一次低涡切变型连续性冰雹过程天气分析

Synoptic analysis of a low whirlpool shear type-hail course with continuity in midsummer of 2004

对2004年7月13-20日西北地区东部出现的一次低涡切变型区域性冰雹天气过程,从其产生的大气环流背景和前期气候背景进行了讨论,并利用MICAPS提供的方法,对物理量场进行了初步分析,总结了其发生发展的客观规律。结果表明:形成这次连续性降雹的影响系统是500 hPa位于青藏高原东北侧到华北的低涡切变;深厚的不稳定层结和随高度增强的不稳定能量,是此次强对流发生的热力条件;有利的低层辐合与高层辐散的散度场是此次强对流发生的动力因子;随高度增强的上升运动为冰雹的形成提供了水汽条件。

Based on the atmospheric circulation and early days climate background, a regional hail weather course of low whirlpool shear type was discussed, the course occurred in July 13 - 20, 2004 in east part of northwest of China. The method offered by MICAPS was used to analyze the fields of physical quantities. Result shows that the influence system inducing the continual hailing is the low whirlpool shear of 500 hPa located at from northwest of Qinghai-Tibet Plateau to North China; the deep unstable layer and unstable energy increased with altitude is the thermal condition for occurrance of strong convection ; favorable low layer radiation combination and high layer radiation dispersion are the dynamic factors of the strong convection and the going up air movement enhanced with altitude offered the water vapoar condition for hail formation.