Observation and Simulation Study of a Hail Storm Process in a Complex Terrain Area
To improve the forecasting level of hailstorms in the southwestern complex terrain region of China,this paper systematically analyzes the terrain effect,microphysical process,and the mechanism of hail formation during a typical hailstorm in the southwestern complex terrain region of China,and numerically simulates it by using the fully elastic three-dimensional convective cloud model.The results show that:(1)this hailstorm process is a cold air intrusion type hailstorm,and the terrain's obstruction of the low-level warm and humid airflow led to the accumulation of water vapor,while the cold air guided by the plateau trough triggered this hailstorm.(2)The existence of vorticity centers greater than 8×10-5/s in the near-surface layer or 500～300 hPa altitude layer,the existence of convergence centers with dispersion less than-8×10-5/s at 750 hPa altitude and turning into convergence dispersion at the level of 500 hPa or above,the near-surface water vapor flux dispersion greater than-12×10-8,the pseudo-equivalent temperature gradient greater than 4 K/km,and the vertical windshear greater than 15 m/s at the 0-6 km altitude are some of the thresholds that can pro-vide early warnings for the hailstorms in the southwestern region of the complex terrain.(3)The strong vertical wind shear of 32.03 m/s and the strong medium cyclone with a rotational speed of 19.85 m/s and a thickness of more than 3 km are the main maintenance mechanisms of the hail monomer.(4)Hail embryos are mainly produced by snow crys-tals hitting frozen supercooled raindrops,and low-density shrapnel is the main hail formation mechanism in the process of precipitation of freezing attached cloud water and supercooled raindrops to grow into hail.The results of the study have a certain guiding effect on the forecasting of hailstorm processes in Guizhouand analyze the topographic effects.
万方数据
维普
