摘要
【目的】为研究云贵高原东侧台地对流云(冰雹)单体形成发展演变过程。【方法】结合冰雹云单体回波演变特征,着重分析了2018年5月17日和2019年4月27日2次冰雹天气过程冰雹云单体Zh、Zdr、φdp、ρhv等偏振参量特征,以及不同相态降水粒子分布与温度形成环境条件的对应关系。【结果】(1)若以45 dBz回波高度在0℃层高度以上、回波强度Z≥55 dBz、VIL≥20 kg·m-2作为冰雹识别指标,比降雹时间提前1~3体扫观测时间,冰雹预警时间提前量为6~18 min。(2)非球形大粒子区的Zdr在2.8~5.4 dB之间,φdp在179~191°之间,ρhv在0.85~0.99之间,与强回波区相对应,主要是有大雨滴粒子群所组成,近似于球形大粒子区的Zdr在-2.3~1.2 dB之间,φdp在180~235°之间,ρhv在0.54~0.90之间,主要分布的是霰或冰雹等球形粒子。(3)当近似于球形粒子(冰雹)位于非球形粒子(雨滴)的前侧且存在Zdr正中心区和负中心区时,这是由于风向风速的拖曳作用,使大雨滴团移动较小,霰或小冰雹朝向风的方向移动较快而使其处于强回波区前沿的结果。(4)研究中粒子识别分类算法没有考虑水凝物粒子所存在的温度环境条件,导致暖云中存在湿雪(WS)、冰晶(CR)等固态降水粒子,且缺少霰粒子分类识别产品,因而需要对水凝物粒子分类识别算法予以改进。【结论】研究结果可为偏振参量订正、数据质量控制和模糊逻辑粒子相态识别算法改进提供参考。
Based on two hailstorm processes on May 17,2018 and April 27,2019,combined with the radar echo evolution characteristics of the single hail-cloud cells,the characteristics of the polarization parameters such as Z h,Z dr,φdp,andρhv of the single hail_cloud cells are analyzed.Moreover,the corresponding relationship between the distribution of precipitation particles in different phases and the ambient condition of temperature formation are also investigated.The analysis results show that:(1)If the 45 dBz echo height is above the 0℃layer height,the echo intensity Z≥55 dBz and VIL≥20 kg·m-2 are used as hail identification indicators,the body scanning observation time will be 1~3 times earlier than the hail fallout time and the advance of hail warning time is 6~18 minutes.(2)The Z dr of the non-spherical large particle area is between 2.8~5.4 dB,φdp is between 179~191°andρhv is between 0.85~0.99,which corresponds to the strong echo area where there are mainly large raindrop particles.The Z dr of the approximately spherical large particle area is between-2.3~1.2 dB,φdp is between 180~235°andρhv is between 0.54~0.90,with spherical particles such as graupel or hail mainly distributed.(3)When approximately spherical particles(hail)are located on the front side of non-spherical particles(raindrops)and there are positive and negative central areas of Z dr,the drag effects of wind direction and speed make the large raindrop cluster move slowly while graupel or small hails move faster in the direction of the wind,which is the result of their staying at the front of the strong echo zone.(4)The particle identification and classification algorithm in this study does not consider the temperature and ambient conditions of hydrometeor particles,so there exist solid precipitation particles such as wet snow(WS)and ice crystals(CR)in warm clouds,and there is a lack of graupel particle classification and identification products.Therefore,the hydrometeor particle classification and identification algorithm needs to be improved.
作者
邹书平
柯莉萍
曾勇
罗雄
黄钰
李丽丽
ZOU Shuping;KE Liping;ZENG Yong;LUO Xiong;HUANG Yu;LI Lili(Guizhou Institute of Mountainous Meteorological Sciences,Guiyang 550081,China;Bijie Meteorological Office of Guizhou Province,Bijie 551700,China;Guizhou Meteorological Observatory,Guiyang 550002,China)
出处
《山地气象学报》
2024年第3期12-23,共12页
Journal of Mountain Meteorology
基金
贵州省气象高层次人才创新团队“冰雹形成机理和防控技术研究”
毕节市科学技术项目(毕科合[2023]8号)
贵州省科技支撑计划(黔科合支撑[2023]一般194)
贵州省科学技术基金(黔科合基础ZK[2023]一般200)。
关键词
冰雹云
演变特征
偏振参量
粒子识别
预警时间
hail cloud
evolution characteristics
polarization parameters
particle identification
warning time
