雷雨次声波的三维动态频谱测量研究

采用三台电容式次声接收器，在北京昌平安装次声三点阵，并测量到2000年7-8月15次强雷阵雨的次声波P-t曲线及其三维动态频谱，频谱分析结果表明：（1）雷阵雨的次声波主要来自雷次声。（2）雷次声的频谱有三大特点：其一是听到雷声越响时，雷次声振幅越强；其二是特强振幅持续时间很长；其三是周期范围时而连续、时布分布在周期较长和较短端，形成谱图上一个个空洞。据此可区别与其它次声波。（3）初步探讨了雷次声的产生机理和传播特点。

Measurements of the three-dimensional dynamic frequency spectrum of infrasonic waves from thundershowers

With three infrasound receivers of the condenser type, a tripartite array in Changping, Beijing was arranged. The infrasonic signals (P-t curve) generated by 15 thundershowers in July and August 2000 were measured. With fast Fourier trans- form, the three-dimensional dynamic frequency spectra were obtained. The results of the spectrum analysis are as follows: (1) The infasonic waves of thundershower come from thunder. (2) The frequency spectrum of infrasonic wave of thunder possesses three characteristics. Firstly the louder the heard thunder is, the stronger the amplitude of the infrasonic wave of thunder; Secondiy the especially strong amplltude lasts a long time; Thirdly the range of period is successive or separated when time increaJses, which leads to lots of hollows in the frequency spectrurm. Accordingly, we may distinguish the infrasound of thunder from that of the others. (3) The generating mechanism and prop- agating trait of infrasoulc waves of thunder were primarily discussed.