A study of numerical modeling of tropical cyclones and formation

本文基于两种模型，即能够解析积云尺度运动的非流体静力轴对称模型和具有积云尺度参数化的三维流体静力模型。为了了解热带气旋的形成机制和中尺度结构，进行了大量的数值试验。关于模型改进。为了更好地模拟热带气旋的中尺度结构，对静水模式中参数化对流释放热量的垂直分布进行了改进。通过数值试验研究了热带辐合带热带气旋的形成过程。发现积云对流的中尺度组织对涡旋的形成和增强至关重要。本实验较好地模拟了中尺度有组织对流中位于涡东南部分的强风和气旋旋转等中尺度结构。详细分析了中尺度风场和温度场的结构。通过数值实验模拟和了解赤道地区rosby模态与Kelvin模态分离的过程。一个由罗斯比模式发展而来的涡旋转变为热带气旋。

In this study, based on two types of models such as a non-hydrostatic axi-symmetric model which can resolve cumulus-scale motion and a three-dimensional hydrostatic model with cumulus-scale parameterization which the author developed. many numerical experiments have been performed in order to understand the mechanism of tropical cyclone formation and mesoscale structure. As for model improvement. vertical distribution of heat released by parameterized convection in the hydrostatic model was improved to get better simulation of mesoscale structure of tropical cyclones.Numerical experiments were performed to understand the formation process of tropical cyclones in intertropical convergence zone. Meso-scale organization of cumulus convection is found to be essential to formation of a vortex and its intensification. In this experiment mesoscale structure such as strong winds located at the southeastern portion of the vortex and cyclonic rotation of mesoscale organized convection were simulated well. The mesoscale structure of wind and temperature fields were analyzed in some detail. Numerical experiments were also performed to simulate and understand the process where Rossby mode is separated from Kelvin mode in the equatorial area. A vortex developed from a Rossby mode and it transformed into a tropical cyclone.