| The atmospheric electric field is the basic parameter of atmospheric electricity.On sunny days,the ground has a vertical downward atmospheric electric field.On thunderstorm days,the ground atmospheric electric field is significantly enhanced.The research on the characteristics of the atmospheric electric field signal is of great significance for lightning early warning,lightning mechanism analysis,and ensuring the smooth progress of aerospace activities.The atmospheric electric field signal has the characteristics of non-stationary signal.Using the modern non-stationary signal processing method to analyze the thunderstorm electric field provides a new idea for the lightning early warning and the research on the charging structure of thunderstorm cloud.The main research contents and conclusions of this paper include:(1)Taking the new FPGA device Artix-7 as the core,combined with sensing and conditioning,broadband amplification,single ended differential rotation,high-speed acquisition,Beidou Positioning and other modules,the atmospheric electric field detection system is designed.Soft core Micro Blaze realizes data processing and control;(2)The method of analyzing the characteristics of atmospheric electric field signal by means of non-stationary signal processing is studied.The Hilbert Huang transform is used to extract the natural mode components and Hilbert two-dimensional spectrum of sunny and thunderstorm weather respectively.It is found that the oscillation of IMF component of electric field in sunny days is uniform and the amplitude is small,with long oscillation period as the main part and stable frequency;the amplitude of IMF component in thunderstorm weather is pulse like,with short oscillation period as the main part Periodic oscillation is dominant.Based on this,a combined lightning early warning method based on the amplitude of atmospheric electric field and Hilbert energy spectrum is proposed.Combined with the monitoring data of Jiangsu lightning positioning system,the experimental analysis is carried out.The results show that the early warning probability is improved to some extent,and the early warning time is about 31 minutes.(3)In order to solve the problem that most of the research on the charging model of thunderstorm cloud is numerical simulation,the inversion method of the parameters of the charging model of thunderstorm cloud based on the measured atmospheric electric field data is studied.Based on the spherically symmetric charge model,the charge of thunderstorm cloud and the distance between charge and observation point are inversed by quantum genetic algorithm.The experimental results show that the charge structure is dipolar,and the QGA fmincon algorithm solves the dependence of the quantum genetic algorithm on the initialvalue. |
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