一次蒙古冷涡影响下固原市冰雹天气过程分析

Analysis of Hail Process under the Influence of a Mongolian Cold Vortex in Guyuan

利用天气监测资料、NCEP/NCAR再分析资料、多普勒天气雷达资料等,对2017年6月7日发生在固原市范围内的一次冰雹天气过程,从环流背景、大气稳定度、雷达回波变化特征等方面进行了分析。结果表明,本次冰雹天气过程发生在宁夏冰雹易发期的初夏季节午后,是在"两槽一脊"有利于强对流天气发生的环流背景下,受蒙古冷涡影响而形成的;对比分析几个常用的冰雹预报指标和本次过程实况值显示,相对湿度指标阈值需降低,其他指标则符合已有的指标阈值;雷达回波特征参量如组合反射率、基本反射率、垂直累积液态水含量、回波顶高在冰雹发生前和发生时都显著增大,对于冰雹预报预警有较好的指示意义。

In this paper,using weather monitoring data,NCEP/NCAR reanalysis data,and Guyuan Doppler weather radar data to analyze an ice hail weather process occurred in Guyuan City on June 7,2017 in terms of the circulation background,atmospheric stability and radar echo characteristics.The results show that the hail weather process occurred in the early summer afternoon of the Ningxia hail-prone period,which is caused by the Mongolian cold vortex under the background of the circulation of the"two troughs and one ridge"which is conducive to form strong convective weather.Comparative analysis of several commonly used hail indices and the actual value of the process show that the relative humidity threshold needs to be reduced,other indexes meet the existing threshold.However,radar combined reflectivity,basic reflectivity,vertical cumulative liquid water content and echo top height increase before and during the occurrence of hail and has a good indication for the prediction of hail.