对流凝结加热的垂直分布与低纬大气的30～60天低频振荡

运用一个包含Wave-CISK机制的斜压半地转8层模式和本征函数展开方法，研究了三种不同的对流凝结加热廓线对低纬大气的30—60天低频振荡的影响。研究表明，不同的加热廓线分布时30～60天低频振荡具有不同的相速和周期，并且低频振荡特征相速的量级都是o(10m／s)，由Wave-CISK机制激发的低频CISK—Kelvin波和CISK—Rossby波都是稳定的。同时，还进一步揭示了不同加热廓线对低纬大气30～60天低频振荡垂直结构的影响。     

Bifurcation of nonlinear Kelvin wave-CISK with conditional heating in a truncated spectral model: A possible mechanism of 30–60-day oscillation at the equator

In this paper, the nonlinear Kelvin wave equations with “positive-only” nonlinear (conditional) heating at the equator are reduced to a sixth-order nonlinear ordinary differential equation by using the Galerkin spectral truncated method. The stability analysis indicates that when the heating parameter increases, the supercritical pitchfork and Hopf bifurcations can occur for the prescribed three heating profiles. Numerical calculations are made with the help of the fourth-order Rung-Kutta method. It is found that the convec-tion heating-related Hopf bifurcation can lead to limit cycle and chaotic solutions. In a wide range of heat-ing parameter, the solutions possess 30-60-day periods, and are dominated by wavenumbers one and two, especially by wavenurnber-one. In addition, the zonal winds of the low-frequency solutions have a phase reversal between the upper and lower tropospheres. Thus, it appears that the convection heating-related Hopf bifurcation might be a possible mechanism of 30-60-day oscillation in the tropical atmosphere.     

Bifurcation of Nonlinear Kelvin Wave-CISK with Conditional Heating in a Truncated Spectral Model:A Possible Mechanism of 30-60-Day Oscillation at the Equator

1.IntroductionSincethe40--50--dayoscillationinthetropicalPacificwasfirstfoundbyMaddenandJulian(1971,1972),ithaslongbeenanimportantresearchtopic.Inobservationalstudies,LauandChan(1985,1986),GhilandMo(1991)showedthattheintraseasonaloscillationsinthetro...     

Wave-CISK、蒸发-风反馈和低频振荡

本文利用一个包含有Wave-CISK和蒸发-风反馈机制的斜压半地转模式来讨论低纬大气运动,其中引入了反映CISK机制的无量纲对流凝结加热参数η和反映蒸发-风反馈机制的无量纲参数α_0,求得了η=0情况下的解析解及η≠0情况下的一级近似解,对η≠0情况下向东传播的类似于低频振荡的波动进行了讨论,从理论上指出了蒸发及非均匀加热对低频振荡的维持所起的重要作用.