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1.
在前文采用半地转近似和行波法来研究层结大气中的非线性波动的基础上,进一步探讨非线性方程及其级数近似方程的解的稳定性,波动解的存在条件和波动的一些特征。研究指出,在平衡点附近,将非线性方程用其级数近似方程代替是可行的、合理的。在初始拟能满足一定的条件下,椭圆余弦波和孤立波是存在的。文中还求得了椭圆余弦波解的周期、ｘ向波长和振幅以及孤立波的宽度和振幅。并指出,孤立波的宽度和振幅不但与波速有关,还与β因子和层结稳定度有关,而且在相同的某条件下,西行的混合Ｒｏｓｓｂｙ－重力孤立波比起东行的惯性重力孤立波来,宽度要小但振幅却大。 相似文献
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切变流中的CISK机制与惯性重力波 总被引：1，自引：0，他引：1
利用板对称，有切变的大气动力学方程组，由行波法导出非线性微分方程，通过非线性稳定性理论讨论方程的稳定性，求解了ＫＤＶ方程，并讨论了线性ＣＩＳＫ，非线性ＣＩＳＫ，惯性稳定度参数和大气风速垂切变对惯性重力孤波强度和宽度的影响，目的早通过了解影响惯性重力孤波发展的因子，更深入地理解低纬中尺度天气系统形成和发展的过程。 相似文献
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By using the symmetric equations of atmospheric dynamics in y-z plane with vertical and horizontal shear of wind, the nonlinear ordinary differential equation is derived with the method of travelling wave.Its stability is discussed by using the theory of nonlinear stability and the KDV equation is solved. The effects of linear CISK, nonlinear CISK, inertial stability and vertical shear of wind on the amplitude and the width of isolated inertial gravitational wave are discussed. In order to understand deeply the formation and development of meso-scale synoptic systems, such as the squall line, MCC, the cold surge of Asia high and typhoon, the factors of development of the isolated inertial gravity wave are analysed. 相似文献
4.
In this paper, the atmosphere is divided into two regions which are governed by different equations. Furthermore, multiple-scale
method is used to obtain the Benjamin-Ono equation satisfied by the nonlinear Rossby wave in weak shear zonal flow. The equation
has algebraic solitary wave solution, and the stationary streamfunction fields in-ithe atmosphere are calculated by using
numerical method, and the results demonstrate that the stationary solution is antisymmetric dipoles with the anticyclone north
of the cyclone, and the structure is similar to the equivalent modon obtained by Mcwilliams (1980). Because the modon obtained
here is an algebraic solitary wave, the modon may be called “algebraic modon”, and the stationary algebraic modon is consistent
with observations of blocking pattern in the atmosphere. 相似文献
5.
本文利用地转动量近似＾「１」并结合行波解的方法,研究了均匀基本气流中的层结大气非线性波动,首先由绝热无磨擦的闭合方程组导得关于垂直Ｐ速度的单一变量的非线性方程,然后讨论了非线性方程解的稳定性,并求得近似的非线性方程的椭圆余弦波和孤立波解及其存在条件。 相似文献
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Lu Weisong 《Acta Meteorologica Sinica》1989,3(1):90-97
Based on a non-frictional and non-divergent nonlinear barotropic vorticity equation and its solutions oftravelling waves,the criteria for linear and nonlinear barotropic instability are gained respectively at an equilibriumpoint of the equation on a phase plane.The linear and nonlinear analytical solutions to instability waves arealso found.The computational results show that if their amplitudes are equal at the initial time,the amplitudeincrements of nonlinear instable barotropic wave are always less than those of linear instable barotropic wave.The nonlinear effects can slow down the exponential growth of linear instability.The time needed for makingthe amplitude double that of initial time by instabilities,is about 6h for linear instability and about 18h fornonlinear instability,the latter is in agreement with the observations in the real atmosphere. 相似文献
8.
Some Possible Solutions of Nonlinear Internal Inertial Gravity Wave Equations in the Atmosphere 总被引：2，自引：0，他引：2
Ｓｏｍｅ Ｐｏｓｓｉｂｌｅ Ｓｏｌｕｔｉｏｎｓ ｏｆ Ｎｏｎｌｉｎｅａｒ Ｉｎｔｅｒｎａｌ Ｉｎｅｒｔｉａｌ Ｇｒａｖｉｔｙ Ｗａｖｅ Ｅｑｕａｔｉｏｎｓ ｉｎ ｔｈｅ ＡｔｍｏｓｐｈｅｒｅＬｉＧｕｏｐｉｎｇａｎｄＬｕＪｉｎｇｈｕａ（ＣｈｅｎｇｄｕＩ... 相似文献
9.
在自然闪电时,闪电通道中能量的瞬间释放造成闪电冲击波。本文计算了闪电冲击波的运动、冲击波内气象要素的分布以及闪电冲击波对云滴运动的影响,讨论了受闪电冲击波作用的云滴运动方程,对受冲击波作用的云滴运动作了个例计算。计算表明,闪电冲击波猛烈地“冲击”云滴,使它加速并在短暂的瞬间移动很长距离。体积不同的云滴获得不同的速度。讨论了闪电冲击波对云滴碰并增长的影响。 相似文献
10.
Summary Nonlinear waves in a stratified atmosphere with basic uniform flow are studied by adopting geostrophic momentum approximation
(cf. Hoskins, 1975) and the method of travelling wave solution. A nonlinear equation containing a unique variable of vertical
p velocity is derived from a complete system of equations considering frictionless and adiabatic fluid. The stability of the
solution for the nonlinear equation is discussed then. Furthermore, the approximate cnoidal wave solution, solitary wave solution
and their existence condition are obtained.
Received July 8, 1998 Revised December 1, 1998 相似文献
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In this paper,the effects of the large-scale mean sea temperature fields of the tropical ocean and the zonal current field (southern equatorial current) have been comprehensively entered in consideration on the basis of Chao and Ji (1985),and Ji and Chao (1986),the equatorial oceanic waves of the tropical ocean have been discussed by use of linearized primitive equations,then,the significant influence of the climatic background fields of the tropical ocean upon the oceanic waves of this region has been further testified.When very cold water appears in the tropical region,and the southern equatorial current is also relatively strong,the effect of the Rossby wave weakens,as a consequence,there are substitutive slow waves (i.e.thermal waves) which travel in opposite direction (eastward) to the Rossby wave.The characteristics of the slow wave are similar to those of Rossby waves,only the travelling direction is opposite.Under a certain environmental background field,the slow wave and the modified Rossby wave may be instable.With this conclusion,the mechanism of the occurrence,development and propagation of El Nino events has been studied.It is pointed out that the opposite travelling direction of the thermal wave and Rossby wave will bring repectively into action under different marine environmental background fields.The physical causes for that the abnormal warm water inclines to occur along the South American coast have also been explored in this paper. 相似文献
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纬向气流对地形Rossby波的影响 总被引：2，自引：0，他引：2
本文在半地转近似下,采用相平面方法讨论了纬向基本气流对线性和非线性地形Rossby波的稳定性及解的性质的影响。结果指出:线性和非线性稳定性判据形式一样,纬向气流及其切变对稳定性有明显影响;在非线性近似下,可形成孤立波槽和孤立波脊。 相似文献
15.
《Dynamics of Atmospheres and Oceans》1999,29(1):41-63
The influence of an accelerating shear flow on the propagation of an internal gravity wave in a continuously stratified fluid is studied by means of two-dimensional numerical simulations. These are motivated by earlier laboratory experiments [Thorpe, S.A. 1978b. On internal gravity waves in an accelerating shear flow, Vol. 88. J. Fluid Mech. pp. 623–639]. In these experiments the mean flow is an accelerated Couette flow and the mean density profile is linear. The laboratory experiments revealed the striking effect of the unsteady shear flow in the evolution of an internal gravity wave leading to the wave focusing in a region where the flow is extremum. This phenomenon is associated with the growth of small scale density fluctuations. As a result density overturns are sometimes observed. This behaviour is well reproduced by the numerical simulations. We provide insights on the flow dynamics in particular on the possible occurrence of wavebreaking. We show that the dynamics is characterized by two competitive mechanisms that is a damping of the wave and a local enhancement of its steepness leading sometimes to density overturns. The budget for the energy of the wave reveals that the initial damping of the wave results from wave-mean flow interactions. These interactions lead to the development of a fine scale vertical density structure which is associated with high vertical shear. We find that in some cases wavebreaking occurs as a result of shear instability. The value of the acceleration of the mean flow is very likely to influence the onset of the instability. The scaling laws of the wave evolution, in particular the rate of decrease of its energy, are determined. From these laws the lifetime of the wave is found as a function of the acceleration of the shear. It may be expected that, in the ocean, this development will result in the largest fluctuations derived from wave-flow interactions occurring where the mean flow in the wave direction is greatest. Waves travelling normal to a two-dimensional shear flow will be unchanged. Waves travelling parallel will be damped. This may have particular application at the continental shelf where flow, mainly parallel to the isobaths, will damp waves travelling along-slope, but allows waves travelling normal to the isobaths (e.g., directly across the shelf-break) to be transmitted without attenuation. Similar effects are expected for the evolution of a high frequency wave interacting with a lower frequency (e.g., near inertial) motion. 相似文献
16.
本文用参数化方法研究积云凝结加热对海陆风的作用。第一部分是线性理论,在静力稳定度参数和湍流扩散系数为常数时,加热使风场的结构发生很大的变化。积云加热还起到修正静力稳定度的作用。第二部分是数值模拟,加热作用的主要贡献是使垂直速度增大,若海陆风是暴雨的触发机制,则积云凝结加热使这一机制加强。比较两部分结果,它们之间有一定的差异,但在风场的变化与加热场分布的对应关系上,两者是一致的。 相似文献
17.
Lu Weisong 《Acta Meteorologica Sinica》1991,5(2):184-196
From a nonlinear quasi-geostrophic equation set containing dissipation and a nonlinear shallow waterwave equation set containing frictional dissipation and large topographic action,by using Serrin-Joseph's energymethod and based on the variation principle,criteria for nonlinear stability of basic shear flows in the abovetwo equation sets have been derived in terms of the total energy and total enstrophy respectively. 相似文献
18.
热力强迫的非线性奇异惯性重力内波与高原低涡的联系 总被引：4，自引：0，他引：4
利用相平面分析法,由非绝热大气运动方程组导出了与非线性惯性重力内波有关的KdV方程,然后用直接积分法得到两类有天气意义的孤立波解,重点分析了与青藏高原暖性低涡有联系的一类具有间断点的奇异孤立波解的特征,进而讨论了高原非绝热加热对高原低涡生成、移动及高原低涡暖心结构的作用。 相似文献
19.
Based on the conservation of entropy and potential vorticity in adiabatic atmospheric motion without theconsideration of friction,calculation is made of the trajectory of a particle on an isentropic surface by use ofthe data of FGGE III-b.Results of several calculation schemes of the trajectory discussed show that thelocal data interpolation and Runge-Kutta time-integral scheme is the best.The calculated trajectory reflectsthe large-scale atmospheric motion only and the small-scale motion emerges as a deviation term of thecalculated trajectory.And then the outbreak and propagation of planetary wave are studied by means ofthe deformation of a material line,with the result showing that the material line can be tracked in the trop-osphere only in a few days,beyond which the interaction between the small-scale waves and large-scale motionleads to its dramatical twisting and deformation.Therefore,the Lagrangian method is assumed to be an effectivemeans of diagnostic research in the nonlinear interaction in atmospheric circulation,in addition to the generalstudy of the atmospheric circulation. 相似文献
20.
热带大气和海洋的半地转适应和发展运动 总被引：5，自引：2，他引：3
半地转适应和半地转发展是热带大气和海洋运动的两种基本形态,它们在时间上是可分的,反映了不同的物理过程。当初始扰动作用于大气或海洋时,首先将激发出重力惯性波,当重力惯性波频散后,建立起半地转的平衡状态,此后运动进入到以Rossby波（长波或短波）、Kelvin波和混合波中的Rossby短波为主导的发展状态。文中研究的纬圈半地转适应和发展运动,是Gill长波近似模式的理论基础。同时研究了经圈半地转适应和发展运动,实际上这相当于短波近似模式,它可以应用到研究海洋经圈边界附近的一类问题。 相似文献