| Abstract: | A numerical experiment was carried out on individual cases of severe convections in the Jianghuai area under cold vortex on April 28, 2015 in order to study the impact of wind field variations at the middle and low troposphere on the development and structure of storms. The results show that the structure and development of convective storm is highly sensitive to the changes of wind fields, and the adjustment of wind field at the middle or low troposphere will lead to significant changes in the development and intensity of storms. When the wind field at the middle or low troposphere is weakened, the convective development suffers different degrees of attenuation compared with the control experiment, and the ways of attenuation of the two levels are different. In the attenuation test of wind field at the middle level, convection is obviously weak at all stages of its development, while for the wind field at the low level, the convective development is weak only in the initial development stage of storm. On the contrary, the enhancement of the wind field at the middle or low troposphere is conducive to the development of convection, especially the enhancement of the wind field at the middle troposphere. In comparison, the convection develops rapidly in this test, as the most intensive one. The wind field variations have a significant impact on the structure and organization of the storm. The enhancement of the wind field at the middle troposphere makes for the intension of the middle-level swirl of convective storm, the reduction of the storm scale, and the organized evolution of convection. The development of the wind field at the low level troposphere is conducive to the development of the low-level secondary circulation of the storm and the cyclonic vorticity at the middle and low levels at the inflowing side. |
