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气象:2021,47(2):170-182
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一次长生命史超级单体降雹演化机制及双偏振雷达回波分析
高丽,潘佳文,蒋璐璐,翁之梅
(浙江省台州市气象局,台州 318000; 厦门市气象局,海峡气象开放实验室,厦门 361012; 宁波市气象局,宁波 315000)
Analysis of Evolution Mechanism and Characteristics of Dual Polarization Radar Echo of a Hail Caused by Long-Life Supercell
GAO Li,PAN Jiawen,JIANG Lulu,WENG Zhimei
(Taizhou Meteorological Office of Zhejiang Province, Taizhou 318000;Laboratory of Straits Meteorology, Xiamen Meteorological Bureau, Xiamen 361012; Ningbo Meteorological Bureau, Ningbo 315000)
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投稿时间:2020-03-05    修订日期:2020-10-21
中文摘要: 2019年3月21日一次长生命史超级单体导致浙江省中部多个县(市)降雹,为了研究超级单体得以长时间维持的环境背景及其云物理特征,利用常规资料以及宁波S波段双偏振雷达数据,结合粒子相态识别算法,对此次过程的演变进行了分析。结果表明:高空槽前、850 hPa切变线附近和地面冷锋为超级单体提供了合适的环流背景;风暴传播区域对流有效位能的增加、风暴承载层的平均风向与风暴移动方向相近、风速大、对流风暴沿地面假相当位温梯度大值区向东传播及沿海强垂直风切变,导致中气旋旋转速度和旋转厚度的增加,这些都是对流风暴长时间维持的原因。通过此次降雹单体风暴结构分析发现:整个生命史对流发展非常旺盛,最大反射率维持在60 dBz以上,风暴顶维持在8 km以上,风暴质心高度出现的三次明显波动,对应三次降雹过程。垂直累积液态含水量(VIL)跃增量虽不及传统指标,但结合垂直累积液态含水量密度(VILD)、VIL最大值及〖JP2〗最大反射率因子大值区,对冰雹业务预报有指示作用。通过降雹单体双偏振特征分析发现:冰雹下落过程中的翻滚现象,导致差分反射率(Zdr)值接近0 dB,水平和垂直偏振波差异导致三体散射特征(TBSS)根部Zdr大值区的出现;冰雹降落融化产生的外包水膜现象,使其Zdr值增大,相关系数(CC)值减小;通过偏振参数Zdr和CC特征,有助于识别高空大冰雹;超级单体的有界弱回波区(BWER)附近的Zdr柱不仅可指示上升运动,同时对降雹单体不同的成长阶段具有指示作用。
Abstract:On 21 March 2019, a hail process caused by long-life supercell occurred in Zhejiang Province. In order to study the environmental background and microphysical characteristics of supercell which maintained for a long time, we analyze the evolution of this process by using conventional data, Ningbo S-band dual polarization radar data and hydrometeor classification algorithm. The results show that the high-level trough, 850 hPa shear line and the surface cold front provided suitable background for the supercell. The increase of effective convective potential energy in the storm propagation area, high speed of storm bearing layer, the similarity of the mean wind direction of the storm bearing layer and moving direction of the storm, as well as the eastward propagation of the convective storm along the high pseudo-equivalent potential temperature gradient of surface, and the increase of rotation speed and thickness of mesocyclone produced by the enhancement of strong vertical wind shear in the coastal area, all these factors are the causes of making the convective storm maintain for a long time. Through the analysis of the structure of the hailstorm, the vigorous convection (the maximum reflectivity above 60 dBz, the storm top above 8 km) was found in the whole life cycle, and three obvious fluctuations in the height of storm centroid appeared, corresponding to three hail processes. In this case the vertical integrated liquid water content (VIL) jump increment was lower than the traditional index, but the combination of the vertical integrated liquid water content density (VILD), the maximum VIL and the maximum reflectivity factor could still indicate the hailstorm. The analysis of the dual polarization characteristics, suggest that the tumbling of falling hail resulted in the Zdr close to 0 dB, and the difference between horizontal and vertical polarization waves led to the appearance of large Zdr region at the root of TBSS. The water coated phenomenon made the Zdr value increase and CC value decrease. The polarization parameters Zdr and CC could be used to identify hail in high altitude; Zdr column, near BWER, could not only indicate the ascending motion, but also reveal the different growth stages of hail cell.
文章编号:     中图分类号:P412    文献标志码:
基金项目:国家自然科学基金项目(41675029)、浙江省气象科技计划项目(2019QN23,2019YB12,2019YB18)和福建省气象局基层科技专项(2019J06)共同资助
引用文本:
高丽,潘佳文,蒋璐璐,翁之梅,2021.一次长生命史超级单体降雹演化机制及双偏振雷达回波分析[J].气象,47(2):170-182.
GAO Li,PAN Jiawen,JIANG Lulu,WENG Zhimei,2021.Analysis of Evolution Mechanism and Characteristics of Dual Polarization Radar Echo of a Hail Caused by Long-Life Supercell[J].Meteor Mon,47(2):170-182.