台风Rammasun(2014)与飓风Wilma(2005)快速增强过程的内核结构变化比较

COMPARISON OF INNER-CORE STRUCTURE CHANGES DURING RAPID INTENSIFICATION BETWEEN TYPHOON RAMMASUN (2014) ANDHURRICANE WILMA (2005)

关键词:  热带气旋  快速增强  内核结构  垂直倾斜  对称和非对称  高分辨率数值模拟

Key words:  tropical cyclone  rapid intensification  inner-core structure  vertical tilt  symmetry and asymmetry  high resolution numerical simulation

摘要:

热带气旋的快速增强机制目前仍然不太清楚，不少研究开始关注快速增强过程中热带气旋内核结构的变化。通过比较模拟的西北太平洋超强台风Rammasun (2014)和大西洋5级飓风Wilma (2005)快速增强过程中内核结构的变化特点，理解内核结构在快速增强过程中的变化特点。飓风Wilma是一个典型的快速增强热带气旋，快速增强期间具有弱的环境垂直切变、对称的眼墙、较小的中心倾斜以及比较直立的眼墙。但是，台风Rammasun快速增强发生在较强切变(超过10 m/s)环境下，眼墙对流呈高度不对称，强对流基本固定在台风中心的南侧。整个快速增强期间，Rammasun在垂直方向上维持较大的中心倾斜以及较大的眼墙倾斜。结果表明，快速增强也可能在不完全对称的内核结构和倾斜垂直结构的情况下发生。

Abstract:

The rapid intensification mechanism of tropical cyclones is still unclear. More recent studies of rapid intensification begin to focus on the processes in the inner-core structure of tropical cyclones. In this study, by comparing the changes of the inner-core structure of the simulated super typhoon Rammasun (2014) in the Pacific Northwest and the Atlantic Category 5 hurricane Wilma (2005), we try to understand the role of the inner-core structure changes in the rapid intensification processes. Wilma is a typical tropical cyclone of rapid intensification with a weak ambient vertical wind shear, a symmetrical eyewall, a small vortex tilt, and a relatively upright eyewall during the rapid intensification process. However, the rapid intensification of super typhoon Rammasun (2014) occurs in an environment with strong vertical wind shear (>10 m/s). Besides, the convections are highly asymmetric with deep convections fixed on the south side of the typhoon center. During rapid intensification period, Rammasun maintains a large vortex tilt and eyewall tilt in the vertical direction. Results show that the rapid intensification of tropical cyclones may also occur when there is an incomplete symmetric inner-core structure and inclined vertical structure.