摘要
利用常规气象观测资料和NCEP GDAS/FNL 0.25°×0.25°再分析资料分析2021年9月20日浙江中部一次冰雹天气过程的环流背景、不稳定性和触发条件,通过金华S波段双偏振雷达对冰雹云的演变及其结构特征展开分析。结果表明:(1)降雹发生在西太平洋副热带高压东退、高空槽和低层低涡东移的环流背景下,大气呈现“上干冷、下暖湿”的对流性不稳定层结,近地面中尺度辐合线提供了辐合抬升条件,是一次准正压类强对流天气。(2)超级单体风暴具备典型的冰雹云特征,回波强度>55 dBZ、异常大的垂直累积液态水含量、三体散射长钉、风暴顶辐散等均对冰雹天气预警有较好的指示意义。(3)超级单体成熟阶段基本反射率因子≥55 dBZ区域的差分反射率因子Z_(DR)为负(极值达-2.12 dB)、差分相移率K_(DP)出现“空洞”现象、相关系数CC<0.9指示出现了大的干冰雹。(4)Z_(DR)柱(>1 dB)伸展的高度与上升气流存在正相关,Z_(DR)柱伸展到-20℃层以上有利于雹胚的生成以及冰雹增长,可作为判别对流风暴能否降雹的指标之一,Z_(DR)柱演变规律在短临预报以及冰雹识别方面具有较好的应用潜力。
Based on the conventional meteorological observations and NCEP GDAS/FNL 0.25°×0.25° reanalysis data,the circulation background and instability as well as triggering condition of a hailstorm occurred in central Zhejiang province on 20 September 2021 were diagnosed.The evolution and structural features of the hail cloud were analyzed as well by using the Jinhua S-band dualpolarization radar.It shows that:(1)The hailstorm occurs with western Pacific subtropical high moving backward to the east while upper level trough and low-level vortex moving eastward.The atmosphere presents convective unstable stratification with cold and dry air above but warm and wet air below.A mesoscale convergence line near the ground provides convergence and lifting conditions,inducing a quasi-barotropic severe convection weather event.(2)The super cell storm has typical characteristics of hail clouds.All the characters have good indications for warning on hailstorms,including echo intensity greater than 55 dBZ,unusually large vertically integrated liquid water,three-body scattering spike,divergence at the top of the storm and so on.(3)In the region where the high reflectivity factor greater than 55 dBZ in the maturity duration of super cell,differential reflectivity (Z_(DR))(the extreme value reaches-2.12 d B)are negative,with missing value of specific differential phase (K_(DP))and correlation coefficient (CC) lower than 0.9.All these phenomena can reasonably indicate the appearance of large dry hails.(4)Stretching height of Z_(DR)column (1 dB) has positive correlation with upward flows.The Z_(DR)column whose stretching height is higher than that of-20℃isothermal line is favorable for generation of hail embryos and growth of hails,which can be an evaluation index for judging whether the convective storm could produce hails.Changing features of Z_(DR)column has good utilization potentiality in short-impending prediction and identification of hails.
作者
吕健
刘圣楠
王俊人
邵伟军
燕荣江
LYU Jian;LIU Shengnan;WANG Junren;SHAO Weijun;YAN Rongjiang(Jinhua Meteorological Bureau,Jinhua 321000,China)
出处
《沙漠与绿洲气象》
2023年第4期53-60,共8页
Desert and Oasis Meteorology
基金
金华市科学技术局项目(2021-4-357)
金华市科学技术局项目(2022-4-081)
金华市气象局一般项目(2021YB08)。
关键词
冰雹
环流背景
超级单体
双偏振雷达
hail
circulation background
super cell
dual-polarization radar
作者简介
吕健(1992-),男,工程师,主要从事天气雷达应用研究。E-mail:lvjianmail@126.com;通信作者:刘圣楠(1992-),女,工程师,主要从事强对流、暴雨等灾害性天气形成机理相关研究。E-mail:snliu2014@163.com。
