烟台市秋季冰雹特征和成因分析

Analysis of Characteristics and Formation Mechanismof Autumn Hail Weather in Yantai City

【目的】为准确预报和防御秋季冰雹天气。【方法】基于高低空观测资料、烟台雷达回波资料和再分析资料(ERA5),统计分析烟台地区2006—2021年出现的5次秋季(9—10月)冰雹天气过程。【结果】冰雹发生前,对流有效位能(CAPE)和对流抑制有效位能(CIN)之差超过724.3 J·kg-1;850 hPa与500 hPa温差超过25℃左右及以上;0℃和-20℃层高度差超过2 900 m;0~6 km垂直风矢量差超过11.1 m·s-1。降雹地区上空400~800 hPa有明显的上升运动,垂直速度超过-1.0 Pa·s-1,并且都有强不稳定能量,为冰雹的形成提供一定的动力条件。雷达风暴参数在冰雹发生前的1~2个体扫中,除了风暴所在高度和回波顶高有可能是下降之外,其余均呈现上升趋势。垂直液态水含量和垂直液态水含量密度均达到37 kg·m-2和4.4 g·m-3上,增量也达到11 kg·m-2和1.3 g·m-3;大冰雹的垂直液态水含量和垂直液态水含量密度超过48 kg·m-2和5.4 g·m-3。【结论】5次秋季冰雹均在有利的环境下产生的,其特征是存在高空冷涡、切变线和急流辐合,地面上有匹配的辐合线。

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.