A study of numerical modeling of tropical cyclones and formation

本研究基于两类模式，即一个能解决积云尺度运动的非静力轴对称模式和一个作者发展的三维积云尺度参数化静力模式。为了了解热带气旋的形成机制和中尺度结构，人们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，对静力模式中参数化对流释放热量的垂直分布进行了改进，并对热带辐合区热带气旋的生成过程进行了数值试验。积云对流的中尺度组织对低涡的形成和加强是必不可少的。试验较好地模拟了低涡东南部的大风和中尺度有组织对流的气旋旋转等中尺度结构。详细分析了风场和温度场的中尺度结构。通过数值实验，模拟和了解了赤道区域Rossby模与Kelvin模分离的过程。一个涡旋由罗斯比模式发展而成，并转变成热带气旋。

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.