First a diagnostic analysis is carried out to research the frequency modulation effect that the el - nino and la - nina events has on atmospheric low - frequency oscillation ( lfo ) in the mid - high latitudes 首先用诊断的方法,研究了el - nino和la - nina事件对中高纬大气低频振荡的调频作用。
The power spectral analysis is performed for daily 500hpa height field data in the mid - high latitudes of the northern hemisphere from 1950 to 1996 . the results show that : ( 1 ) intensity of low - frequency oscillation in winter is stronger than that in summer 应用1950 - 1996年北半球中高纬逐日500hpa高度场资料进行功率谱分析,得出: ( 1 )夏季低频振荡较弱,冬季低频振荡较强。
( 6 ) the results of the stream function field of quasi - resonance three waves transforming with time evolving make sure further that the low - frequency oscillation exists in extratropical latitude , which has greater corresponding relationship with the wave oscillation obtained from the combination of the basic flow , the number of three waves and amplitude ( 6 )在准共振三波流函数场随时间变化的试验结果中,进一步证实了中高纬大气存在较好的低频振荡,且与相应的基流、三波波数和振幅组合所得的波动振荡有较好的对应关系。
Simulation of computer and dynamic experiments show : the sofpss has such characteristics as small overshoot , fast response speed , avoidable micro - amplitude oscillation and is not sensitive to changes of operating modes and external disturbances . the sofpss can effectively damp low - frequency oscillation in a large range and takes on strong adaptability 计算机仿真和动模实验结果表明: sofpss超调小、响应速度快,且避免了微幅振荡;对运行状态的变化以及外界干扰不敏感,能够在较大的运行范围内有效地抑制振荡,适应能力较强。