多上行先导模型先导传播速率比优化及模拟研究  

Optimization and Simulation of Leader Propagation Rate Ratio in Multiple Upward Leader Model

作　　者：王雪雯 谭涌波[1] 林雨荷 吴萌 Wang Xuewen;Tan Yongbo;Lin Yuhe;Wu Meng(Emergency Management College,Nanjing University of Information Science&Technology,Nanjing 210044;State Key Laboratory of Severe Weather&CMA Key Laboratory of Lightning,Chinese Academy of Meteorological Sciences,Beijing 100081)

机构地区：[1]南京信息工程大学应急管理学院,南京210044 [2]中国气象科学研究院灾害天气国家重点实验室/中国气象局雷电重点开放实验室,北京100081

出　　处：《应用气象学报》2024年第2期237-246,共10页Journal of Applied Meteorological Science

基　　金：国家自然科学基金面上项目(42275075);灾害天气国家重点实验室开放课题(2023LASW-A03)。

摘　　要：下行先导与上行先导的相对速率比可能是闪电连接过程的关键因子之一,随机闪电连接模式中先导相对传播速率比不能准确描述下行与上行先导的相对传播距离比值。考虑到光学观测事实及雷暴电场环境,在已有多上行先导三维随机参数化方案的基础上对下行负地闪开展模拟,改进背景电场模块设置,并植入下行负先导与上行正先导相对传播速率模块,以先导传播距离为依据设置先导相对传播速率。将改进后的模型应用于平顶单建筑物触发多上行先导现象的模拟,与改进前相比,该模型的闪击距、上行先导长度等参数与自然闪电一致性更好;在此基础上对发生在广州珠江新城高建筑物群上的地闪连接过程进行模拟,改进后的模型能够较好还原复杂建筑物群的闪电发生规律。城市建筑物群的雷击特征参量主要由各个建筑物的形状特征、相对位置以及相对高度等因素所决定,但仍有特殊事件发生,当下行先导的某一分支与建筑物空间距离临近时,会在建筑物顶部起始上行先导并连接。During the process of cloud-to-ground lightning connection,the propagation of downward leader to the near-ground area can elevate the electric field at one or several points on the surface of ground tip object to the breakdown threshold of surrounding air,initiating one or more upward leaders,which are known as multiple upward leaders.The emergence of tall buildings has led to an increase in the number of observations of upward lightning strikes on different buildings or the same building.The presence of multiple upward leaders means that multiple parts of the building may be struck.Conducting simulation experiments to study the mechanism of the multiple upward leader phenomenon is of great significance for developing lightning protection.The relative velocity ratio of the downward and upward leaders may be one of the key factors in the lightning connection process.The relative speed ratio of leader propagation in random lightning connection mode cannot accurately describe the relative distance ratio of downward and upward leader propagation.Taking into account the optical observation facts and the electric field environment during thunderstorms,the background electric field module setting is improved on the basis of the existing threedimensional random mode for multiple upward leaders.It also incorporates a relative propagation speed module for the downward negative and upward positive leaders,establishing the relative propagation speed of leaders according to their propagation distance.Applying the new model to simulate multiple upward leader phenomena triggered by a flat-roofed single building,compared with the previous version,parameters of the new model,such as flash distance and upward leader length,show better consistency with natural lightning.On this basis,the lightning connection process on the high-rise buildings in the Pearl River New Town is simulated,and the improved model can more accurately replicate the lightning occurrence patterns of complex buildings.Characteristic parameters of lightning stri

关 键 词：先导速率 建筑物群 多上行先导 连接过程 数值模拟 

分 类 号：P427.3[天文地球—大气科学及气象学]