双偏振天气雷达精细化探测技术对2021年两个龙卷风暴识别能力的影响分析

Analysis on the influence of fine detection technology of dual polarization weather radar on recognition ability of two tornado storms in 2021

新一代天气雷达观测的反射率因子和径向速度为强对流风暴和龙卷的识别预警提供了重要支持,新一代天气雷达实施双偏振升级后其基数据分辨率为1.0°×250 m(当前分辨率)。为了测试进一步提高数据分辨率的可行性,杭州和深圳竹子林双偏振雷达将数据分辨率提高到0.5°×62.5 m/125 m(精细分辨率)开展精细化探测技术试验。该文以2个龙卷天气过程为例,分析了径向速度数据质量,对比分析了两种分辨率下的龙卷风暴回波特征和多个雷达特征量以及TVS识别结果。结果表明:(1)精细分辨率的径向速度(特别是参差PRT模式径向速度)中存在一些非速度模糊奇异值,增加了识别虚假TVS的可能性;(2)精细分辨率雷达回波能更好地描述龙卷风暴特征;(3)精细分辨率的中气旋中心位置与龙卷灾害路径更加一致,Zmax、VIL、SHI和中气旋旋转速度、方位切变等雷达特征量大多大于当前分辨率的,TVS识别次数也多于当前分辨率的。因此,在不考虑径向速度质量的情况下,相比当前分辨率探测,精细分辨率探测更有利于龙卷风暴的识别。

Reflectivity and Doppler velocity measurements from the new generation weather radar provide important input for the identifica⁃tion and early warning of severe storms and tornadoes.After the dual polarization upgrade,the radar base data resolution has an azimuthal spacing of 1.0°and range spacing of 250 m for all observations(1.0°×250 m).To test the feasibility of improving data resolution,Hangzhou and Shenzhen Zhuzilin dual polarization radars use fine detection technology,and the data resolution can be improved to 0.5°×62.5 m/125 m.Taking two tornadoes as examples,this paper analyzes the quality of radial velocity data,compares and analyzes the echo characteristics of the tornado storms,multiple radar features and TVS recognition results under the two resolutions.The results show that:(1)Some non-ve⁃locity aliasing outliers appear in the radial velocity data,especially the radial velocity collected using stagger PRT technique,which increas⁃es the possibility of identifying false TVSs.(2)Fine resolution radar echo can better describe the characteristics of tornado storm.(3)The me⁃socyclone centroid position obtained from the fine resolution radial velocity data is more consistent with the tornado disaster path.Radar fea⁃tures such as Zmax,VIL,SHI and mesocyclone rotation speed and azimuth shear of fine resolution tornado supercell are mostly greater than those of the current resolution.The recognition times of TVSs are also greater than those of the current resolution.Therefore,without consid⁃ering the radial velocity data quality,compared with the current resolution detection,fine resolution detection is more conducive to the identi⁃fication of tornado storms.