A322 台風Herbにみられた楕円形眼の形成過程(A-32 大気の流れ(2),一般講演)

概要

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An elliptical eye was observed in Typhoon Herb during its passage around the Sakishima Islands on 30-31 July 1996. We considered that this elliptical eye could be caused by a dynamic instability due to the radial shear of tangential flow. To examine this possibility, the linear stability analysis for three-dimensional perturbations was performed using the asymmetric balance model in which the basic flow was based on the observed surface wind. Results show that the unstable mode appears with wavenumber two perturbation, which is valid for the asymmetric balance model. Especially, the largest growth rate of the perturbation with wavenumber two is seen for the perturbation with three-dimensional structure, which is very close to two-dimensional structure. The eigenmode structure of streamfunction, vertical velocity and the rotation period of wavenumber two perturbation are in good agreement with the observations.
日本流体力学会の論文
2004-08-09