Abstract:

Based on the conventional and non-conventional meteorological data，NCEP/NCAR reanalysis data with 1°×1° spatial resolution and 6 h temporal resolution，one elevated severe convective weather and two surface severe convective weathers were comparatively analyzed. The results showed that TBB of the elevated convective clouds (“120227” weather process occurred on 27 February 2012) was high and caused small hail, while that of two surface severe convective weathers were low and their gradients were large, the value of TBB in cold center was 200 K, and caused large hail, tornado and gale. Echo characteristics of large hail were hung strong reflectivity, bounded weak echo region, mesocyclone, three-body scattering and high VIL(vertically integrated liquid water). The centroid position of strong echoes dropped rapidly before the bow echo which caused the severe precipitation and thunderstorm gale. The echoes characteristic of local tornadoes caused by supercell storm was obvious with the mesocyclone, weak echo region and strong combined shear, and the vertical wind shear from 0 to 3 km in VWP decreased significantly in an hour before the strong storms weakened and disappeared. Three severe convective weathers which occurred on 27 February 2012, 23 March 2013 and 17 April 2013 distributed in the divergence area at the right side of upper-level jet, in which the low and middle level jets converged, and the vertical wind shear was strong and the characteristic of upper-level dry and lower-level wet was obvious. And their lifting trigger systems was the high-middle layer, whole layer and low-middle level convergence systems, respectively, such as trough，shear or convergence line. The instability of the atmospheric layer and the large-scale forced lifting movement in the most severe convection of them were the strongest.

Key words: severe convection, trigger condition, radar echo, infrared cloud image

摘要：

利用常规、非常规观测及NCEP再分析资料，对广西1次高空触发强对流（简称高架强对流）及2次地面触发强对流（简称地面强对流）天气过程进行诊断对比分析。结果表明：高架强对流云系TBB值高，造成小冰雹，而地面强对流云系TBB值低且梯度大，冷中心达200 K，产生大冰雹、局地龙卷等；大冰雹回波具有高悬强回波、弱回波区、中气旋、三体散射及高的VIL；由弓形回波造成的强降水、雷暴大风，其发生前强回波质心迅速下降；超级单体风暴造成的局地龙卷，其回波具有中气旋、弱回波区及强组合切变，0～3 km垂直风切变在强风暴减弱消失前1 h左右明显减弱；“120227”、“130323”、“130417”3次强对流发生在高空急流轴右侧辐散区、中低层急流汇合处，具有强的环境风垂直切变及上干下湿特征，且抬升触发系统分别为近垂直分布的中高层、整层、中低层辐合系统（槽、切变、锋面或辐合线）；“130323”地面过程造成的强对流灾害天气最强，其层结不稳定性及抬升运动也最强。

关键词: 强对流, 触发条件, 雷达回波, 红外云图