Electrification and Lightning of Severe Storms and Mesoscale Convective Systems in STEPS and on the Southern Great Plains

本项目致力于研究孤立雷暴和大型对流风暴系统产生的风场、电结构、微物理和闪电之间的关系。它是基于对2000年STEPS项目期间收集的数据的持续分析，并包括2003年和2004年夏季在俄克拉荷马州收集的额外数据。这些数据主要包括电场的气球探测、极化雷达观测和闪电测绘阵列（LMA）的数据。需要回答的具体问题有：(1)闪电的频率是否与风暴中霰的质量成正比？(2)某些风暴的反向电极性是否有微观物理原因？(3)在中尺度对流系统中观测到的长水平闪光是起源于深对流区还是轻降水区？(4)更一般地说，中尺度对流系统中闪电的特征是什么，它们如何受到云微物理结构的影响？要回答这个问题，需要综合不同观测系统的数据，并根据不同的电荷产生、分离和闪电起始理论分析数据。研究结果不仅有助于了解闪电的物理性质，而且有助于发展数值预报模式中吸收闪电的技术，以及学习如何利用闪电数据预警风暴危险。这项工作是与STEPS的其他参与者合作完成的，特别是新墨西哥采矿和技术研究所分析LMA数据，科罗拉多州立大学分析极化雷达数据。

This project is devoted to the study of relationships among the wind field, the electrical structure, the microphysics, and the lightning produced by both isolated thunderstorms and large systems of convective storms. It is based on the continuing analysis of data collected during the STEPS project of 2000 and includes collection of additional data in Oklahoma during the summers of 2003 and 2004. The data consist chiefly of balloon soundings of the electric field, polarimetric radar observations, and data from a lightning mapping array (LMA). Specific questions to be answered are: (1) Are lightning flash rates proportional to the mass of graupel in a storm? (2) Does the inverted electrical polarity of some storms have a microphusical cause? (3) Do the long horizontal flashes observed in mesoscale convective systems originate in the region of deep convection or in areas of lighter precipitation? (4) More generally, what are the characteristics of lightning flashes in mesoscale convective systems, and how are they affected by cloud microphysical structure? Answers to the question require synthesis of data from the different observing systems and analyzing the data in the light of different theories of charge production, separation, and lightning initiation. Results will contribute not only to the understanding of the physics of lightning, but will also be useful in developing techniques for assimilating lightning in numerical forecasting models and in learning how to use lightning data to warn of storm hazards. The work is done in collaboration with other participants in STEPS, in particular New Mexico Institute of Mining and Technology in the analysis of LMA data and Colorado State University in the analysis of polarimetric radar data.