A Single-station-based 3D Lightning Channel Location Method By Using Differential Arrival Time Of Thunder

The main purpose of this dissertation is to develop a new-type single-station-based 3D lightning channel location system on the basis of thunder observation and the method of thunder location technique. The system consists of a small-size microphone array, a triggering system, a data collection and storage device. The microphone array is consisted of four microphones which work at a frequency range from 15 Hz to 20 kHz. Thunder signals from the microphone array are processed by the cross-correlation analysis to obtain the differential time of arrival at different microphones. The direction of propagation of the acoustic signal is found by using the least square method. The three-dimensional acoustic locations are obtained by combining the acoustic direction and the distance from the acoustic sources to the array determined by the time interval between the arrival of the electromagnetic signal and the thunder. The system has not only realized three-dimensional lightning channel location only by one single station but also has the feature of easy mobility and installation.A reasonable simulation experiment has been designed to examine the principle of the location technique and the software of the system before the field experiment. Through the experiment, it has confirmed that the system is feasible by the comparison between the acoustic locations obtained by the system and the known locations of the simulative thunder sources. Furthermore, the location errors due to the deviation of microphones in the procedure of installation have been analyzed in detail. Some valuable results have been acquired, which provide basis for optimum installation.During the summer of 2008 and 2009, the location system had been applied in"Guangzhou Field Experiment Site for Lightning Research and Testing"and"Guangdong Province Meteorological Administration"to observe the thunder of the rocket-triggered lightning and the natural lightning. Some reliable data has been obtained.With the developed location system, some acoustic locations have been obtained by analyzing the thunder data of the rocked-triggered lightning and the natural lightning. The acoustic sources have been compared with the photographs observed by a high-speed video and the observations from other lightning location systems. All the results agreed fairly well and further confirmed the effectiveness of the proposed location system. Several acoustic locations determined by the system could generally depict the lightning channel, which offer direct evidence to understand the development of the lightning channel with the synchronous data from other observation systems.This work establishes a strong foundation of a convenient three-dimensional lightning channel location system. Furthermore, a further study about the thunder data will be very useful for comprehending the physical characteristic of thunder.