潜江市中小尺度强降水短临预警指标技术研究

Research on Short and Imminent Warning Index Technology of Small and Medium Scale Heavy Rainfall in Qianjiang City

利用Micaps高空、地面逐小时实况资料和多普勒天气雷达资料,对2011—2016年潜江市23次短时强对流天气过程进行统计分析,总结出潜江市中小尺度强降水短临预警指标,在2017年短临预报业务中投入使用并加以订正。结果表明,潜江市短时强降水每年出现4次左右,多发生在4—9月,7月是短时强降水最为频发的月份。短时强降水环流背景特征有锋面、低槽、切变线、低压、低涡等天气系统,短时强降水前,物理量特征为水汽充沛、湿层深厚,暖云层厚度较厚,0℃层高度位于5 000 m左右,对流有效位能CAPE属中等强度,57494站或57461站必有一站K指数在36℃以上的比例为91.3%。短时强降水的雷达回波演变方式有3种类型,即移入型,可分为一般移入型和"列车效应"移入型;合并加强型;本地发展型。短时强降水雷达回波形状以带状居多,涡带状、片状、弓状、涡旋形态较少。短时强降水时,1 h有6个以上体扫反射率因子大于35.0 dBz,强回波40 dBZ伸展到7 km左右,DVIL在2 g/m3左右,垂直风切变值在10 m/s左右。

Based on the MICAPS high altitude,ground actual data by hour and Doppler weather radar data,the 23 short-term strong convective weather process in Qianjiang city in 2011-2016 years was analyzed,and the short term and impending early warning index of the middle and small scale heavy rainfall in Qianjiang was summarized,and it was put into use and revised in the short impending forecast business in 2017.The results show that short term heavy rainfall in Qianjiang appears 4 times a year,mostly in April to September,and July is the most frequent month.The background characteristics of short time strong rainfall are front,low trough,shear line,low pressure,low vortex and other weather systems.Before short-term strong precipitation,the physical quantity is characterized by abundant water vapor,thick wet layer,thick warm cloud thickness,0℃layer height at about 5 000 m.The CAPE of convective effective potential belongs to medium strength,and the proportion of one station in 57494 or 57461 K index above 36℃is 91.3%.There are three types of radar echo evolution in short time strong precipitation:Moving in type,which can be divided into general moving type and“train effect”type,combined strengthening type and local development type.The shape of short time heavy rainfall radar echo is mostly ribbon,while vortex band,sheet shape,arcuate shape and vortex formation are less.In short time strong precipitation,more than 6 body reflectance factors are more than 35.0 dBz in 1 hour,strong echo 40 dBZ extends to about 7 km,DVIL is about 2 g/m^3,and vertical wind shear value is around 10 m/s.