Studies of Convection and Lightning

这项研究以对流研究为中心，特别是中尺度对流系统（MCS），它是美国中部许多地区暖季降水的主要原因。除了产生强降雨外，它们还以破坏性风（包括龙卷风）、冰雹和大量闪电的形式产生恶劣天气。另一种与MCS相关的电活动类型是瞬态发光事件（TLE），被称为精灵、精灵和蓝色射流。这些是发生在高层大气中MCS顶部以上的高空的放电形式，通常是由云内或云与地面之间的闪电活动引发的。这项工作的主要目标是更好地理解风暴动力学、降水形成、闪电产生和TLE之间的联系。研究小组将结合NEXRAD和研究天气雷达数据，以及VHF闪电测绘阵列和国家闪电探测网络的可用数据，开展一项大规模的基于统计的研究，以进一步了解雷暴中的电荷分离、风暴中电荷层的组织、闪电和TLE放电的最终分布，以及这些特征与风暴环境的物理特征之间的关系。这项工作的另一个具体方面是研究弓形回波MCS，并确定弓形发展与风暴云对地闪电模式的演变之间是否存在不仅仅是偶然的关系。这项工作的智力价值在于促进对降水发展过程、云电气化和闪电的理解。这项工作的更广泛影响包括确定闪电观测如何揭示对流中的物理过程，以及协助分析和临近预报恶劣天气特征。这项工作的独特之处在于，它将为未来的极化NEXRAD雷达网络与作战闪电测绘系统相结合铺平道路，从而更好地实时表征对流天气。

This research centers on the study of convection, specifically Mesoscale Convective Systems (MCS's), which are responsible for the bulk of the warm season precipitation in many locations in the central U.S. In addition to producing heavy rainfall, they also produce severe weather in the form of damaging winds (including tornadoes), hail and copious amounts of lightning. Another type of electrical activity associated with MCS's are Transient Luminous Events (TLE's), identified as sprites, elves, and blue jets. These are forms of electrical discharges occurring in the upper atmosphere at great heights above the tops of the MCS's that often appear to be triggered by lightning activity within the cloud, or between cloud and ground. The broad objective of this work is to better understand the linkages between storm dynamics, precipitation formation, lightning generation, and TLE's. The research team will carry out a large, statistically-based study combining NEXRAD and research weather radar data with available data from VHF lightning mapping arrays and the National Lightning Detection Network, to further understand charge separation in thunderstorms, the organization of charge layers in storms, the resulting distribution of lightning and TLE discharges, and how these characteristics may be related to the physical characteristics of the storm environment. Another specific aspect of this work is to study bow echo MCS's and determine if there is more than just a casual relationship between bow development and evolution of storm cloud-to-ground lightning patterns. The intellectual merit of this work is to advance understanding of precipitation development processes, cloud electrification and lightning. Broader impacts of this work include determining how lightning observations may reveal physical processes in convection, as well as assisting in the analysis and nowcasting of severe weather characteristics. This effort is also unique in that it will pave the way for combining the future polarimetric NEXRAD radar network with operational lightning mapping systems to provide better real-time characterization of convective weather.