四川东北部地区一次强风暴过程的特征分析

2007年4月29日在川东北地区发生了一次强风暴天气过程。本文利用大气综合观测和NCEP/NCAR再分析资料,研究了这次强风暴过程发生前的天气形势和物理量场的结构特征。根据多普勒天气雷达和卫星云图资料,分析了风暴的演变过程及结构。研究表明:过程发生前在风暴区上空,低空存在暖平流、高空有冷平流,行星边界层能级低,对流层整层热力差动平流结构十分明显。卫星云图上有中尺度对流云团活动。雷达监测显示:在降雹前有悬垂回波、中气旋和有界弱回波区存在,具有典型超级单体风暴的部分结构和特征。

Analysis on Structure and Characteristics of a Severe Hailstorm Event in Northeast of Sichuan

A severe hailstorm occurred in northeast of Sichuan on Apr.29, 2007.In this paper, the synoptic situation and characteristics of physical quantity field before the hailfall are analyzed by using the data of atmosphere combosite observation and grid-point field from NCEP/NCAR reanalysis.The evolution process and the structure of the hailstorm are also analyzed on the basis of a Doppler weather radar and satellite images.The results show that before hailfall, there is a warm advection at the low level, low energy level in the PBL, cold advection or a center of positive vorticity in the mid-and upper-level, strong cold vortex on the upper leve.The MCS activity occurred on the satellite cloud image over the northwest of the hailfall area.The observation of Doppler radar show that before hailfall, there are overhang echo, mesocyclone, and BWER (bounded weak echo region) with the partial features of the typical supercell storm.