VLF Holographic Imaging of Lightning-Induced Disturbances of the Lower Ionosphere

低电离层闪电引起的扰动的甚低频全息成像

• 批准号: 9910532
• 负责人: Umran Inan
• 金额: $ 32万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-15 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9910532&HistoricalAwards=false
• 关键词: VLF; Holographic; Imaging; Lightning; Induced

9910532Inan, Umran S.An experimental investigation is proposed of localized and transient disturbances of the lower ionosphere which occur in association with lightning discharges. The overall purpose of the proposed program is to understand the physical mechanisms of lightning-ionosphere interaction, which lead to rapid conductivity changes, and to determine the global effects of lightning-induced electron precipitation on the radiation belts. The disturbances are imaged remotely using the Holographic Array for Ionospheric Lightning (HAIL) which measures the amplitude and phase of very low frequency (VLF) signals propagating in the nearby Earth-ionosphere waveguide. The HAIL system was established under the predecessor grant to this proposal and has already led to the discovery of precipitation of radiation belt electrons by obliquely propagating (nonducted) whistler waves. It provides high-resolution measurement of localized disturbances, and thus enables the capture of a sufficient number of events needed to investigate several science questions. The ionospheric disturbances are believed to be produced by direct interaction of lightning radiation and quasi-static fields with the ionosphere or by bursts of energetic electrons precipitated out of the radiation belts by whistler waves originating in lightning discharges. Both of the phenomena are now known to regularly occur; however, assessment of their global significance requires that the spatial extent and distribution of events be determined. HAIL consists of VLF receiver systems deployed at nine high schools in Wyoming, Colorado, and New Mexico. The data from the HAIL sites is transmitted back to Stanford over the Internet, and is made available to the scientific community over the Internet within 12 hours of acquisition. The proposed program provides important educational outreach opportunities, the students and teachers from the HAIL schools and others are encouraged to work with the data and interact with the Stanford investigators.

9910532 Inan，Umran S.提出了一种与闪电放电有关的低电离层局部和瞬态扰动的实验研究。拟议计划的总体目的是了解闪电-电离层相互作用的物理机制，这种相互作用导致电导率的快速变化，并确定闪电引起的电子降水对辐射带的全球影响。使用电离层闪电全息阵列（HAIL）对干扰进行远程成像，该阵列测量在附近的地球电离层波导中传播的甚低频（VLF）信号的振幅和相位。 HAIL系统是在该提案的前身资助下建立的，并且已经导致了通过倾斜传播（非导管）哨声波沉淀辐射带电子的发现。 它提供了局部扰动的高分辨率测量，从而能够捕获足够数量的事件来研究几个科学问题。 电离层扰动被认为是由闪电辐射和准静态场与电离层的直接相互作用产生的，或者是由闪电放电产生的哨声波从辐射带中沉淀出来的高能电子爆发产生的。 现在已知这两种现象经常发生;然而，要评估其全球影响，就需要确定事件的空间范围和分布。 冰雹由部署在怀俄明州、科罗拉多和新墨西哥州的九所高中的甚低频接收器系统组成。 HAIL站点的数据通过互联网传回斯坦福大学，并在获得后12小时内通过互联网提供给科学界。 拟议中的计划提供了重要的教育推广机会，鼓励来自冰雹学校和其他学校的学生和教师使用数据，并与斯坦福大学的调查人员互动。