負渦度領域を持つ軸対称渦の安定性

Abstract

According to the recent analytical studies of mesometeorology, it becomes obvious that thenearly axisymmetric vortices such as the tornadoes and the severe convective meso cyclones aresometimes superposed by non-axisymmetric disturbances. This phenomenon has been also simulat-ed in the laboratory experiments and is called 'multiple vortex phenomenon'. The similar non-axisymmetric disturbance has been found in the Typhoon vortex.Several attempts have been made to explain this phenomenon theoretically. However, theinstalibity of the disturbance of azimuthal wavenumber two has been rather uncertain. In thepresent study. The stability of the axisymmetric vortex is examined. The basic vortex is postulatedto have a negative vorticity region just outside the radius of maximum tangential wind velocity.Using this model, it is verified that the disturbance of wavenumber two could be destablized. Andthis result is compared with the elliptical eye wall of the Second Miyakojima Typhoon.