圆形涡旋中的惯性重力内波不稳定和对称不稳定

Instability of Inertia-Internal Gravity waves and Symmetric Instability in Circular Vortexes

用Ｂｏｕｓｓｉｎｅｓｑ近似下的轴对称径向二维柱坐标系中的线性扰动方程组，讨论了圆形大气涡旋系统中扰动的惯性重力不稳定和对称不稳定。在环境为正压情形时，惯性重力内波不稳定的条件为（μｊ／Ｒ０）２Ｎ２＋ｎ２Ｆ２＜０；当环境为斜压时，具有平行型扰动特征的惯性重力波发展的条件为Ｒｉ＜１－［（３／２）＋ｍ］－２，此时表现为对称不稳定。可见，惯性重力内波不稳定和对称不稳定都可作为台风、气旋一类圆形涡旋中扰动形成和发展的机制。

Inertia-gravitational instability and symmetric instability of the disturbance in circular atmospheric vortex systems are discussed by using linear perturbation equations in a two-dimensional axisymmetric cylindrical coordinate under Boussinesq approximation.When the environment is barotropic,the condition of instability of inertia-internal gravity waves is(μj/R0)2 N2+n2 F2<0.When the environment is baroclinic,the condition for development of inertia-gravity waves with parallel perturbation is Ri *<1-[(3/2)+m]-2 which shows a symmetric instability.Instability of inertia-internal gravity waves and symmetric instability are the mechanisms for formation and development of the perturbation in circular vortexes such as typhoons and cyclones.