一次致灾强降雹过程的形成机制分析

Formation Mechanism Analysis of a Disaster Induced Hail Process

本文对发生在2015年7月18日的一次致灾强降雹过程进行分析, 在分析环流背景、 热力、 动力、 稳定度条件的基础上, 结合新一代多普勒天气雷达资料, 探讨此次致灾强降雹的成因及发展.通过分析可知：500hPa处在低槽中, 槽后有冷平流的输送, 地面冷空气移动促使前方暖湿空气抬升, 可造成冰雹天气; 地面中尺度低压内的辐合上升运动为此次降雹提供了很好的动力辐合抬升条件, 并呈现明显的 “人” 字形特征; 上干冷、 下暖湿的不稳定层结、 合适的一20℃和0℃层高度、 大的不稳定能量均为此次过程提供了有利的成雹和降雹条件; 小尺度对流单体的迅速生消、 合并增长, 发展成弓形回波, 最终导致此次强降雹; 强的回波中心、 回波悬垂结构、 径向速度的中尺度辐合流场、 垂直累积液态水含量和回波顶高均有利于产生冰雹.

Based on the analysis of the circulation background, thermal, dynamic and stability conditions, and combined with the new generation Doppler weather radar data, this paper discussed the cause and development of a disastrous hailstorm on July 18, 2015. The analysis showed that 500hPa was in a low trough, cold advection was conveyed behind the trough, and the movement of cold air on the ground caused warm and humid air to rise in front of the trough, which could cause hail weather. The unstable stratification of upper dry-cold and lower warm-wet, the suitable height of - 20℃ and 0℃ layers, and the large unstable energy all provided favorable conditions for hail formation and hail fall; the rapid growth and disappearance of small-scale convective monomers, merging and growth, developed into bow echoes, eventually led to the strong hail fall; the strong echo center, echo suspension the vertical structure, the mesoscale convergent flow field of radial velocity, the vertical cumulative liquid water content and the echo top height were all favorable for hail formation.