赤道高频纬向风强迫对ENSO事件强度的影响

ENSO强度的影响因子是一个具有争议性的问题.作者探讨了一种理想的赤道高频纬向风强迫对ENSO强度的影响.将该问题转化为一类关于模式参数扰动的非线性最优化问题;基于所用的理论ENSO模式,研究了赤道高频纬向风强迫在调制ENSO强度中的角色.结果表明,对于E1 Ni(n)o和La Ni(n)a事件,存在两类外强迫,一类促进E1 Ni(n)o事件的发展却抑制La Ni(n)a事件的发展,另一类则抑制E1 Ni(n)o而促进La Ni(n)a事件的发展.这两类外强迫的主要区别在于初始相位的不同.相位决定了外强迫对ENSO事件是促进的还是抑制的,而外强迫的振幅和周期则决定了外强迫影响ENSO强度的大小.这些外强迫主要是通过海洋波动对斜温层深度的调节来影响ENSO事件的强度的.

The Effect of Equatorial High-Frequency Zonal Wind Forcing on ENSO Amplitude

What controls ENSO amplitude remains controversial. The authors explore the effect of a kind of ideal-ized equatorial high-frequency zonal wind forcing on ENSO amplitude.This problem is first transformed into a non-linear optimization problem related to model parameters.Based on a theoretical ENSO model,the role of high-fre-quency zoml wind forcing in modulating ENSO amplitude is explored.The results shoW that there are two kinds of high-frequency zonal wind forcings for ENSO events,where the differences lie in the amplitude of the forcing,the period,and the phase.These differences make one kind of forcing enhance the E1(n)o event,but suppress the La Ni(n)a event,while the other kind suppresses the E1 Ni(n)o event and enhances the La Ni(n)a event.The further analysis shows that the phase of the high-frequency zonal wind forcing determines the forcing whether enhances ENSO events or suppresses them,while the amplitude and period of the forcing control the degree of its effect on ENSO intensity.Both of these two types of forcings affect ENSO amplitude mainly by the adjustment of oceanic wave on the thermo-eline.