厄尔尼诺/南方涛动现象对热带西太平洋大气外强迫的响应

A Study of the Response of El Nino/Southern Oscillation to External Forcing in the Tropical Western Pacific

利用1个热带太平洋中等海气耦合模式,针对厄尔尼诺/南方涛动(ENSO)现象对热带西太平洋季节内振荡(MJO)和季风的响应进行了研究。数值试验的结果表明:热带西太平洋的MJO和季风这类周期比ENSO周期短的大气外强迫对ENSO的影响随强迫强度的不同具备不同的表现形式:当MJO或季风很弱时会使ENSO振幅加强;当为中等强度时,几乎对ENSO没有影响;当MJO或季风较强时,ENSO振幅加强,锁相时间从冬季转移至秋季;外强迫非常强时,会因为短周期外强迫形成的海洋波动干扰了ENSO循环,ENSO循环振幅减弱或消失。

This paper studies how the inter-seasonal oscillation（MJO） and monsoon in the tropical western Pacific influence the E1 Nino/Southern Oscillation（ENSO） by using the coupled ocean-atmosphere model. The numerical experiment shows that the influence of MJO or monsoon in the western Pacific on the ENSO is different when the intensity of MJO or monsoon is different. When the intensity of MJO or monsoon is weak, it may excite strong ENSO events, but when the intensity of MJO or monsoon is intermediate, it can hardly affect the ENSO; and when the external forcing is stronger, the amplitude of the ENSO is decreased, the period is shortened and the phase-locking changes from Wintertime to fall time; when the external forcing is extremely strong, the ＂frequency entrainment＂ of the MJO or monsoon and low frequency variability of ENSO leads to the decrease of the amplitude of the ENSO and the appearance of new oscillation with new periods.