2010年8月丹东连续两次副热带高压暴雨多普勒雷达回波对比分析

Comparative analysis of two heavy rains caused by subtropical high in August 2010 based on Doppler radar data in Dandong

利用丹东多普勒雷达的基本反射率、基本径向速度和风廓线资料,对2010年8月19日和20日丹东地区大暴雨天气过程进行分析,探讨丹东短时强降水天气形势和多普勒雷达回波特征。结果表明:在丹东处于副热带高压内部或边缘时,南下的冷空气与副热带高压后部暖湿空气势力相当时,形成丹东地区较典型的暴雨模式。风廓线产品在强降水前期,会产生一个水汽累积的过程,两次过程中出现短时强降雨时段均表现为高空急流出现和高空动量下传。这种高空动量的下传使低空急流得到加强,低层进一步辐合,使雨强明显增大。两次过程中降水回波区均形成一条40 dBz以上的回波带,回波移动方向与回波带轴向一致,导致沿途站降水时间偏长,降水总量偏多。逆风区出现时间与强降雨时段有较好的配合,其位置与强回波区的对应关系揭示出逆风区厚度越大、对应的反射率因子强度越强,产生的降水强度也越大。

Based on the basic reflectivity,basic radial velocity and wind profile data from Doppler radar,two heavy rain processes in Dandong area on August 19 and 20,2010 were analyzed,and their weather situations and radar echo characteristics were discussed.The results indicate that the forces of southward cold air and warm wet air of the rear subtropical high are compatible when Dandong is located within subtropical high or near the margin,so it comes into being a typical heavy rain model in Dandong.The VWP（vertical wind profile） has a water vapor accumulation process during the prophase of precipitation,and it shows that upper level jet stream appears and upper momentum transports downward during the short-time heavy rain of two processes.The downward transportation of upper momentum makes lower level jet stream strengthened and the lower level converges,so rain intensity increases obviously.An echo strip with 40 dBz is formed in the precipitation echo areas of two processes,and the echo moving direction is consistent with the echo axial direction,which makes precipitation time prolonged and rainfall intensity increased.The occurrence time of inverse wind area is corresponding with that of the short-time strong rainfall.The corresponding relationship between the location of inverse wind area and strong echo area suggests that the larger the thickness of inverse wind area is,the stronger the corresponding reflectivity factor is,and so rainfall intensity is also strong.