Development of Efficient Three-Dimensional Models of Lightning Discharges

高效三维闪电放电模型的开发

• 批准号: 0652148
• 负责人: Victor Pasko
• 金额: $ 46.25万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0652148&HistoricalAwards=false
• 关键词: Development; Efficient; Three; Dimensional; Models

A five-year effort will develop a set of efficient three-dimensional lightning models and apply these models to theoretically investigate a range of outstanding science questions related to thunderstorm electrification and development of different forms of lightning discharges. The outstanding questions which the research will seek to answer are:(1) Can lightning models based on a fractal approach provide realistic descriptions of different types of lightning discharges? What are the specific limitations of these models in terms of description of charges, potentials and electric fields of the overall lightning-thundercloud electric system? Can these models be modified to provide a computationally efficient parameterization of the streamer zones of both positive and negative lightning leaders? (2) What are the effective time scales of streamer-to-leader transition in air as a function of air pressure? What are the altitude range and other relevant physical conditions for which formation of leader channels is not possible in the Earth's atmosphere?(3) What are the specific thundercloud charge configurations which allow upward extensions of lightning leaders above thundercloud tops leading to recently discovered blue jet and gigantic jet phenomena? Are pressure scaled fractal models of streamer zones of positive and negative lightning leaders capable of describing experimentally observed features of blue jets and gigantic jets?The specific activities directed toward answering these questions will include development of three-dimensional numerical models based on a probabilistic approach to lightning modeling. These models will account for the best currently available knowledge for efficient representation of leader trees in the three dimensional computation domain and will include such features as open boundary conditions, preservation of full charge neutrality of leader trees at any point during simulations, and accurate modeling of lightning channels with finite resistivity. Model development will synergistically complement existing observationally-based research efforts at the New Mexico Institute of Mining and Technology directed toward investigation of electrical structure of thunderstorms, including studies of inverted-polarity electrical structures, lightning initiation studies, and studies of different and newly discovered types of lightning discharges.Broader impacts of the proposed activity include student training and education, synergistic collaboration between theoretical modelers and experimentalists, and the dissemination of results in the form of models to be shared with the community and in the form of publications summarizing new results.

一项为期五年的工作将开发一套有效的三维闪电模型，并应用这些模型从理论上研究与雷暴带电和不同形式闪电放电发展有关的一系列突出科学问题。 该研究将寻求回答的突出问题是：（1）基于分形方法的闪电模型能否提供不同类型闪电放电的真实描述？ 这些模型在描述整个雷电云电系统的电荷、电势和电场方面有哪些具体的局限性？ 这些模型可以被修改，以提供一个计算效率的参数化的流光区的积极和消极的闪电领导人？(2)在空气中，随气压变化的拖缆到先导过渡的有效时间尺度是多少？ 在地球大气层中不可能形成先导通道的高度范围和其他相关物理条件是什么？(3)是什么样的雷暴云电荷结构使得闪电先导在雷暴云顶上方向上延伸，导致最近发现的蓝色喷流和巨大喷流现象？ 正负闪电先导流注区的压力标度分形模型是否能够描述实验观察到的蓝色喷流和巨型喷流的特征？针对回答这些问题的具体活动将包括三维数值模型的基础上的概率方法闪电建模的发展。 这些模型将占目前最好的知识，有效地表示领导树在三维计算域，并将包括开放边界条件，在模拟过程中的任何一点的领导树的完全电荷中性的保护等功能，并准确建模的闪电通道与有限的电阻率。 模型开发将协同补充新墨西哥州采矿和技术研究所现有的基于观测的研究工作，这些研究工作旨在调查雷暴的电气结构，包括反极性电气结构研究、闪电引发研究以及不同和新发现的闪电放电类型的研究。拟议活动的更广泛影响包括学生培训和教育，理论建模者和实验者之间的协同合作，以及以与社区共享的模型形式和以总结新成果的出版物形式传播成果。