cyclonic wind

Results show as follows. The heavy rain taking place in the west side of Dabie Mountain is caused by β-scale cyclone on α-scale shear, and the heavy rain near the boundary area between Hunan and Hubei provinces is caused by cyclonic wind perturbation.

结果表明：（1）大别山西侧的暴雨由中α尺度切变线上中β尺度低涡造成，湘鄂交界地带的暴雨由切变线上气旋性扰动造成。

It is shown that the inner and outer regions of Tropical Cyclone have different governing equations. The inner region is governed by the cyclonic wind and an evolution equation, the outer region is governed by the gradient wind and another evolution equation.

研究表明，热带气旋内区和外区有不同的控制方程，内区受旋转风和一个演化方程制约，而外区受梯度风和另一个演化方程制约。

The reasons are as follows: the evolution of the northern cyclonic circulation system of the SCS mainly attributes to the existence and southbound extension of the cyclonic wind stress curl in the northwest of the SCS.

原因如下：南海北部气旋型环流系统的演变主要归于南海西北部气旋风应力涡度的存在和南扩。