2022年江西大暴雨回波面积识别特征分析

Recognition and feature analysis of echo area during large rainstorm in Jiangxi in 2022

为了做好大暴雨天气的监测预警工作,文章使用MICAPS、自动气象站、雷达拼图等数据,采用天气学、雷达气象学等原理和回波面积自动识别等方法,对2022年江西6次大暴雨天气过程进行分析,结果表明:1)500 hPa低槽东移,低层辐合线、切变线与高空分流区重叠,大气层结不稳定,并伴有中等强度的对流有效位能和偏强K指数是江西大暴雨过程的基本天气系统和环境条件。2)大暴雨的回波具有絮状回波特征,在大范围混合性降水回波中有≥45 dBZ的回波单体、短带、回波带(团)存在,是造成短时强降水的主要回波系统;45 dBZ强回波顶高一般在6 km或以下,低质心特征明显。3)通过DBSCAN算法和散点轮廓算法计算出≥45 dBZ暴雨回波面积、回波强度、回波中心位置等特征,为预报方法提供接口数据。研究结果为江西大暴雨天气的监测预警提供了分析依据。

In order to do a good job in monitoring and early warning of large rainstorm,this paper,by utilizing MICAPS,automatic meteorological station,radar mosaic and other data and adopting the theories such as synoptic meteorology,radar meteorology,etc and methods including automatic identification of echo area,etc,analyzes 6 large rainstorm weather processes in Jiangxi in 2022.It is concluded that:1)the basic weather system and environmental conditions of the large rainstorm process in Jiangxi are listed below,including 500 hPa low trough moving eastward,the low-level convergence line and shear line being overlapped by upper diverging area,the atmospheric stratification being unstable,accompanied by moderate convective available potential energy and stronger K index.2)The echo of large rainstorm features flocculent echo.In the large range of mixed rainfall echo,the echo monomer(≥45 dBZ),short band and echo band(cluster)are regarded as the main echo systems that cause short-term strong rainfall.The crest height of 45 dBZ strong echo is generally 6 km or below and the characteristics of low mass core can be observed obviously.3)The DBSCAN algorithm and scatter point contour algorithm are applied to calculate echo area,echo strength,echo center position and other features of rainstorm(≥45 dBZ),providing interface data for forecasting methods.The research results provide analytical basis for the monitoring and early warning of large rainstorm weather in Jiangxi.