利用自然振子方程研究赤道东太平洋海温演化的准非线性特征

USING NATUER-OSCILLATOR EQUATION TO STUDY THE QUASI-NONLINEAR EVOLUTION FEATURES OF THE SEA TEMPERATURE OF THE EASTERN EQUATIONAL PACIFIC

在前人利用时滞自然振子方程研究赤道东太平洋海温演变特征的基础上，根据实际观测资料，反演获得了描述赤道东太平洋海温演变的时滞自然振子方程，并根据反演获得的非线性时滞自然振子方程、摄动理论和微分方程稳定性理论研究了赤道东太平洋海温演变的准非线性特征，获得一些有意义的结论：①计算所得时滞τ＝１４，与理论分析所得的在研究区域中激发产生向西传播的Ｒｏｓｓｂｙ波到达太平洋西海岸后反射出向东传Ｋｅｌｖｉｎ波，此波到达研究区域约滞后几个月至２年的结论一致：②在零级近似并考虑时滞作用条件下，赤道东太平洋海温在其演变过程中存在稳定的 Ｅ１Ｎｉｎｏ位相和稳定的ＬａＮｉｎａ位相；③在一级近似条件下，当赤道东太平洋前期海温值处于远离平均值的条件下，赤道东太平洋海温系统为一稳定的动力系统，随着时间ｔ的增长，赤道东太平洋海温的演化将趋于平均值；而一旦赤道东太平洋海温的演化趋于平均值时，赤道东太平洋海温系统将有可能转变为一不稳定动力系统，随着时间ｔ的增长，赤道东太平洋海温的演化将远离平均值。由此构成了赤道东太平洋海温在Ｅ１Ｎｉｎｏ位相和ＬａＮｉｎａ位相间来回振荡，循环往复的基本演变图象。④根据τ＝１４月。

On the basis of that use researches of using time-lag nature-oscillator equation to study the nonlinear evolution features of the sea temperature of the eastern equatorial pacific, and according observational data, the time-lag nature-oscillator equation for description of the evolution of the sea temperature was retrieved. According to the equation, the perturb theory and the stable theory of differential equation, some significant results about the eastern equation pacific sea temperature were obtained as follows. ①The calculated time-lag that is τ=14 month agrees with the period that is from several months to 2 years when the stimulated western Rossby wave arrived at the Pacific west coast and then was reflected to the researched region as Kelvin wave. ②Under the condition of the zero order approximation and the effects of the time-lag, the sea temperature evolution of the eastern equatorial Pacific has the stable El Nino phase and the stable La Nina phase. ③ Under the condition of the first order approximation, when the earlier stage sea temperature of the eastern equatorial Pacific is far away from its average value, the sea temperature system is a stable dynamic system, that is with the increasing of time t, the temperature tends to be near the average. Once the sea temperature has tended to be around its average, the sea temperature system of the eastern equatorial Pacific probably becomes an unstable dynamic system, that is the sea temperature of the eastern equatorial Pacific is far away from its average with the increasing of the t. So the principal evolution picture that the sea temperature of the eastern equatorial pacific oscillates from El Nino phase to La Nina phase, and vice versa, are obtained. ④According to τ=14 month, the result was also obtained that the sea temperature of the eastern equatorial Pacific has quasi-triennial oscillation periods, whether or not the sea temperature system of the eastern equatorial Pacific is stable.