EAR-PF: Quantifying the Difference between Volcanic and Meteorological Lightning: Using Globally Detected Lightning and Multi-Parametric Volcanic Monitoring.

Cassandra Smith博士获得美国国家科学基金会EAR博士后奖学金，在美国地质调查局阿拉斯加火山观测站开展研究活动。这项研究调查了危险的火山灰羽流，它们对飞越美国西部、阿拉斯加、夏威夷以及全球的飞机构成危险。火山灰有可能损坏喷气发动机，并经常导致航班延误或取消。含火山灰的火山羽流也会产生闪电。然而，火山闪电和气象闪电之间的区别还没有得到系统的研究。我们能否确定全球探测到的闪电是火山还是气象成因？这些差异是如何在数据中表现出来的——即海拔高度、极性或电荷强度？这些差异是否使我们能够测量羽流参数，如羽流高度、羽流移动方向、羽流中的火山灰浓度或喷发速率？总结：火山闪电将如何补充目前的火山羽流遥感方法？史密斯博士将结合火山闪电事件的系统目录和2016/2017年AK Bogoslof和2018年印度尼西亚Anak Krakatau火山爆发的详细案例研究来调查这些问题。这将使科学界能够克服目前阻碍人们了解火山闪电的观测差距。PI正在与阿拉斯加本土科学与工程项目进行外展，以便让学生接触火山学，并更好地了解当地的阿拉斯加地质。火山爆发可能演变得很快，产生的火山灰可以在几分钟内到达飞机巡航高度（约10公里）。及时的预警依赖于对发展中的火山灰羽流的快速表征，而实现这一目标的新工具之一是火山闪电。闪电是强烈的、富含火山灰的火山爆发的特征信号，它是由空气中粒子的产生、碰撞和运动过程中的电荷引起的。全球闪电网络，包括陆基和卫星，已经开始提供丰富的数据来源，以了解单个火山的火山过程。然而，科学界仍然不完全了解火山羽流是如何以及为什么带电的，以及闪电能告诉我们什么关于危险火山灰的注入。本研究将验证以下假设：(1)火山闪电与喷发源参数（如羽高或喷发强度）相关；(2)区分气象和火山闪电是可能的，以提高喷发探测能力。Smith博士将使用空间和多变量统计来整合不同纬度火山爆发的卫星、地球物理和气象数据，特别关注2016/2017年阿拉斯加阿留申群岛的波哥斯洛夫火山爆发和2018年印度尼西亚的阿纳克喀拉喀托火山爆发。这些分析的结果将探索火山闪电在火山爆发的快速表征中的效用，并使其成为全球范围内火山的强大遥感技术。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Cassandra Smith has been granted an NSF EAR Postdoctoral fellowship to carry out research activities at the U.S. Geological Survey Alaska Volcano Observatory. This study investigates hazardous volcanic ash plumes, which pose a danger to aircraft flying over the western US, Alaska, Hawaii as well as globally. Volcanic ash has the potential to damage jet engines and often results in flight delays or cancellations. Ash-bearing volcanic plumes also generate lightning. However, understanding the difference between volcanic and meteorological lightning has not yet been systematically investigated. Can we determine if globally detected lightning is volcanic or meteorological in origin? How do these differences present in the data - i.e. altitude, polarity, or charge strength? Might these differences enable us to measure plume parameters such as plume height, plume travel direction, the ash concentration in the plume, or eruption rate? In summary: how will volcanic lightning supplement current remote sensing methods for volcanic plumes? Dr. Smith will use a combination of a systematic catalog of volcanic lightning events and detailed case studies of the eruptions of 2016/2017 Bogoslof, AK and 2018 Anak Krakatau, Indonesia to investigate these questions. This will allow the scientific community to overcome the observational gap that currently hampers the understanding of volcanic lightning. The PI is engaging in outreach with the Alaska Native Science and Engineering Program in order to expose students to volcanology and a greater understanding of their local Alaskan geology.Explosive volcanic eruptions can evolve quickly, producing ash plumes that can reach aircraft cruise altitudes (~10 km) within minutes. Timely warnings depend on rapid characterization of developing ash plumes, and one of the new tools to accomplish that is volcanic lightning. Lightning is a characteristic signal of vigorous, ash-rich eruptions -it results from electrical charging during the creation, collision, and motion of airborne particles. Global lightning networks, both land-based and satellite-based, have begun providing a rich source of data to understand volcanic processes at individual volcanoes. Yet, the scientific community still has an incomplete understanding of how and why volcanic plumes become electrified, and what lightning can tell us about the injection of hazardous ash. This study will test the hypotheses that: (1) volcanic lightning is correlated to eruption source parameters, such as plume height or eruption strength, and (2) it is possible to distinguish meteorological and volcanic lightning for improved eruption detection. Dr. Smith will use spatial and multivariable statistics to integrate satellite, geophysical, and meteorological data for volcanic eruptions at differing latitudes, with particular focus on the 2016/2017 Bogoslof eruption in the Alaskan Aleutians and the 2018 Anak Krakatau eruption in Indonesia. Results from these analyses will explore the utility of volcanic lightning in the rapid characterization of volcanic eruptions and enable its use as a powerful remote-sensing technique for volcanoes on a global scale.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.