球面定常行星波射线的变化与波列的分支

为了解释大气低频波列的结构特征,本文把慢变介质中波传播的理论应用于行星波。采用射线追踪方法,借助于几何直观,在波射线与纬线平行的纬度附近,讨论了波数k_s的分布对波射线变化与波列分支的作用。并讨论了沿波射线路径波幅的变化。提出,在波数k_s为极值的纬度附近,定常行星波列存在着明显的分支现象。在传播期间,波幅在分支纬度附近为极大值。这些结论与双测和模拟的结果是相当一致的。此外,本文还讨论了“大圆路径理论”的局限性。

THE VARIATIONS OF THE STEADY PLA-NETERY WAVE RAYS AND THE BIFUR-CATIONS OF THE WAVETRAINS

In order to explain the structures of low-frequency atmospheric wavetrains the theory for propagating in a slowly varying medium is applied to the planetary waves. Using the ray tracing techniques, this paper discusses the effect of the variations of the warenumber Ks on the variations of ray and the bifurcations of wavetrains nearby latitudes where the ray parallels to the latitude circle. The amplitude variations along the ray path are also discussed. It is pointed out that the phenomena of the wavetrain bifurcations obviously exist nearby the latitudes where Ks has the extremism, and wave amplitude is the maxima near the latitude during propagating. They agree with observational and numerical model results. The limitation of the great circle theory is also discussed.