下行梯级先导诱发的上行先导的观测与研究

项目名称： 下行梯级先导诱发的上行先导的观测与研究

项目编号： No.41475003

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 吕伟涛

作者单位： 中国气象科学研究院

项目金额： 96万元

中文摘要： 基于已有的广州高建筑物雷电观测站，通过补充新的观测手段，针对下行梯级先导在高建筑物上诱发的上行连接和未连接先导开展综合观测与研究：远距离单站/双站光学观测和统计分析雷电连接过程中下行和上行先导的二维/三维发展特征，研究不同先导之间的相互作用；对近距离的上行未连接先导开展电流和高速摄像的同步观测，分析其电流特征和对应的通道发展特征，并结合对诱发这些上行未连接先导的地闪事件的全视野闪电通道图像、雷声和电磁场变化的观测，分析下行梯级先导对上行先导起始及发展的影响；改进现有的先导发展模式，实现对上行先导不稳定-稳定阶段的转化以及发展速率变化的模拟，并对孤立和多个高建筑物以及顶部有无高耸尖端等下垫面条件时上行先导的激发及其与下行先导的连接过程进行模拟研究。本研究将提升我们在雷电连接过程中不同先导的发展特征、不同先导之间的相互作用以及城市区域高建筑物（群）对下行地闪的影响等方面的科学认识。

中文关键词： 地闪；高建筑物；上行先导；下行梯级先导；光电同步观测

英文摘要： Based on the Guangzhou tall-object-lightning observation platform, new instruments will be supplemented to observe and study the characteristics of the upward leaders (including the upward connecting leader, UCL, and the unconnected upward leader, UUL) initiated from tall structures under the influence of the downward stepped leader (DL) in natural cloud-to-ground lightning. The two-dimensional/three-dimensional propagation characteristics of the downward and upward leaders in the attachment process will be statistically analyzed by using single-station/dual-stations long-distance optical observation data, and the effects between different leaders will be studied. The simultaneous channel current measurement and high-speed video observation of the UUL close to the observation site will be carried out. The UUL's current characteristics and the corresponding propagation characteristics of the channel will be analyzed. The total-sky lightning channel image, thunder, electric field change, and magnetic field change observations of the nearby lightning flash that induces the UUL will also be performed, and these data can be used to analyze and discuss the effect of the DL on the inception and propagation of the UUL. The existing lightning leader propagation numerical model will be improved by implementing the simulations of the transform of unstable-stable stages and the variation of the propagation speed of the upward leader. The inception of the upward leader and the attachment process will be simulated and studied under different underlying surface conditions, such as single or multiple tall structures, with or without towering tip on the structure top. The research of this project will improve our scientific knowledge on the propagation characteristics of different leaders in lightning attachment process, the effects between different leaders, and the influence of tall structure (or structures complex) on the process of natural downward lightning flash.

英文关键词： Cloud-to-ground Lightning;Tall Structure;Upward Leader;Downward Stepped Leader;Optical and Electrical Observation