Possible high-altitude discharge due to narrow bipolarevents
Narrow Bipolar Events (NBEs) are intense, impulsive, in-cloud, radio-frequency li ghtning events that are commonly observed by both groun d-based and satellite-based RF receivers and electric-field-change sensors. These events tend to occur in the middle and upper part of thunde rcloud and are comparative to return stokes in strength. By a simple dipole model we estimate that these events may be produced by the current moment on the order of 5 kA-km. In this paper we evaluate the electric field produced by NBEs at the bottom of ionosphere to investigate the possible breakdown of high-altitude atmospheree by NBEs. A program was developed to calculate the electromagnetic field at any place between ground and ionosphere by taking the ionosphere as aninfinite conductivity plane. The NBEs are modeled as animpulse current propagating along a short channel at a speed comparative to the speed of light. The calculated electrical field at the bottom of ionosphere was compared with the air br eakdown threshold at the same altitude to identify the possible breakdown region. Calculations indicate that a current of 20 KA is enough for a NBE to cause air breakdown at the bottom of ionosphere. For a vertical NBE, the breakdown regi on appe ars as a large ring, with a diameter of several hundred kilometers, which is in good consistence with former observations of ELVES. For a horizontal NBE, the breakdown region appears as a solid ellipse, with a horizontal extent of tens of kilometers or less. Future optical observation is needed to testify this phenomenon.
NBEs high-altitude discharge
Zhuang Baotong Zhu Baoyou Tao Shanchang
School of earth and space science, university of science and technology of China, P.R. China
国际会议
第13届国际大气电学会议(The 13th International Conference on Atmospheric Electricity)
北京
英文
2007-08-13（万方平台首次上网日期，不代表论文的发表时间）