2020年梅雨期长江中下游地区雨滴谱垂直结构特征  

Vertical structures of raindrop size distributions over the middle and lower reaches of Yangtze River during the Meiyu period in 2020

作　　者：周伶俐 付志康[1] 徐桂荣[1] 王基鑫 王斌[1] ZHOU Lingli;FU Zhikang;XU Guirong;WANG Jixin;WANG Bin(China Meteorological Administration Basin Heavy Rainfall Key Laboratory/Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research,Institute of Heavy Rain,China Meteorological Administration,Wuhan 430205;Lanzhou Central Meteorological Observatory,Lanzhou 730020)

机构地区：[1]中国气象局武汉暴雨研究所中国气象局流域强降水重点开放实验室/暴雨监测预警湖北省重点实验室,武汉430205 [2]兰州中心气象台,兰州730020

出　　处：《暴雨灾害》2023年第4期455-466,共12页Torrential Rain and Disasters

基　　金：国家自然科学基金项目(42230612,41620104009);中国气象局创新发展专项(CXFZ2022J010);湖北省气象局科技发展基金项目(2020Z04);甘肃省青年科技基金计划项目(21JR7RA704);湖北省气象局科研项目(2023Y18);湖北省自然科学基金气象创新发展联合基金培育项目(2022CFD122)。

摘　　要：雨滴谱是反映降水微物理特征的重要参数,研究雨滴谱垂直结构特征有助于认识降水演变过程和改善雷达定量降水估计。基于秭归、荆州和南京三站并址观测的微雨雷达和二维视频雨滴谱仪数据,探讨了2020年梅雨期不同地区、不同降水强度下的雨滴谱垂直结构特征。结果表明,雨滴下落过程中,小雨滴的数浓度和对降水强度的贡献在减少,中等雨滴和大雨滴的数浓度和对降水强度的贡献在增加,最后导致对地面降水强度有最显著贡献的是中等雨滴。不同降水强度的雨滴谱垂直结构存在明显差异,弱降水时,雨滴谱较窄,雨滴蒸发和碰并作用相均衡,雨滴谱参数变化小;强降水时,雨滴谱明显拓宽增高,雨滴间存在明显的碰并过程,中滴和大滴数浓度随高度降低而增大,雨滴谱参数出现明显变化。统计分析显示,雨滴谱有明显的区域性差异,秭归数浓度最高但雨滴直径最小,荆州数浓度中等且雨滴直径中等,南京数浓度最低但雨滴直径最大。不同地区的μ-Λ关系具有差异,采用不同地区构建的Z-R关系估算的降水强度与观测值比较一致。Droplet size distribution(DSD)is an important parameter reflecting microphysical characteristics of rainfalls,research on vertical structures of DSD is helpful to understand rainfall evolution processes and improve radar quantitative precipitation estimations.Vertical structures of DSDs under different rain rates over different regions during the Meiyu period in 2020 have been investigated using the co-located two-dimensional video disdrometer(2DVD)and micro rain radar(MRR)at the stations of ZiGui,JingZhou and NanJing.It is found that,when raindrops fall,the number concentration of small raindrops and their contribution to rain rates decrease,while the number concentration of medium and large raindrops and their contribution to rain rates increase,which finally leads to that medium raindrops contribute most significantly to surface rain rates.Vertical structures of DSDs under different rain rates are different.For weak rainfall,there are narrow DSDs and the equilibrium of raindrop evaporation and coalescence causes small variation in DSD parameters.For heavy rainfall,there are significantly widened and increased DSDs,because obvious collision process increases the concentration of medium-large raindrops when raindrops falls and thus causes large variation in DSD parameters.Statistical analysis shows that DSDs present significant difference over different regions:the highest number concentration and the smallest raindrop diameter at ZiGui,medium number concentration and medium diameter at Jinzhou,the lowest number concentration and the largest diameter at Nanjing.Moreover,μ-Λ relationships present regional difference,and the fitted values of rain rates with local Z-R relationships over different regions agree well with the observations of 2DVD.

关 键 词：雨滴谱 微物理过程 Z-R关系 μ-Λ关系 

分 类 号：P412.13[天文地球—大气科学及气象学]