基于双偏振雷达对一次多单体雹暴微物理特征的观测及数值模拟研究

Observation and Numerical Simulation of Microphysical Characteristics of a Multi-cell Hail Storm based on Dual Polarization Radar

为了解多单体合并作用对雹胚及冰雹演变的微物理特征,利用位于贵州威宁县雪山镇的X波段双偏振雷达,在观测资料质量控制的基础上,结合模糊逻辑粒子相态识别算法(HID)和WRF中尺度模式,对2018年6月28日云南鲁甸县的一次多单体合并降雹天气过程进行分析。结果表明:此次多单体合并过程,观测识别与模式模拟结果整体一致,经历3个主要阶段:合并前阶段、合并中阶段(合并初期)、合并后阶段(合并后期)。合并前阶段:低密度霰(LDG)由雪晶(AG)和冰晶(CR)作为共同低密度霰胚源进行凇附增长;高密度霰(HDG)的两种源项分别为LDG粒子撞冻过冷云水和以AG为高密度霰胚的凇附增长。合并阶段:AG主要由CR为晶核聚合而成,CR的凝华增长参与较小;霰粒子主要以AG为胚源,形成于-5℃~-35℃层,为过冷云水与AG的混合相态区。合并后期:合并作用促进了单体内HDG的碰并增长,并最终以HDG为雹胚源形成冰雹(RH),在RH下落过程中继续撞冻过冷水保持增长并及地。合并作用使单体内部产生新的动力,使处于衰减状态的单体出现新的发展趋势;合并作用导致降雹过程产生,且降雹过程出现在多单体合并的第三个阶段,即合并后阶段(合并后期)。

For understanding the microphysical characteristics of hail embryo and hail evolution by multi-cell interaction,by the X band double polarization radar located in Xueshan Town,Weining County,Guizhou Province,on the basis of quality control of observation data,combined with fuzzy logic particle phase state recognition algorithm(HID)and WRF mesoscale model,the hail weather process of a multi-cell merger in Ludian County,Yunnan Province on June 28,2018 was analyzed.The results show that the multi-cell merging process,the observation recognition and pattern simulation results are the same as the whole,a total of three main stages,which contains the pre-merger stage,the merging stage(the initial stage of the merger)and the post-merger stage(the late phase of the merger).The pre-merger stage:snow crystal(AG)and ice crystal(CR)are used as the common source of low-density graupel(LDG)embryo to carry out the growth of riming adhesion,the two source terms of high density graupel(HDG)are respectively LDG particle collision with frozen supercold cloud water and growth of riming with AG as high density graupel embryo.The merging stage:the AG is mainly composed of CR nucleation polymerization,and the CR condensation growth is less involved;the graupel particles are mainly AG as the embryo source and formed between the-5℃--35℃layers,which are the mixed phase region of super-cooled cloud water and AG.The post-merger stage:the combination promoted the collision and growth of the HDG in the monomer,and finally took the HDG as the source of hail embryo to form hail(RH),and continued to collide with the cold water to maintain the growth and reach the ground during the RH falling process.Merger will create a new dynamic inside the monomer and a new development trend of the attenuated monomer.Merger will lead to hail,and this processes appear in the third stage of multi-cell merging,that is,the post-merger stage(the late phase of the merger).