青岛机场一次冰雹过程的双偏振雷达分析

利用常规气象观测站点资料、探空资料、青岛S波段多普勒和双偏振雷达资料对2023年7月8日下午青岛机场一次对流单体冰雹过程天气背景以及雷达回波特征进行分析。结果表明:此次冰雹过程是在500 hPa强西风带、冷涡槽的共同作用下发生的,具有很强的局地性。整层大气具有强的不稳定性,上干下湿特征明显,低层垂直风切变强度中等,深层垂直风切变较强,0~6 km风矢量差达到21 m/s,高低空温差较大,湿球温度0℃高度为4 km。雷达回波具有高耸的强回波、有界弱回波区、回波悬垂和三体散射结构,同时中层4~8 km的高度处有明显中气旋结构,气旋直径约4 km,辐合层厚度约为3.2 km,高层出现速度辐散,这些均为典型雹暴的雷达特征。单体的垂直液态水含量(C-VIL)和垂直液态水含量(VIL)密度的大值能够很好对应冰雹粒子,C-VIL突变还能作为预报冰雹和大风参考指标,C-VIL跃增出现比青岛机场降雹提前30 min,骤降出现比青岛机场大风出现提前7 min。这次冰雹过程,双偏振雷达差分反射率因子Z_(DR)和相关系数ρhv能有效区分冰雹和强降水,而差分相位常数K_(DP)大值区对应大雨或融化的冰雹,需要结合其他参量进一步判断粒子形态。这次冰雹过程出现了明显的Z_(DR)和K_(DP)柱结构,Z_(DR)柱高于K_(DP)柱,Z_(DR)柱对应较强的上升运动,与速度图上的中气旋位置相对应,K_(DP)柱对应着较明显的下沉气流。分析的结果能为青岛机场的冰雹短临预报提供一定的参考,也对于实际应用双偏振雷达产品有一定的指示意义。

高山上新一代天气雷达的探测分析与效能发挥

以泰山新一代天气雷达CINRAD/CD为例,结合泰山原713天气雷达多年的使用经验,计算并分析了天气雷达的最佳探测仰角和最低探测高度,根据泰山新一代天气雷达(简称泰山CD雷达)与济南新一代天气雷达(简称济南SA雷达)回波的DBZM、C-VIL对比分析,揭示不同海拔高度雷达在相同仰角下观测的回波的差异,指出泰山CD雷达由于使用了与平原雷达统一的0.5°以上仰角的观测模式,造成了对降水回波的探测能力不足,并指出泰山CD雷达要发挥最大效能应如何改进的建议。

Detection Analysis and Efficiency of New Generation of Weather Radar over High Mountains

Based on years of use experience of previous 713 weather radar in Mount Tai,the optimal detection elevation and minimum detection height of the new generation of weather radar CINRAD/CD in Mount Tai were calculated and analyzed. According to the comparative analysis of maximum reflectance factor( DBZM) and vertical integrated liquid water based on cells( C-VIL) of the new generation of weather radar in Mount Tai( CD radar in Mount Tai) and Jinan( SA radar in Jinan),differences of echoes observed by the radar at the same elevation at different altitudes were revealed. It is pointed out that the ability of CD radar in Mount Tai to detect precipitation echoes was inadequate because the radar used the same elevation of above 0. 5° as the radar in the plain. Moreover,some suggestions were put forward to improve the efficiency of CD radar in Mount Tai.