摘要
利用激光雨滴谱仪资料、地面观测资料、合肥双偏振雷达资料和欧洲中心ERA5再分析资料,对发生在整层暖平流大气层结中的高架雷暴所引起的江淮地区一次短时强降雪天气过程进行分析,并探讨降水相态变化超前地面温度变化的原因,结果表明:(1)强降雪过程中,雨雪转换迅速,降水相态变化时间提前于地面温度变化,合肥地区温度变化明显强于周边地区。(2)强降雪发生在锋生强迫过程形成的高架雷暴中,强烈的上升运动、降水粒子的融化和蒸发引起温度负变化,导致降温过程自上而下产生,表现为地面温度下降落后于雨雪相态的变化。(3)降水过程先后出现降雨、雨夹雪、纯雪3个阶段,雨(雪)滴谱的时间演变特征变化明显;转雪后降水粒子的下落末速度降低、粒径增大、滴谱明显变宽。(4)雷达观测显示此次降雪回波顶高较高,超过6.5 km,低空1 km有强度超过50 dBZ强反射率因子带并延伸到地面。反射率因子、相关系数(CC)和降水粒子产品(HCL)在降雪过程的发展中有明显特征。
Based on the raindrop spectrum data,ground observation data,dual polarization radar data of Hefei radar station and ECMWF ERA5 reanalysis data,a short-term heavy snowfall in Jianghuai region caused by elevated thunderstorms occurred in the whole layer of warm advection was analyzed,and causes of precipitation phase variation earlier than that of ground temperature were also discussed as well.It shows that:(1)During the process of this heavy snowfall in Jianghuai region,the rain transformed to snow rapidly,the time of precipitation phase change was ahead of that of the ground temperature change,the varation of ground temperature in Heifei was obviously stronger than adjacent regions.(2)The short-term heavy snowfall was generated in the elevated thunderstorm formed by frontogenesis force.The negative change of temperature,caused by the strong ascending motion,and melting and evaporation of precipitation particles,resulted in the detemperature process occurred from above to below,which showed up as the change of ground temperature falled behind the conversion of rain-snow phase.(3)The precipitation process had three stages,including rainfall,sleet and snowfall.The temporal evolution characteristics of raindrop size distribution changed obviously.After transitioned to snow,the final falling velocity of precipitation particles decreased,the particle size increased,and drop spectrum increased visibly.(4)The radar observation showed that the height of the echo top of this snowfall was higher than 6.5 km,which was relatively higher than average.There were reflectance factor with intensity stronger than 50 dBZ below 1 km.
作者
李萌萌
王云
朱冰
杨祖祥
LI Mengmeng;WANG Yun;ZHU Bing;YANG Zuxiang(Anhui Weather Modification Office,Hefei 230031,China;Anhui Meteorological Observatory,Hefei 230031,China)
出处
《沙漠与绿洲气象》
2023年第4期7-15,共9页
Desert and Oasis Meteorology
基金
国家重点基础研究发展计划资助项目(2019YFC1510303)。
