台风暴雨过程中不同尺度系统的相互作用

The interactions of different scale systems in the heavy rain caused by typhoon

采用数值模拟和带通滤波相结合的方法,对一次台风暴雨过程中的大中尺度系统进行了分离;推导出一个包含大中尺度系统相互作用机制的涡度方程,对中尺度系统发生发展的主要影响因子和大中尺度系统之间的相互作用机制进行了定量诊断分析。结果表明:大中尺度系统之间的相互作用是中尺度系统发展增强、进而造成强降水的一种重要机制;当中尺度系统发展到一定阶段后,由中尺度涡度场、散度场和垂直速度场之间的相互配置所决定的散度项和扭曲项又会引起中尺度系统的减弱消散,这种中尺度系统发展演变的内在调节机制使得强降水在时间上也呈现出中尺度特征。

In this paper numerical modeling and band-pass filter are used to separate the large-scale and meso-scale systems from a heavy rain process caused by typhoon. A vorticity equation is deduced which includes interactions mechanism of various scales. The equation diagnoses and analyses the main factors for the meso-scale systems＇development and the interactions mechanism of the large-scale and meso-scale systems. Results indicate that the interactions are an important kind of mechanism for the development and reinforcement which result in the meso-scale heavy rain. When the meso-scale systems develop to the certain stage, divergence and twisting terms dominated by the allocation of the divergence, vorticity and vertical velocity fields of the meso-scale systems may cause the dissipation of the meso-scales. The inside regulation mechanism from the evolvement of the meso-scale systems induces the time-mesoscale character of the heavy rain.