大尺度流型年际变化可能机制的研究

A STUDY ON PHYSICAL MECHANISM OF INTERANNUAL VARIATIONS OF LARGE-SCALE FLOW PATTERNS

本文将年变周期和非年变周期热力强迫项引进正压涡度方程,用方程的截谱形式实施了几十组时间长度为100年的数值积分,研究了非年变周期热力强迫和大气内部动力过程共同激发的大尺度流型的年际变化问题。在一定的参数集合,当非年变外源强迫的振荡周期与大气内部动力过程单独激发出来的振荡的周期相同时,流型年际振动的振幅明显加大,振动的周期则为倍化。在另外的参数集合,随着非年变强迫参数的渐变,流型年际变化的幅度显示出清楚的突变以及其它富有非线性特色的行为。

The thermal forcings of annual and interannual periodic variations are introduced into the barotropic vorticity equation, by using low order spectral model of the equation, more than 40 numerical experiments whose integration time is larger than 100 model years are performed in order to investigate variations of large-scale flow patterns arised from both external interannual thermal forcing and internal dynamical processes. In certain parametric region, when the frequency of the forcing term with interannual period equals to the frequency which is created by the internal dynamical processes alone, the amplitude of interannual variations of flow patterns increases obviously, and the period becomes double. In other parametric region, amplitude jump of interannual variations of flow patterns and other nonlinear behavious can exhibit, along with gradual changes of interannual forcing parameters.