Abstract:

Based on the conventional observation data, precipitation data from automatic weather stations, the reflectivity and radial velocity of Doppler radar at Tongren station and NCEP reanalysis data with 1°×1° spatial resolution, a rare large area hail weather process occurred in Tongren of Guizhou Province on 2 April 2016 was diagnosed and analyzed. The results are as follows:(1) The large-range hail weather process occurred in the unstable stratification which the dry and cold northwest air behind the trough in upper and middle levels overlaid on the warm and moist southwest airflow in lower layer. The strong vertical wind shear and lower level convergence and upper level divergence were conducive to the development and maintenance of convective storms. (2) The intrusion of dry cold air in upper layer and weak cold air in boundary layer were favorable to stimulate the strong convection. (3) It’s conducive to the development of large-range hailstorm system when the vertical wind shear from ground to 400 hPa over Tongren surpassed 8×10-3 s-1. (4) The multiple convective cells organically formed a bow echo, and the strong echo with the reflectivity over 50 dBZ stretched to the height of -20 ℃ layer above. The boundary weak echo region, echo overhang and three-body scattering phenomenon were typical characteristics of hail weather. The echo top height of strong echo with reflectivity over 50 dBZ in hail points was 8.1 km to 9.8 km, and the vertical integrated liquid (VIL) was 38.4 kg·m-2 to 66.8 kg·m-2, which can be regarded as important prediction indicators of hail in Tongren region.

Key words: hail, dry intrusion, bow echo, vertical wind shear

摘要：

利用常规观测、地面加密自动站降水、雷达观测及NCEP/NCAR再分析资料，对2016年4月2日发生在贵州省铜仁市多个县（区）的一次大范围冰雹天气过程进行分析。结果表明：（1）此次大范围冰雹过程发生在中高层低涡槽后西北冷空气与低层西南暖湿气流叠加的不稳定层结中；强垂直风切变及低层辐合高层辐散有利于对流风暴的发展和维持；（2）中高层干冷空气和边界层弱冷空气入侵是激发强对流产生的有利条件；（3）当铜仁地区地面至400 hPa垂直风切变超过8×10-3 s-1时，有利于大范围冰雹系统发展；（4）多个对流单体有组织地形成弓形回波，且强回波伸展至-20 ℃层高度之上；有界弱回波区、悬垂回波、三体散射现象表征了冰雹产生的典型特征；降雹点50 dBZ以上的强回波顶高在8.1～9.8 km之间，VIL在38.4～66.8 kg·m-2之间，这些可作为铜仁地区产生冰雹的重要指标。

关键词: 冰雹, 干侵入, 弓形回波, 垂直风切变