A323 非軸対称な2重眼構造の形成と蛇行運動との関係について(A-32 大気の流れ(2),一般講演)

概要

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A periodic oscillation of the track of the eye fixed by radar is ocassionally observed in tropical cyclones. In the occurrence of this phenomenon, an asymmetric double eyewall structure, which the center of the tropical cyclone did not agree with the geometric center of the whole tropical cyclone, was observed in some tropical cyclones. We considered that some periodic ocsillations of tropical cyclone track could be caused by a interaction of asymmetric double same-sign vortices. To examine this possibility, the numerical experiment about the interaction with the inner vortex and the outer ring-shape vortex was performed as an idealized model of asymmetric double eyewall structure using the contour dynamics model. As a result, the behavior that the inner vortex rotated cyclonically inside of the outer ring-shape vortex was seen. Furthermore, we found that the rotation period of the inner vortex depends on the strength of the outer ring-shape vortex, and the amplitude depends on the asymmetric structure of two vortices. The rotation period and the amplitude of the inner vortex are in good agreements with observations. Therefore, an asymmetric double eyewall structure is considered as a new mechanism which causes a small-scale looping motion.
日本流体力学会の論文
2004-08-09