A time-of-arrival (TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province, China. The 3D images of the lightning progression have been obtained successfully for the first time in China. The 3D-channel evolutions of typical negative CG, positive CG and IC lightning flashes have been discussed together with the data of fast electric field change. It was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation sources. The preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2×10 4 m/s. The stepped leader of negative CG lightning flashes was trigged by negative initial breakdown. Thereafter, it propagated downward at a speed of 1.3×10 5 m/s. The initial process of the positive CG lightning flashes was also a propagation process of negative streamer. These streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning, and as a consequence, initiated downward positive streamers. A new type of lightning discharge that was triggered by a narrow bipolar pulse (NBP) is discussed in this study. The NBP was originated at altitude of about 10.5 km in the upper positive charge region. As a distinct difference from normal IC flash, its channels extended horizontally all around and produced a lot of radiation sources. The source power of the NBP could approach 16.7 kW, which is much greater than that of normal lightning discharge ranging between 100 mW and 500 W. The 3D propagation of this new type of lightning discharge was observed and obtained for the first time in China. The possible initiation mechanism of this new type of lightning is discussed here. time-of-arrival (TOA) technique, three dimensional lightning locating system, discharge process, narrow bipolar pulse, new-type of IC lightning Citation:Zhang G S, Wang Y H, Qie X S, et al. Using lightning locating system based on time-of-arrival technique to study three-dimensional lightning discharge processes.Realization of three dimensional (3D) location of lightning radiation process provides a new approach to study meticulously the lightning discharge process, as well as the electrical structure of thunderstorms and their electrification mechanism. Lightning discharges are categorized as cloudto-ground (CG) and intracloud (IC) flashes. People are more concentrated on the CG flash since CG flash is the cause of most lightning damage, injury, and death. Many meaningful results [1-3] based on the lightning locating technology and
[1] Statistical distributions of channel base currents and close magnetic fields have been investigated by using data measured during Shandong Artificially Triggering Lightning Experiment (SHATLE) from 2005 to 2009. Effects of different factors on close magnetic fields have been examined by using numerical method. Statistical results showed that return stroke peak currents varied from 5.8 kA to 45.7 kA with a geometric mean (GM) of 14.1 kA. The GM of 10-90% risetime, 30-90% risetime, and half-peak width in current waveforms were consistent with most of the results found in the literature. The magnetic fields at 60 m, based on 32 return strokes, varied from 18 mT to 148 mT with a GM of 52 mT. The peak value of the 10-90% risetime in magnetic field waveform was between 1 and 2 ms with a minimum of 0.4 ms and a maximum of 8.4 ms, covering a relatively wide range compared with other studies. The numerical modeling results showed that for larger return stroke speeds, the magnetic field peaks are larger, half-peak widths and risetimes are smaller. Effects of distance on time-variation contribution of induction and radiation components are quite different from that of return stroke speed and current risetime. With increasing the distance or current risetime, the magnetic field peak decreases, but the risetime and half-peak width increase.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.