热带东、西风界面附近的扰动流场

在正压无辐散的条件下,讨论了东、西风不连续面上的正压不稳定性,得出:在这种情形下,东、西风界面上的扰动总是不稳定的。文中用小参数的方法,对界面附近扰动发展的非线性问题进行了计算,算到二级近似。结果表明,非线性过程引进短波长的谐波。界面的变形和扰动随时间增长较快,经过0.5天,界面有很小的变形,附近只有很弱的闭合环流;到1.5天,界面变形显著,环流范围增长达300公里,而且短波占主要部分,界面北侧东风气流中的气旋式环流进一步发展,风速也显著增强。

THE DISTURBED FLOW FIELD IN THE NEIGHBOURHOOD OF THE COMMON SURFACE BETWEEN THE EASTERLY AND THE WESTERLY CURRENT IN THE TROPICS

Under the barotropic and non-divergent conditions, the barotropic instability at the discontinuous surface between the easterly and the westerly current in the tropical latitude is investigated. Conclusively, under these conditions, the perturbation at the interface is always unstable. By the method of small parameter expansion, the non-linear problem of the development of the disturbance around the interface is calculated to the second order approximation and the result shows that non-linear process induces harmonic waves of shorter wave length. The deformation and the growth of the disturbance around the common surface both proceed fast along with time. At the end of half a day, there is some slight deformation of the common surface, and in the neighbourhood of it only very weak closed circulation develops. But, at the end of one and half days, the interface deforms remarkably, the domain of the circulation expands to anextent of 300 kms, and the shorter wave dominates. At the same time, the cyclonic circulation in the easterly current on the north side of the common surface achieves sufficient development, and the wind velocity also intensifies notably.