diagnosis of linear and nonlinear response of quasi - quadrennial ( qq ) and quasi - biennial ( qb ) component of nino3 . 4 index by using reanalyzed ncep / ncar data of sst , wind stress ( pseudo stress ) field , ssp , then have a time and spatial analysis of wind stress field by using mssa , and finally find the importance and contrast the effect of different wind stress field forcing the sea so as to find the cause ofenso irregularity 本文首先分析海表温度( sst ) 、风应力场、海表面气压( slp )等ncep ncar再分析的月距平场对于nino3 . 4指数的准4a ( qq )和准2a ( qb )振荡成分的线性和非线性响应，接着用mssa (多通道奇异谱分析)对风应力场进行时空特征分析，最后用一个热带太平洋动力海洋模式研究具有不同振荡性质的风应力场对海洋强迫作用的重要性及差异，寻找enso不规则性的原因。
( 4 ) latitude and meridional wind stress fields both have the character of quasi - quadrennial and quasi - biennial oscillation , but their phases are different . so their conjunct effect makes enso oscillation have both quasi - quadrennial and quasi - biennial periodicity and erratic , which causes the forecast of enso events uncertainty ( 4 )纬向和经向风应力距平场具有准4a和准2a的振荡性质，但是位相存在差异，因此共同作用下造成enso振荡既有准4a和准2a的周期性，又有不规则性，对于enso事件的预报带来不确定性。
