Collaborative Research: Characterizing Small-scale Lightning Discharges Associated with Explosive Volcanic Activity at Sakurajima Volcano

合作研究：描述与樱岛火山爆发性火山活动相关的小规模闪电放电特征

• 批准号: 1445704
• 负责人: Stephen McNutt
• 金额: $ 31.25万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1445704&HistoricalAwards=false
• 关键词: Collaborative; Research; Characterizing; Small; scale

Volcanic lightning discharges have length scales ranging from tens of meters to tens of kilometers. Most small discharges occur proximally to a volcanic vent concurrent or within a few minutes of an explosive volcanic eruption. Large scale discharges typically occur throughout a mature plume formed 5 or more minutes subsequent to an explosive eruption. This research work focuses on studying the small, proximal discharges that occur concurrent with explosive volcanic eruptions. The main goal is to better characterize the proximal electrical activity within the context of the eruptive activity to gain a better understanding of the eruptive conditions that are required to produce different types of small-scale discharges. This characterization will be accomplished by making high-resolution 3-D lightning mapping observations of lighting discharges during small explosive eruptions of Sakurajima Volcano located in the Kyushu region of southwestern Japan. Other instrumentation (infrasound, video cameras, and electric field change sensors) will be used to monitor the explosive activity, plume development, and changes in electric field caused by lightning. The data will be used to determine when different types of electrical discharges occur relative to the onset of an explosive eruption and in relation to the ascent of volcanic ejecta. Electrical discharges will be characterized by determining the length scales, speeds, and polarities of the discharges, as well as by locating where the discharges initiate.Intellectual Merit: The research would be the most detailed study of volcanic lightning to date, combining measurements of volcano infrasound, electric field changes, and plume development with high-resolution Lightning Mapping Array (LMA) data and high-speed video observations of volcanic lighting. The inclusion of electric field change measurements, high-speed video, and visual plume observations distinguishes this project from previous research. The research will increase knowledge of electrical activity that occurs as a direct result of an explosive volcanic eruption. This will contribute to our understanding of the eruption processes that are responsible for producing electrical activity proximally to a volcanic vent.Broader Impacts: Because small-scale discharges frequently accompany volcanic eruptions of a large range of sizes, the results of the research will be applicable to developing an eruption monitoring system that utilizes VHF observations of lightning and electrical activity. In addition, the results of the research will be used to determine if one can predict eruption magnitudes or ash plume heights based on observations of electrical activity. The research will also provide training for an early career researcher from an underrepresented group and three graduate students. They will participate in gathering, organizing, archiving, and analyzing the data.

火山闪电放电的长度尺度从几十米到几十公里不等。 大多数小的排放发生在火山口附近，同时或在火山爆发的几分钟内。 大规模放电通常发生在爆发后5分钟或更长时间形成的成熟羽流中。 这项研究工作的重点是研究小，近端放电，同时发生的爆炸性火山爆发。 其主要目标是更好地表征近端电活动的范围内的喷发活动，以获得更好地了解所需的喷发条件，以产生不同类型的小规模放电。 这一特性将通过在位于日本西南部九州地区的樱岛火山小型爆炸性喷发期间对闪电放电进行高分辨率三维闪电测绘观测来完成。 其他仪器（次声、摄像机和电场变化传感器）将用于监测爆炸活动、羽流发展以及闪电引起的电场变化。这些数据将用于确定相对于爆炸性喷发的开始和相对于火山喷出物的上升何时发生不同类型的放电。放电的特征将通过确定放电的长度、速度和极性以及定位放电开始的位置来确定。智力优势：这项研究将是迄今为止对火山闪电最详细的研究，结合了对火山次声，电场变化，利用高分辨率闪电测绘阵列（LMA）数据和火山闪电的高速视频观测， 包括电场变化测量，高速视频，和可视化羽流观测区分这个项目从以前的研究。这项研究将增加对火山爆发直接导致的电活动的了解。 这将有助于我们了解的喷发过程，负责产生电活动接近火山vent.Broader影响：由于小规模放电经常伴随着火山喷发的大范围的大小，研究的结果将适用于开发一个喷发监测系统，利用甚高频观测闪电和电活动。此外，研究结果将用于确定是否可以根据对电活动的观测来预测喷发幅度或灰柱高度。这项研究还将为一名来自代表性不足群体的早期职业研究人员和三名研究生提供培训。 他们将参与收集、组织、归档和分析数据。