基于X波段双偏振雷达对雷暴单体中水成物粒子演变特征的研究

为了解雷暴单体内部水成物粒子分布结构及演变过程，综合X波段双线偏振天气雷达的参量及环境温度参数，结合小波去噪和自适应约束算法进行资料预处理后，基于模糊逻辑算法对北京一个结构演变相对完整的典型雷暴单体内水成物粒子分布随时间演变特征进行系统的分析，得到如下结果:（1）按雷暴单体的宏观特征将其演变过程分为发展、成熟和消散阶段。三个阶段中单体平均高度分别为11、12、10 km；回波强度最大可达40~45 dBZ、大于50 dBZ和40~45 dBZ；霰粒子占各自阶段单体内所有粒子百分比分别为2%、12%和1%。（2）各阶段主要微物理过程及演变特征是:发展阶段，单体0℃层以下由暖云过程主导，毛毛雨占5%，雨滴占24%；少量液态粒子上升至0℃层以上与冰晶反应生成1%干霰，冷云过程较弱。成熟阶段，相较发展阶段0℃层以下毛毛雨减少约2个百分点，雨滴增多约2个百分点，粒子碰并加强，暖云过程增强；较多液态粒子上升至0℃层以上，约有4%的雨滴与5%的冰晶通过凇附作用生成7%的霰，冷云过程增强。消散阶段，下层液态粒子难以上升至0℃层以上形成初始冰晶，使暖云及冷云过程都减弱，0℃层以下毛毛雨相较成熟阶段平均增多约1个百分点，粒子碰并减弱；0℃层以上冰晶消耗减少2个百分点，霰生成减少5个百分点。（3）基于雷暴单体内各类水成物粒子分布、演变及其动力场背景特征建立了雷暴单体演变过程微物理模型。本文研究有助于加深对典型雷暴单体内部水成物粒子分布和微物理过程的认识，可以为雷暴天气的预警和预报提供必要的指导。

Research on the Evolution Characteristics of Hydrometeors in a Thunderstorm Cell with X-Band Dual-Polarimetric Radar

In order to understand the distribution and evolution of hydrometeors in thunderstorm cells,a fuzzy logic algorithm is applied to analyze the evolution characteristics of hydrometeors in a typical thunderstorm cell that occurred in Beijing by utilizing the dual-polarization radar parameters and environmental temperature.Furthermore,a wavelet de-noising method and a self-consistent method with constraints (SCWC) are combined to preprocess the data.The results are as follows.(1) According to the macroscopic characteristics of the thunderstorm cell,the process is divided into three stages,i.e.the development stage,the mature stage and the dissipation stage.The average heights of the cell are 11,12 and 10 km,and the reflectivity can reach 40-45 dBZ,greater than 50 dBZ and 40-45dBZ in the three stages,respectively.Moreover,the percentages of graupels are 2％,12％ and 1％ in the three stages.(2) The main microphysical processes and evolving characteristics in each stage are as follows.In the development stage,the main microphysical process below the freezing level is warm-cloud process with 5％ of drizzle (DR) and 24％ of rain (RA).A small amount of liquid hydrometeors rises to the layer above the freezing level,reacting with dry crystal (DC) and generating 1％ of graupels,which actually is a weak cold cloud process.During the mature stage,there is an enhanced warm-cloud process with DR decreasing by a percentage of 2 and RA increasing by a percentage of 2.More liquid hydrometeors can rise to the layer above the freezing level and there is an enhanced cold cloud process with 4％ of RA and 5％ of DC converting to 7％ of graupels.At the last stage,the liquid hydrometeors below 0℃ layer cannot rise to the layer above 0℃,which leads to weaker warm and cold cloud processes.DR increases by a percentage of 1 below the freezing level while DC increases by a percentage of 2,and graupels above the fieezing level reduces by a percentage of 5.(3) Based on the above results and dynamic characteristic,a microphysical model of the thunderstorm cell's evolution process is established.This study is important for understanding the structure and microphysical processes of thunderstorm cells as well as improving the forecast of thunderstorm weather.