线性和非线性横波型不稳定的数值研究

本文应用一个准二维的非线性非静力数值模式研究了线性和非线性横波型不稳定的中尺度模态的发展、演变和结构特征。结果表明：Ｒｉｃｈａｒｄｓｏｎ数对横波型不稳定的发展和演变有影响。Ｒｉ数越小，不稳定增长越快，且增长率最大的波的波长就越短。非线性横波型不稳定在其发展初期，可以用线性理论作很好的近似；随着不稳定的进一步发展，扰动增强，非线性作用增强，其扰动结构与线性情况相比发生了很大变化，扰动结构最后演变成以顺时针环流为主的结构。

THE NUMERICAL STUDY OF LINEAR AND NON-LINEAR TRANSVERSE INSTABILITY

A non-linear and non-hydrostatic two-dimensional numerical model is used to study the development,evolution and structure of meso-mode transversal instability.The numerical test states that development and evolution of transverse instability are affected by Ri number.The smaller Ri is,the larger it s incresing rate and the shorter its wave length with the largest incresing rate is.The initial growing of the transverse instability perturbations canbe fairly well approximated by lineartheory.With increase of the perturbations,non-linear interaction of advection termenhances,and its sturctrues has great change,at last clock-wise circulations dominate in the disturbance structures.