两次春季暴雨过程的对比分析

对山东2003年4月17-18日（以下简称4·17）和2008年4月20～21日（以下简称4·20）两次春季暴雨进行对比分析。环流形势对比分析表明，两次降水过程中500hPa具有相似的环流背景，但850hPa和地面具有不同的环流形势，低空急流的类型和切变线的位置不同以及地面是否形成气旋与这两次降水量级是密切相关；物理量参数对比分析表明，4·17过程中各种物理量级别较4·20偏大偏强；雷达回波对比分析表明，4·17降水过程表现为积云层状云混合降水回波，并出现了逆风区，降水中伴有雷暴，而4·20降水过程表现为层状云降水回波，以稳定性降水为主。

Contrastive Analysis on Two Spring Rainstorms

Two spring rainstorms which occurred in April 17-18th 2003(hereinafter referred to as 4·17) and April 20-21 st 2008(hereinafter referred to as 4·20) in Shandong Province were carried on the contrastive analysis.The circulation contrast analysis showed that 500 hPa in the two precipitation course had a similar circulation background while 850 hPa had a different situation with the surface circulation.The type of low-level jet,the different location of shear line and whether conforming cyclone were closely related to the twice precipitation magnitude. The physical parameters contrast analysis showed that,the various physical quantities of 4·17 were larger and stronger than that of 4·20.Comparative analysis of the radar echo showed that the precipitation process of 4·17 appeared as a characteristic that stratiform cloud mixed cumulus precipitation echo.Simultaneously,it presented an adverse wind area with thunderstorm during precipitation.The precipitation process of 4·20 presented stratiform cloud precipitation echo.