能量方程与对称不稳定判据

从对称型扰动能量方程出发，应用广义的ｎｏｒｍａｌｍｏｄｅ方法，导出了不仅适用于常参数而且适用于变参数的对称不稳定判据。在热成风平衡或准热成风平衡的条件下，这个判据和Ｅｍａｎｕｅｌ用气块法得到的判据及Ｈｏｓｋｉｎｓ使用ｎｏｒｍａｌｍｏｄｅ方法得到的判据是完全一致的。还指出，在扰动的初生阶段，扰动的对称不稳定发展是和基本场能量向扰动场能量转换联系在一起的。

ENERGY EQUATION AND SYMMETRIC INSTABILITY CRITERION

In this paper, by using generalized normal mode method the symmetric instability criterion which can be used not only in theeccnstant parameters but also in the variable parameters are derived from the energy eequation on thehsymmmetriccdistdrbance. If the thermal wind is balance or quasi-balance,nthe criteriritwas consiteent with the criterion which is obtained by Emanuel with parcel method and Hoskins with normal mode method. It is showed in here that in the generating stage of disturbance, the symmetric instabilitic development of disturbance is connected with that the energy of the basic field is transfered into the energy of the disturbance field.