南海地区中层气旋生成的斜压不稳定与CISK机制

本文所用的动力学模型是在给定切变基本流情况下,加进积云加热效应。结果表明斜压不稳定扰动的临界波长,因积云加热作用而明显变短,当积云加热达每天3.5度时,扰动发展的尺度和中层气旋的尺度是吻合的。在本文的后一部份,考察了积云对流的摩擦作用,结果也得出扰动的不稳定性,但一般而言,积云摩擦对扰动是起阻尼作用的,当摩擦造成的次级环流产生不稳定的加热效应时,摩擦可促进不稳定发展。

THE BAROCLINIC-CISK INSTABILITY OF THE MID-TROPOSPHERIC CYCLONE FORMATION OVER THE SOUTH CHINA SEA

In this paper, the dynamic model incloudes the effect of cumulus heating in the condition of given shear basic flow The result shows that the critical wave-length of baroclinic unstable disturbance shortens apparently When the cumulus heating amounts to 3.5°C/day, the scale of the developed disturbance coinsides with that of the mid-tropospheric cyclone. In the latter part of this paper, the frictional effect of cumulus convection is studied, and the results show the instability of disturbance too.But the cumulus convection, generally speaking, has damping effect on disturbance.