摘要
实际业务中对冰雹大小的判断一直是难点之一,为区分和识别不同尺寸的冰雹,基于地面观测资料和南昌、吉安两部双偏振雷达探测资料,筛选出2021—2024年2—5月44次冰雹事件,统计分析不同尺寸的冰雹在不同高度层的雷达偏振量及其变化,得到江西中北部地区冰雹过程雷达偏振量的阈值特征。结果表明:1)在相同高度层上,冰雹尺寸越大,反射率因子(Z_(H))的中位数越大,差分反射率因子(Z_(DR))和相关系数(C_(C))的中位数越小,其中特大冰雹与小冰雹的Z_(H)中位数差值在近地层和-20℃层以上高度层都大于等于10 dBZ。2)在融化层以下高度小冰雹的Z_(DR)中位数基本为正值,大冰雹的在多个高度层接近0 dB,特大冰雹的则基本为负值;融化层以下高度特大冰雹的C_(C)值基本小于0.9。3)在-20℃层以上高度Z_(H)对冰雹尺寸较敏感,C_(C)和Z_(DR)表现不明显;-20—0℃层的Z_(H)和C_(C)对冰雹尺寸较敏感,Z_(DR)表现不明显;融化层以下高度Z_(H)、C_(C)和Z_(DR)对冰雹尺寸均有一定的指示意义。4)结合多类偏振量可以更好地判断冰雹的尺寸大小,冰雹尺寸越大,出现三体散射的概率越高,利用三体散射的偏振特征可有效辅助识别大冰雹。
In practical operations,the judgment of hail size has always been one of the challenges.To distinguish and identify hails of different sizes,44 hail events in Jiangxi from February to May during 2021-2024 were selected based on ground observation data and dual-polarization radar data from Nanchang and Ji'an stations.According to the radar polarization values and their variations at different altitude levels for hail of different sizes in the central-northern regions of Jiangxi Province,the threshold characteristics for distinguishing different sizes of hails were obtained.The results showed that:1) At the same altitude level,the larger the hail size,the greater the median Z_(H) value,and the smaller the median Z_(DR) value and C_(C) value.The median difference in Z_(H) values between giant hail and small hail were more than or equal to 10 dBZ in both the near-ground layer and the altitude layer above-20 ℃ layer.2) The median Z_(DR) value of small hail below the melting layer was generally positive,the median Z_(DR) value of large hail was close to 0 dB at multiple altitude levels,while the median Z_(DR) value of giant hail was generally negative.The C_(C) value of giant hail below the melting layer was typically less than 0.9.3) Above the-20 ℃ layer,Z_(H) was more sensitive to hail size,while C_(C) and Z_(DR) showed less significant variation.Among-20 and 0 ℃ layer,Z_(H) and C_(C) were more sensitive to hail size,while Z_(DR) showed less variation.Below the melting layer,Z_H,C_(C) and Z_(DR) all provided certain indications of hail size.4) The size of hails would be better determined by combining multiple types of polarization parameters.The larger the hail size,the higher the probability of TBSS.The polarization feature of TBSS would be used to identify large hail effectively.
作者
彭恩翔
张帆
曾唯睿
胡怀坚
孙素琴
Peng Enxiang;Zhang Fan;Zeng Weirui;Hu Huaijian;Sun Suqin(Ji'an Meteorological Bureau,Ji'an Key Laboratory of Ecological Meteorology,Ji'an 343000,China;Ganzhou Meteorological Bureau,Ganzhou 341000,China;Jiangxi Provincial Meteorological Observatory,Nanchang 330096,China)
出处
《气象与减灾研究》
2024年第3期163-172,共10页
Meteorology and Disaster Reduction Research
基金
2022年江西省气象局预报员专项(编号:JX2022Y05)
2022年江西省气象局面上项目(编号:JX2022M11)
2022年吉安市生态气象重点实验室面上项目(编号:2022JEM201)。
关键词
天气雷达
冰雹尺寸
偏振特征
三体散射
温度层高度
weather radar
hail size
polarization characteristics
TBSS
height of temperature layer
