雷电过程中大气电场信号处理方法探究

Study on Signal Processing of Atmospheric Electric Field in Thunder and Lightning

基于天津市蓟州区大气电场探测数据和闪电定位数据,利用功率谱分析、小波降噪和快速傅里叶变换等信号处理方法,分析了雷电天气过程中地面大气电场变化特征。结果表明,雷电过程中大气电场能量主要集中在低频部分,利用sym5小波函数进行7层或8层分解,提取的低频信号能够反映大气电场的主要变化特征。在首次闪电发生前1 h,大气电场的频谱幅值起伏变化明显,且远高于非雷电天气电场频谱幅值。通过欧氏距离判别法,判断大气电场频谱特征更接近雷电天气还是非雷电天气,可为雷电预报预警提供参考。

Based on the data from atmospheric electric field detection and lightning location system in Jizhou District of Tianjin,the variation characteristics of surface atmospheric electric field during thunder and lighting weather are analyzed by using some signal processing methods such as power spectrum analysis,wavelet noise reduction and fast Fourier transform.The results indicate that the atmospheric electric field energy is mainly concentrated in low frequency part in the process of lightning,Sym5 wavelet function is used for 7-layer or 8-layer decomposition,the extracted low frequency signals can reflect the main variation characteristics of atmospheric electric field.1 h before the occurrence of the first lightning,the spectral amplitude of atmospheric electric field fluctuates obviously,and is much higher than that in non-lightning weather.Through the Euclidean distance discriminant method,judging whether the frequency spectrum characteristics of atmospheric electric field are closer to lightning weather or not,can provide an effective method for thunder forecasting and early warning.