雨滴谱分布参数化对改进新疆强降水过程预报的评估  

Assessing Raindrop Size Distribution Parameterization for Enhanced Prediction of Heavy Precipitation Process in Xinjiang

作　　者：舒未希 范水勇 黄颖 任婧 沈淑婧 SHU Weixi;FAN Shuiyong;HUANG Ying;REN Jing;SHEN Shujing(Key Laboratory of Cloud–Precipitation Physics and Severe Storms(LACS),Institute of Atmospheric Physics(IAP),Chinese Academy of Sciences(CAS),Beijing 100029;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences(UCAS),Beijing 100049;Institute of Urban Meteorology,China Meteorological Administration(CMA),Beijing 100089;College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000;School of Information Engineering,Zhengzhou University,Zhengzhou 450001;Cloud–Precipitation Physics and Weather Modification Key Laboratory(CPML),China Meteorological Administration,Beijing 100081;Weather Modification Center,China Meteorological Administration(CMA),Beijing 100081)

机构地区：[1]中国科学院大气物理研究所云降水物理与强风暴重点实验室,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]北京城市气象研究院,北京100089 [4]兰州大学大气科学学院,兰州730000 [5]郑州大学信息工程学院,郑州450001 [6]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 [7]中国气象局人工影响天气中心,北京100081

出　　处：《大气科学》2023年第4期1131-1150,共20页Chinese Journal of Atmospheric Sciences

基　　金：国家重点研发计划项目2018YFC1507105。

摘　　要：本文利用2018年7月3日至10月3日新疆乌鲁木齐的雨滴谱观测资料,改进了乌鲁木齐区域高分辨率数值预报系统中WRF模式的WSM6单参数方案,对新疆2021年6月15日12时(北京时,下同)至17日00时一次强降水过程的预报改进效果进行评估研究。结果表明:观测显示,乌鲁木齐地区雨滴平均直径(D0)、最大直径(D_(max))和质量加权平均直径(D_(m))分别为0.65 mm、1.60 mm和0.93 mm。引入新疆地区参数lgNw和D_(m)拟合关系的WSM6-new方案对降水强度和强中心范围的预报能力均有一定提高。从TS、BR、ETS和TSS四个指标的评分结果上看,随着降雨等级的增加,WSM6-new方案预报能力相比WSM6方案明显提高,对于大雨和暴雨的预报显示出明显的优势。不同雨滴谱分布参数化方案对降水云系结构特征、垂直速度、大气层结和散度场都有着一定的影响,对于云微物理过程的影响主要体现在雨水含量和分布上。WSM6-new方案引入了新疆雨滴谱统计特征,在模式中对雨滴谱分布的描述更接近实际。雨滴谱的大雨滴数浓度明显增加,雨滴下落末速度增加,拖曳作用增强,有利于零度层以下的下沉气流增强和维持。强下沉气流在近地层形成更强的辐散出流,加强了近地面对流区气流的辐合,有利于上升气流的发展加强,从而地面产生更强的降水,对暴雨的预报能力明显增强。Utilizing the raindrop spectrum observation data from Urumqi,Xinjiang,collected between 3 July and 3 October 2018,this study aimed to enhance the WRF Single-Moment 6-class(WSM6)scheme in the Urumqi regional highresolution numerical prediction system.The improved scheme’s effectiveness in predicting heavy precipitation events was evaluated in Xinjiang from 1200 BJT(Beijing time)on 15 June to 0000 BJT on 17 June 2021.The results indicated that the average diameter(D0),_(max)imum diameter(D_(max)),and mass-weighted average diameter(D_(m))of raindrops in Urumqi were 0.65 mm,1.60 mm,and 0.93 mm,respectively.Furthermore,the refined WSM6-new scheme,which considered the fitting relationship between parameters lgNw and D_(m)in Xinjiang,enhanced the prediction capability for precipitation intensity and strong center ranges to some extent.Evaluation metrics,such as TS,BR,ETS,and TSS,revealed that the WSM6-new scheme significantly improved the prediction accuracy as precipitation grade increased,specifically for heavy and torrential rainfall.Different raindrop size distribution parameter schemes influenced precipitation cloud systems characteristics,vertical velocities,atmospheric stratification,and divergence field.Moreover,the effect on cloud microphysical processes primarily manifested in rainwater content and distribution.The WSM6-new scheme incorporated the statistical characteristics of Xinjiang’s raindrop spectrum,rendering the raindrop size distribution in the model more accurate.The number concentration of larger raindrops in the raindrop spectrum increased significantly,along with terminal raindrop velocity and enhanced drag effects.This facilitated the intensification and maintenance of downdraft below the freezing level.The strong downdraft generated a powerful divergent outflow near the ground layer,which intensified air convergence in the ground-level convection area,promoting updraft development and strengthening.Consequently,a more intense precipitation process occurred at the surface,and the prediction c

关 键 词：新疆 WRF模拟 WSM6参数化方案 暴雨 雨滴谱 降水预报评估 

分 类 号：P435[天文地球—大气科学及气象学]