STUDY ON SENSITIVITY OF WIND FIELD VARIATION TO STRUCTURE AND DEVELOPMENT OF CONVECTIVE STORMS

In order to study the impacts of wind field variations in the middle and lower troposphere on the development and structure of storms, we carried out numerical experiments on cases of severe convection in the Jianghuai area under the background of cold vortex on April 28, 2015. The results show that the structure and development of convective storms are highly sensitive to the changes of wind fields, and the adjustment of wind fields in the middle or lower troposphere will lead to significant changes in the development and structure of storms. When the wind field in the middle or lower troposphere is weakened, the development of convective storms attenuates to some extent compared with that in the control experiment, and the ways of attenuation in the two experiments are different. In the attenuation test of wind field at the middle level, convective storms obviously weaken at all stages in its development, while for the wind field at the low level, the convective storms weaken only in the initial stage of storm. On the contrary, the enhancement of the wind field in the middle or lower troposphere is conducive to the development of convection, especially the enhancement in the middle troposphere. In contrast, the convective storms develop rapidly in this test, as the most intensive one. The wind field variations have significant impacts on the structure and organization of the storm. The enhancement of wind field in the middle troposphere facilitates the intension of the middle-level rotation in convective storm, the reduction of the storm scale, and the organized evolution of convective storms. The strengthening of the wind field in the lower 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 on the inflowing side of the storms.