四川盆地秋季一次层状云弱降水过程的微物理特征观测分析  

Analysis on the microphysical characteristics of weak precipitation process observation of a stratiform cloud in Sichuan Basin in autumn

作　　者：范思睿[1,2,3] 王维佳 FAN Sirui;WANG Weijia(Weather Modification Office of Sichuan Province,Chengdu 610072;CMA Cloud-Precipitation Physics and Weather Modification Key Laboratory(CPML),Beijing 100081;Key Laboratory of Atmosphere Soundin of China Meteorological Administration,Chengdu 610103)

机构地区：[1]四川省人工影响天气办公室,成都610072 [2]中国气象局云降水物理与人工影响天气重点开放实验室,北京100081 [3]中国气象局大气探测重点开放实验室,成都610103

出　　处：《暴雨灾害》2022年第4期445-457,共13页Torrential Rain and Disasters

基　　金：公益性行业气象科研专项(GYHY201406032);四川省科技计划项目(2022YFS0545);中国气象局云雾物理环境重点实验室开放课题(2019Z01602);中国气象局大气探测重点开放实验室开放课题(2021KLAS04M);高原与盆地暴雨旱涝灾害四川省重点实验室科技发展基金(SCQXKJQN2019025)。

摘　　要：利用Ka波段毫米波云雷达联合雨滴谱仪、L波段探空和地面常规气象台站等观测资料对四川盆地秋季一次层状云弱降水过程进行观测,分析研究了其宏、微观结构特征及雨滴谱分布特征,并对云中融化层(零度层亮带)进行详细的分析和对比。结果表明:(1)云系内有对流泡,雨强大部分集中在2 mm·h^(-1)以下,降水峰值与对流泡具有较好的对应关系。(2)降水发生前主要为层状云,云顶高度约为3 km,云底高度约为1.5 km,云中主要以粒径小、相态单一的液相粒子为主;降水发展期的云系以层状云为主,伴随对流泡发生,层状云顶高度约为4 km,云系内的对流泡云顶最高可达10 km,雷达回波及地形成地面降水,云中有明显的零度层亮带(融化层)现象;降水消散期的云系变为双层云,下层以层积云为主,云顶高度在4 km以下,以粒径小、相态单一的液相粒子为主,上层云以高积云为主,云底高度约在5 km,云顶高度延伸到8 km以上,以粒径小、相态单一的冰相粒子为主。(3)降水发生前和降水发展期云滴谱呈单峰结构,谱较窄,谱宽在0.312~2.375 mm之间,峰值位于0.437 mm,以小粒子为主,降水消散期为双峰型,峰值位于0.437 mm和1.375 mm之间。降水发展期雨滴谱和数浓度相对更大。(4)层状降水云零度层亮带厚度为200~600 m,不同雷达参量上亮带厚度不同;退偏振比对零度层亮带最为敏感,最早在垂直廓线上出现亮带信息,是粒子相态变化的重要指标;亮带厚度与径向速度、谱宽、退偏振比差值相关度很高,但与回波强度差值关系不大。Using observation data from a Ka-band millimeter wave cloud radar, a raindrop spectrometer, a L-band Basin in autumn is analyzed, especially focusing on its macro and microstructure characteristics and raindrop spectrum distribution characteristics. The melting layer(radar echo bright band) is analyzed in detail. The results are as follows.(1) There were convective bubbles in the cloud system. The rainrate was mostly below 2 mm·h^(-1), and the peak precipitation had a good correspondence with the convective bubbles.(2) The cloud system before precipitation was mainly stratiform with the cloud top about 3 km and the cloud base about 1.5 km. Cloud drops were mainly liquid particles with small particle size and in single phase state. The cloud system during the precipitation development period was dominated by stratiform clouds, accompanied by convective bubbles. The stratified cloud top was about 4 km, and the convective bubble cloud top in the cloud system reached up to 10 km. The radar echoes reached the ground and ground precipitation formed. There was a clear bright band(melting layer) phenomenon in the cloud system. Above the melting layer were ice crystals, graupels, super-cooled water, etc. In the melting layer clouds were consisted of mixed-phase particles. Below the melting layer there were raindrops, super-cooled water, drizzles, etc. The cloud system during the precipitation dissipation period became double-layer. The lower layer was dominated by stratocumulus clouds, with cloud tops below 4 km, dominated by liquid particles with small particle sizes and in single phase state. The upper layer was dominated by altocumulus clouds, the cloud base was about 5 km, and the cloud top extended above 8km, which was dominated by ice particles with small particle size and in single phase state.(3) The cloud drop spectra in the early precipitation period and the development period showed single peak structure, mainly small particles. The spectra were narrow. The spectra width was between 0.312 mm and 2.375 mm. The

关 键 词：四川盆地 层状降水云 云雷达 雨滴谱分布 微物理特征 

分 类 号：P426.62[天文地球—大气科学及气象学]