Dynamic Instability of the Stratospheric Polar Vortex

[摘要] Stability properties of the stratospheric polar vortex deformed under the influence of external forces are examined by use of the barotropic vorticity equation and energy equation.Time integration of perturbation equation as an initial value problem shows that a barotropic instability corresponding to deformed vortex exists and this instability increases when the vortex is more deformed.Comparison of stability properties between the northern and southern hemispheric polar vortex is shown by numerical model, and the results of computations show that the northern hemispheric type polar vortex with wave number 2 is more unstable than the southern hemispheric type vortex with wave number 1, and the breakdown is shown for the former case.Some theoretical considerations are also given concerning the kinetic energy equations for our model. It is found that total kinetic energy much increases when the phase of perturbations is L/4 (L: wave length) different from that of the basic flow.

[学科分类] 大气科学