江西西部一次局地对流性暴雨过程诊断分析

Diagnostic Analysis of a Local Convective Rainstorm in Western Jiangxi

利用Micaps常规资料、多普勒雷达资料、地面加密自动站点资料,从环流形势、物理量场、回波特征方面,诊断分析了2014年5月24日08∶00—25日08∶00江西西部局地对流性暴雨天气过程。结果表明,这次对流性暴雨是在亚欧中高纬度环流经向度较大及副热带高压边缘扰动气流的背景下,中低层低槽和切变线共同影响下发生的;西南低空急流的建立、西南暖湿气流的增强,为这次对流性暴雨的产生提供了丰富的水汽、动力和热力条件。低层辐合、高层辐散和强烈的上升运动是产生这次对流性暴雨的重要动力条件;中低层有大的水汽积聚和水汽输送是产生这次对流性暴雨的重要水汽条件;大气层结不稳定、存在产生较强对流的有利条件、高能量区与中低层湿区和急流配合是产生这次对流性暴雨的重要热力条件。这次暴雨过程在雷达回波上以对流性回波为特征,出现2个主要降水时段(24日20∶00—25日01∶14、25日01∶24—09∶00),其中第2个降水时段维持降水时间长、降水强度大,是这次对流性暴雨的主要降水时段。

Using Micaps data, doppler radar, ground encrypted automatic station data, a local convective rainstorm in Western Jiangxi during 08：00 May 24 -08：00 May 25 in 2014 was analyzed from aspects of circulation situation, physical quantity, echo characteristics. The results showed that the rainstorm was under the influence of the middle and low trough and shear line ; the establishment of southwest low level jet, enhancement of the southwest warm and humid air, provided abundant water vapor, dynamic and thermal conditions for the generation of convective rainstorm. Low level convergence and upper level divergence and strong ascending motion were important driving conditions of the convective rainstorm; in the middle and lower layers, the water vapor accumulation and water vapor transport were the important water vapor conditions ; unstable atmospheric stratification, favorable conditions for the existence of strong convection, and the high energy zone and the middle and low wet zone and jet flow were the important thermodynamic conditions for the convective rainstorm. The rainstorm process was reflected by convective radar echo, which is characterized by two main precipitation periods （20：00 May 24 - 01 ： 24 May 25,01 ： 24 - 09： 00 May 25 ）. The second precipitation period maintained long time and high intensity, which is the main precipitation period of the rainstorm.