STUDY ON DYNAMICS OF TROPICAL CISK-ROSSBY WAVES AND MECHANISM OF 30-50 DAY OSCILLATIONS

To add to the growing mature research on the tropical 30-50 day oscillations from a new prospective, the current work bases on dynamic analysis of baroclinic quasi-geostrophic models to discuss dynamic mechanisms for the generation and propagation of CISK-Rossby waves, and to understand restraints and effects of different wave structures and thermodynamic forcing on the 30-50 day oscillations in the tropical atmosphere. Some important properties of the oscillation propagation have been explained and, in detail, with respect to its meridional propagation and vertical “baroclinic” structure. The work has come up with some new opinions and viewpoints. New opinions about the propagation and energy dispersion are to be proved by more observations and study.     

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。     

CISK-related Rossby Waves in the Tropical Atmosphere

In terms of a baroclinic quasi-geostrophic wave-filtering technique in connection with a dimensionless paramet-er, η(z), of condensation-released latent heat that indicates the CISK mechanism, a model is established for des-cribing tropical atmosphere CISK-Rossby waves alongside its analytical solution. Theoretical study shows that there exists pronounced difference between Rossby waves, CISK-involving and classic, and the former can be used to in-terpret some aspects of the low-frequency oscillation in the tropical atmosphere     

热带大气的CISK-Rossby波和30-50天振荡

利用斜压准地转滤波方法，通过引入一个反映ＣＩＳＫ机制的无量纲凝结潜热参数η（Ｚ），建立了描述热带大气的ＣＩＳＫ－Ｒｏｓｓｂｙ波模式，并求得了该模式的解析解。理论研究表明，考虑ＣＩＳＫ机制的ＣＩＳＫ－Ｒｏｓｓｂｙ波与经典的Ｒｏｓｓｂｙ波有明显差别，它可较好地解释热带大气３０—５０ｄ振荡现象。     

CISK-rossby wave and the 30-60 Day Oscillation in the Tropics

The 30-60 day oscillation is an important aspect of the atmospheric variance in the tropical area. A number of works have been done on this phenomenon, this article is a further one. A quasi-geostrophic linear model that consists of a two-layer free atmosphere and a well-mixed boundary layer is used to investigate the instability of intraseasonal oscillation, its propagation and vertical structures. Results show that the dynamical coupling and interaction between the barotropic and baroclinic components via boundary layer convergence / divergence are responsible for the appearance of a new kind of low-frequency wave. Such wave is very different from the traditional tropical Rossby wave. It can propagate westward and eastward. Some behaviours of it appear to resemble the observed 30-60 day oscillation mode in many aspects, such,as vertical structures, zonal and meridional propagations. Now many researchers emphasize the direct relationship between CISK-Kelvin mode and the tropical atmospheric 30-60 oscil     

Wave-CISK和低纬大气低频振荡

本文运用一个包含Wave-CISK机制的斜压半地转模式来讨论低纬大气中的低频振荡。在我们以前研究工作的基础上，不仅考虑了CISK机制的作用，而且考虑了CISK机制垂直速度w[B]随纬度的变化。这样，建立的半地转模式和相应的解析解更能反映CISK机制对低纬低频振荡的作用。在求解中，我们运用了本征函数S[-3/2][m]（Sonine多项式）展开的方法，结果不仅得到了模式中所含的CISK-Kelvin波和CISK-Rossby波波速与对流凝结潜热参数η的关系，而且显示了低纬高、低层大气间的相互耦合作用。在这样     

Low-Frequency CISK-Rossby Wave and Stratospheric QBO in the Tropical Atmosphere

1.IntroductionThelow~frequencyoscillation(LFO)isaveryimPOrtantweatherphenomenonintheatmosphere.The30--50--dayandquasichiweeklyoscillationsinthetropicalatmospherearemostintensivelystudied,andcomParativelyspeaking,anotherkindofLFOconcernillgtheQBOofthestratosphericzonalwindsismuchlessstudied,which,althoughoccurringinthestratosphere,bearsacloserelationtothetroposphericactivitiesandtheevolutionoflow--latitudecirculationssothatitisworthwhiletoexploreindepththephysicalmechanismfortheQBOoccurre…