Numerical simulation of the effect of lower positive charge region in thunderstorms on different types of lightning  

作　　者：TAN YongBo LIANG ZhongWu SHI Zheng ZHU JunRu GUO XiuFeng 

机构地区：[1]Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology [2]Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology

出　　处：《Science China Earth Sciences》2014年第9期2125-2134,共10页中国科学（地球科学英文版）

基　　金：supported by the National Basic Research Program of China(Grant No.2014CB441403);the National Natural Science Foundation of China(Grant No.41175003);Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)

摘　　要：Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulations are performed to quantitatively investigate the effect of lower positive charge(LPC) on different types of lightning. The results show:(1) The LPC plays a key role in generating negative cloud-to-ground(CG) flashes and inverted intra-cloud(IC) lightning, and with the increase of charge density or distribution range of LPC region, lightning type changes from positive polarity IC lightning to negative CG flashes and then to inverted IC lightning.(2) Relative to distribution range of charge regions, the magnitude of charge density of the LPC region plays a dominant role in lightning type. Only when the maximal charge density value of LPC region is within a certain range, can negative CG flashes occur, and the occurrence probability is relatively fixed.(3) In this range, the charge density and distribution range of LPC region jointly determine the occurrence of negative CG flashes, which has a linear boundary with the trigger condition of IC lightning.(4) The common effect of charge density and distribution range of the LPC region is to change the distribution of positive potential well of bottom part of thunderstorms, and inverted IC lightning occurs when the initial reference potential is close to 0 MV, and negative CG flashes occur when the initial reference potential is far less than 0 MV.Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulations are performed to quantitatively investigate the effect of lower positive charge （LPC） on different types of lightning. The results show： （1） The LPC plays a key role in generating negative cloud-to-ground （CG） flashes and inverted intra-cloud （IC） lightning, and with the increase of charge density or distribution range of LPC region, lightning type changes from positive polarity IC lightning to negative CG flashes and then to inverted IC lightning. （2） Relative to distribution range of charge regions, the magnitude of charge density of the LPC region plays a dominant role in lightning type. Only when the maximal charge density value of LPC region is within a certain range, can negative CG flashes occur, and the occurrence probability is relatively fixed. （3） In this range, the charge density and distribution range of LPC region jointly determine the occurrence of negative CG flashes, which has a line- ar boundary with the trigger condition of IC lightning. （4） The common effect of charge density and distribution range of the LPC region is to change the distribution of positive potential well of bottom part of thunderstorms, and inverted IC lightning occurs when the initial reference potential is close to 0 MV, and negative CG flashes occur when the initial reference potential is far less than 0 MV.

关 键 词：lower positive charge charge density distribution range lightning type numerical simulation 

分 类 号：P427.321[天文地球—大气科学及气象学]