The Solitary Waves of the Barotropic Quasi-Geostrophic Model with the Large-scale Orography

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半地转近似下的非线性波

本文应用半地转的概念分析和求解了正压和斜压的大气运动。指出:(1)在水平无辐散或准地转条件下求单波解无法表现非线性作用的困难,可以应用半地转的假定来解决。为了避开上述困难,不得已仅保留部分非线性项,但为了准确表征大尺度运动,最好应用半地转假定,保留全部非线性项。(2)准地转的假定可以滤去快速波动,半地转的假定同样也可以滤去快速波动,而且半地转条件下的Rossby波具有充分的非线性特征。所以,它为讨论非线性问题提供了一个途径。     

NONLINEAR WAVES IN BAROTROPIC MODEL

In this paper, from the system of equation describing a barotropic atmosphere using the method of Taylor expansion for the nonlinear terms, the periodic solutions of the nonlinear inertio-surface gravity waves and Rossby waves have been obtained.The finite-amplitude nonlinear inertio-surface gravity waves and Rossby waves with horizontal divergence satisfy all the KdV equation. The solutions are all the cnoidal function, i, e., the cnoidal waves which include the linear waves and form the solitary waves under certain conditions. For the finite-amplitude Rossby waves with horizontal divergence, we find the new dispersive relation including both the wave number and the amplitude parameter. In case of small amplitude it is reduced to the Yeh formula. It is shown that the larger the amplitude and width, the faster the finite-amplitude inertio-surface gravity waves and the slower the finite-amplitude Rossby waves with horizontal divergence propagate. The blocking or cut-off system in which the amplitude and width are large may be considered as Rossby solitary waves.     

关于热带气旋尺度变化机制的初步分析

应用小参数方法和缓变波包理论分析了热带气旋尺度变化的主要原因。分析指出：热带气旋尺度变化主要决定于其内部要 通常的热带气旋内惯性性重力波由中心外传播的情况下，当层结稳定度和惯性稳定度参数随着离中心的距离增加而增加时，热带气旋尺度增加，它可以称为热带气旋“膨胀”；而当层结稳定度和惯性稳定度参数随着离中心的距离增加而减小时，热带气旋尺度减小，它可以称为热带气旋“收缩”。     

A Simple Quasi-Geostrophic Coupled Ocean-Atmosphere Model

The quasi-geostrophic atmospheric and oceanic equations of momentum and thermodynamics with dissipation factors are used to create a simple coupled ocean-atmosphere model describing the large-scale shallow-water motion. We discuss the ocean-atmosphere coupling effect in mid-high and low latitudes separately and analyze characteristics of which the oscillatory periods of coupled low-frequency modes (ocean mode) vary with the coupling frequency and latitudinal number. This can interpret the correlation between low-frequency oscillation and ocean-atmosphere interaction. Then from the dispersion curves of atmosphere and ocean, we reveal effect of the coupling strength on the propagation of Rossby waves. The convection mechanism between the two modes is also discussed in view of the slowly varying wave train.The results show that Newtonian cooling and Rayleigh friction play a stable rule in oceanic Rossby waves, the period of coupled low-frequency mode grows with the increment of the coupling frequency. The     

Effects of Turbulent Dispersion of Atmospheric Balance Motions of Planetary Boundary Layer

New Reynolds' mean momentum equations including both turbulent viscosity and dispersion are used to analyze atmospheric balance motions of the planetary boundary layer. It is pointed out that turbulent dispersion with r 0 will increase depth of Ekman layer, reduce wind velocity in Ekman layer and produce a more satisfactory Ekman spiral lines fit the observed wind hodograph. The wind profile in the surface layer including tur-bulent dispersion is still logarithmic but the von Karman constant k is replaced by k1 = 1 -2/k, the wind increasesa little more rapidly with height.     

台风移动的一个简单模型

本文分析了在江河中摆渡船的运行，并将台风比拟为摆渡船，给出了台风移动的一个简单模型。研究指出：若船速为Ｖ１→，流速为Ｖ２→，船驶向对岩的目标为Ｆ，则当│Ｖ１→│〈〈│Ｖ２→│时，船的运行轨迹为一直线；而当│Ｖ１→│≈│Ｖ２→│时，船的运行轨迹为以Ｆ为焦点的抛物线，将上述分析应用于台风，则台风速度相当于Ｖ１→，台风环境空气的速度相当于Ｖ２→，因台风主要是切向运动，可利用角动量守恒原理计算它在台风范围     

Wave-CISK的一个斜压半地转模式和低频振荡

本文建立了一个描写低纬大气运动的斜压半地转的wave-CISK模式,其中引入了一个反映CISK机制的无量纲的凝结潜热参数η(z),并求得了η=0和η≠0条件下wave-CISK模式的解析解,理论研究进一步说明wave-CISK机制对于大气低频振荡起重要的作用。     

RADIATIVE COOLING AND BROADBAND PHENOMENON IN LOW-FREQUENCY WAVES

In this paper, we analyze the effects of radiative cooling on the pure baroclinic low-frequency waves under the approximation of equatorial β-plane and semi-geostrophic condition. The results show that radiative cooling does not, exclusively, provide the damping effects on the development of low-frequency waves.Under the delicate radiative-convective equilibrium, radiative effects will alter the phase speed and wave period,and bring about the broadband of phase velocity and wave period by adjusting the vertical profiles of diabaticheating. When the intensity of diabatic heating is moderate and appropriate, it is conductive to the development and sustaining of the low-frequency waves and their broadband phenomena, not the larger, the better. The radiative cooling cannot be neglected in order to reach the moderate and appropriate intensity of diabatic heating.     

热带大气半地转适应理论的尺度分析和物理机制

对热带大气行星尺度运动所做的尺度分析和物理分析表明:热带大气 的行星尺度运动在y方向容易实现气压梯度力与Coriolis力的平衡，它称为纬圈的 半地转运动。半地转平衡的建立过程，也就是半地转适应过程相对是很短暂的，它不需 要考虑f=β0y随y的变化，因而主要依靠惯性重力波为频散；而半地转平 衡建立后的演变过程相对是很缓慢的，它主要受Kelvin波和Rossby波控制。