Analysis of Characteristics and Formation Mechanism of Autumn Hail Weather in Yantai City
In order to accurately forecast and prepare for hail weather in autumn,this paper conducts a statistical analysis of five autumn(September-October)hail events that occurred in the Yantai region of northern Shandong Peninsula since 2006 on the basis of high-and low-level observation data,radar echo data in Yantai,and reanalysis data from the fifth-generation European Center for Medium-Range Weather Forecasts(ERA5).The results show that prior to hail formation,the difference between Convective Available Potential Energy(CAPE)and Convective Inhibition Energy(CIN)exceeds 724.3 J·kg-1,the temperature difference between 850 hPa and 500 hPa is greater than or equal to 25 ℃ approximately,the height difference between the 0 ℃ and-20 ℃ layers is more than 2,900 m,and the vertical wind shear between 0-6 km exceeds 11.1 m·s-1.There is a significant upward movement at 400-800 hPa above the hail prone area,with a vertical velocity exceeding-1.0 Pa·s-1 and strong unstable energy,providing certain dynamic conditions for the formation of hail.In the one to two volume scans prior to the occurrence of hail,the radar storm parameters exhibit an upward trend except for the possibility of a decrease at the storm height and the echo top.The vertical liquid water content and vertical liquid water content density reach 37 kg·m-2 and 4.4 g·m-3,respectively,with an increment of 11 kg·m-2 and 1.3 g·m-3,while large hailstones require an accumulation of vertical liquid water content and vertical liquid water content density to exceede 48 kg·m-2 and 5.4 g·m-3,respectively.These findings reveal that all five autumn hail events occurred in the favorable atmospheric conditions characterized by the presence of upper-air cold vortices,shear lines and jet stream convergence,as well as the surface convergence lines correspondingly.
NETL
NSTL
万方数据
