Collaborative Research: Lightning Studies in a Polluted Atmosphere

对流云的带电过程包括通过收集过冷的云滴（霰）而生长的大冰降水粒子与通过气相沉积而生长的冰晶的碰撞。带负电荷的霰下降并下降，而带正电荷的晶体则随着上升气流上升，从而分离了电荷并增加了电场，直到它以闪电的形式破裂。该过程所需的过冷云滴和强上升气流的存在可归因于气团的热力学和气溶胶特性。将动力效应和气溶胶效应分开是一个长期存在的问题，因为气溶胶和热力学性质往往不是独立的。本研究通过首次应用于该问题的观测工具的新组合来解决这一挑战。云的微观结构是由新的NPP/VIIRS卫星测量得到的，它将以375米的分辨率提供云的特性。地面真实气溶胶测量将持续可用。休斯敦闪电测绘阵列（LMA）和俄克拉何马州中部LMA将提供精确的闪电源及其极性的三维测绘。新的极化雷达将提供云中降水的演变。这些测量将在休斯顿地区进行，那里有炼油厂和其他空气污染源。将对休斯敦污染羽流内外的类似云进行检查，以将气溶胶与云微观结构、降水形成过程和电气化（包括充电极性）的热力学影响分离开来。类似的研究将在俄克拉荷马州中部进行。这项研究将有助于几名直接参与研究的本科生和研究生的教育，包括他们在数据采集和分析方面的分享。这项研究包括对学生的支持，他们将撰写论文和学位论文，并在研讨会和专业会议上展示他们的成果。研究成果将纳入云物理和中尺度现象课程。研究小组将继续通过项目网站向更广泛的科学界通报、参与和传播信息和数据。休斯敦社区和周边地区免费获得LMA实时闪电显示。

The process of electrification of convective clouds involves collisions of large ice precipitation particles that are growing by collecting supercooled cloud droplets (graupel) with ice crystals that grow by vapor deposition. The negatively charged graupel fall and lower whereas the positively charged crystals ascend with the updraft, thus separating the charges and increasing the electric field until its breakdown in the form of lightning flashes. The existence of supercooled cloud droplets and strong updrafts that are required for the process can be ascribed to both thermodynamic and aerosol properties of the air mass. Disentangling the dynamic and aerosol effects is a long-standing question, because the aerosol and thermodynamic properties are often not independent. This study addresses this challenge with a new combination of observational tools that are applied to this problem for the first time. The cloud microstructure is retrieved by the new NPP/VIIRS satellite measurements that will provide retrieved cloud properties at a resolution of 375 m. Ground-truth aerosol measurements will be continuously available. The Houston Lightning Mapping Array (LMA) and the central Oklahoma LMA will provide accurate 3-dimensional mapping of the lightning sources and their polarity. The new polarimetric radars will provide the evolution of the precipitation in the clouds. These measurements will be conducted over the Houston area, which has refineries and other sources of air pollution. Similar clouds in and outside of the Houston pollution plume will be examined for separating the aerosol from thermodynamic effects on cloud microstructure, precipitation forming processes and electrification, including charging polarity. Similar studies will be conducted in central Oklahoma.This research will contribute to the education of several undergraduate and graduate students who will directly participate in the research, which will include their sharing in data acquisition and analysis. Included in this study is support for students who will write theses and dissertations and present their results at seminars and professional meetings. Research results will be incorporated into courses on cloud physics and mesoscale phenomena. The research team will continue to inform, engage, and disseminate information and data to the wider scientific community through the project website. Access to the LMA real-time lightning display is provided at no cost to the Houston community and surrounding areas.