冰晶核化对雷暴云闪电行为影响的数值模拟研究  

A numerical study on the effect of ice nucleation on thundercloud lightning behavior

作　　者：谭涌波[1] 向春燕[1] 马肖[1] 夏艳羚 张鑫[1] 

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心/中国气象局气溶胶与云降水重点开放实验室,南京210044

出　　处：《气象学报》2017年第2期328-341,共14页Acta Meteorologica Sinica

基　　金：国家重点基础研究发展计划(973计划)项目(2014CB441403);国家自然科学基金项目(41475006)

摘　　要：为了探讨冰晶核化对雷暴云闪电行为的影响,通过已有的三维对流云起、放电模式探讨对比了3种冰晶核化方案,分别为原模式中的经验公式YS方案及与气溶胶相关的DE方案和LP方案。研究表明冰晶核化方案对雷暴云内冰晶微物理发展特征、起电及放电过程均有一定影响。模拟结果显示:(1)考虑了气溶胶的两种新参数化方案中冰晶粒子在高温区(高于-13.8℃)出现,在雷暴云发展过程中DE方案和LP方案冰晶的垂直分布均大于YS方案。(2)DE方案和LP方案中高温区出现的冰晶所带电荷极性有明显的反转现象,导致雷暴云电荷结构产生差异;雷暴云发展旺盛时刻DE方案和LP方案出现三级性电荷结构,而YS方案在整个雷暴云过程都是偶极性,并且DE方案和LP方案中电荷空间分布区域更加广泛。(3)不同核化方案下雷暴云放电特征存在差异,YS方案在偶极性电荷结构背景下没有负地闪产生,而DE方案和LP方案中次正电荷区的存在促进了负地闪的发生,并且负先导出现在较低的高度范围内;DE方案和LP方案中电荷量级较大,因此云闪发生频次以及正、负先导传播次数增加明显。A three-dimensional （3-D） cumulus model with electrification and lightning process is used to investigate the differ- ences in electrification and lightning process between different ice crystal nucleation schemes. Three ice crystal nucleation schemes are adopted in this study, which are the original empirical formula YS scheme and DE scheme and LP scheme associat- ed with aerosols. The present study indicates that the micro-process and electrification and lightning process of thunderstorm are influenced by different ice crystals nucleation schemes. Simulation results show that.. （1） ice crystals appear in high temper- ature（〉- 13. 8℃） region in the two new schemes associated with aerosols, the vertical distribution of ice crystals in DE scheme and LP scheme is greater than that in the YS scheme throughout the thundercloud development process; （2） ice crystals in high temperature region with charges in DE scheme and LP scheme show an obvious polarity reversal phenomenon, which leads to differences in the charge structure among the three schemes. The charge structure is tripolar in DE and LP scheme across the development time of thunderstorm, while it is dipolar in the YS scheme during the entire lifespan of the thunder- storm. The charge distribution area and the number of charges in DE and LP scheme are greater than in the YS scheme; （3） the thundercloud discharge behavior in different schemes is discrepant. Negative cloud-to-ground lightning is not generated in YS scheme because of the dipolar charge structure, whereas the lower positive charges in DE and LP scheme increase negative cloud-to-ground lightning and negative leader segments appear in the lower levels; the intra-cloud flash frequency and the trans- mission of positive and negative leader segments significantly increase in DE and LP scheme because the magnitude of charge in DE scheme and LP scheme are greater than that in YS scheme.

关 键 词：冰晶 核化方案 起电率 电荷结构 放电特征 

分 类 号：P426.51[天文地球—大气科学及气象学]